Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
  • B65G1/00—Storing articles, individually or in orderly arrangement, in warehouses or magazines
  • B65G1/02—Storage devices
• • E—FIXED CONSTRUCTIONS
  • E04—BUILDING
  • E04H—BUILDINGS OR LIKE STRUCTURES FOR PARTICULAR PURPOSES; SWIMMING OR SPLASH BATHS OR POOLS; MASTS; FENCING; TENTS OR CANOPIES, IN GENERAL
  • E04H9/00—Buildings, groups of buildings or shelters adapted to withstand or provide protection against abnormal external influences, e.g. war-like action, earthquake or extreme climate
  • E04H9/02—Buildings, groups of buildings or shelters adapted to withstand or provide protection against abnormal external influences, e.g. war-like action, earthquake or extreme climate withstanding earthquake or sinking of ground
  • E04H9/021—Bearing, supporting or connecting constructions specially adapted for such buildings
  • E04H9/0237—Structural braces with damping devices
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
  • F16F7/00—Vibration-dampers; Shock-absorbers
  • F16F7/10—Vibration-dampers; Shock-absorbers using inertia effect
  • F16F7/104—Vibration-dampers; Shock-absorbers using inertia effect the inertia member being resiliently mounted
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
  • B65G1/00—Storing articles, individually or in orderly arrangement, in warehouses or magazines
  • B65G1/02—Storage devices
  • B65G1/14—Stack holders or separators
• • E—FIXED CONSTRUCTIONS
  • E04—BUILDING
  • E04H—BUILDINGS OR LIKE STRUCTURES FOR PARTICULAR PURPOSES; SWIMMING OR SPLASH BATHS OR POOLS; MASTS; FENCING; TENTS OR CANOPIES, IN GENERAL
  • E04H9/00—Buildings, groups of buildings or shelters adapted to withstand or provide protection against abnormal external influences, e.g. war-like action, earthquake or extreme climate
  • E04H9/02—Buildings, groups of buildings or shelters adapted to withstand or provide protection against abnormal external influences, e.g. war-like action, earthquake or extreme climate withstanding earthquake or sinking of ground
• • E—FIXED CONSTRUCTIONS
  • E04—BUILDING
  • E04H—BUILDINGS OR LIKE STRUCTURES FOR PARTICULAR PURPOSES; SWIMMING OR SPLASH BATHS OR POOLS; MASTS; FENCING; TENTS OR CANOPIES, IN GENERAL
  • E04H9/00—Buildings, groups of buildings or shelters adapted to withstand or provide protection against abnormal external influences, e.g. war-like action, earthquake or extreme climate
  • E04H9/02—Buildings, groups of buildings or shelters adapted to withstand or provide protection against abnormal external influences, e.g. war-like action, earthquake or extreme climate withstanding earthquake or sinking of ground
  • E04H9/021—Bearing, supporting or connecting constructions specially adapted for such buildings
  • E04H9/0215—Bearing, supporting or connecting constructions specially adapted for such buildings involving active or passive dynamic mass damping systems
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
  • B65G2207/00—Indexing codes relating to constructional details, configuration and additional features of a handling device, e.g. Conveyors
  • B65G2207/20—Earthquake protection

Definitions

• the present invention relates to a force limiting and energy dissipating system. More particularly, but not exclusively, it relates to an energy absorbing system to reduce the impact of earthquake induced sway or racking motion of storage racks and buildings.
• a storage rack typically consists of a plurality of upright column pairs that are ordered in a rectilinear fashion to form two rows of upright columns. Usually a front row that is adjacent the passage way where forklifts may drive or automated systems operate, and a back row that may be adjacent a wall or a parallel passage. Between the columns are multiple horizontal shelves. The array of such shelves extends upwards to the top of the upright columns. Shelving or pallets installed across pairs of beams normally hold the items or materials being stored. The columns bear the weight of the items or materials and transfer that weight to the bottom of each column to the foundation on which the columns are installed.
• the racks in plan view are typically rectangular with lengths over 100 m possible, and typical widths of between 0.9 m and 3 m.
• Swaying of the racks in the lengthwise direction can occur during an earthquake. This is due to the foundation moving in one direction and the inertial resistance of the masses (pallets) supported by a flexible structure resulting in a motion lag induced swaying of the rack. This movement can be described as racking. Lengthwise racking can result in very high forces being developed in the rack structure.
• Typical ways to reduce the effect of lengthwise racking is to use diagonal ties.
• the ties may be tensioned cables that are generally anchored at one end to an upper region of the rack and at the other end to the foundation. Multiple ties may be used that form a zig zag pattern along the lengthwise direction of rack.
• the ties help brace and reduce movement in the lengthwise direction relative to the bottom of the racks. They can make the rack very rigid. This is not ideal as it may result in very high peak loads being experienced by the ties and/or the racks. This may result in catastrophic failure.
• the present invention may be said to be a device or
• control mechanism or more preferably a control structure which is able to limit forces developed within itself and/or a structure (e.g. building or storage rack) it connects with and is seismically supportive of as it resists and endures ground or base motion input from a seismic event.
• a structure e.g. building or storage rack
• the control structure may be comprised of a (preferably relatively inflexible) rocker frame assembly which is pivotably connected to a structural base or structural member. Rotation of the rocker frame about its base pivot(s) causes a flexural member(s) (e.g. preferably plate) within a rotary unit which is directly or indirectly connected to the rocker frame, but distal to one of the rocker frame pivot(s), to flexurally displace (preferably deform by for example bending).
• a flexural member(s) e.g. preferably plate
• the flexural member(s) (plate(s)), which is a part of the rotary unit, which in turn is part of the control structure, is configured with particular free translational or free translational and free rotational boundary conditions at one of its ends, to allow it to flex and yield about its minor bending axis to high elasto-plastic displacements (deformation) and high displacement and curvature ductilities, while maintaining a constant resistive yield force (and preferably not allowing or causing membrane forces to develop within itself).
• translational or translational and rotational properties above also enable the length along the elasto-plastically flexing curve of the plate (between its reaction points) to freely increase or decrease as it displaces and/or enable the plate to develop a horizontal reaction at its reaction points or boundary surfaces as it (the plate) flexes and displaces.
• the pivotably based control structures are structures that the rotary yield units can be efficiently incorporated into. That is, they (control structures) are of a form that enables them to efficiently utilize the constant resistive yield forces produced by the elasto-plastically flexing plates within the rotary units which (rotary units) are a connected part of the control structure.
• the stable constant resistive yield force produced by the flexing plate(s) within the rotary unit enables the pivotable control structure to also form a stable elasto-plastic mechanism which is able to flow and cycle to high elasto-plastic displacements and high ductilities with a constant resistive force while internal forces within it, or within any adjacent structure it is connected with and seismically supportive of, are maintained and limited to maximum values which are a function of the yield force produced by the flexing yield plate(s) which are part of it.
• control structure By flowing as a stable, high displacement and high ductility capable, elasto- plastic mechanism, with constant resistive yield force, the control structure is limiting the magnitude of accelerations and dynamic forces that can develop within its members within its supporting foundations or within the members of another structure it may be seismically supportive of, as it resists and endures the ground motion (displacement, velocity, acceleration) input of a seismic event.
• control structure is able to resist and endure severe ground or base motion input (i.e. high peak ground accelerations, PGA) while (both) maintaining a constant resistive yield force (limiting peak response acceleration of masses supported by the control structure, limiting forces developed within the control structure, limiting forces within its foundations and limiting forces within a structure the control structure may be seismically supportive of) while maintaining a low peak (elasto-plastic) displacement response for the control structure as a whole (i.e. low lateral drift).
• severe ground or base motion input i.e. high peak ground accelerations, PGA
• resistive yield force limiting peak response acceleration of masses supported by the control structure, limiting forces developed within the control structure, limiting forces within its foundations and limiting forces within a structure the control structure may be seismically supportive of
• a rocker frame assembly comprises a vertical (e.g. a tower) aspect and is pivotably connected to a horizontal structural base or foundation.
• the rocker frame connects by a double pin link or push rod to the extended arm of a rotary unit, which is distal to the rocker frame pivot, and connects to a horizontal structural base or foundation.
• the rotary unit comprises a first part being a relatively inflexible rotatable circular drum (or disc) set between and rigidly connected at each of its ends to rotor plates each with an integral arm which extends from the rotor plates and pin and slot connects with the ties (or push rods) (first structural member) of the control structure.
• Flexure member(s) (plates) are rigidly fixed one end (first region) to, and distributed around, the circumference of the drum (or disc) (first anchor) in the form akin to an impeller. The first region of the plate moving in a circular arc with the first anchor to the rotatable drum.
• the first part of the rotary unit comprises the drum, rotor plates with arms, and flexure plate(s).
• This assembly is supported off an axle shaft centroidal with the rotational axis of the drum and which rotatably connects the first part with the second part which comprises an outer casing or housing which is mounted off a horizontal structural base or foundation (second structural member).
• peripheral ends (second region) of the flexure member(s) (plates) (opposite the first region of the plate rigidly fixed to the drum) have particular translational or translational and rotational boundary conditions and are restrained from circular arc motion at their ends, such as by pins (second anchor) connecting their translationally or translationally and rotationally free end(s) (second region) to the exterior housing (or second part) of the rotary unit.
• the first and second part of the rotary unit are preferably pivotably connected by the axle shaft.
• Rotation of the rocker frame of the control structure about its base pivot(s) causes the connected pin and slot ended ties (or push rods) to push and pull the extended arms of the rotor plates, and rotate the circular drum (or disc) (first anchor) of the rotary unit to which the flexure member(s) (plates) are fixed and circumferentially distributed about.
• the end region (first region) of the flexure member(s) (plates) which is rigidly fixed to and distributed around the circumference of the drum (first anchor) rotates and arcs with the drum.
• the rotary unit again comprises a relatively inflexible rotatable inner circular drum(s) (first anchor) to and about which the flexure member(s) (plates) are rigidly fixed at their first region and distributed around the circumference of the drum (first anchor) in the form of an impeller.
• the peripheral end (second region) of the flexure member(s) (plates) again have the same particular translational or translational and rotational boundary conditions and are restrained from circular arc motion at their ends by pins (second anchors) connecting the peripheral ends (second region) with a second (outer) annulus of the form of a turbine casing (or cowling) which is concentric with the inner rotatable drum.
• the outer drum (casing) is fixed against movement and anchors to a structural base (second structural member).
• the inner rotatable drum(s) may be set between circular end plates (rotor plates) which are rigidly fixed to and supported off a torque axle shaft rotatably fixed to a structural base (second structural member).
• a rigid arm located exterior to the concentric drums connects orthogonally with the axis of the torque shaft and extends to pin and slot connect at its opposite end with the push rods (first structural member) of the control structure.
• the inner rotatable drum extends through and beyond the outer circular casing to function as both the first anchor and the torque shaft.
• the ALPHA1 rocker frame has two pivots and connects in a similar way to both a horizontal base or foundation and a relatively inflexible overhead structure member.
• the rocker frame has a horizontal (spanning truss) aspect and is pivotably connected at each end to vertical chords or towers which are pivotably connected to a horizontal base or foundation.
• the rotary units and flexure member(s) (plates) within, are preferably similarly distal to the rocker frame pivots and preferably connect to the rocker frame through a double pin link or push rod and are fixed to the vertical chords or towers.
• a rocker frame assembly comprises a vertical (tower) aspect and is pivotably connected to a horizontal base or foundation.
• the vertical chord(s) of the rocker frame are parallel with another set of adjacent exterior chords pivotably connected to the structural base of the foundation. These exterior chords may connect first to the pivot inclusive centreline of the rocker frame with horizontal relatively inflexible pin ended ties.
• the rotary unit within which the flexure member(s) (plates) are set are again distal to the rocker frame pivots, and are connected between and distributed along the rocker frame (first or second structural member) and the opposite face of the adjacent pivotable exterior chords (first or second structural member).
• Rotation of the ALPHA2 rocker frame about its base pivot(s) produces an inter- lamina relative displacement between the chord of the rocker frame and the base pivotable exterior chord.
• This displacement is restrained by the rotary units (yield connectors) located between and along the respective chords which produce a reactive inter-lamina shear force between the sliding pin connection of the rotor arm to the exterior chord and the outer casing of the rotary unit which is fixed to the interior chord of the rocker frame.
• This shear force causes the drum of the rotary unit to rotate and the flexure members (yield plates) of the rotary unit to engage and elastically or elasto- plastically flex about their minor bending axis.
• the elasto-plastic flexure limiting forces and dissipating energy within the control structure and any other structure it may be seismically supportive of.
• the ALPHA2 rocker frame(s) may have a horizontal (spanning truss) aspect and is preferably pivotably connected at each end to the vertical chords or towers which are pivotably connected to a horizontal base or foundation.
• the horizontal exterior chords parallel with the horizontal chords of the rocker frame are similarly pivotably connected to the vertical chords or towers.
• the rotary unit within which the flexure members (plates) are set are distal to the rocker frame pivots and are preferably located between and along the horizontal chords of the rocker frame and the opposite face of the parallel exterior chords.
• Vertically orientated pin ended ties may link the exterior chords with the pivot included centreline of the rocker frames.
• pivotable horizontally orientated (spanning truss aspect) rocker frames horizontal exterior chords pivotably connected to the vertical chords or towers with pivotable structural base or foundation connections, rotary unit with flexure plates and vertical ties connections horizontal exterior chords to centrelines of rocker frame all parts of the control structure.
• control structure comprises rotary yield units with double pin ended push rods which form the diagonal braces of a pivotably based and eccentrically braced frame (tower) structure, in which (horizontal) beams pin connect with (vertical) columns, the rotary unit of the diagonal brace connecting to an (upper) beam adjacent (eccentric to) the beam to column pin connection, and the diagonal opposite end of the brace, being the pin end of the push rod connecting concentrically with the (lower) beam to column connection.
• control structure comprises rotary yield unit(s) located along and between one pivotably based wall element (or stiff chord) and another parallel and pivotably based wall element (or stiff chord), both wall elements also connected with pin ended motion control ties, all forming a pivotably based coupled shear wall (or stiff chord) control structure.
• control structure comprises a series of parallel pivotably based wall elements (or steel chords) along and between which are located rotary yield units, all wall units also connected with motion control ties and all forming a control structure comprised of a series of coupled shear walls (or stiff chords).
• the flexural member is composed of steel.
• the elongate flexural member is composed of metal plate.
• the flexural member is replaceable.
• the flexural member undergoes plastic deformation at a yield zone intermediate first anchor and second anchor during a seismic event as a result of oscillatory movement of the rocker frame and the subsequent rotation of the drum of the rotary unit.
• the primary structure i.e. structure seismically supported by control structure
• the primary structure is or is part of a warehouse rack, building and/or large civil structure.
• the first anchor or second anchor rigidly constrains the first region so received at the anchor, in 6 degrees of freedom.
• the present invention may be said to consist of a device or mechanism, and more preferably a force limiting and energy dissipating rotary unit within which flexural member(s) (plates) are anchored, which by its form is capable of producing a stable, constant, cycling resistive yield force, while the structural plates within it flexurally yield about their minor bending axis to high elasto-plastic
• the plate(s) within the rotary unit in yielding at a constant force through its own high elasto-plastic flexural displacements is modifying the natural response
• the magnitude of the peak elasto-plastic displacement demand on the plates is a function of a number of variables including; ground motion (acceleration) input, mass seismically supported by structure and its distribution, elastic natural frequency of structure(s) (inclusive of plates) and yield strength of plate(s).
• the ability of the plate(s) to sustain the cycling peak displacement demands on them, while maintaining a stable constant resistive yield force is further dependent on their material stress-strain characteristics, and structural form.
• the flexural member's (plate's) geometry (shape) and strength along its direction of flexing is configured so that flexural yielding (i.e.
• plastic flow, plastic straining, plastic curvature) within the plate is preferably confined to a specific and finite 'yield zone' within the end regions of the plate immediately adjacent one or all of the plate's anchors.
• the plate remains preferably elastic between the yield zone within the first region(s) of the plate adjacent its first anchor and the distal yield zone within the second end region(s) of the plate adjacent its second anchor(s) or between the yield zone within the first end region (adjacent the first anchor) of the plate and a distal non- yielding second end region (adjacent a second anchor).
• confinement of yielding to these zones may simply be achieved by the use of a rectangular plate of constant cross section and material properties (prismatic) along its direction of flexure.
• the present invention may be said to be a force limiting and energy dissipating device for absorbing energy during movement between two structure members, the device comprises
• a resiliently deformable flexural member within the rotary unit having a first region and a second region(s) spaced from the first region and located respectively by the first anchor and the second anchor(s), whereby the first anchor secures the first region to the first part of the rotary unit so that the first region is able to move with the first part relative to the second region(s) and second part of the rotary unit during a seismic event, and the second anchor(s) allows translation or translation and rotation of the second region(s) (with particular boundary conditions) relative to the second anchor(s) during oscillatory movement of the first structure relative the second structure and subsequently first part of rotary unit relative to second part of rotary unit, allowing the flexural member to flexurally yield while maintaining a stable constant resistive yield force (and preferably not causing internal membrane forces to develop in said elongate member).
• the flexure member extends at least between the two anchors in a first direction, wherein the first anchor secures the first region to the first rotary unit part so as to move with said first rotary unit part during the seismic event, and the second anchor is configured to allow the second region
• control structure may consist of a rotary unit alone (without a rocker frame) in which the rotary system is mounted directly to a foundation, or, above and to, a secondary flexural member (base) in turn fixed to an underlying foundation, and in which the extended arm of the rotary unit connects directly or via diagonal ties to the structure it is seismically supportive of.
• the present invention may be said to be a rotary tie anchor for anchoring at least one diagonal tie of or for a seismically supported structure to a foundation.
• the present invention may be said to be a racking
• constraining system having at least one diagonal tie to resist racking of a structure mounted on a foundation or base; wherein the at least one tie attaches from the rack to a rotary tie anchor, the tie anchor being, as described above, a rotary unit within which flexure member(s) (plates) are set and from which an extended arm connects with at least one diagonal tie.
• the rotary unit with elongate flexure member is held at the foundation or secondary flexure member base without compromise, or substantial compromise, of the flexure member's resilient and/or plastic flexure response to rack racking and/or load inputs via the at least one tie.
• the seismically supported structure is either a rack or a building.
• the ties are connected to an uppermost region of the seismically supported rack.
• the 2 ties are connected to either side of the vertically extended arm of the anchor.
• the ties are subjected to tensile loads during seismic activity in operation.
• the tie anchor comprises a hold down anchor at each anchor region of a secondary flexure member, (which underlies and supports the rotary system (unit)) where the rotary system is centrally located between both hold down anchors.
• At least one hold down anchor of the secondary member is configured to allow its respective anchor region to move in a lateral translational direction towards and away from the other anchor.
• both hold down anchors of the secondary member are configured to allow the respective anchor region of the secondary flexure member to rotate about a rotational axis, located at the respective end region, perpendicular to said elongate direction of the secondary flexure member and parallel to the foundation or base during flexure of the primary flexure member (rotary unit) .
• the central pivotal connection is formed in a centra l hold down anchor intermediate the 2 end hold down anchors of the secondary flexure member.
• the secondary flexure member is over 1 m long.
• the secondary flexure member is 2 m long.
• the drum, rotors with arms and housing of the rotary unit is significantly stiff relative to the flexure plates to resist substantial elastic deformation so as to transfer the tie forces directly into the flexure member.
• the primary flexure member (plates) is highly flexible relative the overall rotary system.
• the primary flexure member is highly ductile relative the overall rotary system.
• the secondary flexure member which underlies the rotary unit and primary flexure member (plates), substantially forms a curved shape of a standing second order harmonic wave during deformation.
• the secondary flexure member substantially forms a sideways S shape during deformation.
• the secondary flexure member substantially forms a positive lobe to one side of the upstand and a negative lobe to the other side of the upstand.
• the curved shape of the secondary flexure member has a point coincident with the pivot point of the central anchor that does not translate in any direction.
• the secondary flexure member is divided into two wings, a first wing located at a first side of the central anchor and a second wing located at a second of the central anchor.
• the tie anchor is located and connected above each of the first wing and second wing.
• the primary flexure member within the rotary unit and secondary flexure member act substantially in series.
• the present invention may be said to be an anchored storage rack assembly, the use of diagonal ties from the rack into a rotatable upstand from a triple anchored damping system capable of absorbing or dissipating energy provided in the upstand via the ties during a seismic or high force load event.
• the triple anchoring of the supporting secondary member allows a single curvature flexure upwardly on one side of the secondary member and a single curvature flexure downwardly on the other side of the secondary member under any racking of the rack relative to the underlying support for the anchors.
• the present invention may be said to an energy absorbing structure assembly, the spaced anchoring from an underlying support of an energy absorbing flexure member attached directly or indirectly (e.g. via bolts, ties, ties via an upstand, or the like) to the rack to anchor the rack, the anchoring allowing a symmetric and/or asymmetric arc like movement of the flexure member without endwise
• the present invention may be said to consist of a bracing anchor that is able to substantially convert lateral tensile forces from a structure
• the rotational action is transmitted to the flexure member that absorbs energy, received from the tensile forces, in a controlled manner.
• the structure is held rigidly to the foundation (second structural member) in the absence of seismic activity.
• the structure upon seismic activity the structure has its energy damped via the rotary unit.
• the rotary unit is held (elastically and effectively) rigidly to the foundation in all degrees of freedom with the absence of seismic activity, upon seismic activity and yielding of the flexure members, there is a (kinematically) relative ease of lateral translation along the elongate direction at at least one end region of the flexure member, and (kinematically) relative ease of rotation about a rotational axis, perpendicular to the elongate axis and parallel to the foundation at both end regions of a flexure member.
• the present invention may be said to an assembly for absorbing energy from a structure, mounted to a foundation, that will rock in a lateral plane from a seismic event, the assembly comprising
• a stiff elongate body configured to rock, during said seismic event, about a pivotable anchor located at a first end of the body, the pivotable anchor having a pivot axis perpendicular to the lateral plane and parallel to the foundation, a deformable yield member within a rotary unit dependent from the body and spaced apart from the pivotable anchor in at least a direction perpendicular to said pivot axis, the rotary unit with deformable yield member connecting the body to a first member of one selected from;
• the rotatable anchor configured and located so that the body during rocking causes relative movement between the body and the first member and wherein one or more selected from the body, and vertical chord, are configured to engage, or are integral, with the structure in operation so the movement of the structure is transferred to the one or more selected from the body, and vertical chord.
• the relative movement causes elasto-plastic deformation of the deformable member within the rotary unit.
• the body is a column.
• the body is a truss.
• one or both of the chords are columns.
• one or both of the chords are trusses.
• the deformable yield member is plate like.
• the deformable yield member comprises a steel plate.
• the deformable yield member comprises a damper comprising a spring or rubber element, or friction plate element, or shear yielding element.
• the deformable member bends about its minor axis.
• the body and chords are substantially stiff compared to the yield member(s).
• the body (rocker frame) is pivotally fixed to another seismically dependent structure two thirds up the height of the control structure.
• the vertical chord of the control structure is pivotally fixed to the seismically dependent structure two thirds up the height of the control structure.
• the pivotable anchor is configured to pivotally engage the body with the foundation.
• the deformable member within the rotary unit is engaged between the body and the foundation.
• the body comprises rotary anchors located at each end of the body, a first rotary anchor and a second rotary anchor.
• the second rotary anchor is attached to an upper region such as an upper floor, ceiling or other upper region of said structure.
• further deformable members are engaged between the body and the upper region.
• the stiff elongate body is substantially horizontal.
• the first rotary anchor is attached to the said first vertical chord and the second rotary anchor is attached to the 2nd vertical chord.
• both vertical chords are configured to pivotally attached to the foundation.
• both vertical chords are configured to pivotally attached to an upper region.
• the body is further engaged to each vertical chord by spaced apart deformable members.
• the deformable members are substantially plate like members within and part of rotary units intermediate the body and the vertical chord.
• the rotary units with deformable members transfer shear forces between the vertical chord and the body.
• the rotary unit has two end regions, one first end region constrained relative the body, and the vertical chord is configured to act at the second end region opposite the first end region to cause rotation of the drum of the rotary unit and to deform the deformable member during relative movement.
• the body is substantially elongate in a horizontal direction and pivotally engaged intermediate 2 vertical chords.
• chords pivotally engaged intermediate the two vertical chords.
• the rotary units with deformable members are intermediate the body (rocker frame) and the horizontal chord/s.
• the foundation is one of a ground, a floor, a ceiling, a beam, and a truss. In one embodiment, at least one end region of the deformable member has a sliding engagement.
• the present invention may be said to consist in an energy absorbing system for a structure mounted to a foundation, to constrain lateral movement of an upper region of said structure during a seismic event with respect to the
• rocker rigidly connected at a first end of a stiff body engaged to said structure and configured to transfer lateral movement of said upper region about the body, the rocker comprising
• pivot anchor that is configured to pivot the body about a pivot axis perpendicular to said lateral movement and parallel said foundation
• each anchor comprising at least two spaced apart rotary unit anchors, one anchor each side of the pivot axis, each anchor dependent from, and intermediate, said foundation and the body, each anchor comprising at least one deformable member configured to elastically or elasto-plastically deform during said lateral movement, and
• said structure is a rack, ceiling, and/or building.
• the foundation is one of a ground, a floor, a ceiling, a beam, and a truss.
• the deformable member within the rotary unit is dependent from the foundation.
• the deformable member is dependent from a vertical chord engaged to said structure.
• the vertical chord is substantially stiff compared to the deformable member.
• the vertical chord is pivotally dependent from the
• a vertical chord pivot anchor comprising a vertical chord pivot axis parallel to the pivot anchor pivot axis.
• the body is a truss. In one embodiment, the body is substantially rigid compared relative to the deformable members.
• the upper region of the vertical chords are engaged to the structure.
• the vertical chords are engaged to a seismically dependent structure two thirds up the height of the control structure.
• the present invention may be said to an energy absorbing system for a structure mounted to a foundation to absorb lateral movement of said structure during earthquake, the upper region of the structure moving laterally during a seismic event, wherein the system comprises a body comprising a top region laterally constrained in operation to the upper region of said structure and a base opposite the top region comprising
• a pivot that is configured to pivotally depend from said foundation about an axis perpendicular to the lateral movement and parallel the foundation, the pivot allowing the body to rock back and forth about the axis and
• At least two spaced apart yield connectors (rotary units), one yield connector on each side of the pivot, each spaced apart yield connector dependent from said foundation and body, and comprising one or more deformable members configured to plastically deform during rocking.
• the upper region of the seismically dependent structure is engaged to the control structure two thirds up the height of the seismically supported structure.
• the height of the structure (dependent or control) is more than 30 metres.
• the top region of the body is constrained with the upper region via cables.
• one yield connector (rotary unit) will deform in a clockwise direction and the opposite yield connector will deform in a counter clockwise direction when the body is rocked about the pivot.
• the two ties are connected to the structure either side of the body.
• the ties are subjected to tensile loads during seismic activity in operation.
• the body is substantially stiff so as to allow minimal elastic deformation, and no plastic yielding, during lateral movement of the structure.
• the body may be a multimember truss system.
• the yield connectors are intermediate the body, and one selected from a vertical chord, horizontal chord, and foundation.
• the system comprises cables retaining the body to the vertical and/or or horizontal chord.
• the top region of the body is constrained to the structure from a substantially single point.
• the top region of the body is constrained to the structure from laterally spaced apart regions.
• the deformable member within the rotary unit has at least two spaced apart anchor regions.
• a seismic event creates relative movement between the foundation and body, which creates relative movement between the deformable member anchor regions.
• the anchors are configured to allow
• At least one anchor region to move in a rotary arc direction away from the other anchor region
• At least one anchor region to rotate about a rotational axis
• the deflection of the deformable member caused by plastic yielding is far greater than the deflection caused by elastic deflection.
• the deformable member is highly flexible and/or ductile relative the truss.
• a secondary flexural member is located intermediate of the rocker frame(s) inclusive of rotary unit with primary flexural members (plates), and a horizontal (e.g. foundation) or vertical (e.g. columns) structural base.
• the invention relates to a control structure which helps direct and control the motion of connected force limiting and energy dissipating structural members (preferably a plate or plates), which are capable of stable cycling high displacement elasto-plastic flexure about their minor bending axis.
• the plates enable the control structure to form a stable cycling high
• control structure inclusive of the rotary units directs and controls the motion of the yielding plates; while the plates, yielding at a constant resistive force, limit the forces generated within the structure(s).
• the present invention incorporates a rocker as part of a substantially stiff pivotably based control structure that incorporates at least one yield connector (rotary unit) to
• the present invention may utilise a yield connector (rotary unit) for absorbing energy during oscillatory movement between two structure members, the connector comprises:
• a first anchor comprising the drum of the rotary unit
• a second anchor comprising the peripheral pins fixed to the casing of the rotary unit
• a flexural member having a first region (preferably an end region of the flexural member) supported at the first anchor and a second region (preferably an end region of the flexural member) spaced from the first region and supported at the second anchor in a simply supported manner.
• the flexural member is able to rotate and translate relative to its respective anchors and at the other of the first and second regions the flexural member is cantilever (rigidly fixed) to its respective anchor.
• the present invention may be said to be a control structure incorporated with a primary structure or seismically dependant structure (e.g. a building or storage rack) to limit forces and dissipate energy in said primary structure during a seismic event, the control structure comprising :
• the yield connector (rotary unit) connecting with the rocker frame at a location away from the pivot of the rocker frame, the yield connector (rotary unit) comprising of at least one elongate flexural member able to bend about its minor axis and connected by the yield connector (rotary unit) to the rocker frame in a manner to produce a stable, constant resistive yield force while flexurally yielding about its minor bending axis in response to relative displacement between the rocker structure (first structural member) and horizontal (e.g. foundation) or vertical second structural member.
• 'diagonal' and its derivatives refers to any angle(s) obliquely of the vertical and the horizontal directions.
• 'Single curvature' means without forming a plural lobed arch form. It includes a symmetric form on either side of its intended attachment to the structure or rack from its anchoring, encumbered, fettered or like adaptions or zones.
• plastic or ductile can be interchangeable and relate to material deformation past elastic deformation.
• a stress is sufficient to permanently deform a material (such as a flexure member), it is called plastic or ductile deformation.
• This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known
• Figure 1 shows a schematic front view of a control structure comprised of a rotary unit alone with inclined tension bracing, connecting to a structure it is seismically supportive of.
• Figure 2 shows a schematic front view of a control structure of Figure 1 but with extended vertical arm connecting to plan bracing, of a structure it is seismically supportive of.
• Figure 3A shows a schematic front view of a control structure comprised of an
• Figure 3B schematically shows the control structure of Figure 3A in sway mode
• Figure 3C shows the schematic front view of the control structure of Figure 3A but with multiple rotary units.
• Figure 3D shows a schematic view of a control structure with multiple rotary units which are vertically stacked.
• Figure 4A shows control structures of Figures 1-3 within a rack structure or
• Figure 4B shows an end view of Figure 4A showing location of control structures of Figures 1-3 located intermediate of two storage racks
• Figure 5A shows a schematic front view of a control structure with APLHA1 rocker frame horizontally orientated and located between two stiff vertical chords which are pivotably based.
• Figure 5B shows the displaced form of the control structure of Figure 5A in sway mode.
• Figure 5C shows the displaced form of the control structure of Figure 5A when subject to differential vertical base displacement of the vertical chords
• Figure 5D shows the displaced form of the control structure of Figure 5A in sway mode and subject to differential vertical base displacement of the vertical chords.
• Figure 6A shows a schematic front view of a BETA1 rotary unit with extended rotor arm, pin and slot connecting to the push rod of an ALPHA1 rocker frame.
• Figure 6B shows the displaced form of the rotary unit of Figure 6A when the
• Figure 6C shows a schematic plan (overhead) view of the rotary unit of Figure 6A.
• Figure 6D shows the rotary unit of Figure 6A with a secondary flexural base
• Figure 6E shows a part plan view of Figure 6D
• Figure 7A shows a schematic front view of a BETA2 rotary unit with extended rotor arm pin and slot connecting to the push rod of an ALPHA1 rocker frame.
• Figure 7B shows the displaced form of the rotary unit of Figure 7A when the
• ALPHA1 rocker frame it connects with, is in sway mode.
• Figure 7C shows a schematic detail of a DELTA4 yield plate within the rotary unit of Figure 7A.
• Figure 7D shows a schematic detail of the displaced form of the DELTA4 yield plate of Figure 7C within the rotary unit of Figure 7A.
• Figure 7E shows a schematic plan view of the rotary unit if Figure 7A with
• Figure 7F shows a schematic plan view of the rotary unit of Figure 7A with
• Figure 7G shows a schematic plan view of a dual rotary unit in transverse
• Figure 7H shows a schematic plan view of a dual rotary unit in longitudinal
• Figure 8A shows a rocker frame pivot anchor to vertical chord connection.
• Figure 8B shows a plan cross sectional view of Figure 8A.
• Figure 9 shows a schematic front view of a control structure with a two pivot rocker frame located between top and bottom beam with anchor ties.
• Figure 10 shows a schematic front view of two framing control structures located between top and bottom beam.
• Figure 11 shows a schematic front view of the control structure of Figures 5 in tower form.
• Figure 12A shows a schematic front view of a control structure with an ALPHA2 rocker frame assembly and inter-lamina rotary units.
• Figure 12B shows the control structure of Figure 12A in sway mode.
• Figure 13A shows a schematic front view of a control structure with an ALPHA2 rocker frame assembly which is horizontally orientated and located between two stiff vertical chords, which are pivotably based.
• Figure 13B shows the control structure of Figure 13A in sway mode.
• Figure 14A shows a schematic detail of a DELTA4 yield plate within a BETA2 rotor
• Figure 14B shows the displaced form of the DELTA4 yield plate of Figure 14A.
• Figure 15A shows a detail schematic of a DELTA5 yield plate within a BETA2 rotor
• Figure 15B shows the displaced form of the DELTA5 yield plate of Figure 15A.
• Figure 16A shows a detail schematic of a DELTA6 yield plate within a BETA2 rotor
• Figure 16B shows the displaced form of the DELTA6 yield plate of Figure 16A.
• Figure 17A shows the control structure of Figure 12A inclusive of motion control ties.
• Figure 17B shows the control structure of Figure 12B (in sway mode) and inclusive of motion control ties.
• Figure 17C shows the control structure of Figure 13B (in sway mode) and inclusive of motion control ties.
• Figure 18A shows a schematic front view of the control structure of Figure 5A with secondary flexural member(s).
• Figure 18B shows the control structure of Figure 18A in sway mode.
• Figure 18C shows a load displacement graph for a two-tier elasto-plastic system
• Figure 19A shows a schematic view of control structure comprised of a rotary unit alone connected to inclined tension bracing and within a rack structure
• Figure 19B shows a schematic view similar to Figure 19A but with cable guides maintaining a practicably horizontal connection of the tension bracing to the vertically extending arm of the rotary unit,
• Figure 20A shows a schematic front view detail of a BETA2 rotary unit supported off a secondary flexural base.
• Figure 20B shows a schematic front view of the rotary unit of Figure 20A in
• Figure 20C shows a schematic front view of the rotary unit of Figure 20A in
• Figure 21A shows a schematic of a rocker frame which is able to directly support gravity loads without reliance on flexure members (plates) within the rotary unit to provide vertical stability.
• Figure 21B shows the displaced form of the frame of Figure 21A.
• Figure 22 shows a schematic elevation of a non-symmetrical rocker frame with a rotary unit to one side only.
• Figure 400 shows a side elevation of a plate, similar to Figure 14A, which is fixed one end and free to slide and rotate by way of a slot in the outer annulus of a Type II (BETA2) rotor,
• Figure 401 shows the displaced form of Figure 400.
• Figure 402 shows the plan view of Figure 400.
• Figure 403 shows a side elevation of a plate, similar to Figure 15A, with continuous anchored end regions which are free to slide and rotate by way of slots in the outer annulus of a Type II rotor.
• Figure 404 shows the plan view of Figure 403.
• Figure 405 shows a side elevation of a plate, similar to Figure 16A, with an end region which is free to slide but rotationally restrained by way of slots in the outer annulus of a Type II rotor.
• Figure 406 shows a plan view of Figure 405.
• Figure 407 shows the side elevation of a plate in which the sliding and rotating end regions of the plate by way of slotting of anchors is located at the rotatable inner anchor of a Type II rotor and where the fixed end of the plate is located at the outer annulus.
• Figure 408 shows the displaced form of Figure 407.
• Figure 501A shows the elasto-plastically displaced form of a DELTA4 yield plate with hatched yield zone.
• Figure 501B shows the plan view of Figure 501A inclusive of yield zone.
• Figure 501C shows a plan view similar to Figure 501B but with a reduced
• Figure 502A shows the elasto-plastically displaced form of a DELTA5 yield plate with hatched yield zones.
• Figure 502B shows a plan view of Figure 502A inclusive of yield zones.
• Figure 502C shows a plan view similar to Figure 502B but with a reduced
• Figure 503A shows the elasto-plastically displaced form of a DELTA6 yield plate with hatched yield zones.
• Figure 503B shows a plan view of Figure 503A inclusive of yield zones.
• Figure 503C shows a plan view similar to Figure 503B but with a reduced
• Figure 504 shows a schematic plan of a DELTA4 yield plate, where the plate is locally tapered in its yield one region, the angle of taper equating to elastic moment demand.
• Figure 600 shows a schematic of a rotary unit with lever arm of length a.
• Figure 601 shows a schematic of the displaced form of Figure 600 and generating a constant yield force, Pi, in the push rod of a control structure.
• Figure 602 shows a schematic of a rotary unit with lever arm of length b.
• Figure 603 shows a schematic of the displaced form of Figure 602 and generating a constant yield force, P2, in the push rod of a control structure.
• Figure 604 shows a schematic of a control structure in displaced form, with yield force of PI in its push rods and equivalent resistive yield force, Vi (at height h).
• Figure 605 shows a schematic of a control structure in displaced form, with yield force, P2, in its push rods and equivalent resistive yield force V 2 (at height h).
• Figure 606 shows a schematic of a rotary unit integral with a secondary flexural member.
• Figure 610 shows a schematic detail of a rotary unit with a sleeve guided BETA rocker unit (third part) connected to its peripheral (second) part.
• Figure 611 shows a schematic similar to Figure 610 but with a non-specific force limiter and energy dissipater.
• Figure 612 shows the displaced form of part of Figure 611.
• Figure 613 shows a schematic similar to Figure 611, with friction plate force
• Figure 614 shows a schematic of a rotary friction unit composed of a circular plate
• Figure 615 shows the non-displaced and displaced form of part of Figure 614.
• Figure 616 shows a schematic of a rotary unit composed of annular friction plates and discs with rotor arm length a.
• Figure 617 shows a schematic similar to Figure 616 but with rotor arm length b.
• Figure 618 shows the non-displaced and displaced form of part of Figures 616 and
• Figure 619 shows a schematic section through Figures 616 and 617.
• Figure 620 shows a part schematic similar to Figures 616 and 617 but where the friction plates of the first part of the rotary unit are individual units
• Figure 621 shows a schematic section of Figure 620.
• Figure 622 shows a schematic part view of the tension bolts through the outer annular (first) part of Figure 621 and through the slotted pads of the inner second part
• Figure 623 shows a schematic of the rotary units of Figures 616 and 617 integral with a secondary flexure member base.
• Figure 624 shows a schematic section similar to Figure 619, but where the rotary unit has a flat inner disc and external lever arms, the slotted inner disc rotating with the lever arms.
• Figure 625 shows a case similar to Figure 624 but where the external plates rotate with the lever arm, both relative to the slotted inner plate (disc).
• Figure 628A, 628B, 628C show various schematic sections of rotary friction units with friction units centrally located and rotating with lever arms, both located between outer plate.
• Figure 629 shows a plan view schematic of Figure 628A.
• Figure 630 shows a schematic elevation of a rotary unit similar to Figure 7.
• Figure 631 shows a schematic cross-section of Figure 630.
• Figure 632 shows a schematic of a rotary unit, where the yield plates are
• peripherally distributed, and their plane is normal to the plane of the first part (circular disc) of the rotary unit.
• Figure 633 shows a part front elevation of a yield plate with annular ring anchors.
• Figure 634 shows a side elevation of a yield plate fixed one side and pin
• Figure 635 shows a plan view of Figure 634.
• Figure 636 shows a part front elevation of a yield plate, similar to Figure 633, with connecting pivotable anchor pin both in non-displaced form.
• Figure 637 shows the displaced form of Figure 636.
• Figure 638 shows a plan view of the (flexing) displaced form of the flexure
• Figure 639 shows a schematic cross section of Figure 632.
• Figures 640, 641, 642 show various schematic sections of rotary yield units, where the yield plates are connected (anchored) to the peripheral edges of two integral discs (Part A) which are centred on two outer discs (Part B).
• Figure 643 shows a plan view schematic of Figure 640.
• Figure 645 shows a schematic of a rotary unit comprised of circular discs, and with a general force limiter and energy dissipater.
• Figure 646 shows a plan view of Figure 640.
• Figure 647 shows a schematic of a friction plate force limiter and energy dissipater within the rotary unit of Figure 640.
• Figure 650 shows a schematic view of a rotary friction unit similar to Figures 628 but where an elastic component (spring leaf) has been integrated with the two rotary parts.
• Figures 651 to 653 show how the spring leaves (or elastic plates) displace with the friction units (or pads).
• Figure 654 shows a cross sectional schematic of Figure 650.
• Figure 655 shows the outer plates of Figure 654 relative to the inner plates.
• Figure 656 shows a schematic view of a rotary unit, similar to Figure 650 but
• Figure 657 shows a cross sectional view of Figure 656/
• Figures 658 and 659 show the tension bolts relative to the movements of the inner and outer plates.
• Figure 660 shows a schematic view of a rotary friction unit with elastic
• Figure 661 shows a schematic cross sectional view of Figure 660.
• Figure 662 shows a schematic of a rotary friction unit with elastic component similar to Figure 660, but where the outer plates rotate with the lever arms.
• Figure 663 shows a schematic cross sectional view of Figure 662.
• Figure 664A to 664D show the progressive displacements of the inner friction plate (sow or pad), the elastic flexing of the spring plate, and the displacement of the outer plate relative to the inner friction pad after displacement of the inner plate (pad) has ben stopped (arrested).
• Figure 665 shows the tension bolts through the outer plate.
• Figures 666A and 666B show schematic side views of a BETA rocker friction unit with elastic component.
• Figure 667 shows a schematic section of Figures 666 inclusive of guides.
• Figures 668-1 to 668-15 show further rotary units in which the friction
• Figures 669-1 to 669-70 consider a corrugated friction yield block, with
• clamped frictionless sloping surfaces which provide an elastic component and clamped flat frictional surfaces which provide a separate plastic component.
• Figure 669-71 shows a schematic view of a sleeve guided rocker unit with DELTA1 yield plates
• Figures 669-72 to 669-75 show schematic views of a sleeve guided rocker unit with friction blocks and elastic (DELTA1) flexural plates.
• Figures 669-76 to 669-79 show schematic views of a sleeve guided rocker unit with corrugated friction yield blocks.
• Figure 669-80 shows a sleeve guide rocker unit within which shear yield blocks are located.
• Figure 669-81 shows the displaced form of Figure 669-10.
• Figure 670 shows a DELTA4 yield plate which elasto-plastically displaces in one direction only and returns under load to an effectively horizontal position.
• Figure 671 similarly shows a DELTA4 yield plate which elasto-plastically displaces in one direction only but returns under load to a displacement just below its initial horizontal position.
• Figure 672 shows a DELTA4 yield plate which primarily elasto-plastically displaces in one direction but returns under load to a displacement just above its initial horizontal position.
• Figure 673 shows an ALPHA1 control structure in which the yield plates elasto- plastically displace in one direction only
• Figures 674-678 show a connector located between the lever arm and the rotor plate of the drum which enables each to connect and disconnect as the control structure sways.
• Figure 679 shows both a lever arm and rotor plate coincidentally displaced
• Figure 680 shows a lever arm and rotor plate coincidentally returned to a
• Figure 681 shows a lever arm and rotor plate now rotationally displaced
• Figure 690 shows a non-displaced braced frame control structure within which rotary units with pin ended diagonal push rods are located.
• Figure 691 shows the braced frame of figure 690 in displaced form.
• Figure 692 shows a schematic of a two bay braced frame arrangement in which connect-disconnect-connect joints between the lever arm and rotor plates are employed.
• Figure 693 shows the braced frame of Figure 692 in displaced form.
• Figure 700 shows a schematic of a flexure member (DELTA1 plate) within a BETA1 rocker with sleeve guides which is part of a control structure with an ALPHA1 rocker frame as described in WIPO, PCT/IB2017/056135 and WIPO, PCT/IB2017/056137.
• DELTA1 plate a flexure member within a BETA1 rocker with sleeve guides which is part of a control structure with an ALPHA1 rocker frame as described in WIPO, PCT/IB2017/056135 and WIPO, PCT/IB2017/056137.
• Figure 701 shows a schematic of a flexure member (DELTA4 plate) which is part of a control structure with an ALPHA2 rocker frame as described in WIPO, PCT/IB2017/056135 and WIPO, PCT/IB2017/056137.
• DELTA4 plate a flexure member which is part of a control structure with an ALPHA2 rocker frame as described in WIPO, PCT/IB2017/056135 and WIPO, PCT/IB2017/056137.
• Figure 702 shows a schematic of a flexure member (DELTA4 plate) within a BETA rotor which as with Figures 700 and 701 is the force limiting and energy dissipating part of a control structure with an ALPHA1 or ALPHA2 rocker frame.
• DELTA4 plate flexure member
• Figure 703 shows a flexure member (plate) in a state of plastic flow under applied load P.
• the deforming length of the plate, between boundary reaction points increases from 2a to 2b and a reaction R, orthogonal to the plate, is generated.
• Figure 704 shows the reaction R of Figure 703 resolved into a vertical, Rv, and a horizontal, RH, component.
• Figure 705 shows the resolved components of Figure 704 in terms of the (half) angle of rotation of the yield zone Q'.
• Figure 706 derives the applied load, P, as a function of the yield zone moment, M, and the (half) angle of rotation of the yield zone, Q'.
• Figure 706A shows a further description of the mechanics of the yielding plate.
• Figure 707 shows the reaction direction for the reverse direction of applied load P.
• Figure 708 shows the reactions for a DELTA1 plate in a state of plastic flow under applied load P.
• Figure 709 shows the reactions for a DELTA1 plate in a state of plastic flow under reverse direction applied load P.
• Figure 710 shows the reactions for a plate of constant deforming length with a curved boundary and derives the applied (or resistive) load, P, as a function of the boundary curve Q and the (half) angle of rotation of the yield zone Q'.
• Figure 711 is similar to Figure 710 but with a concave boundary surface
• Figure 712 is similar to Figures 710 and 711 but with a contra-curving boundary.
• Figure 713A derives a boundary curve Q which is equal to the (half) angle of rotation of the yield zone Q'.
• Figure 713B derives the boundary curve, Q, of Figure 713A in terms of
• Figures 715A 8i 715B show the displacements and reactions for a plate with
• Figure 716 gives the resistive (or applied) load, P, for a plate with end region extensions of length a and convex boundary.
• Figure 717 similarly gives the resistive (or applied) load, P, for a plate with end region extensions of length a, and concave boundary.
• Figure 718 derives the resistive load, P, for Figures 716 and 717.
• Figure 719 shows a plate in a state of plastic flow, in which the horizontal
• Figures 720 to 732 show various non-displaced and displaced forms of plates with a curved boundary in finite dimension.
• Figure 733 shows the stress-strain curves of common structural steels produced in the United States, Europe and the United Kingdom.
• Figure 734 shows the ratio of stress at a given strain, to yield stress for Histar 460 and A992 steel.
• Figure 735A shows a direct trace of the maximum (cycled) amplitude a grade
• Figure 735B similar to Figure 735A, shows a direct trace of the maximum cycled amplitude a 12mm grade 460 plate was load tested to.
• Figure 736 shows the ratio of stress at a given strain to yield stress for Histar 460
• Figures 737 to 743 show the stress strain curves of Figure 733 along with the inverses of the load reduction factors derived on Figures 706 and 710.
• Figures 744 to 750 show the resistive (or applied) load, P, as a percentage of initial (first yield) resistive force for the steels of Figure 733.
• Figure 751 shows a plate with free translational and free rotational boundary
• Figure 752 shows the plate of Figure 751 in a state of plastic flow, and the vertical
• Figure 753 shows the plate of Figure 751 subject to reverse applied (or resistive) load.
• Figure 754 shows the displaced form of a plate with constant curvature.
• Figure 755 shows a schematic view of a triangular tapered plate and displaced form with slotted anchor.
• Figure 756 shows local yielding within the plate of Figure 755.
• Figure 757 shows a schematic view of an X-plate and its displaced form.
• Figure 758 shows displaced forms of the X-plate of Figure 757 inclusive of tensile membrane forces.
• Figure 759 shows the load-displacement curve for the plate of Figure 751, for plates which generate membrane forces, and for plates with the particular free translational and free rotational boundary conditions of Figures 700 to 717, and Figure 735.
• Figure 760 shows the hysteresis loop obtained from cyclic loading the plate of
• Figure 761 shows the pinched hysteresis loop of a plate which generates
• Figure 762 shows the hysteresis loop obtained from cyclic loading a plate with the boundary conditions of Figures 700 to 717.
• Figures 800A, 800B, 800C show direct traces of the same 8mm test plate, cycled to three increasing amplitudes.
• Figures 801A, 801B, 801C show close ups of the yield zones of Figures 800.
• Figure 802 shows the yield zones of Figures 801 superimposed onto concentric circles.
• Figures 803 to 807 show the strain and stress profiles for a Hi-Star 460 yield plate at linearly varying flexural strains.
• Figures 808 to 812 show the strain and stress profiles for a Grade A992 yield plate at linearly varying flexural strains.
• Figure 813 shows the ratio of yield force to initial yield force for Hi-Star 460 steel with the flexural stress profiles of Figures 800 to 807.
• Figure 814 shows the ratio of yield force to initial yield force for Grade A992 steel with the flexural stress profiles of Figures 808 to 814.
• Figure 815 shows a schematic view of a composite yield plate.
• Figure 820 relates displacement ductility to a yield zone of given plastic curvature.
• Figures 850 to 852 compare load paths of a conventional linear elastic system with load paths of an elastic system of two load direction dependent stiffnesses.
• Figures 853 to 858 compare elasto-plastic load paths with elastic load paths including the elastic load paths of systems with clamped frictional sloping surfaces.
• Figure 900 shows a control structure comprised of a pivotably based rocker frame, double pin ended push rods and base located rotary yield units all forming a pivotably based control structure of vertical (tower) aspect (or pivotably based cantilever wall).
• Figure 901 shows a control structure comprised of pivotably based vertical chords, rocker frames in horizontal (spanning) aspect pivotably connected to vertical chords, double pin ended push rods and rotary yield units all forming a pivotably based control structure of a moment frame aspect.
• Figure 902 shows a control structure comprised of a pivotably based rocker frame, pivotably based exterior chords (parallel with the chords of the rocker frame) and rotary yield units distributed between and along the rocker frame and exterior chords, all forming a pivotably based control structure.
• Figure 902A shows an ALPHA2 rocker frame assembly with secondary flexural members.
• Figure 903 shows a control structure comprised of pivotably based vertical chords, rocker frames in horizontal (spanning) aspect pivotably connected to the vertical chords, exterior chords (parallel with the chords of the rocker frame) and pin connected to the vertical chords; and rotary yield units distributed between and along the rocker frame and external chords all forming a pivotably based control structure,
• Figure 904 shows a control structure comprised of pin connected beams
• Figures 905 and 906 show a control structure comprised of pivotably based wall elements, connected by pin ended motion control ties, with rotary yield units located and connected between the walls, all forming a pivotably based control structure of coupled shear wall form,
• Figures 910 and 911 show a plan view of rotary units located between the
• Figure 912 shows a schematic plan detail of the rotary units of Figure 910/911 with a secondary flexural member.
• Figure 913 shows a longitudinal section of Figure 910, one part of the rotary unit connecting to the foundations and the other part to the base of the superstructure.
• Figure Al shows a schematic view of a rotary unit with DELTA1 yield plates.
• Figure A2 shows a plan view of Figure Al.
• Figure A3 shows a schematic view of a rocker unit.
• Figure A4 shows a close up detail of Figure A3.
• Figure A5 shows a rocker unit similar to Figure A4 but with ten DELTA1 yield plates.
• Figure A6 shows a plan view of the rocker units of Figures A3 to A5.
• Figure A7 shows a plan sectional view of a guide within the rocker unit
• Figure A8 shows a cutout in the DELTA1 yield plate.
• Figure A9 similar to Figure A7 but with an enlarged guide.
• Figure A10 similar to Figure A8 but with two cut outs and ties.
• Figure All shows a rotary unit with rocker yield units forming a third connecting part.
• Figure A12 shows a plan view of Figure All.
• Figure A13 shows a plan view of the connection of the push rod (of the rocker frame assembly to the rotary unit of Figure All),
• Figure A50 shows a schematic view of a 10 storey/35m building with ALPHA1 frames and base located rotary units.
• Figure A51 shows a schematic view of a 20 storey/70m building with ALPHA1 frames and base located rotary units.
• Figure A52 shows a schematic view of a 40 storey/140m building with ALPHA2 frames and rotary units connecting to and distributed between the interior and exterior chords of the control structure.
• Figure A52-1 shows a rotary unit with composite plates.
• Figure A53 shows a schematic view of a 100 storey/342m building with ALPHA2 frames and rotary units distributed over its height.
• Figure A54 shows a plan view of Figure A53.
• Figure A55 similar to Figure A53 but with rotary units located closer to the base of the control structure.
• Figure A56 similar to Figure A53 but with rotary units located closer to the top of the control structure.
• Figure A57 shows a schematic view of motion control ties, for the ALPHA2 control structure, pin connecting the exterior chords to the centreline of the rocker frame.
• Figures A100 to A101 show schematic plan views of rotary units configured as base isolation units.
• Figures B1 and B2 show a DELTA1 yield plate in undisplaced and displaced form.
• Figure B3 shows a flexing plate with pivotable roller supports.
• Figure B4 shows one case of a simply supported plate in which the length along its flexing curve between supports increases/decreases with displacement and with flexure the plate generates a horizontal reaction.
• the second case shows a plate whose flexing length remains constant and in which no horizontal reaction is generated.
• Figures B10 to B14 show the yield zones of DELTA1, DELTA2, and DELTA3 yield plates.
• Figures B20 to B23 show schematic views of a DELTA1 yield plate within a
• Figures B30 to B39 show schematic views of a DELTA1 yield plate and connect- disconnect-connect joint which produces flexing within the plate in. primarily, one direction only.
• Figure B40 shows a sleeve guided rocker unit with DELTA1 yield plate
• Figures B50 to B55 show sleeve guided rocker units within concentrically and eccentrically braced frames and with CDC joints.
• Figures B60 and B61 show a sleeve guided rocker unit with friction plates and a flexing plate which provides the elastic component of the unit.
• Figures B62 to B64 show the displacement profiles of the friction yield unit of Figures B60 and B61.
• Figures B70 and B71 show schematic views of a sleeve guided rocker unit with shear yield blocks in non-displaced and displaced form.
• Figures B80 to B86 show sleeve guided rocker units within various pivotably based control structures.
• Figures B90 to B92 show sleeve guided rocker units configured as base isolation units.
• Figures B100 to B107 show schematic views of sleeve guided rocker units with multiple DELTA1 yield plates.
• Figures B110 to B122 show various pivotably based ALPHA1 and ALPHA2 control structures within which are located the rocker yield units of Figures B100 to B107.
• the invention relates to a control structure which helps direct and control the motion of connected force limiting and energy dissipating structural members (preferably a plate or plates of a yield anchor (rotary unit)), which are capable of stable cycling high displacement elasto-plastic flexure about their minor bending axis, or out of plane bending axis.
• connected force limiting and energy dissipating structural members preferably a plate or plates of a yield anchor (rotary unit)
• rotary unit rotary unit
• the invention may comprise a device and mechanism, or more specifically a pivotably based control structure with a pivoting rocker frame assembly and rotary unit(s), which directs and governs the motion of a connected force limiting and energy dissipating structural plate(s) which are within and part of the rotary unit (yielding connector or yield connector).
• the plate(s) by its form is capable of producing a stable, constant resistive yield force while flexurally yielding about its minor (or out of plane) bending axis to high elasto-plastic displacements and high ductilities (while preferably not allowing or causing any membrane forces to develop within itself).
• the particular boundary conditions of the plate(s), which enables it to produce a constant resistive yield force while flexing to high elasto-plastic displacements are described in detail further on.
• the plate(s) action within the rotary unit(s) enables the control structure, it is a part of, to form a stable elasto-plastic mechanism which is able to flow and cycle to high elasto- plastic displacements and ductilities also with constant resistive yield force, in resistive response to ground (base) motion input, while internal forces within it (control structure) or any adjacent structure it may also be seismically supportive of, are maintained and limited to maximum values which are a function of the yield force of the structural plates which are part of it.
• the control structure by governing the motion of the yielding plates within it in a controlled manner is subsequently modifying its own natural response (displacement, velocity, acceleration) and the response of masses or adjacent structures it may be directly or indirectly seismically supportive of.
• control structure By flowing as a stable, high displacement and high ductility capable, elasto- plastic mechanism with constant resistive yield force; the control structure is limiting the magnitude of accelerations and dynamic forces that can develop within its members as it endures the ground motion (displacement, velocity, acceleration) input of a severe seismic event.
• control structure directs and controls the motion of the yielding plates; while the plates, yielding at a constant resistive force, limit the forces generated within the structure(s) (while preferably not allowing or causing any membrane forces to develop within itself).
• the plates are effectively cushioning the control structures response to ground motion or base excitation.
• the magnitude of the peak elasto-plastic displacement (and ductility) demand on the plates is a function of a number of variables including; ground motion (acceleration) input, mass seismically supported by structure and its distribution, elastic natural frequency of structure(s) (inclusive of plates) and yield strength of plate(s).
• the ability of the plate(s) to sustain the cycling peak displacement demands on them, while maintaining a stable constant resistive yield force is further dependent on their material stress-strain characteristics, and structural form.
• the lateral strength to elastic limit, (i.e. lateral yield strength) and ductility of the control structure as a whole is solely dependent on the replaceable flexural member(s) (plate(s)). Further, neither the control structure or the plate(s) which are a part, are necessarily providing additional lateral strength or ductility to another structure (e.g. structural frame) which has a given lateral strength or ductility of its own. In other words, the control structure may simply be an independent standalone structure
• control structure (supportive of, or not supportive of, masses) rather than one seismically supporting another structure. Further, the control structure (and its flexural member(s) (plates)) is able to return, after each cycle, to its original positions, solely through lateral action and without any reliance or assistance from gravity loads to 'flatten back' the yield plates.
• the rotary units may be used to resist/absorb single acceleration pulses (e.g. blast impact) and mechanical impact (e.g. train engine/station buffers).
• single acceleration pulses e.g. blast impact
• mechanical impact e.g. train engine/station buffers.
• the equivalent force applied to the structure can be approximated to be acting at say around 70% the height of the storage rack 3 or load supporting structure. This does, depend on the weight distribution of goods supported on the rack 3.
• the system of the current invention can be incorporated (and retrofitted) to a storage rack or structure to modify and control the displacement, velocity and
• the present invention utilises a system as part of or incorporated into a structure to restrain (but not prevent) the structure against movement during a seismic event and to dissipate energy and limit forces developed within the control structure or any structure it may be seismically supportive of as it endures ground motion input.
• the present invention incorporates a rocker 2000 as part of a substantially stiff and pivotably based control structure that incorporates at least one yield connector (rotary unit) to
• the simple structural behaviour of the yield plate of the yield connector (rotary unit) 230 allows for its performance to be both load tested and calculated accurately. Its design is such that its yield force and energy absorbing performance remains predictable during each movement cycle of the control structure and storage rack during a seismic event.
• the yield connector (rotary unit) utilises a flexure member 100, that is able to elasto-plastically deform. Because the structural behaviour or performance of the flexure member 100 (plate(s)) is readily defined by calculation and test, and because of the simple (effectively single degree of freedom) response of the rocker frame of the control structure; the response of the control structure, as a whole, to ground motion input is readily established.
• flexure member 100 (plate) is not able to develop tensile or compressive membrane forces within itself as it flexes to high transverse plastic displacements during yield.
• Membrane forces generated within a yielding member (plate) will both increase the (plate) stiffness and result in an increasing force resistance within the plate with increased deformation. This in turn will reduce its energy dissipating and force limiting ability, resulting in higher forces being developed in both the control structure and any adjacent structure the control structure may be seismically supportive of.
• Figures 1 to 3 show a variety of energy absorbing systems 1000 (also herein referred to as control structures) that can be included or that can form part of a storage rack or general building structure. Their incorporation in a storage rack or building is shown in Figure 4A.
• Figure 3 comprises a rocker 2000 that includes a frame 280 and a pivot anchor 240.
• the systems may be directly connected to the foundation 4. In other embodiments herein after described, the systems may be connected to other structures or other component.
• the control structure may comprise the rotary units alone as in Figures 1 and 2 or a rocker 2000 (frame 280 and pivot 240) with a rotary unit(s) yield connector 230 (with flexure member(s) 100) as in Figures 3, or be part of a pivotably based rocker frame assembly within which the rotary units are located.
• the pivot anchor 240 provides a dedicated pivot for rotational movement of the frame 280 of the control structure it is part of.
• the movement is constrained at least in part by the yield connectors (rotary units) 230 that are disposed outwardly from each side of the pivot anchor 240 in the lengthwise direction.
• the pivot anchor 240 is located centrally and intermediate two spaced apart connectors 230A and 230B.
• the connectors 230A and 230B are the same.
• the rocker 2000 comprises a frame 280 which engages the two spaced apart yield connectors 230 and the pivot anchor 240.
• the frame 280 may be part of the storage rack or be incorporated therewith preferably to extend and be secured (directly or indirectly) to an upper region 27 of the storage rack 3 or to each floor of a general building structure.
• the upwardly extending parts of the frame 280 connecting to the storage rack allow for some or all of the forces from the swaying of the rack 3 or structure to be transferred to the pivot anchor 240 and the yield plates of the yield connector (rotary unit) 230.
• the motion of the frame 280 being compatible with the motion of the rack 3 or structure.
• connection between the control structure and any other adjacent structures it is seismically supportive of must be compatible with the motion of the control structure.
• the frame 280 may be short as shown in Figure 1 or tall as shown in Figures 2 8i 3.
• a short frame 280 may be joined to an upper region by ties, struts or cables 270 to provide the force transfer during swaying, as shown in Figure 1.
• the control structure is comprised of the rotary unit alone (without a rocker frame).
• the short frame embodiment as shown in Figure 1 may be utilised where lower rack heights are encountered. Where higher rack 3 heights are encountered, a tall frame embodiment may be desirable.
• Figure 1 shows an embodiment that may be best suited for a low storage rack height or where tie cables 270 may be used.
• the tie cables 270 do not exceed a 45 degree angle with the foundation. This helps them efficiently transfer lengthwise forces from the storage rack 3 to the rotary unit.
• the tension bracing wires connecting to the rotary unit are preferably maintained horizontal. This is achieved in Figures 19B by the use of cable guides.
• the energy absorbing system 1000 (control structure) may be joined to an upper region 27 of a storage rack 3. This may be two thirds up the height of the storage rack 3. This is a typical approximation of where the equivalent applied forces from seismic activity may be focused. It is envisaged that a person skilled in the art will realise that the energy absorbing system 1000 may be engaged at any height and at any number of heights to a storage rack or building.
• the energy absorbing system 1000 comprises a top attachment 250.
• the top attachment 250 is be configured to attach to a member such as bracing 26 (sometimes known in the industry as plan bracing) of the storage rack 3. If the bracing is a strut or other similar stiff member, preferably this top attachment can pivot so it does not create any torque or moments in the frame 280 or rack 3.
• the bracing 26 is merely a method of connecting the top of the frame 280 or top attachment 250 to the storage rack 3. Where two racks are provided back to back, bracing is typically located intermediate of the racks as shown in figure 4B. Plan bracing and connections can also be located at beam levels below the top of the structure.
• the plan bracing 26 can span two or more racks. Intermediate the two racks is gap 23 where the energy absorbing system 1000 is located. In alternative embodiments the energy absorbing system 1000 is located at the front face of a storage rack or on both the front and back face.
• the frame 280 is preferably a relatively stiff structure compared to the flexible nature of the flexure member 100 (yield plates).
• the frame 280 is of a truss type configuration.
• the truss may be of a multitude of designs and configurations as appropriate for the construction and required functional characteristics of the energy absorbing system 1000.
• a stiff planar reinforced concrete element could also be used for frame 280.
• the energy absorbing system 1000 (control structure) is connected or able to be connected to the storage rack 3 or other structure at or near its upper region 27. It is retrofittable to the storage rack or other structure.
• the stiff frame 280 has little internal displacement (distortion) under applied load, the stiff frame 280 gets rocked or rotated about the pivot anchor 240.
• the role of the frame 280 is to transfer forces during length wise movement from the upper region 27 to the pivot 240.
• the rocking movement about the pivot anchor 240 is transferred to the spaced apart yield connectors (rotary units) 230.
• the rocking movement is then at least partially absorbed by the flexure members 100 (yield plates) (within and part of the rotary system) as these plastically flex.
• a lengthwise movement of the storage rack 3 to the right will cause clockwise rotation of the frame 280 about the pivot anchor 240.
• This will cause the extended arm of the yield connector (rotary unit) 230A to move in an upwards manner and the extended arm of the yield connectors 230B to move downwards.
• the lengthwise movement (induced by ground motion) of the upper region 27 is transferred into substantially rotational movement (in one embodiment) in the yield connectors 230.
• the rotational displacement (motion) of the yield plates within the rotary unit is directed and controlled by the control structure of which the yield plates are a part.
• the yield plates with their particular free translational or free translational and free rotational end region boundary conditions, in deforming (flexing) beyond their yield deflection produce a constant resistive yield force which in turn limits the forces that could develop within the control structure and any adjacent structure it may be seismically supportive of.
• Figure 5A 8i 5B show another embodiment of the energy absorbing system 1000.
• Figure 5A shows a control structure in its non-displaced condition
• Figure 5B shows a control structure in a displaced condition.
• the energy absorbing system 1000 effectively comprises two pivot anchors connected by a frame 380.
• the frame 380 pivots about each pivot anchor 340 and also connects to the rotary units (yield
• the yield connectors 331-334 are rotary units of which the flexure members (yield plates) are part of.
• the control structure of Figures 5A and 5B is a pivotably based rocker frame assembly with rotary yield units.
• the energy absorbing system 1000 locates a rocker 2000 intermediate of two substantially stiff vertical chords 310 (also known as vertical chords) that can sway relative to the ground.
• the vertical chords 310 are pivotally connected by pivot anchors 315 to the foundation 4.
• the vertical chords 310 are shown schematically in Figure 5.
• the rocker 2000 comprises a frame 380 and two pivot anchors 340.
• the four yield connectors 331 - 334 are engaged to the respective vertical chords 310.
• the yield connectors 331-334 are rotary units (with yield plates) which connect to vertical chords 310.
• the extended lever arms of the rotary units connect to the rocker 2000 via pin connected push rods.
• the frame 380 is preferably a stiff truss like configuration, as described previously, to help transfer forces and movement between the two stiff vertical chords 310.
• the function of the two pivot rocker 2000 is much the same as the rocker 2000 previously described. It comprises pivot anchors 240 that allow the frame to pivot relative the vertical chords 310.
• the yield connectors 331-334 and the frame pivots 240 in this embodiment are not anchoring the rocker 2000 or frame 380 directly to the foundation, but anchoring the frame 380 to each vertical chord 310 that in turn is pivotally anchored to the foundation 4.
• the foundation 4 is the floor of a structure, a foundation, or a beam or truss type system.
• the pivot anchor 315 is engaged to the foundation 4 and defines a rotational axis parallel to the foundation 4 and perpendicular to the lengthwise direction of the control structure.
• the upper regions 312 of the stiff vertical chords 310 may or may not be connected/engaged with the upper region of the storage rack 3 or building structure.
• first upper yield connector 331 and a second upper yield connector 332 respectively connected to a first of said stiff vertical chords 313 and a second of said stiff vertical chords 314.
• second first yield connector 333 and a lower second yield connector 334 connected to respective first vertical chord 313 and second vertical chord 314.
• FIG. 5C shows the displacement of the control structure for the case of differential vertical displacement between vertical supports due to vertical ground acceleration.
• Figure 5D shows displacement due to combined horizontal and vertical ground displacement.
• yield connector (rotary unit) 230 that may be used for many embodiments of the energy absorbing system 1000 herein described is shown in Figures 6A - 6E.
• the flexure members 100 peripheral end regions 232 should be able to translate freely without impediment or restriction, or being encumbered, fettered or the like during a yielding condition.
• the ability of the end region 232 to translate relatively freely during yielding or flexing of the flexure member is preferred to allow the flexure member 100 to be pulled and deformed/deflected into a curve.
• the yield member 100 plates are free to flex simply and extend without generating any tensile or compressive membrane forces in the end regions 232 and hence within themselves and for the plate, shown in Figure 6, also be free to rotate at its end regions so as not to develop any unintended end moments.
• the peripheral end of the flexure member has a translational and rotational end condition as shown in Figures 6E, 7C and 7D.
• This particular free translational or free translational and free rotational boundary condition is an extension of the plate itself.
• the deforming length of the plate is able to change (increase/decrease) between its reaction points as the plate flexes.
• the peripheral end of the flexure plate described herein alternatively may be a continuous boundary with translational freedom or a rotationally restrained boundary with translational freedom as shown in Figures 15 and 16.
• Figures 14, 15, and 16 are of yield plates defined herein as DELTA plates (specifically DELTA4, DELTA5 and DELTA6). Their particular boundary conditions (e.g. sliding hinge) allow the yielding plate(s) to change length (extend/retract) along their deforming curves (between reaction points) as they elasto-plastically flex. The significance of this property/feature, which enables the yielding plate to maintain a constant resistive yield force as it elasto-plastically flexes to high-displacements is described in detail further on.
• the yield connector must also allow for relatively easy lateral translation of a flexure member 100 end region during yielding. This lateral translation during yielding, allows the flexure member 100 to deform and flex and extend during yielding without stretching, or generating membrane tension in the flexure member, or prying at the end regions. And subsequently the substantially lateral translation of an end region allows the flexure member 100 to be driven in the opposite direction, during its operational yielding in the opposite direction, without the flexure member 100 crumpling or kinking.
• Figure 6A shows the yield connector 230 (rotary unit) in non-deflected condition
• Figure 6B shows a yield connector 230, with the flexure members 100 in displaced form
• Figure 6A and 6B utilise a pin 234 and slot 235 system to allow both translation and rotation at end region 232.
• the slot or hinge is an extension of the plate itself. The deforming length of the plate along its line of flexure, inclusive of the slotted hinge, increases or decreases as the plate flexes. The pin remaining fixed in space.
• the rotary unit comprises a first part being a relatively inflexible circular drum 600 set between and rigidly connected at each of its ends to rotor plates 601 each with an integral arm 602 which extends from the rotor plates and pin and slot connects (with return spring) with the ties 603 (or push rods) (first structural member) of the control structure.
• Flexure member(s) (plates) 100 are rigidly fixed one end (first region) 100 to, and distributed around, the circumference of the drum (first anchor) 600 in the form of an impeller.
• the first region of the plate moving in a circular arc with the first anchor at the rotatable drum.
• the first part of the rotary unit comprises the drum 600, rotors 601 with arms 602, and flexure plate(s) 100.
• This assembly is supported off an axle shaft 604 centroidal with the rotational axis of the drum and which rotationally connects the first part with the second part of the rotary unit which comprises an outer casing 605 or housing which is mounted off a horizontal structural base 4 or foundation (second structural member).
• peripheral ends (second region) 232 of the flexure member(s) (plates) (opposite the first region of the plate 231 rigidly fixed to the drum 600) have particular translational or translational and rotational boundary conditions 235 and are restrained from circular arc motion at their ends by pins (second anchor) 234 connecting their translationally or translationally and rotationally free end(s) (second region)
• the rotary unit 230 again comprises a relatively inflexible rotatable inner circular drum(s) (first anchor) 600 to and about which the flexure member(s) (e.g. plates) 100 are rigidly fixed at their first region 231 and distributed around the circumference of the drum (first anchor) 600 in the form of an impeller.
• the peripheral end (second region) 232/235 of the flexure member(s) (plates) 100 again have their particular translational or translational and rotational boundary conditions 235 and are restrained from circular arc motion at their ends by pins (second anchors) 234 connecting the peripheral ends (second region) 232/235 with a second (outer) annulus 607 (second part of rotary unit) of the form of a turbine casing which is concentric with the inner rotatable drum 600 (first part of rotary unit).
• the outer (casing) 607 is fixed against movement and anchors to a structural base 4 (second structural member).
• the inner rotatable drum(s) 600 may be set between circular end plates (rotor plates) 601 which are rigidly fixed to and supported off a torque axle shaft 604 rotatably fixed to a structural base 609.
• a rigid arm 606 located exterior to the concentric drums 600, 607 connects orthogonally with the axis of the torque shaft 604 and extends to pin and slot connect (with return spring) 608 at its opposite end with the push rods 603 of the control structure (first structural member).
• the inner rotatable drum 600 extends beyond the outer circular casing 607 to also function as both the first anchor 600 and the torque shaft.
• Figures 7E - 7H show various arrangements of rotary units in plan view.
• Figure 7E shows a single rotary unit with a pair of symmetrically arranged arms.
• Figure 7F shows a single rotary unit eccentric to the push rods of the rocker frame 2000.
• Figure 7G shows a pair of rotary units in transverse or parallel formation, overall centred on the rocker frame.
• Figure 7H shows a pair of rotary units longitudinally arranged or in series, overall centred of the rocker frame 2000.
• Figures 7G and 7H can be combined to form an overall system with four rotary units.
• the horizontally extended arms 602 of Figures 6 and 7 can similarly be vertically extended.
• FIG. 8A A detailed view of the pivot anchor 340 engaged to a vertical chord 310 as per the configuration of Figure 5A is shown in a side view in Figure 8A.
• a plan cross sectional view is shown in Figure 8B.
• the pivot anchor 340 is pinned by a pin 342 to the vertical chord 310 through the centroid of the vertical chord.
• the pivot anchor 340 has a pivot axis 341, and the pin 342 allows the frame 280 to pivot about the pivot axis 341 on the vertical chord 310.
• Figures 9 and 10 show two embodiments of the energy absorbing system 1000.
• the system 1000 comprises a two pivot rocker 2000 as previously described. Instead of the system 1000 being engaged intermediate two vertical chords as in figure 5, it is engaged between a base (like a foundation 4 or floor) and a beam, roof, ceiling or upper region of a rack 2.
• each energy absorbing structures 1000 there may be multiple energy absorbing structures 1000.
• a very tall (and/or heavy) storage rack 2 or structure may have four to twenty (or more) energy absorbing structures 1000 spaced apart along its height.
• each energy absorbing structures 1000 is preferably identically configured and of a kind herein described.
• top hat 500 such as a stiff beam or truss
• a lower beam or foundation of a storage rack may be connected to a top hat 500, such as a stiff beam or truss, and a lower beam or foundation of a storage rack.
• the top hat 500 may be connected to the plan bracing of the storage rack.
• the top hat 500 is connected to the upper pivot of rocker 2000.
• the top hat 500 both increases the elastic stiffness of the control structure, reducing its elasto-plastic displacement during a seismic event and increases the strength and energy absorbing capacity of the control structure.
• These lateral extensions of a system can be attached to plan bracing of a storage rack or structure and increases the amount of contact and leverage the energy absorbing structure 1000 has with the rack 2.
• Ties 501 may also be used where the system is used on the end of a storage rack, and not on the side of a rack.
• Figure 10 shows a further embodiment where a top hat joins to energy absorbing structure 1000.
• the energy absorbing structures 1000 is engaged at their upper and bottom regions so the effects of any lateral movement will be moved through into each yield connectors much like as described in Figure 5.
• FIG. 11 An example of an energy absorbing structure 1000 (control structure) in a general building structure form is shown in Figure 11 where the stiff vertical chords are shown as trusses.
• FIG. 11 A close-up view of the yield connectors (rotary units) 230, having multiple flexure members 100 (plates) joined to a frame 380, and the vertical chord 310 is as shown in Figures 6 and 7.
• FIG. 12 A further embodiment of an energy absorbing system 1000 - 'shear type' embodiment, with 'shear type' yield connectors 230, is shown in figures 12 and 13.
• flexural yielding in the plates is a response to the inter-lamina shear forces and displacements generated between an exterior chord and an interior frame chord as the pivotably based control structure sways in response to ground motion input.
• Figure 12 shows an energy absorbing system 1000 (control structure), with a frame 280 pivotable about a pivoting anchor 240.
• the frame 280, and pivot anchor 240 are as described previously.
• the yield connectors (rotary units) 230 are located on either side of the frame 280.
• Two stiff vertical chords 310 are located on either side of the frame 280, and are pivotably anchored to the foundation (or like, such as a floor or beam) preferably by a vertical chord pivot 315.
• Intermediate each vertical chord and the frame 280 are one or more yield connectors 230.
• the yield connectors 230 transfer inter-lamina shear force between the exterior chords 310 and the interior chords of the frame 280.
• This shear force rotates the drum of the rotary unit relative to its casing and produces flexing in the plates (flexure member 100).
• Their flexural yielding absorbs energy and limits forces within the control structure or any adjacent structure it may be seismically supportive of.
• the control structure produces a shearing motion between the frame 280 and a stiff vertical chord 310 when the system is rocked by an earthquake for example.
• This embodiment still shares the same concepts as the energy absorbing systems 1000 as previously described - where the rocker 2000, translates lateral movement from the upper region 27 about the pivot anchor 240, to thus influence the yield connectors (rotary units) 230 on each lateral side of the pivot anchor 240.
• the 'shear type' energy absorbing system 1000 (control structure) may also be utilised in a horizontal configuration.
• the energy absorbing system 1000 is rotated horizontally.
• the two pivot 240 rocker 2000 is placed intermediate two stiff horizontal chords 510.
• Both the energy absorbing system 1000 and the horizontal chords 510 are retained and engaged intermediate two stiff pivotably based vertical chords 310 as previously described.
• the energy absorbing system 1000 shares the same yield connectors (rotary units) 230 as described earlier.
• the horizontal chords 510 are pivotally attached at each of their ends to the two spaced apart and pivotably based vertical chords 510.
• Figure 14A - a non-displaced condition The yield connectors 230 as used in the vertical or horizontal shear embodiment are shown in detail in Figure 14A - a non-displaced condition, and Figure 14B - a displaced condition.
• Figures 15 and 16 respectively show the cases of flexurally continuous and rotationally restrained inter annular shear transfer flexural plates. Non displaced and displaced conditions are shown.
• Figure 14 shows a simple embodiment with only one flexure member 100. In other embodiments there are multiple flexure members circumferentially distributed about and fixed to the surface of the drum of the rotary unit.
• the flexure member 100 is preferably connected at its end regions 231 and 232.
• the end regions of each flexure member 100 are connected to, or engage with the drum (inner annulus) 600 and circularly distributed pin restraints 234 fixed to the housing 605/607 of the yield connector (rotary unit).
• the yield connector (rotary unit) 230 is engaged intermediate or is integral with and along a) the vertical chord 310 and rocker 2000, in the vertical embodiment, or b) the horizontal chord 510 and rocker 2000, in the horizontal embodiment.
• each end region of the flexure member 100 has different engagement types. As shown in figure 14, one end region 231 of the flexure member 100 has a rigidly fixed connection which is rigidly constrained to the drum of the rotary unit. The opposite end region 232 of the flexure member 100 has a sliding and pivoting engagement with the pin restraints fixed to the outer housing of the rotary unit. The sliding engagement helps prevents the flexure member 100 (plates) from developing direct tensile or compressive membrane forces within itself.
• the ties 400 are preferably pin connected to the centrelines of the exterior chords 310 and the centreline of the frame 280.
• the ties 400 are seen in Figures 17A and 17B, a non-displaced and displaced condition respectively.
• Figure 17C shows the ties in a displaced condition for the horizontally orientated system.
• rocker frames with pin ended push rods which connect to horizontally or vertically mounted rotary units (yield connectors) ( Figures 3, 5, 9-11) are designated as ALPHA1 rocker frames
• flexure member(s) 100 plates with second end regions which are simply supported ( Figures 14), flexurally continuous ( Figures 15) or rotationally restrained ( Figures 16) are respectively designated as DELTA4, DELTA5, DELTA6 plates
• rotary units with side housings ( Figures 6) and rotary units with annular (turbine type) housing ( Figures 7) are respectively designated as BETA1 rotors and BETA2 rotors.
• the entire system is composed substantially of metal. Even more preferably, composed of steel.
• the pivotable anchors, chords, frame, trusses are substantially stiff and strong so as not to substantially flex or yield during a seismic event.
• the frame 280 could comprise a stiff planar reinforced concrete element. This results in a composite concrete/steel control structure.
• any of the embodiments above may utilise a secondary flexure member for added control and resilience ( Figures 18A and 18B).
• the secondary flexure member is intermediate a yield connectors (rotary units) and the equivalent foundation (i.e. the foundation 4 or a vertical chord, or ceiling).
• the secondary flexure members add in a second structural layer.
• the yield plates of the rotary units can have flexural deflection (travel) limiters (e.g. a drum rotation brake) which stop plastic flexure in them at a prescribed limit. Only after these limiters engage is the second tier system able to yield.
• the secondary flexure member allows the elastic frequency of the control structure, and any structure the control structure may be seismically supportive of, to be varied without change to the rotary units or plates within. As above it can also be used to provide a two-tier ductile system.
• Figure 18C shows a load-displacement graph for a two tier ductile system.
• Line a represents the elastic response of the yield plate (elastic stiffness ki) combined with the elastic response of the secondary flexural member (elastic stiffness k 2 ).
• Line b represents plastic yielding of the flexural plates at constant resistive yield force.
• Line c represents the continued elastic response of the secondary flexural member only, after the flexural displacement of the yielding plates has been stopped by motion or travel limiters, and line d represents the second tier of plastic yielding, this time in the secondary flexural member.
• a further embodiment is where a spring or elastic structural component is added to the pin ended ties connecting the frame 280 to the yield connectors in the ALPHA1 frame or a spring added at the connection of the exterior chords to the horizontal or vertical bases of the shear action ALPHA2 frames.
• This also allows another independent adjustment of the control structures natural elastic frequency.
• a ground 2 has been mentioned, it is envisaged that the ground could also be a floor or ceiling of a building or structure, a beam, or truss, or part of a structure that is engaged to the anti-racking system as described.
• the systems may be halved or doubled or so forth and still be effective.
• the energy absorbing system 1000 may only have one yield connector 232 on one side of the pivot anchor 240.
• the energy absorbing system Figure 17A may also be halved so there is only one set of yield connector 430 spaced between a frame 400 and one stiff column 310.
• characteristics of a structure or storage rack Such as the height of the structure or storage rack, the number of storage racks to restrain, the weight of the structure or storage rack, the weight of the goods or structure, the tendency and frequency and magnitude of seismic events where the structure or rack is installed. Furthermore these configurations may be adapted depending on the materials used and the factor of safety required.
• the control structure comprised of a base pivoting rocker frame assembly and force limiting and energy dissipating flexural members (plates) contained within rotary units, is able to form a kinematically simple and stable elasto- plastic mechanism which is able to flow and repetitively cycle, and sustain very high elasto-plastic (deformations) displacements and ductilities while maintaining a constant resistive yield force.
• the constant resistive yield force produced by the yielding flexural members enables the control structure, of which the rotary units are a part, to limit response accelerations and dynamic forces within itself, within its foundations, or within or any masses or structures it may be seismically supportive of as it resists and endures severe ground or base motion input.
• control structure produces a simple elasto-plastic dynamic response which is primarily of single degree of freedom. Its dynamic behaviour is consequently predictable and simple to analyse.
• the flexural members (plates) within the rotary units remain structurally stable while flexurally yielding about their minor bending axis to very high reversing elasto-plastic displacements (deformations).
• the flexural members are detailed to translate or translate and rotate at one of their end regions allowing them to flex (deform) to very high elasto- plastic displacements without generating any membrane stresses within themselves.
• the flexural members (plates) and rotary units containing them are able to maintain a high and consistent
• the attributes of the flexural plates Because of the form of the overall control structure, the attributes of the flexural plates; high ductility, stability, toughness, constant resistive yield force, analytical simplicity, predictable response and load test established performance, all translate to be attributes of the control structure as a whole.
• the grade and type of material (e.g. steel) of the yielding elements (plates) is able to be specified independently of the material (e.g. steel) used for the overall superstructure of the control structure.
• the constant resistive force produced by the rotary units in yielding, and the subsequent constant resistive yield force of the control structure as a whole, is able to be continuously adjusted simply by varying the length of the lever arm (extended arm) of the rotary unit, i.e. without any change to the flexural members of the rotary unit.
• a secondary flexural base member integral with the rotary unit in conjunction with the variable length lever and of the rotary unit allows both the constant resistive yield force of the control structure and the elastic natural frequency of the control structure to be each continuously and independently varied without any change made to the flexural members of the rotary unit.
• Elasto-plastic yielding (deformation) within the control structure is confined to flexural yielding of the plates within the rotary units. These plates and units are able to be replaced while the overall structure is retained and re-aligned.
• the yielding elements (plates) and rotary units, on which the structural and dynamic performance of the control structure and any other control structure it may be seismically supportive of, are dependent, are able to be independently produced using independently sourced materials in a quality controlled environment (i.e. factory).
• the rotary units smooths the effect of any material or construction (e.g. weld) defects or variations within a particular plate or unit. That is, the rotary units are able to provide a high degree of structural redundancy (backup) to overall structure.
• the rotary units are able to contain multiple flexural yield members (plates) distributed around their rotatable drum (first part) which are able to produce a high combined resistive yield force; while the rotary unit is able to be relatively compact.
• the yield plates (with their particular boundary conditions which enable them produce a constant resistive yield force while flexing to high elasto-plastic displacements) limit and control internal (dynamic) forces within the control structure (or structure the control structure is seismically supportive of) as the control structure resists and endures input. Because of the reduced internal forces, the control structure's superstructure its supporting foundations and any structure it is seismically supportive of are able to be more economically designed.
• the constant resistive yield force produced by the plates while flexing to very high elasto-plastic displacements and very high ductilities (plastic strains) allows a constant value for yield strength to be used in an elasto-plastic time history analysis.
• the accuracy and reliability of the analysis is maintained at very high ductilities. While allowances are made for yield plateau gradients and strain hardening with analysis of conventional structures, accuracy and reliability of the analysis is rapidly lost with increasing ductilities (plastic straining). For example the assumption of a bi-linear material response with a simple 5% yield plateau, results in strengths (used in the analysis) of twice initial yield strength at ductilities of 20 and three times initial yield strength at ductilities of 40. These values resulting in both an incorrect and unsafe analysis. All plates (flexure member 100) described here are able to cyclically flex to high elasto-plastic displacements and high ductilities while remaining stable and maintaining a constant resistive yield force.
• control structures that they are part of are consequently also able to maintain a constant resistive yield, and limit forces generated within their structures as they endure and respond to base motion (seismic) input.
• base motion spontaneous
• the particular boundary conditions of the plate(s), which enables it to produce a constant resistive yield force while flexing to high elasto-plastic displacements are described in detail further on.
• the flexural member's (plate's) geometry (shape) and strength along its direction of flexing is configured so that flexural yielding (i.e. plastic flow, plastic strains, plastic curvature) within the plate (refer Figures 501, 502, 503) is preferably confined to a specific finite 'yield zone' 5000 within the end regions 5002, 5004 of the plate immediately adjacent the plate's anchors 5003, 5005.
• flexural yielding i.e. plastic flow, plastic strains, plastic curvature
• the plate remains preferably elastic 5001 between the yield zone 5000 within the first region(s) 5002 of the plate adjacent its first anchor 5003 and the distal yield zone 5000 within the second end region(s) 5004 or between the yield zone 5000 within the first end region 5002 (adjacent the first anchor) 5003 of the plate and a distal non-yielding second end region 5004 (adjacent a second anchor) 5005.
• the elasto-plastic deflection profiles shown in Figure 501A are a direct trace taken from a rectangular constant section (prismatic) 8mm plate which was cyclically load tested, first to ten load reversals, each to an elasto-plastic to elastic limit deflection ratio (ductility factor) of 25 and then into a final ratio (ductility) set of 50.
• a constant yield load and yield zone was obtained with each cycle with no breakdown (e.g. cracking or splitting) in the plate.
• the natural extent of the yield zone obtained from such testing can be further ensured, controlled or reduced by reduction (necking) of the width (or thickness) of the plate in the yield zone regions as shown in Figures 501C, 502C, 503C.
• the yield zone region of the plate may be tapered as in Figure 504.
• Figures 600 to 606 show that by simply varying only the length of the extended arm (lever arm) of the rotor plate of the rotary unit, the constant resistive yield force of the control structure (as a whole) is directly and proportionally varied. That is, the constant resistive force, R, ( Figures 601 & 603) or torque, T, produced by the elasto- plastically flexing yield plates within the rotary unit(s) is maintained, while the subsequent (geared) constant resistive yield force of the control structure (equivalent to V, Figures 604, 605) may be continuously adjusted (varied) by changing the lever arm length from say a to b ( Figures 600 to 603), i.e. the rotary unit has gearing adjustment.
• the elastic natural frequency of the control structure as a whole is also subsequently varied with the change in lever arm length (while the structural (global) displacement ductility capacity of the control structure is maintained).
• a secondary flexure base member ( Figure 606) integral with the rotary unit allows for both the constant resistive yield force of the control structure and its elastic natural frequency to be each continuously and independently adjusted (variable). This allows for the elastic and elasto-plastic displacement, velocity and acceleration response (response spectra) of the control structure to be continuously varied, with no change made to the
• superstructure e.g. rocker frame
• the control structure or the flexural members of the rotary unit, or any structure it may be seismically supportive of.
• Figure 610 shows a further embodiment of the rotary unit.
• the force limiting and energy dissipating flexural member(s) (plate) are located at the outer periphery of the rotary unit.
• the rigid impeller arms rigidly connected circumferentially to the circular drum (cylinder), rotate with the drum, their peripheral pin ends arcing in a circular motion and causing the (second) push rods of the sleeve guided BETA1 rocker unit to elastically or elasto-plastically displace the DELTA1 yield plate, and similarly produce a constant resistive yield force, R, and constant resistive torque, T.
• the length, LI, of the extended lever arm of the rotor plate (integral with the drum and pin/slot (with return spring) connecting to the push rods of the control structure) can be continuously varied (or geared) to adjust the constant resistive yield force, P, of the push rods, and the constant resistive force, V, of the control structure as a whole.
• a secondary flexure member base can be integrated with the rotary unit to provide continuous and independent adjustment of both the resistive yield force and elastic natural frequency of the control structure as a whole.
• the flexure member (DELTA1 yield plate) of Figure 610 is substituted with another type or form of force limiter and energy dissipater.
• Figure 612 shows a part of Figure 611 in displaced form.
• Figure 613 shows the general force limiter and energy dissipater of Figure 611 as a clamped friction plate(s) with slotted central plate.
• the threshold force, R is the force required to overcome the resisting friction forces between the friction plates, which are clamped together by friction grip bolts, with or without spring washers, to a known and specified clamping force, C.
• the force, R, required to slide the plates is preferably constant while the plates slide.
• the force, R determined by load test.
• Friction unit assemblies discussed herein typically consist of three friction block or friction plate elements. These comprise a slotted central or interior plate or block sandwiched between two outer or exterior plates. The clamping force from a tensioned bolt or sprung washer is applied directly to the outer plates only. That is, bolt heads, bolt nuts or sprung washers are in contact only with the outer plates or blocks. Only the inner plate is slotted. The contact surfaces (friction surfaces) between the inner plate and outer plates are able to displace (slide) without exerting any lateral force on the clamping bolts.
• Figure 614 shows a further embodiment of a rotary unit.
• the rotatable plate connects with the second part of the rotary, unit (here annular rings, either side of the central plate), with clamping friction grip bolts with or without spring washers.
• the two parts of the rotary unit will rotatably displace relative to each other once the frictional resistance of the plates is overcome, the force required to overcome this frictional resistance, R, preferably constant as the plates slide relative to each other.
• Figure 615 shows the non-displaced and displaced forms of the clamped regions of the plates.
• Figure 616 shows a further embodiment of a rotary unit.
• the lever arm length is a and the resistive force within the push rod of the control structure is Pi.
• Figure 617 shows a rotary unit similar to Figure 616 but here the lever arm length is b and the resistive force within the push rod of the control structure is P2.
• varying the length of the extended lever arm alone allows for adjustment of the force P in the push rods of the control structure, and the resistive force of the control structure as a whole.
• a secondary flexure base member is added to the rotary units of Figures 616/617 in Figure 623. This, as previously, allows for both the resistive force of the control structure and its elastic natural frequency to be each continuously and independently adjusted.
• the (elastic) stiffness of the rotary units of Figures 616 and 617 is very high prior to frictional forces being overcome.
• the addition of the secondary flexure member base allows for this elastic stiffness to be reduced and the elastic response of the control structure modified.
• Figure 618 shows the non-displaced and displaced form of the clamped regions of the rotary units of Figures 616 and 617.
• Figure 619 shows a section through Figures 616 and 617. Here the continuous annular contact (friction) plates (rings) of the first and second parts of the rotary unit are shown with a clamping force, C, and the force, R, produced at the contact points as the plates slide relative to each other.
• Figure 620 shows a further embodiment where the friction plates of the first part of the rotary unit are individual (shoe) plates.
• Figure 621 shows a section through Figure 620.
• Figure 622 shows a schematic part view of the tension bolts through the outer annular (first) part of Figure 621, and through the slotted pads of the inner second part.
• Figure 624 shows a schematic section similar to Figure 619, but where the rotary unit has a flat inner disc and external lever arms, the slotted inner disc rotating with the lever arms.
• Figure 625 shows a case similar to Figure 624 but where the external plates rotate with the lever arm, both relative to the slotted inner plate (disc).
• Figures 628A, 628B, 628C show various schematic sections of rotary friction units with friction units (e.g. block) centrally located and rotating with lever arms, both located between outer plates.
• Figure 629 shows a plan view schematic of Figure 628A.
• Figure 630 shows a rotary unit similar to the rotary unit(s) of Figure 7; but here the flexure members (plates) are located
• Figure 631 shows a section of Figure 630.
• Figure 632 shows a further embodiment of a rotary unit with DELTA4 yield plates.
• the first part of the rotary unit comprises a circular disc (single or double disk) to which the flexure members (plates) are fixed, (the plane of the flexure members normal (orthogonal) to the plane of the disc) and distributed about the circumferential periphery of the disc (first part).
• a lever arm in the plane or parallel with the plane of the first part (disc) and integral with the first part; extends from the axis of rotation of the first part and pin/slot connects with a first structural member (show in this case as a push rod of a control structure).
• Figure 633 shows a part front elevation of the flexure member with stiffening and anchoring annular rings in the (dotted) background and the outer circular edge of the first part (the flexure member projecting out of the page) .
• Figure 634 shows a side elevation of a flexure member (plate) fixing one end to the first part of the rotary unit, (here a double disc with connecting annular rings which also provide anchorage for the flexure member).
• the opposite end of the flexure member comprises a sliding hinge, as described previously, connecting with (around) the anchor pin (shaft) of the second part of the rotary unit.
• the second part of the rotary unit also being a circular disc rigidly connecting to a second structural member (shown here as a foundation base). Distributed around its circumferential periphery and pin connecting to the circular disk of the second part, are pivotable connectors within which the anchor pins (shafts) are located.
• Figure 639 shows the first and second parts of this rotary unit rotatably connecting at their axis of rotation and further connecting at their circumferential periphery via connection between the flexure members (plates) (fixed to the first part of the rotary unit) and the anchor pins (rods/shafts) (pivotably connected to the second part of the rotary unit).
• Figure 635 shows a plan view of Figure 634.
• Figure 636 shows an end elevation of a non-displaced flexure member (similar to Figure 633), along with the location of the connecting pivotable anchor pin (shaft) all relative to the axis of rotation.
• Figure 637 shows the displaced form of Figure 636.
• the flexure member has rotated and translated both horizontally and vertically relative to its non-displaced position and the anchor pin it connects with has pivoted (rotated) with the flexure member to the same angle of rotation as the flexure member.
• the sliding hinge of the flexure member has also translated, relatively, along the rotated axis of the anchor pin (shaft).
• Figure 638 shows a plan view of the displaced form of the flexure member (plate) inclusive of its anchor pin (shaft) along the principal line of rotation.
• the principal direction of flexure of the elastic or elasto-plastically flexing yield plate is parallel with the axis of rotation of the rotary unit.
• the principal direction of flexure of their yield plates is normal (orthogonal) to the axis of rotation of the rotary unit.
• no membrane forces or torsional stresses
• the flexure member yields at a constant resistive yield force to high elasto-plastic displacements.
• the rotary unit subsequently, rotatably yields at a constant resistive yield force (torque) and the control structure it is part of yields at a constant resistive yield force as it resists and endures ground (base) motion input.
• Figures 640, 641, 642 (similar to the rotary friction yield units of Figure 628), show various schematic sections of rotary yield units, where the yield plates are connected (anchored) to the peripheral edges of two integral discs (Part A) which are centred on two outer discs (Part B).
• Figure 643 shows a plan view schematic of Figure 640.
• a force limiter and energy dissipater of specific or general form as shown in Figures 610 to 613 is, as with Figure 632, located and pivotably connected about the peripheral circumference of a rotary unit, comprised of circular disks.
• Figure 646 shows a plan view of Figure 645.
• the inner disc is the first part of the rotary unit (with as previously, extended and integral lever arm) and the outer disc(s) is the second part fixed to a second structural member.
• Figure 647 shows a part schematic, of one case, where the force limiter and energy dissipater is comprised of friction plates, as described previously, within the rotary unit of Figure 645.
• Figure 650 shows a schematic view of a rotary friction unit similar to Figure 628, but where an elastic component, in this case in the form of a cantilever spring leaf (or plate) has been incorporated within the rotary unit. This is in contrast to the case of the secondary flexural member, described above, which is integral with but exterior to the rotary units.
• Figure 654 shows a schematic cross section of Figure 650.
• a fixed or base anchored central plate is located between two outer plates which rotate with the lever arm(s) of the rotary plate which is integral with the outer circular plates. Clamped between the two outer plates are slotted friction blocks. Larger slots in the central plate allow the blocks to run directly through them.
• Figure 651A shows a part of the rotary unit in its non-displaced (or original) position.
• Figure 651B shows the outer plates displacing (rotating) relative to the inner plate.
• the inner friction blocks which are friction clamped (with or without tension washers) to the outer circular discs travel with the outer plates.
• the central friction blocks in displacing with the outer plates displace the elastic cantilever spring leaves which are fixed to the inner base fixed plate. Motion of the friction blocks (or shoes) clamped between and moving with the outer circular discs is hence (elastically) resisted by the spring leaves, this resistance force increasing with displacement of the friction pads (shoes) and the spring leaf until as in Figure 652A the friction shoes make contact with the end of the slot within the inner fixed plate. At this stage movement of both the friction shoe and elastic spring leaf is stopped (or arrested).
• Figure 652B shows the outer plate continuing to displace relative to the friction shoe.
• the tension clamping bolts (with or without tension washers) fixed to the outer plates able to displace (relatively) along the slots within the (inner) friction block.
• the frictional force overcome between the outer plates and the inner friction block(s) is preferably maintained as a constant resistive force as the outer plate displaces from its position in Figure 652B. If the clamping force between the inner block and outer plates and hence frictional resistive force is configured to match the elastic resistive force of the elastic cantilever spring leaves at their travel or displacement limit as shown in Figure 652A, an elasto-frictional system equivalent to an elasto-plastic system is obtained.
• the constant resistive yield force produced by the plastically straining yield plates with their particular boundary conditions equating with the preferably constant resistive friction force produced between the outer plates and inner friction block as they displace
• Figure 653 schematically shows the elastic (yield equivalent) displacement component of the system, a, and the fricitonal (or plastic) displacement component b.
• Figure 655 shows the tension clamping bolts fixed in position relative to the outer plate, and moving relative the othe inner friction block.
• Figure 656 shows a case similar to above, but here the clamping bolts do not run through the friction block but are located outside and adjacent to it.
• the rotary unit of Figure 656 is here shown integral with a secondary flexural member.
• Figure 657 shows a schematic cross section of Figure 656.
• Figure 658 shows the clamping bolts (with or without tension washers) located within the outer plates and within the slotted inner plate.
• Figure 659 shows the friction block, as clamped between the two outer plates, being arrested from further movement as it makes contact with the end of the (larger) slot within the inner plate, and the outer plates (after overcoming friction resistant forces) continuing to displace, the clamping bolts moving with it within the (smaller) slots within the inner plate, and the frictional resistance force as the outer plates displace relative to the inner friction block being preferably constant.
• Figure 660 shows a schematic view of a rotary friction unit similar to those of Figures 650 and 656 but here the inner plate rotates with the lever arm of the unit.
• Figure 661 shows a schematic cross sectional view of Figure 660.
• Friction blocks are clamped either side of the central disc. As above the friction plates move with the inner disc while elastic plates (in contact with the friction plates) resist this motion but do not produce forces high enough to produce slippage between the friction blocks and the central plate.
• the displacing friction plates (rotating with inner plate) and flexing (spring) plates make contact with their travel limiters which are fixed and span across the two outer based fixed plates, they and the elastic spring plates are arrested or stopped from moving.
• the inner plate once it overcomes the frictional forces between it and the now arrested friction blocks, is able to continue moving, its clamping bolts travelling along the slots within the friction blocks.
• the inner plate outcrops are hence effectively slicing through the friction blocks while the friction blocks produce a preferably constant resistive (frictional) force to this motion.
• Figures 662 and 663 show a rotary friction unit similar in form to Figure 660 but where the outer plates move with the lever arm while the inner plate is base anchored. This is similar to the rotary unit of Figure 650.
• Figure 663 shows a schematic cross section of Figure 662.
• Figures 664 and 665 illustrate (in linear form) the movement of the friction blocks, plates (inner and outer), elastic spring plates and clamping bolts of Figure 660.
• Figure 664A shows the centred friction block (with slots), outer plate(s), clamping bolts (with or without tension washers), elastic spring plate and travel limiter all in initial position.
• Figure 664B shows the outer plate(s), (that is, the first part of rotary unit) displacing to the right.
• the central friction block clamped between the outer plates moves with the outer plates as it (friction block) pushes against the elastically flexing spring plate.
• the elastic force produced by the spring plate increasing as the friction block and connected (clamped) outer plates move further to the right, but not of a sufficient force to produce slippage between the friction block and outer plates.
• Figure 664C shows the spring plate making contact with the travel limiter and both the flexing of the spring plate and displacement of the friction block stopping. At this instant there is still no slippage between the friction block and outer plates.
• Figure 664D shows the outer plate(s) displaced further to the right. For the outer plates to achieve displacement further to the right of their position shown in Figure 664C they must first overcome the frictional forces between them and the central friction block. Once this is achieved the plates are able to move from their position in Figure 664C to their position in Figure 664D, effectively pushing against a constant resistive (frictional) force.
• Figure 665 shows a schematic view of the clamping tension bolts fixed to the outer plates and relative to the inner friction block.
• Figures 666A and 666B show the same system as described above but located within a sleeve guided BETA rocker unit similar to that shown in Figure 645.
• Figure 667 shows a cross sectional view of Figures 666A and 666B inclusive of guides.
• the friction blocks/plates/shoes/pads and their interface surfaces can be made or configured from or by any number or types or materials.
• the elasto-frictional rotary unit either as a stand alone unit or located and distributed within a pivotably based rocker structure is able to produce a preferably constant resistive (frictional) force as clamped plates within it slide or slip relative to each other.
• the elastic component of the rotary (friction) unit being able to be provided by spring plates or similar, within the rotary unit, by secondary flexural members integral with but exterior to the rotary unit, or by the use of both.
• the elastic component of the friction rotary unit also able to be configured, so that slippage occurs between the friction plates once a resistive elastic force within the elastic component (e.g. spring plates) is reached. In other words, slippage at a constant resistive force could be achieved through use of the elastic components alone, that is without travel limiters (motion blocks) as described above.
• the rotary friction unit of Figure 660 is able to be configured with an elastic component (e.g. spanning plate) which would produce the same elastic response as the (elasto-plastic) yield plates of the rotary yield unit of for example Figure 641 or similar.
• an elastic component e.g. spanning plate
• the frictional yield (slip) force of the friction plates of Figure 660 is able to be configured to produce the same (plastic) yield force produced by the yield plates of the rotary yield unit of Figure 641 or similar.
• secondary flexural members are able to be added to both the rotary yield and rotary friction units of for example Figures 641 or 660.
• the elasto-plastic response of both the rotary friction units are hence able to be configured to be effectively the same, each also with the same adjustable length lever arms and each being able to be developed into a two tier ductile system.
• Figures 668-1 to 668-15 show further rotary friction units where the friction elements comprise continuous circular rings or circular curved pads/shows/blocks.
• the interface displacement between the curved surfaces of the friction elements is tangential to the curved surfaces, the tangent normal to both the axis of rotation of the rotary unit and to the radial, to the surface line.
• Figure 668-1 shows a schematic side elevation of a part inner ring integral with two discs and lever arms. They are located within two outer discs which both, anchor or prevent the friction shoes (clamped to the inner ring and spanning laterally between the two outer discs) from arcing, and anchor the whole assembly to a structural base.
• Figure 668-2 shows a schematic side elevation of the two outer discs, with the friction shoes which are spanning to and laterally restrained by them.
• Figure 668-3 shows a cross sectional view of the two base anchored outer discs, the inner rotatable discs, the continuous ring friction element and the two friction shoes which span to the outer discs and between which the continuous ring is slot clamped.
• Figure 668-4 shows a plan view of the continuous ring (slotted), the friction shows and the inner and outer discs.
• Figure 668-5 shows a schematic elevation of a rotary unit comprised of two outer discs, each with a continuous circular friction ring, all of which are integral and rotate with the lever arm(s), and a central and slotted disc which anchors the assembly to a structural base.
• the slots within the centred and base anchored discs are to both enable the friction shoes to be freely clamped to each outer friction ring, and to restrain the friction shoes from circular arcing again, the continuous friction ring clamped between the laterally (or arc) anchored friction shoes, being slotted. That is the rings rotate relative to the shoes, the slotted friction element being the one sandwiched between the two outer friction shoes.
• Figure 668-6 shows a detail of the friction shoes, slot in inner plate and continuous friction ring.
• Figure 668-7 shows a plan view of section 668-6.
• Figure 668-8 shows a schematic elevation of a friction rotary unit similar to that of Figure 668-5, but here the friction pads are prismatic, that is they run continuously through holes in the inner disc and are located by guides to the inner plate, as shown on Figure 668-9.
• Figure 668-10 shows a schematic elevation of a rotary friction unit in which the larger central curved shoe spans between and is anchored to the two outer discs which are integral with the lever arms and are the rotatable part of the unit.
• the larger (and slotted) friction shoe is clamped between the two smaller friction shoes, which laterally span between two inner discs of the unit which both restrain the smaller shoes from arcing action and anchor the assembly to a structural base.
• the cutout on Figures 668-10 and 668-11 is to the two inner discs. It restrains the smaller shoes from arcing, while allowing the inner shoe to rotate.
• Figure 668-12 is a sectional view of the plate assembly and Figure 668-13 a plan view.
• Figure 668-14 shows a part elevation detail similar to Figure 668-11 but here an elastic plate(s) has been introduced as an internal elastic component to the rotary unit.
• the (cantilever) plates are in contact with the smaller outer friction shoes as the larger inner friction shoe rotates, the clamped outer plates travel with it but are subjected to an increasing (with displacement) elastic resistance from the cantilever plates as shown in Figure 668-15 and as in previous rotary friction units described above, the elastic plates are able to flex until they make contact with the cutout of the inner ring. At this stage both elastic displacement of the (spring) plates and
• the rotary friction unit as with other rotary friction units previously described is responding elasto- plastically.
• a secondary flexural member is also able to be added to the rotary units to provide a (or further) elastic component.
• the device referenced above is an elastic device that is configured to return to its origin after load is removed, but to also dissipate energy through frictional work, in the process.
• the device has frictionless (or very low friction) clamped sloping contact surfaces and frictional flat (or horizontal) clamped contact surfaces.
• the frictionless sloping surfaces (which may also be of a roller surface form) provide the elastic component of the device, and separately to it, the flat clamped frictional contact surfaces provide the plastic component of the device.
• the result being an elasto-plastic system which responds to a similar capacity or performance as the rotary friction units discussed previously.
• FIG. 669-1 An elasto-plastic friction yield block with frictionless sloping surfaces and flat frictional contact surfaces (relative to clamping forces) is as shown in Figure 669-1. It is herein referred to as a corrugated block or corrugated friction yield block. In the initial or non-displaced position in Figure 669-1, only the sloping surfaces are in (clamped) contact. Tension, T, in the ties (whether pre-tensioned or not) increases with relative displacement of the sloping surfaces (up the slopes) as shown in Figure 669-2 until it reaches a maximum value, say T m , at the top of the respective slopes and before further displacement between two, now horizontal surfaces, clamped together with a constant clamped force T m .
• the two horizontal surfaces as shown in Figure 669-3 are providing a preferably constant resistive force to displacement.
• Figure 669-4 derives the basic force and equilibrium relationships between two clamped sloping frictional surfaces in contact and displacing one relative to the other.
• the (slotted) central block is moving to the left and the sloping surfaces of the two outer clamping blocks are relatively moving or sliding up the slopes of the central block.
• Displacement of the central block to the left is resisted by the horizontal components (summed) of both the direct force, R, orthogonal to the surface, which is due to the transverse clamping force, T, and the frictional force, p.R, parallel to the surface and due to the orthogonal force R. That is, both forces are resisting displacement of the centre block to the left and force P is increasing with displacement in this direction.
• Equation 1) relates the force P at any time, t, to the clamping tension T(t), the angle of the contact surfaces, Q, and the coefficient of friction PSLI for displacement in this direction.
• Figure 669-5 is similar to Figure 669-4; but here the central block is moving to the right and force P is reducing (or unloading) with displacement in this direction.
• the direction of frictional resistance along the sloping surface has switched and its horizontal component is now in the opposite direction of the horizontal component of the force R, orthogonal to the surface.
• the relationship between the now reducing force, P, and again the clamping tension T(t), angle of surfaces, Q, and coefficient of friction psL2 for displacement in this direction is derived on Figure 669-5 as equation 2).
• Equations (1) and 2)) describe the loading and unloading paths of a clamped sloping frictional surface and are essentially the same as those given in the above referenced WIPO publication.
• Figure 669-8 shows an arbitrary normalised load path for a slope angle of 30° and with friction coefficients of 0.35 and 0.25 for loading and unloading respectively.
• Figure 669-9 shows the same case again of the clamped sloping frictional surfaces but here the clamping ties are pretensioned.
• Figure 669-10 considers the case of the two horizontal surfaces of the friction block displacing relative to each other, at a constant resistive force P y .
• T Tm
• PSL Pplateau
• equations 1) and 2) each reduce to
• the force P to displacement angle relationship is the same whether the central block is moving to the left (e.g. loading) or moving to the right (e.g. unloading), as shown on Figures 669-11 and 669-12.
• the load paths are on the same lines as with a conventional elastic straining system. This is simply because the clamping tension bolts are elastically straining.
• varying the slope of the contact surfaces while maintaining clamping force T) varies the elastic stiffness, k, of the system, as shown in Figure 669-13 where:
• Figure 669-14 shows the combined force-displacement relationships of the corrugated system with frictionless sloping surfaces and horizontal or flat surfaces with a coefficient of friction (e.g. p Pia teau) . This being the same load-displacement relationship as a conventional ideal elasto-plastic system.
• the load-displacement path of, for example, the central block moving to the left as shown in Figure 669-4 differs from the central block moving to the right as shown in Figure 669- 5.
• the response remains linear as for the frictionless case, but the two load directions each have a different stiffness and a different load path as shown in Figure 669-15.
• Equation 1) describes the increasing load with increasing displacement as shown on line a).
• Line b) is a result of the switch in direction of the frictional forces along the sloping surfaces with change in displacement direction, and line c) is that of reducing load with displacement as described by equation 2) as the sloping surfaces return to origin.
• Line d) on the same figure represents the case of a frictionless sloping surface and of similar surface slope angle.
• the mechanics of the system can be illustrated in a simple form by use of conventional elastic springs or elastic rods.
• Figure 669-16 shows an elastic rod which is progressively loaded and unloaded.
• Figure 669-17 shows its load path which is along the same straight line for loading and unloading; the rod being of a linear elastic material.
• Figure 669-18 shows another elastic rod subject to progressive loading and unloading; but here a restraint against displacement is located at around half the total length of the rod.
• the rod is first subject to a force PA acting to the left; and the right hand side, of initial length L, contracts by DA. Further load is applied in the same direction load magnitude PB and the right hand side of the rod contracts (or compresses) further to displacement DB.
• Figure 669-19 shows the linear response along the upper line to load PB and displacement DB.
• the centrally located restraint is removed which results in a reduction in elastic stiffness, a relaxation of the system and an instantaneous or step drop of load PB to load Pc, while displacement remains constant.
• Load Pc is next reduced (part unloaded) to load PD.
• Load PD is then reduced further to load PE.
• the response again is linear, but along the lower line which is of a lower slope (i.e. lower stiffness) than the upper line. Load is reduced further until the rod returns to its original (total) length.
• the hatched area shown in Figure 669-22 is the difference between work done on (or internally by) the system as load is increased and work done on (or by) the system as displacement is reversed and load is reduced, and the elastic rod returns to its original length. This is not damping, which is a function of strain velocity, but simply the difference in work done by a system which has two elastic stiffness values, one for loading and one for unloading.
• Figure 669-23 shows the load (and unload) path of the conventional elastic rod of Figures 669-16 and 669-17 bisecting the upper and lower load path lines of the two- stiffness system of Figures 669-18 and 669-19.
• the elastic (strain) rod system of Figures 669-18 and 669-19 is similar to the elastic (friction) system of Figures 669-4 and 669-5.
• the load step of 6PB in Figure 669-19 equating to the reduction in load (or reversal of displacement direction) and reversal of frictional force direction on the sloping contact surface.
• Figure 669-24 shows the case of a corrugated friction block in which the clamps or clamping bolts are pretensioned.
• the blocks are internally strained but in a state of static equilibrium with the rotary units. That is, undisplaced, there is no effect on any structure they are a part of.
• a force Pi as shown in Figure 669-25 is required to maintain equilibrium.
• Figure 669-26 shows the elastic load displacement curve for the case of pretensioned corrugated blocks with frictionless sloping surfaces
• Figure 669-27 shows the elastic load displacement curve(s) for devices with friction forces along their sloping surfaces. There is little or no movement with initial force. This equates to a high initial stiffness and force resistance. With increasing load the system shifts from rigid to linear elastic and displaces along line a) on Figure 669-26 and along line b) on Figure 669-27.
• Figure 669-28 shows a further possible embodiment of this concept.
• the frictional resistance of the sloping surfaces is directionally sensitive, akin to a telemark ski.
• Figure 669-29 shows the closed loop return to origin load path. This is an elastic system of continuously variable stiffness. It resists lower applied loads with a higher stiffness (low displacements) but softens as load increases from for example a seismic event. The softening, or reduction in stiffness with load, reduces the natural frequency of masses (and structure) it may be seismically supportive of, and hence the response acceleration of masses supported by the control structure and forces within the control structure.
• Figure 669-30 shows the closed loop load path for clamped sloping surfaces with a friction component, and the single line load path of a clamped sloping surface of same slope angle but with no friction component.
• the elastic (frictionless) line typically lies close to the bisecting line of the closed loop path and, from above, the systems with friction and without friction respond with similar total energy while displacing to the same displacement and returning to origin. In static terms the system produces a greater resistive load under displacement than the frictionless system, but in dynamic terms attracts a higher force because it is a stiffer system.
• Figure 669-31A shows the load paths for sloping surfaces with and without a friction component for various surface slope angles and coefficients of friction.
• the stiffness under load (along line b)) of the systems with a friction component is around twice that of the sloping surface without a friction component (line a)). This will result in the acceleration response of masses (for same input) directly connected to the sloping (friction) system and forces in connecting structures (and their foundations) being of the order of 40 to 50% more than that of the frictionless (sloping) clamped system but with 70% the response displacement. Elastic strain energies in the (sloping) frictionless system will hence be of the same order as that of the same slope friction system.
• Figure 669-31B shows physically the angles (44° and 49°) of the frictionless contact surfaces required to produce the same
• Figure 669-31C shows the lower limit angle for frictional surfaces with frictional coefficients of 0.35 and 0.4 respectively. This is the angle below which (under clamping forces) the surfaces will not (without external force) return to origin (that is not slide back). This angle is simply the tan 1 PSL.
• Figure 669-31D shows the load paths of a pretensioned frictionless sloping surface element (lines a) and b)) and that (line c)) of sloping surface without
• Figure 669-31E shows the increasing slope or gradient of a clamped frictionless surface load path, with increasing slope angle, and constant clamping force.
• Figure 669-31H shows the elasto-plastic load displacement curves of clamped corrugated friction yield blocks with frictionless sloping (elastic) surfaces and frictional flat (plastic) surfaces.
• the frictionless clamped sloping surfaces or clamped roller surfaces
• the (clamped) frictional flat surfaces are providing the plastic component of the system.
• Figure 669-32 shows the load path for a conventional linear elastic system.
• the path represents any conventional linear elastic element or system, such as a flexing plate (or a yield plate in its elastic phase), a structure, or as discussed here two sloping frictionless surfaces which are clamped (obliquely) together.
• the area under the path (line a)) represents the (elastic strain) energy stored in the system or work done on the system by an applied load, or for the case of reducing load, the energy released by the system or (reverse) work done by/on the applied load.
• Figure 669-34 shows the load paths of the same systems for reversal of displacement direction and reducing load.
• the load path for the frictionless system (line a)) is the same as that in Figure 669-33 but as described above the load path c) for the friction system now lies below line a).
• the energy effectively released by the system is in this case lower than for the frictionless system. Again this is due to friction forces this time acting against stored elastic forces as displacement reduces to origin.
• the combined areas A1 and A2 ( Figure 669-35) represent unrecoverable or lost energy (through frictional displacement) in the load cycle of the friction system. That is, energy dissipation.
• Areas A1 and A2 are of similar order. That is, the increase in work done (or of internal forces) with displacement in one direction is of the same order as the decrease in work done (or of internal forces) with displacement in the opposite direction. Both relative to the frictionless (or neutral) sloping surface.
• Figure 669-36 shows the case of a frictionless sloping surface (or conventional elastic system) within an elasto-plastic system of yield strength P y .
• the plastic component is provided by for example the frictional resistance of two clamped flat surfaces.
• This is an ideal elasto-plastic response.
• the ideal elasto-plastic response is that of the rotary friction units described previously in which the elastic component is independently provided by, for example, a flexing plate and the plastic or yield component by two friction surfaces which are clamped together, the line or direction of the clamping forces being normal to their (flat or curving) contact surfaces.
• rotary units with flexural yield plates (being the principal subject here) that are able to produce a constant resistive yield force, also produce the ideal elasto-plastic response of Figure 669-36.
• Figure 669-37A further illustrates (in linear form) through the combination of a spring and flat frictional surfaces, the mechanics of a pretensioned clamped sloping frictional surface.
• both spring and frictional surface resist applied load.
• the outer blocks are relatively fixed in position.
• There is no displacement in the spring (or applied load) until the frictional resistance of the clamped flat surfaces is overcome.
• both spring and clamped surface work in unison to resist the applied load.
• Increase in resistance with displacement occurs in both the spring and the frictional surface. This is because the spring is elastically compressing and the clamping force on the flat surfaces is increasing with displacement.
• With change in displacement direction (or unloading) the direction of frictional resistance has reversed and spring force and frictional force are now in opposing directions and the magnitude of each is reducing with displacement.
• Figures 669-37B and 669-37C illustrate the mechanics of the rotary friction units described previously.
• the springs e.g. flexing plate
• Figure 669-38 shows a clamped corrugated friction yield block.
• the sloping surfaces at angle Q have no (or very low) friction component. That is the surfaces are frictionless.
• the flat surfaces however, have a friction component. That is they are frictional surfaces and with a friction coefficient of p Pia teau.
• Figure 669-39 shows the sloping frictionless surface(s) of Figure 669-38 displaced relative to each other.
• the clamping ties are stressed and providing a vertical clamping force, T, at the surface contacts. This resolves as a horizontal resistance force of
• Figure 669-39 shows the system at its elastic limit. With continued displacement in this direction it is the two horizontal surfaces that are in contact. With continued displacement the clamping force remains constant at Tm, and orthogonal to the two displacing surfaces. This produces a preferably constant resistive force with
• Figure 669-40 shows three elastic-plastic load paths.
• Figure 669-40A shows the case where the tangent value of the angle, Q, of the frictionless sloping surface is greater than the coefficient of friction of the flat surfaces
• Figure 669-40B shows the case where the tangent value is less than the coefficient of friction of the flat surfaces.
• Figure 669-40C shows the case where the tangent value of the angle of the frictionless sloping surfaces is the same as the coefficient of friction, p Pia teau, of the flat contact surfaces.
• Figure 669-40C is that of an ideal elasto-plastic response. If, for example, the coefficient of friction of the flat surfaces, p P iateau, was 0.3, for this ideal case the angle of the sloping frictionless surfaces would be 16.67° (i.e. tan -1 0.3). Similarly, if p p iateau was 0.4 the required slope would be 21.80° as shown in Figure 669-41.
• Figure 669-27 shows the load-displacement path of clamped frictional sloping surfaces which have been pretensioned.
• Figure 669-26 shows the load-displacement path of clamped frictionless surfaces which have also been pretensioned.
• the load path to pretension force Pi (and then beyond) is that of a rigid-elastic response.
• the ratio of response acceleration to base input acceleration will be high in the rigid region. That is for low ground accelerations response accelerations will be high.
• the corrugated friction yield block with frictionless sloping contact surfaces (elastic phase) and frictional flat contact surfaces (plastic phase) has the following properties: angle of frictionless sloping surfaces is able to be adjusted to a wide range of practicable angles, thus directly adjusting elastic stiffness, while ability to (elastically) return (slide back) to origin is not impeded by friction • in elastic state (displacing along frictionless sloping surfaces), it is able to be configured to maintain low response accelerations within masses it is supportive of
• the corrugated friction yield block returns to its origin, as with all elastic systems, only when its elastic strength or elastic yield displacement has not been exceeded. It (the block) is able to be configured to remain elastic at given earthquake input (or particular earthquake record). But when this magnitude is exceeded the friction yield block shifts into its plastic phase (that is shifts from frictionless sloping contact surfaces to frictional flat surfaces), where it is again able to be configured to endure and resist with constant resistive yield force considerably higher earthquake input (e.g. PGA). But once in this (plastic) stage the corrugated yield block does not (without an exterior force) return to its original state.
• Figure 669-50 shows the load-displacement paths for an elastic (that is return to origin) slip friction device with pre-tensioned clamped frictional sloping contact surfaces, as referenced above.
• the hatched area represents energy dissipation (non recoverable work done by the displacing frictional surfaces).
• Figure 669-51 shows the load displacement paths for a corrugated friction yield block, as discussed above, which comprises frictionless sloping surfaces and frictional flat surfaces.
• the elastic paths in Figure 669-51 are drawn to match the maximum resistive force and displacement that the device as shown in Figure 669-50 is configured for. That is, up to a resistive force P, both systems are elastic, and return to origin.
• the corrugated friction yield block has capacity for post-elastic displacement, and this capacity is increased simply by increasing the length of its flat contact surfaces.
• Figure 669-52 shows the elasto-plastic load displacement path of a flexural yield plate as described herein. The plate has an elastic displacement limit (to yield) of 1mm and is shown yielding to a total displacement of 30mm.
• Figures 669-53, 669-54, 669-55 show the elasto-plastic displacement curves for flexural yield plates of different sizes (here 8mm, 12mm and 8/10 space/8 composite) and of different spans, each producing different elastic stiffnesses, that is different load paths to yield displacement. Superimposed on these paths are the load paths of various clamped sloping frictional surfaces of similar elastic stiffness. From these load paths ductility factors for the yield plates may also be derived (in terms of energy) by determining the total area under the elasto-plastic curves and equating with the area of the elastic component. Effective ductility can similarly be derived from the load paths of the sloping frictional surfaces which have elastic and non-recoverable energy
• the flexibility (elastic stiffness) of the flexural yield plates (and rotary unit) is able to be adjusted directly by varying the thickness and/or span of the yield plates or indirectly by introducing a secondary flexural member or by adjustment of both.
• the yield strength (elastic limit strength) and yield displacement of the flexural yield plates is able to be adjusted by again varying the plate span or thickness, or further varying the plate material yield stress (e.g. type of steel), or varying the width of plates or number of plates. Both the flexibility and yield strength of the yield plates, that is their elastic parameters, are able to be configured with relative ease, to be the same as practicably any other elastic system.
• the system with the flexural yield plates, and of same elastic strength and stiffness as the frictional sloping surface system is able to provide or produce an elastic strength equivalent, in resisting a base motion input, of 10 times that of the sloping surface friction system while limiting and controlling forces within itself and any mass it may be seismically supportive of. That is, the flexural yield plate system is (conventionally) able to resist and endure a base motion input (i.e.
• PGA peak ground acceleration
• Figure 669-3 shows the case of the two clamped horizontal surfaces (in their effectively plastic phase). If (plastic) displacement stops (i.e. relative surface velocity is zero), the surfaces remain in this position. There is no springback or continuation into an elastic phase. Displacement must, this time, start from or continue directly into a plastic state. This is a rigid-plastic response, as opposed to the systems initial elasto-plastic response. The system is no longer emulating an elasto-plastic response with a finite stiffness (or elastic frequency), but at this time is behaving as a rigid-plastic system. This is illustrated by the vertical line to the right of the load-displacement Figure 669-70.
• the friction unit assemblies with flat clamped surfaces described previously (i.e.) not corrugated) and with an elastic component, are behaving in the same manner as a conventional elasto-plastic system which involves the elastic and plastic straining of ductile materials (e.g. steels).
• the elastic component of the friction unit comprises conventional elastic straining and the plastic component comprises the preferably constant resistive force produced by the relative displacement of the two clamped frictional surfaces.
• a ductility factor for the friction system can hence be obtained in the same way that it would for a straining system. That is the ratio of the total (elastic plus slip displacement) displacement to elastic (yield) displacement.
• the corrugated friction system behaves only in part as a conventional elasto-plastic system. As it displaces from its initial position with frictionless sloping surfaces displacing relative to each other, the system is behaving elastically, in that further force is required for the sloping forces to continue displacing (upwards), because with increasing displacement there is increasing (elastic) tension in the clamping bolts (and sprung washers if present) and increasing (force) resistance to displacement (the sloping surfaces returning to their initial positions with load reduction). As above, as the sloping surfaces reach their maximum relative (sloped) displacement, the force in the bolts (and sprung washers if present) is at a maximum.
• tension in the bolts remains preferably constant as does (preferably) the resistance force to further displacement (or force required to keep the surfaces displacing).
• Peak response accelerations of masses supported, by this system, or a conventional elasto-plastic system are governed by the yield strength of the system, and hence are no different between the two systems having the same yield strength.
• the significance of having an elastic component (or not having one) (in either a straining or friction system) is that it enables either system (the elastic component) to sustain or endure higher base or ground motion input (accelerations) before plastic yielding occurs in the plastic straining system or before sliding occurs in the friction system, and hence before permanent deformation occurs in either system.
• a rigid-plastic or near rigid-plastic system or a rigid-friction system of a given yield strength or slip resistance will plastically displace (plastically strain) or in the friction system (slip); at lower base or ground accelerations than an elasto-plastic or elasto-friction system of the same yield strength or slip resistance, but configured with sufficient flexibility in its elastic range.
• a secondary flexural member to a rotary unit which contains the corrugated friction blocks enables the system to behave as an elasto-plastic system at all stages, but one in which there are two elastic components. That is secondary flexural member flexibility when friction surfaces are horizontal and secondary flexural member combined with effective elastic component when the two contact surfaces are sloping surfaces.
• Figure 669-71 shows a schematic view of DELTA1 yield plates within a sleeve guided rocker unit.
• Figures 669-72 to 669-75 show schematic views of a friction yield unit within a sleeve guided rocker unit.
• the elastic component is provided by DELTA1 flexural plates and the separate plastic component by the clamped friction plates.
• the friction plates travel with the elastically displacing plates until the frictional resistance between the friction plates is overcome, at which stage the friction plates slide (displace) relative to each other while displacement in the flexing (DELTA1) plates has stopped, either because their elastic resistance exceeds the frictional resistance of the plates, or their flexing is arrested by travel limiters.
• Figures 669-76 to 669-79 show schematic views of a corrugated friction yield block within a sleeve guided rocker unit.
• the central block displaces with the sleeve guided push rods, while the two clamped outer plates are configured to not displace in this direction (along the line of the push rods) but are configured to freely displace or open in the lateral direction by restraints which produce preferably no resistance in this (transverse) direction (e.g. frictionless or roller).
• shear yield blocks are located within a sleeve guided rocker unit as shown in Figure 669-80.
• the shear blocks are of a material with very high plasticity but relatively low yield strength (e.g. lead or a composite or alloy of). Displacement of the push rods of the sleeve guided rocker unit produces a preferably constant yield resistance force as the confined or unconfined shear blocks plastically deform (shear) as shown in Figure 669-81.
• Secondary flexural members as previously described are able to be integrated with the rotary units (of which the sleeve guided rocker units, as shown previously in Figures 611 and 645 are a third part) to provide an elastic component to the system.
• the BETA rotor and push rod to rocker frame connection of the ALPHA1 control structure are configured so that elasto-plastic displacement of the yield plate(s) within the rotary units is primarily, or only, in one direction; as the rocker frame displaces (rocks) in opposing (both) directions while enduring base motion input.
• Figure 670 shows a DELTA4 yield plate within a rotary unit which first elasto- plastically displaces downwards under the action of a push rod displacing and causing rotation of the rotary unit's drum, and is then (with change in sway direction of the rocker frame) pulled upwards to its approximate initial condition and after a rocker cycle return is then pushed downwards again.
• Elasto-plastic curvature within the yield zone of the yield plate is primarily of one sign (positive or negative) only.
• Figure 671 shows a DELTA4 plate similar to that of Figure 670 where the plate returns after vertical down displacement to a position just below the horizontal line, that is, curvature is of only one sign.
• Figure 672 shows another case where the DELTA4 plate returns to a position just above the horizontal line that is curvature of two signs but one curvature significantly larger than the other.
• Figure 673 shows an APLHA1 control structure with yield plates within a rotary unit. As the frame rocks, back and forth, the yield plates are elasto-plastically displacing primarily in one direction only: downwards. To achieve this, the rotor arm fixed to the drum no longer extends to pin connect with the push rod of the rocker frame. A separate lever arm is introduced which first connects to the free spin axle of the rotor drum, and second extends to pin connect with the push rod, and third connects to the end rotor by a connector which enables the lever arm and rotor plate to connect and pin-connect as the rocker frame sways back and forth.
• Figure 673 shows a rocker frame first swaying to the left.
• the yield plates within the rotary unit to the left of the base pivot are flexurally displaced while the yield plates to the right of the base pivot do not flex, and the lever arm and end rotor plate, rotate relative to each other.
• the rocker frame next sways to the right, and the yield plates within the rotary unit to the left of the base pivot are pulled up by the push rod to their original (effectively flat or now displaced) positions while the yield plates in the rotary to the right remain non-displaced.
• Figures 674 to 678 show schematic details of the connection between the end rotor plate of the drum and the lever arm which enables the two to, in this case, first push the yield plates (or elasto-plastically displace them), as the rocker frame displaces (rocks) in one direction and then, second, pull up the yield plates, after the rocking direction reverses, to their initial relative horizontal positions which coincide with the rocker frame being in its initial (non-displaced) position and then third release or dis- engage the connection between the rotor plate and lever arm so that the rocker frame is able to continue rocking while not influencing the yield plates to its (say) left of frame pivot, but re-engage with and displace the yield plates to its (say) right of frame pivot.
• Figure 674 shows the connector at a position which equates to the yield plates to one side of the rocker frame base pivot being elasto-plastically displaced to their maximum displacement and is depicted in Figure 679 as the lever arm and rotor plate being in a downwards position.
• the frame typically reverses, the lever arm rotates up, and the square (pin) peg of the lever arm pulls the end rotor plate of the drum up with it, while guides or tracks integral with the arm open the connector.
• Figure 675 shows the connector in a position that equates to the plates having been pulled back to their original non-displaced (or effectively flat) position, as depicted in Figure 680 where lever arm and rotor plate position coincide horizontally.
• the lever arm can either be pushed down (i.e. the peg moves downwards) and engage with the rotor plate which would rotate and elasto-plastically displace the yield plates again, or it can rise and disconnect from the rotor plate, hence leaving the rotor plates and yield plates to its side of the base pivot non-displaced.
• Figure 676 shows the peg in a maximum free slide position which equates to maximum rotational separation of the lever arm and the rotor plate as depicted in Figure 681.
• Figure 677 shows a plan sectional view of the connector between the lever arm and the rotor plate, the connector, rotary unit and yield plates to the opposite side of the unit described above, connecting and disconnecting in a similar (but with half cycle phase difference) manner.
• the connector is enabling primarily one direction elasto-plastic displacement, within the yield plates of the rotary units. This reduces differential (trough to peak) elasto-plastic displacement (or travel) on the yield plates by up to one half and will increase the number and amplitude of displacement (half-cycles) it can endure.
• the connecting and disconnecting joint detail which enables the yield plates to elasto-plastically flexurally displace in primarily one direction only may also be incorporated into the ALPHA2 control structures.
• the connector For vertically (tower) orientated rocker frames the connector would be located between the bottom of the external chords and foundation or structural base.
• rotary energy dissipator and force limiter is located within a braced frame control structure.
• Figure 690 shows a rotary unit, with pin ended diagonal push rods located within the braced frame.
• DELTA4 yield plates are located within the rotary unit.
• the frame is effectively an eccentrically braced frame. This allows for the beam to which the rotary unit is fixed to be considered as a secondary flexural member similar to that, as described previously. This arrangement allows for a two-tier (or two stage) elastic-ductile system to be developed as previously described.
• Figure 690 shows the braced frame in its non-displaced form.
• Figure 691 shows the braced frame in its displaced form with elasto-plastically flexing DELTA4 yield plates.
• Figure 692 shows a two bay braced frame arrangement which enables the connect/dis-connect joint described previously, to be employed. As described above this would result in elasto-plastic displacement in the yield plates, being primarily in one direction.
• Figure 693 shows the braced frame of Figure 692 in displaced form.
• the connector between lever arm and rotor plate, of the rotary unit of the left bay is disengaged and the yield plates within the rotary unit this side are not elasto-plastically displacing, while the connector between lever arm and rotor plate of the rotary unit of the right bay is engaged and the yield plates within this rotary unit are elasto-plastically flexing (yielding).
• Figure 700 shows a schematic of a flexure member (DELTA1 plate) within a BETA1 rocker with sleeve guides, all parts of a control structure within an ALPHA1 rocker frame as described in WIPO PCT/IB2017/056135 and WIPO PCT/IB2017/056137.
• DELTA1 plate a flexure member within a BETA1 rocker with sleeve guides
• Figure 701 shows a schematic of a flexure member (DELTA4 plate) which is part of a control structure within an ALPHA2 rocker frame as described in WIPO
• Figure 702 shows a schematic of a DELTA4 yield plate within a BETA rotor which as described above and as with Figures 700 and 701 is the force limiting and energy dissipating part of a control structure within an ALPHA1 or ALPHA2 rocker frame.
• the resultant R, at the reaction point, is orthogonal to the tangent of the restraining boundary surface (e.g. pin) at the plate to boundary surface contact point and in this case also remains orthogonal with the plate at the reaction point while the plate slides and rotates at that point. This is consistent with there being no membrane forces in the line of the plate at this point. That is, the principal directions at the reaction points are one, orthogonal to, and parallel with the plate at the reaction point.
• the internal work done at the yield zone must balance the external work done on the plate.
• the external work done by the applied load can be configured in this case to two components of virtual work done by the vertical reaction (Rv) and the horizontal reaction (RH) .
• Figures 710 to 717 show a further case in which the anchor pins of the free translational and rotational end regions of the plate are able to move (slide) along the restraining boundary of a general curve.
• a horizontal reaction is similarly generated with displacement of the plate, but here, the length along the deforming line of the plate remains constant while the transverse (horizontal) distance between reaction points change.
• the boundary curve tangent equation, Q may be described as a function of the (half) plastic hinge rotation, Q', of the yield plate.
• Figure 712 shows a general boundary curve
• Figure 714 shows the same case as Figure 713 but in a spanning form.
• the second case P2 is able to travel a further distance (A c.w B) for the same rotation (work done) at the yield zone as in the first case.
• a c.w B the second case is able to provide a higher displacement ductility than the first case for the same amount of yielding, or same plastic curvatures (but at a lower resistive force (P2 ⁇ Pi) ⁇
• Figures 716 & 717 show similar cases, but here the flexure member 100 (yield plate) has extensions of length a at its end regions. This allows not only a horizontal boundary reaction to develop but also enables an increase in the spanning distance to be increased or kept constant as the plate displacement increases (contrary to Figures 710 to 715, where the spanning distance is decreasing).
• Figures 700 to 718 show three cases in which a horizontal reaction is generated at the boundary. That is, one with a constant horizontal span, one with a reducing span and one with a increasing span.
• Figure 719 shows a further case in which a horizontal reaction is generated at the boundary and both the length along the deforming plate is increasing and the horizontal distance between reaction points in increasing.
• an additional displacement/force compatible restraint spring or guide
• free body non-yielding/sliding
• Figures 720 to 732 show the non-displaced and displaced forms of the cases above but in a finite dimension form.
• a hinge end region is used here only to provide tolerance for any length 'growth' in the plate during cycling reversals.
• Figures 726 and 727 show the non-displaced and displaced form of a yield plate with curved boundary within a BETA rotor.
• the drum radius, r, and length of yield plate, L are similar.
• the drawback dr is able to be exponentially decreased by increasing the drum radius r, without effecting the plastic hinge curvature.
• Figure 733 shows the stress strain curves for a range of common steels produced in the US, Europe and the UK.
• Figure 734 shows the ratio of stress at a given strain to yield stress for two steels; a) Histar 460 steel produced by ArcelorMittal (Europe)
• Figure 735A shows a direct trace of the maximum cycling displacement an 8mm plate endured.
• Figure 735B shows a direct trace of the maximum displacement amplitude a 12mm grade 460 plate was cyclically tested to.
• the displacement and curvature ductility demands on the plate both exceed 40 (that is a displacement of 40 times (initial) full yield displacement or curvature).
• all plastic curvature occurs within the yield zone, the plate remaining elastic between the yield zone adjacent the first end region and the non-yielding second end regions.
• Figure 736 (similar to Figure 734) shows the ratio of stress at a given strain to yield stress for steels c), e) and f) and adds to the horizontal axis the displacement and plastic rotation of the plate of Figure 735 equated with the general strain values. Further added to the graph of Figure 736 are the reciprocals of the load reduction values derived on Figures 706 8i 710 i.e. :
• Figures 737 to 743 show the stress-strain curves for steels a) to g).
• Figures 744 to 750 show the resistive force as a percentage of initial yield resistance (force). Constant resistive yield forces are obtained over very high strain ranges for a wide range of steels.
• HPS70 response on Figure 750 is the exception. This is a high performance steel (HPS) produced in the US primarily for bridge construction. It has a relatively high tensile to yield stress ratio.
• HPS high performance steel
• the constant resistive yield forces shown on Figures 744 to 749 are consistent with the (post elastic) resistive yield forces obtained from the high displacement/high cycling tests on the plate of Figure 735.
• Figure 707 shows the case of load reversing from positive to negative direction in the reverse elasto-plastic flexing direction (say from positive yield
• the horizontal reaction again negates strain hardening effects as the plate straightens, with Bauschinger effects adding a further softening effect on return to origin.
• Continued displacement in this (negative) direction (post origin) again generates a (now squeezing) horizontal reaction which again negates the effects of a yield plateau with a positive gradient and strain hardening effects; the result being again a constant resistive yield force in the negative (cycled) direction.
• Figure 751 shows a plate also with free translational and rotational boundary conditions, but produced by a rotatable cylinder directly fixed to the end of the plate, which is able to slide within a slotted anchor.
• the plate elasto-plastically deforms under load, the length along the deforming line of plate (between cylinder reduction points) remains constant while the spanning distance of the plate between cylinder reaction points reduces. In this case no horizontal reactions at the ends of the plate are generated. If the plate was made of a material with a zero gradient yield plateau and which did not strain harden (i.e. constant yield stress), the load resistance of the plate would increase with deflection.
• Figure 753 shows the strength reducing with reverse cycle.
• Figures 754 to 756 show a triangular plate as described in United States patent 5,533,307 which has the same free translational and free rotational boundary conditions as the previous rectangular plate. ( Figures 751 to 753).
• the plate is tapered to its cylindrical reaction points, the intention being, in the elastic case, to match the linearly increasing moment demand (produced by the reaction load at the cylinder) along the flexing direction of the plate with a linearly increasing cross section and hence linearly increasing strength along the principal flexing direction of the plate.
• Figure 757 shows an X-type plate as described in Whittaker (1991) (two triangles meeting at their narrowest section). Relative displacement causes the plate to contraflex; its inflexion point under loading taken as an effective point of free rotation. If local yielding occurs, membrane forces (stretching) developed by displacement, spreads yielding to other areas. The closer local yielding occurs to the centre of the plate (centre of the X) the more efficient membrane forces will be in straightening and spreading the yield zone (refer Figure 758). This will not be the case for the triangular plate of Figure 755 with its free translational and rotational boundary conditions which do not allow membrane forces to develop.
• Figure 759 shows the load displacement response for a plate with the free rotational and translational boundary conditions of Figure 751.
• Curve a shows the increase in internal forces with displacement due to both reduction in span and strain hardening which would occur for the plate of Figure 735 with the boundary condition of Figure 751.
• Curves b) and c) show the effects of membrane forces being present.
• Curve d) shows the load displacement response for a plate with the boundary conditions of Figures 700 to 717 consistent with the testing of the plate of Figure 735.
• the plate produces a constant resistive yield force as the plate flexes to very high elasto-plastic
• Figure 760 shows the hysteresis loop which would be obtained from cyclic loading a plate with the boundary conditions of Figure 751.
• load and internal forces within a structure it may be seismically supportive of increase due to span shortening and strain hardening to typically, at least, 1.6 yield force on first cycle.
• Softening occurs in region b) due to Bauschinger effects and increasing span of the plate with reverse displacement.
• Figure 761 shows the pinching effect on the hysteresis loop of Figure 760, if membrane forces are generated within the structure.
• Figure 762 shows the hysteresis loop obtained for a plate with the boundary conditions of Figures 700 to 717 and as obtained from the cyclic loading of the plate of Figure 735.
• a constant resistive force occurs through region a). This means that forces and accelerations within a control structure the plate is part of are both maintained and limited to a constant.
• Figures 800A, 800B, 800C show direct traces, of the 8mm plate of Figure 735A, at three displacement amplitudes that the plate was load cycled to.
• Figures 801A, 801B and 801C show close up detail of the plastic deformation in the yield zone of the plate at each displacement stage.
• the extent, ds of the yield zone remains constant with increasing displacement. From the total angle of rotation, dO, of the yield zone, this plastic curvature, K, at each stage can be determined from
• strains are linearly varied from surface, £ s , to neutral axis (i.e. plane sections remaining plane).
• Figures 803 to 807 show the associated stresses for the given linearly varying strains for Hi-Star 460 steel produced by Arcelormittal.
• Figures 808 to 812 show the associated stresses for the given linearly varying strains for A992 (Grade 50S) produced by Bethlehem Steel. For each of these stress profiles the yield moment with respect to surface strain variation (or plastic curvature variation) and hence angle of rotation can be determined.
• Figure 748 shows the variation or the ratio of yield force (or applied or resistive force) to initial yield force related to surface stress (i.e. constant plastic stress profile) for Hi-Star 460 steel.
• Figure 749 similarly shows the variation of the ratio of yield force to initial yield force related to a constant (with depth) stress profile for A992 steel.
• Figures 813 and 814 show the variation of ratio of yield moment to initial yield moment (both in terms of surface strain) for Hi Star 460 and A992 steels, plotted on the linear strain graphs of Figures 748 and 749 for the same steels. All moment values are based on the assumption that plane sections remain plane after flexure (i.e. linear strain variation with depth of section). Values for composite plates as shown in Figure 815 (still assuming plane sections remain plane) will lie between the linear and flexing values. The load tests (as discussed previously) on plane grade 460 8mm and 12mm plates as shown in Figures 735A and 735B showed no variation with load force. This is consistent with the curved strain variation with depth (e.g. parabolic) obtained from an exact strain analysis at least for the elastic case, as opposed to the (straight line) linear variation assumption of plane sections remaining plane.
• the displacement ductility derived from it (that is its total elasto-plastic displacement divided by its elastic (yield) displacement) is a function of the span of the plate, and reduces with increasing plate span (and increases with reducing span). This is illustrated in Figure 820.
• Figure 850 shows the load displacement path of a linear elastic system.
• Figure 850 shows a spring and mass system in its undisplaced form.
• the elastic force generated in the spring is Fi, and this is the force applied to the fixed position mass.
• Fi is here a compressive force.
• the force F2 With the base next moving to the left (but still to the right of the origin) the force F2 is still in the same direction as Fi.
• force within the spring On the base returning to the origin, force within the spring is again of zero value.
• the force F3 is generated in the spring and the force with respect to the spring is tensile, and the direction of force F3 is opposite to Fi and F2. If the mass is not fixed in position the response motion of the mass
• Figure 851 shows a similar case to the spring-mass model of Figure 850, but here the load displacement curves of the spring have two stiffness values. One that is greater than that of Figure 850 when load is increasing (or the base is moving to the right) and one that is equally less when the base is moving to the left. With displacement Di a force Fi + is generated. This produces a greater force on the mass (than with same displacement of Figure 850), and if the mass was free to move, a higher acceleration (than with Fi of Figure 850). When the base moves to the left and displacement is reducing from Di to D2 a force F 2 (still in the same direction as Fi + and as F2 in Figure 850) is generated. This movement is coinciding with the lower stiffness load path.
• the base then continues to original position where the forces within the spring are zero.
• the base motion in first moving from the origin to the right a displacement value D and then moving to the left and returning to origin, has produced in the systems of Figure 850 and Figure 851 both the same average force and same internal energy in the spring for each case. If the mass were free to move it is not clear which system would produce the larger response acceleration for the mass or the larger response displacement for the spring. This can however be readily determined by for example, as above, a time history analysis.
• the initial response of increased mass response acceleration and reduced structure (spring) displacement response associated with the increased stiffness for base motion in one direction will be potentially nullified by the reduced stiffness with base motion in the opposite direction.
• both the (horizontally) resolved direct force and (horizontally) resolved friction forces increase with displacement.
• the frictional forces in one direction are increasing work (when compared with a same clamped but frictionless sloping surface) and decreasing it in the other ( Figure 852).
• Figure 853 shows the elasto-plastic load displacement curve of two 12mm flexural yield plates of 200mm cantilever span. The total elasto-plastic displacement equates with the plastic curvature (or hinge rotation) shown on Figure 735B.
• Figure 854 shows the same load displacement curve, but superimposed onto it is the load path of a slip friction device with clamped sloping frictional surfaces.
• the upper load-displacement path (increasing load) for the slip friction system is the same as that of the flexural yield plates. That is, same elastic stiffness, with same resistive load to same displacement.
• Figure 855 shows the same elasto-plastic load curve for the yield plate of Figure 853 and 854 but here the elastically responding load paths for the slip friction system are shown for the case of its displacement being the same as that of the elasto-plastic displacement, Atot, of the yield plates. To reach this displacement the force within the slip friction system and the force applied to any mass directly connected to the device, and forces within foundations supporting the slip friction device would be 14 times that of the yield plate system.
• Figure 856 shows a similar system to Figure 855.
• the same (wider) yield plates produce a higher yield force at same yield displacement (8mm) as a now pretensioned slip friction system.
• Figure 857 similar to Figure 855 shows the load path of the pretensioned sloping surface slip friction system when its displacement equates with the elasto-plastic displacement of the yield plates, Atot. At this displacement forces within the slip friction system are (similarly) 11 times higher than that with the flexural yield plates.
• the difference in Figures 855 and 857 between the clamped frictional sloping surface device and the flexural yield plates, is the same difference that occurs between the clamped frictional sloping surface device, and the rotary friction units described earlier which comprise an elastically straining (e.g. flexural plate) elastic component and a separate frictional plastic component.
• the differences between the device with clamped frictional sloping surfaces and the corrugated yield block described above with frictionless clamped sloping surfaces and clamped frictional flat surfaces is also similarly the same.
• Figure 858 shows a similar case but one in which pre-tension forces are higher.
• the equal displacement theory which forms the basis of most seismic codes states that, for a given base motion input, the maximum displacement response in an elastically responding system of a given natural frequency (i.e. function of mass and stiffness) is the same as that in a weaker yielding elasto-plastic system but of the same natural frequency. That is, as with Figures 855, 857, 858, for a given and same base motion input the maximum displacements of the flexural yield plate system is the same as that in the slip friction system with clamped sloping frictional surfaces. But the forces generated within a structure and within its foundations that the yield plates are a part of are at least l/10 th that in a same structure which the sloping slip friction device would be a part of.
• the flexibility (elastic stiffness) of the flexural yield plates (and rotary unit) is able to be adjusted directly by varying the thickness and/or span of the yield plates or indirectly by introducing a secondary flexural member or by adjustment of both.
• the yield strength (elastic limit strength) and yield displacement of the flexural yield plates is able to be adjusted by again varying the plate span or thickness, or further varying the plate material yield stress (e.g. type of steel), or varying the width of plates or number of plates.
• Both the flexibility and yield strength of the yield plates, that is their elastic parameters are able to be configured with relative ease, to be the same as practicably any other elastic system.
• the system with the flexural yield plates, and of same elastic strength and stiffness as the frictional sloping surface system is able to provide or produce an elastic strength equivalent, in resisting a base motion input, of 10 times that of the sloping surface friction system while limiting and controlling forces within itself and any mass it may be seismically supportive of. That is, the flexural yield plate system is (conventionally) able to resist and endure a base motion input (i.e. earthquake) of (at least) 10 times peak ground acceleration (PGA) of the sloping friction system or any other equivalent system of same elastic strength and stiffness while maintaining a constant resistive yield force. Further, the flexural yield plate system when subject to the same maximum base motion input that the (e.g.
• FIG. 19 to 20 Further variations of a system 1000 (control structure) are shown in Figures 19 to 20 where an energy absorbing system 1000 may be used to both restrain storage racks 3 and dissipate racking energy during a seismic event.
• the energy absorbing system 1000 utilises restraining ties 300 to brace itself to the racks 3. These ties 300 are connected to a control structure (energy absorbing system 100) which consists of a rotary unit alone.
• the forces transferred through the ties 300 are tensile forces.
• More than one tie 300 can be attached to a rotary unit.
• the rotary unit is preferably provided intermediate two ties 300.
• the rocker 2000 may be at the end of a rack and only attached to a single tie 300.
• the ties 300 have a low elasticity and minimal deformation during seismic activity.
• the ties 300 are metal cables.
• the ties 300 may be braided line, or solid bar or the like. Any material and geometry substantially strong enough to take the tensile forces with low deformation may be used for the ties 300.
• the flexure member 100 (plate) is part of the yield connector (rotary unit).
• the flexure member 100 (plates) are able to flex to high elasto-plastic displacements.
• the material variables of the rotary unit, and more specifically the flexure member(s) 100 do not change significantly after each cycle.
• the variables that stay substantially similar are the yield strength and elastic stiffness of the flexure member(s) 100.
• the flexure member(s) 100 has 1) a stable and constant cycling yield strength and 2) a stable and constant cycling elastic stiffness.
• the structural behaviour of the yield plates is simple to calculate or verify by load test their performance can be accurately assessed. This allows the performance of the control structure and any adjacent structure it seismically supports to also be accurately assessed. For example, the stiffness, deflection and deformation in operation, weaknesses, stress concentrations et cetera are able to be readily calculated. This allows the rotary unit to be specifically designed. As such the more simplified the design can be, and the more accurate the analysis can be.
• the energy absorbing system 1000 (control structure) of the present invention utilises the flexure member(s) 100 as described above, that throughout the oscillating forces does not significantly change its material properties.
• Figures 20 are schematic figures of finite dimension, of a tie restraining control structure.
• control structures are seismically supportive of load carrying rack structures or general building structures. Connection of these structures to the control structures is through typically inclined tensile cables or rods.
• Figure 20A shows a control structure (rotary unit) as described previously.
• the rotary unit connects to a base member whose flexibility is independently adjustable.
• Figure 20B shows the displaced form of figure 20A under the action of a tensile force in the ties.
• Figure 20B shows the displacement form for the case of a rigid (inflexible) base.
• Figure 20C shows the similar but increased displacement form for the same case but with a flexible base member.
• the base member allows i. the fixing (anchor) forces to the foundation (base) generated by the moment couple within the rotary unit to be reduced by leverage through the base member about its central pivot.
• control structure ii. the natural elastic frequency and force/displacement characteristics of the control structure, in conjunction with any other structure it is seismically supportive of, to be adjusted independently.
• the control structure in most instances is intermediate two ties 300 of a racked system.
• the tie anchor may be at the end of a rack system and only attached to a single tie 300 (not shown).
• the examples shown in Figure 19 onwards show a tie anchor located intermediate to ties 300.
• the desirability of having two ties 300, acting in opposite directions, is due to the cycling response of the restrained structure during a seismic event.
• the ties are typically in cable or rod form and are only able to carry tensile loads. Hence at any time only one tie is engaged in load transfer from main structure to energy absorbing system 1000 (control structure). Load and motion reversal between both the main structure and ground results in switching tensile loads in the ties, the rotation of the 1000 system and the yield working of the flexure members 100 (plates). With only one tie 300, after deformation in one direction, racking during the next cycle will incur slack in the tie 300 due to the previous deformation. However, one tie may be used albeit with less effectiveness than two tie, this could be at the ends of a rack where one tie is better than no ties to a tie anchor.
• the flexure member(s) 100 could be substituted with hydraulic energy absorbent members. This is used to absorb the energy of the lever.
• the tie anchor is converting the substantially lateral forces of the ties into substantially circular distributed forces.
• FIG. 21A and 21B A further embodiment of the rocker frames is shown in Figures 21A and 21B.
• the frames are able to directly support gravity loads without any reliance on the flexure members (plates) within the rotary unit providing vertical stability.
• Single direction compression load dampers are added to the base of the vertical gravity load carrying columns to cushion the rocking action as the frame returns to vertical (original) position, with each cycle, under the added effect of gravity load (GR).
• the entire rocker 2000 is substantially composed of metal. Even more preferably, the rocker 2000 is composed of steel.
• the rocker, rocker arms, upstand, and anchors are substantially stiff and rigid so as not to yield during a seismic event. There are many alternatives in the design to fabricate a rigid rocker frame.
• the ground could also be a floor or ceiling of a building or structure, a beam, or truss, or part of a structure that is engaged to the anti-racking system as described.
• the systems may be halved or double or so forth and still be effective.
• the energy absorbing system 1000 may only have one yield connector 230 on one side of the pivot anchor 240.
• Figures 900 to 906 show a range of pivotably based control structures, all within which are located rotary yield units which produce a constant resistive yield force (torque) while the yield plates within them cyclically flex to high elasto-plastic
• the constant resistive yield force (torque) produced by the rotary units is utilized and transferred by lever arm to the control structure, enabling it (as a whole) to also form a stable elasto-plastic mechanism which is able to displace to high cycling elasto-plastic displacements and high ductilities while maintaining a constant resistive yield force as it resists and endures base motion input from a seismic event.
• Figure 900 shows an ALPHA1 control structure comprised of a pivotably based rocker frame, double pin ended push rods and base located rotary yield units all forming a pivotably based control structure of vertical (tower) aspect (or pivotably based cantilever wall).
• Figure 901 shows a control structure comprised of pivotably based stiff vertical chords, rocker frames in horizontal (spanning) aspect pivotably connected to vertical chords, double pin ended push rods and rotary yield units all forming a pivotably based control structure of a moment frame aspect.
• Figure 902 shows a control structure comprised of a pivotably based rocker frame, pivotably based exterior chords (parallel with the chords of the rocker frame), pin-ended motion control ties and rotary yield units distributed between and along the rocker frame and exterior chords, all forming a pivotably based control structure.
• Figure 902A shows an ALPHA2 rocker frame assembly with rotary units connecting one part by lever arm to two (each side) stiff and pivotably based exterior chords and other part to secondary flexural member, in turn connected to rocker frame.
• Pin ended motion control ties connect the centreline of the rocker frame with the centrelines of the exterior chords.
• Figure 903 shows a control structure comprised of pivotably based vertical chords, rocker frames in horizontal (spanning) aspect pivotably connected to the vertical chords, exterior chords (parallel with the chords of the rocker frame) and pin connected to the vertical chords; pin ended motion control ties, and rotary yield units distributed between and along the rocker frame and exterior chords all forming a pivotably based control structure.
• Figure 904 shows a control structure comprised of pin connected beams and columns, double pin ended push rods and rotary yield units forming a pivotably based eccentrically braced frame.
• Figures 905 and 906 show a control structure comprised of pivotably based wall elements, connected by pin ended motion control ties, with rotary yield units located and connected between the walls, all forming a pivotably based control structure of coupled shear wall form.
• the yield plate has particular boundary conditions which allow the flexing or deforming length of the plate to increase (or decrease) as the plate cyclically flexes to high elasto-plastic displacement, while its spanning distance (or distance between anchors or supports) remains effectively constant (test attained).
• Plastic yielding occurs only in specific and fixed zones of the plate and the plate remains elastic (non-yielding) between yield zones or between a yield zone and non-yielding reaction point (test attained).
• the plastic curvature remains constant throughout the yield zone. That is, the plate is flexurally yielding into circular arcs whose radii of curvature decreases (or increases) with increasing (or decreasing) displacement of the plate (or increasing/decreasing plastic curvature of the yield zone) (test attained). ) The resistive yield force produced by the plate as it cyclically flexes to high elasto-plastic displacements remains constant (test and calculation attained).
• the constant resistive yield torque produced by the rotary unit converts or transfers to a direct constant resistive yield force by a lever arm integral with the axis of rotation of the rotary unit.
• a lever arm integral with the axis of rotation of the rotary unit.
• a rotary unit incorporated with a secondary flexural member allows for both the constant force produced by the rotary unit and the stiffness (or flexibility) of the rotary unit to be independently adjusted.
• the constant resistive yield force produced by the yielding rotary units enables a control structure, of which the rotary units are a part, to also form an elasto-plastic mechanism of constant resistive yield force.
• the control structure is able to utilize the constant resistive yield force (torque) produced by the rotary units, and form a stable plastic mechanism which is also able to cyclically displace to high elasto-plastic displacements (and ductilities) while maintaining a constant resistive yield force.
• the pivotably based control structures described above have high elasto-plastic displacement and high ductility capability. They are able to form and maintain a stable constant resistive yield force mechanism while cycling to high elasto-plastic
• control structure The constant resistive yield force mechanism formed by the control structure enables it (control structure) to control and limit forces developed within itself, to control and limit forces developed in its supporting foundations, and to control and limit response accelerations (dynamic forces) developed in masses (e.g. floors and
• Figures 900 to 905 include a (non-exhaustive) range or family of pivotably based control structures, all of which are able to maintain a constant resistive yield force (at high cycling elasto-plastic displacements and ductilities), and limit forces developed within themselves, within their foundations, or within structures that they are seismically supportive of, as they resist and endure base motion input from a seismic event.
• yield plates Located within each of the rotary units shown in the control structures of Figures 900 to 905 are yield plates (DELTA4 to DELTA6) which are able to elasto-plastically flex to high cycling displacements and ductilities while maintaining a constant resistive yield force; their summing producing a constant resistive yield (torque) for the rotary unit.
• the yield plates each have free translational or free translational and free rotational boundary conditions at one of their support points or regions.
• the deforming length of the yield plates along their flexing curve(s) between support or reaction points or regions is able to freely increase or decrease as the plates displace, and/or develop horizontal reactions at their reaction points, regions or reaction surfaces (alternatively, friction block assemblies with or without an elastic component may be located within the rotary units).
• Components within the control structures and/or part of the rotary units may also include:
• Secondary flexural members integrated with the rotary units of any form, with any support conditions and of any displaced shape (curve) which are able to be configured to produce a two tier ductile system. • A joint integral with the arm(s) or lever(s) of the rotary unit which is able to cyclically connect and disconnect and produce within the yield plates of the rotary units elasto-plastic flexing, displacement, and curvature of primarily one direction or sign.
• Figure A1 shows a rotary yield unit within which DELTA4 yield plates are located.
• Figure A2 is a schematic plan view of Figure Al.
• the yield plates are distributed at approximately 150mm spacing around the periphery of the rotary unit and the radial distance to the yield plates is 1000mm.
• the unit In conventional terms (or approach), at a displacement ductility factor (for the plates) of 10, the unit is providing an elastic strength or elastic performance equivalent of 5000kN elastic strength. Halving the lever arm length increases (doubles) this value to 10,000kN.
• the yield plates and rotary unit, as drawn are capable of displacement ductility factors in excess of 25.
• the rotary unit With 12mm grade 460 plates of same dimensions (rotary unit and plates) the rotary unit has a yield strength in excess of lOOOkN. Again at a displacement ductility factor of 10 (plates and unit), the rotary unit provides an elastic strength or elastic performance equivalent to 10,000kN elastic strength. Again, halving the lever arm length doubles this value to 20,000kN. And again, the yield plates and rotary unit are capable of displacement ductility factors in excess of 25.
• Figure A3 shows a sleeve guided rocker unit with push rods, as described previously, connecting with and forming an ALPHA1 rocker frame assembly.
• the unit comprises 15 DELTA1 yield plates in three groups of 5 plates between which guides for the ties linking all plates are located.
• Figure A4 shows a close up detail of Figure A3 and Figure A5 shows a similar unit but with 10 plates.
• Figure A6 shows a plan view of the yield plate inclusive of a cut out in it to accommodate the ties.
• Figure A7 shows a plan view of the guide and tie within the rocker unit casing.
• Figure A8 similarly shows a plan view of a DELTA1 yield plate and
• Figure A9 shows a plan view, again, of a guide and tie, but here the guide and tie take up the entire interval space of the rocker unit.
• Figure A10 shows a plan of a yield plate with two ties and cut outs in the plate.
• FIG. 1 shows a schematic view of a rotary unit as described previously in which a sleeve guided rocker unit(s) forms a third part of the rotary unit.
• rocker units are located within the rotary unit.
• Each of the rocker units contains five DELTA1 yield plates.
• Figure A12 shows a schematic plan view of Figure All.
• rocker unit of Figure A3 with 8mm grade 460 plates of 200mm effective width and 200mm span has an elastic yield strength in excess of 500kN and is capable of displacement ductility factors in excess of 25.
• rocker unit has an elastic yield strength in excess of lOOOkN, and again is capable of displacement ductility factors in excess of 25.
• control structure is able to resist and endure severe ground or base motion input (i.e. high peak ground accelerations, PGA) while (both) maintaining a constant resistive yield force (limiting peak response acceleration of masses supported by the control structure, limiting forces developed within the control structure, limiting forces within its foundations and limiting forces within a structure the control structure may be seismically supportive of) all (while) maintaining a low (or manageable) peak (elasto-plastic) displacement response for the control structure as a whole (i.e. low lateral drift).
• the plane of the rotary units is oriented not in the vertical plane as previously described, but it lies effectively flat in the horizontal plane. That is, its axis of rotation is vertical.
• the rotary units may be located between the base of a building's superstructure and its supporting foundations.
• First part (e.g. casing) of the rotary unit laterally connecting with the foundation (e.g. first structural) member and the second part (e.g. slot and pin end of lever arm) of the rotary unit laterally connecting with the base of the overlying superstructure.
• the rotary units behave or displace as previously described, that is, the yield plates (DELTA4 to DELTA6) within the units are able to flex to high elasto-plastic displacements and high ductilities while maintaining a constant resistive yield force.
• the rotary unit is subsequently able to displace (rotate) with a constant resistive yield torque, and its lever arm, transfer or produce a direct constant resistive yield force.
• the base of the superstructure and its (gravity) supporting foundation structure are configured to laterally displace relative to each other, preferably without developing shear (lateral) forces between their bearing or contact surfaces, this could be achieved for example by use of load bearing shearing materials (e.g. slip pads) or pivoting roller systems, between the two.
• the only lateral (shear) forces developed between and across the superstructure and its foundation base are the constant resistive yield forces developed within and by the displacing rotary units which connect the superstructure with its foundation base.
• the rotary units are preferably limiting the lateral (shear) force that can be transferred between and across the foundations and its overlying
• the response (displacement/velocity/acceleration) of the superstructure is hence governed by the elastic flexibility of the rotary units (with or without secondary flexural members) and the constant (limited) resistive yield force produced by them and transferred across them between foundation and superstructure.
• the rotary units are dynamically separating or isolating the superstructure from its foundation which is moving with or responding to the ground motion input
• Figures 910 and 911 show a plan view of rotary units located between the foundation and overlying superstructure of a building structure.
• Figure 912 shows a schematic plan detail of the rotary units of Figure 910/911 with a secondary flexural member.
• Figure 913 shows a longitudinal section of Figure 910, one part of the rotary unit connecting to the foundations and the other part to the base of the superstructure.
• the direct force generated from the constant torque produced by the elasto-plastically rotating units is able to be directly adjusted by varying the lever arm length of the rotary unit, the lever arm (first part) connecting to the superstructure and the housing of the rotary unit (second part) connecting to the foundation or vice versa.
• a secondary flexural member is able to be integrated with the rotary unit and a two tier ductile system developed from it.
• a connect-disconnect-connect (CDC) joint is able to be integrated with the rotary unit. Friction units or shear yield units as described previously with or without an integral elastic component can alternatively be used within or as part of the rotary unit.
• Figures A50 to A53 show a range of pivotably based ALPHA1 and ALPHA2 control structures of varying heights, (arbitrarily) supporting proprietary (e.g. steel tray composite) concrete floors, each (arbitrarily) of a seismic mass (inclusive of contributary applied load) of 600kg/m 2 .
• Figure A51 shows an ALPHA1 control structure to 70m height and supporting 20 floors.
• Each frame (again arbitrarily) supports a contributary floor area of 325m 2 (or 195 tonnes per floor level).
• For this control structure to resist and endure the floor mass acceleration response (for this structure as read from a standard code response spectra) to a base motion acceleration input of 0.4g peak ground acceleration associated with standard soils; would (arbitrarily) require four base located rotary units, each of 1600mm diameter, located at each end of the frame and connecting to the pin ended push rods of the ALPHA1 frame.
• a different arrangement of rotary units (number and size of units, number and size of yield plates within, lever arm length) is equally able to be configured (in conjunction with the superstructure) to produce the same (or different) strength stiffness and ductility values to the control structure.
• the strength, stiffness, and strength/stiffness ratios of the yield plates within the rotary units are able to be independently adjusted by simply varying the thickness and span of the yield plates. This adjusts the same values for the rotary units as a whole which may be further adjusted by varying the length of their lever arms or by adding a secondary flexural member.
• the combined elastic flexibilities of the (non yielding) superstructure and the (yielding) rotary units are able to be configured to produce stiff (low drift) combinations in which P-DELTA effects are minimised, or more flexible (and economic) structures but in which the additive P-DELTA force and displacement effects are higher.
• the rotary units are readily configured to provide the required strength, flexibility and ductility for the control structure.
• Figure A52 is a schematic view of a control structure, similar to Figure A51 but of twice the height (140m) and supportive of twice the number of floors (40 levels) but with same contributary floor area per frame (325m 2 ).
• the control structure would require (arbitrarily) four 2500mm base located rotary units at each end of its 25m wide ALPHA1 frames. Again these rotary units connect to the push rods of the ALPHA1 control structure, the rotary units able to be located below base (or ground) level. Again lateral drift of the yielding structure is able to be limited by configuring the elastic flexibilities of the yielding rotary units and non-yielding superstructure.
• One of the plate options used in this analysis comprised composite plates of 8mm thickness, of span 600mm and width 600mm, as shown in Figure A52-1, the plates effectively of the form of flaps.
• the span (dimension) of the yield plates is of the same order as the hub radius of the rotary unit, and the flexibility of the unit is (visually) tangible.
• the 40 storey example to resist and endure a base motion input of 0.4g associated with standard soils or 0.5g associated with rock, of the order of 400 of these 8/10space/8 composite plates distributed over e.g. 8 (2500mm DIA) rotary units (50 per unit) would be required, each side of the 40 storey frame.
• This rotary unit configuration is one of any (of varying stiffness and strength) which could be used for this case.
• This particular configuration due to its flexibility produces an overall design in which the superstructure is at its drift limit (and governed by this), for this base motion input, and in which ductility demand on the yield plates is very low.
• the example is used to illustrate the two extremes that this particular unit is operating at (at the same time) while limiting response base shears.
• base motion input e.g. to l.Og
• number of, and yield strength of rotary unit can still be used. But one in which the yield plate's elastic stiffness is increased.
• Figures A53 shows a schematic view of the extreme case of an ALPHA2 control structure of 342m height and supportive of 100 concrete floors of 600kg/m 2 mass.
• Figure A54 shows a plan view of the representative building.
• the structure is of the same height, number of stories and average floor area as the John Hancock Centre. It is similarly cross braced only at its perimeter, with internal columns carrying gravity loads only (i.e. providing no lateral resistance).
• the John Hancock Centre is rectangular in plan (79m x 49m base) and tapers with height
• the control structure considered here is square in plan and prismatic. That is it does not taper (i.e. all floors are of equal weight and area).
• the very high total mass supported by these structures results in the structures having very low angular frequencies (i.e. long natural periods).
• the efficiency of the rotary units ductility decreases with increasing flexibility (inclusive of the rotary unit flexibility) of the control structure as does the mass acceleration response and hence force demand on the control structure. That is with increasing natural (elastic) period of the control structure
• the rotary units were still able to produce a ductility capability for the control structure as a whole for a range of base motion inputs which enables tonnages of half that required for the elastic model, while accommodating additive (higher order) forces and displacements due to drift (elasto-plastic) and P-DELTA effects. Further to the reduction in tonnage, floor (response) acceleration and foundation forces are more than halved.
• ground accelerations from say 0.4g to l.Og
• the rotary units become more efficient.
• the steel tonnage required of the superstructure with rotary units is of the order of 1 / 4 that of the same height/weight elastically designed structure. Foundation loads from the yielding control structure and floor accelerations are again less than 1 ⁇ 4 that of an elastic structure.
• control structures as described above are of the order of 3 ⁇ 4's the tonnage of conventional (same initial yield strength) ductile structures and similarly produce foundation loads and floor accelerations of 3 ⁇ 4's that of ductile structures of same initial yield strength.
• the flexibility of rotary units located between and along the exterior chord, and the interior chord integral with the rocker, all part of the ALPHA2 control structure can be individually adjusted by variation of number, span and thickness of plates within the rotary unit, variation of the rotary units diameter and lever arm length and variation or addition of secondary flexural members.
• the adjustment of each rotary unit's flexibility and their (vertical) location between chords in conjunction with the frame and exterior chord flexibility enables displacement differentials between exterior and interior chords (from one rotary unit to the next) due to elastic shortening or stretching of the chords to be compensated for, so that yielding occurs in each of the rotary units at the same time.
• the rotary units may be concentrated nearer the base of the control structure as shown in Figure A55, or nearer the top as shown in Figure A56 or in any other regular (or irregular) arrangement.

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• 2019
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