SANDWICH STRUCTURE, DEVICE INCLUDING THE SANDWICH
STRUCTURE AND DEVICE NETWORK FOR TAKING OVER AND
DAMPING THE LOADS FOR STRUCTURE BEHAVIOUR CONTROL
The invention refers to a sandwich structure capable to develop hysteresis type characteristics with geometrical non - linearities and encreasing non-linear elastic extension, to a device made by means of such a sandwich structure which is capable to take over static and/or dynamic loads which are damped as well as to a network of devices that support and or are inserted into a structure or system or equipment or pipe network for the control of their behaviour at static and dynamic loads.
According to BRIDGESTONE and SKELLERUP, there are sandwich structures to take over the loads, structures made of steel and rubber blades or steel - plate made only.
The disadvantages; of such structures are represented by their quite low bearing capacity and damping, by failing to allow displacements from thermal expansions with small reaction forces, by their short service life and by the possibility to develop only limijtted force-displacement characteristics which do not allow the generation of a preset force for a given displacement and a pre-set gradient for them, specially.
Accprding to ROt i o, 116739B1 Patent, there are secondary elastic subassamblies with a structure made up of a lower lid, profiled inside usually in the shape of a tapered cone inside which a disk is provided. The djsk is having the same profile a with constant slope on the edges on both faces like the cavity, and to which a rod is fastened in view of installing some elastic disks spaced between them by inner washers pressed by another disk, usually having a tapered profile on the edges. Some cylindrical elastic crowns spaced among themselves by means of outer washers are provided between the elastic disks and pressed against the lower lid by means of another lid having an inner cavity of the same profile like the disk.
The disadvantage of such subassamblies rests with the fact that, due to the profile with only one slope of the central disks, the required control of the force- displacement characteristic is not possible; they do not allow large displacements from
thermal expansions with small reaction forces and the distortion of the blades is not controlled in the peripherial area towards the central area.
According to BRIDGESTONE and SKELLERUP, there are elastic devices which take over the loads, devices made up of two steel flanges between which a sandwich structure consisting of steel and rubber blades provided with a central hole that can be filled in or not with a lead pellet, is fixed.
The disadvantage of such devices consists in the fact that they have a low bearing capacity, small damping, high stiffness on the normal direction of the blades and the service life is short due to the aging of the rubber blade components in the sandwich structure; they also do not allow displacements from thermal expansion with small reaction forces.
According to Proceedings to 10th European Conference on Earthquake Engineering, Editor Gerald Duma, publish of A. A. BALKEMA / ROTTERDAM / BROOKFIELD / 1995, there are networks of elastic supports to provide the control of structure behaviour, supports on which the structures are installed. There are also elements of rubber type or stoppers or hydraulic shock absorbers which are included in the structural bracing, comming into operation when certain relative pre - set distorsions occur. '■ "
The disadvantage of such networks consists in the fact that the variation of their stiffness cannot be controlled, and their damping is small; and, maϊiy times, they generate shocks when starting suddenly to operate, generating an amplification of the stresses; they can not reduce the e foι|s;from large thermal expansions; these networks also show low reliability and a short service life which require their periodical inspection or replacement.
Accordingly, on object of the present invention is to accomplish a sandwich structure which is not affected by the accelerated aging phenomenon; be capable to develop a force-displacement controlled, characteristic of geometrical non-linear hysteresis type with encreasing non-linear elastic extensions, capable to disipate important energies at low levels and average levels of distortion allowing for the displacements from thermal expansions with small reaction forces and, in respect of the sandwich structure distortion beyond a pre - set value, it can provide a very large encrease of the force at low distortion variations.
Another object of the invention is to provide a device including a sandwich structure capable to take over displacements from thermal expansions, to take over
large static loads on which dynamic loads may overlap and be damped and which can be fabricated in small mediu and large sizes still preserving the capacity to take over large distortions.
Another object of the invention is to make a network of devices, highly reliable and long - life, capable to take over large static loads, to allow displacements from thermal expansions and provide behaviour control of structures, pipe network or equipment, either new or the existing ones, at static and dynamic loads, including seismic loads either by their support or insertion of the devices.
According to this invention, the sandwich structure eliminates the previously mentioned disadvantages by the fact that it is made up of a blade package consisting of inner set and outer set of coaxial blades having a relative paralel or tapered position. The inner set of blades is made of some internal elastic blades usually circular or rectangular in shape and spaced by some central coaxial inner washers, intermingling with the outer set consisting of exterior elastic blades usually in the form of crowns or lateral stripes spaced by outer washers located outside of the internal elastic blades.
The entire blade package is pre-compressed by some rigid central and peripherical deforming parts. Each ϊof the central deforming part having central plane surfaces, mediane convex or concave surfaces and outer surfaces concave or convex and each of the peripherial deforming parts having outer plane surfaces and inner convex or concaversurfaces so that the contact area betweep( the deforming parts and the blade package mQ s;fj;om the center towards the periphery an<$ from the periphery towards the center while! simultaneously distorting with the radial movement between the two sets of blades, finally leading to the formation of a force-distortion characteristic of hysteresis type with encreasing elastic extension. The distorting parts central and peripherial, having relative axial paralel or tapered positions function of the sandwich structure geometry.
According to the invention, the device for taking over and damping the loads eliminates the previously mentioned disadvantages particularly because it is made up of one or several sandwich structures fixed on some fastening elements by means of elastic or stif rods, function of the operation procedure imposed to the device. The devices are capable to operate better in series or in paralel, function of the manner to fasten the sandwich structures.
According to the invention, the network of devices eliminates the previously mentioned disadvantages because it usually consits of some devices or column of
devices installed in paralel between the structure and the foundation and may be connected among themselves by some diagonals including some devices. There is also the possibility to install some devices inside the structure usually to make a square with deforming diagonals as to pre - set values containing devices which take over and damp the loads. The network may also be installed for equipment or pipe lines and it may also include the installation of devices between the assambly components with different dynamic characteristics in order to improve the dynamic behaviour of the assambly and damp the component movement.
The application of the invention results in the following advantages:
- the development of a sandwich structure with controlled elasticity and damping whose force - distortion characteristic is of geometric non-linear hysteresis type with encreasing non-linear elastic extension, non-affected by the accelerated aging phenomenon;
- the development of compact devices with controlled stiffness and damping, which can support the static loads, allow the thermal expansions and take over and damp the dynamic loads;
- the deveSoβsnehtirof device networks to control tfte behaviour of structures, equipment, machines and pipe lines, either existing or new ones, in order to encrease their capacity to stand the static and dynamic loads, reducing the stresses due to thermal expansion without negatively affecting the operability and architecture of structures.
Here below there are some examples of how the invention may be applied related to fig. 1 - 15 which represent: ig. 1 , axial section through a sandwich structure; ig. 2, axial section through a sandwich structure in another constructive alternative; ig. 3, axial section through a sandwich structure in another constructive alternative; ig. 4, force - displacement characteristic of a sandwich structure; ig. 5, axial section through a device including a sandwich structure components; ig. 6, axial section through a device in another constructive alternative; fig. 7, axial section through a device in another constructive alternative; ig. 8, axial section through a device in another constructive alternative; ig. 9, axial section through a device in another constructive alternative; ig.10, axial section through. a device in another constructive alternative;
- fig. 1 , bird eye view of a device in another constructive alternative;
- fig.12, axial section through a device in another constructive alternative;
- fig.13, network of devices for the control of structure behaviour;
- fig.14, network of devices for the isolation of structures and equipment;
- fig.15, network of devices for the control of pipe network behaviour;
- fig.16, network of devices for the control of pipe network behaviour in another constructive alternative;
- fig.17, network of devices for the control of pipe network behaviour in another constructive alternative;
- fig.18, axial section through the in a casing device;
- fig.19, axial section through the in a casing device in another constructive alternative;
- fig.20, axial section through the in a casing device in another constructive alternative;
- fig. 21, axial section through the in a casing device in another constructive alternative.
According to the invention, the structure is made up of a blade package A which includes A1 and A2 internally and externally sets which are coaxial, lubricated or not lubricated having a relative paralel or tapered position, with the%ase angle between 5° - 85° function of the ratio
the normal force and the shear forcβ applied to the sandwich structure. Set AlVeonsisting of elastic blades 1 of circular: or rectangular shape, each of them provided iiwith a cientral hole a and spaced between themselves by means of central inner washers 2 coaxially located with blades 1. Set A2 consisting of outer elastic blades, 3, circular or rectangular in shape, provided with a central hole, b, in which inner washer 2 are inserted. Blades 3 may have or not some peripherial holes, c, uniformly distributed. The blades, 3, being spaced by means of peripherial outer washers, 4, located outside blades 1 and that may be provided or not with some
I peripherial holes, d, of the same size and coaxial with holes c. Blades 3 may also be fabricated of strips spaced between them in order to form the hole b.
Package A is pre-stressed by means of central lower and upper deforming parts 5 and 6 each of them having the surfaces e, f and g which are interior plane, mediane, concave or convex and externally convex or concave related to set A1 and central holes h and i which are coaxially located and of the same size like the hole a and also with
some peripherial, lower and upper deforming parts, 7 and 8, home surfaces j and k, externally plane and internally convex or concave related to set A2. They may have or not with some peripherical holes i and m of the same size and coaxial with holes c.
By the application of a force E on axial direction, on parts 5 and 6, and parts 7 and 8 being fix, package A is deformed in a controlled manner by parts 5, 6, 7 and 8, obtaining a δ displacement, geometrically non - linear, given by the modification of the contact surface between the deforming parts 5, 6, 7, 8 and the package A. The force F is uniformly distributed between elastic blades 1 and 3 respectively. Due to the in - paralel taking over of force F , the contact pressure between blades 1 and blades 3 is low, below the jamming value and a radial displacement accompanied by energy consumption friction can be obtained between blades 1 and 3. The contact surfaces are modified because of the displacements of the contact areas lines associated to part 5 and part 6 and respectively part 7 and part 8 with package A, moving from the center towards the periphery and vice - versa, function of the geometry of their surfaces, e, f, g, j and k, simultaneously with a consumming energy relative from radial displacement between Sets A1 and A2.
The parts §, 6, 7 and 8 may have a relative position^ paralel or tapered with the same base angle (ike package A.
The variation of the reaction force, equal in the modulus with force F , is strongly dependent onv-Λhe surface geometry , f, g, j and k, which may have any imposed sba , e. g. spherical,-. eliptical, parabolic,, ' p.: as well as on the thickness, diameter, ■ ntirr er and elasticity modulus of blades 1 a»i 3*.
The geometry of surfaces f, g, k, which Tnay be convex or concave, determines the variation speed of gradient F(δ). The convex geometry generates a relatively high variation speed of the gradient and the concave geometry generates a relatively small variation speed of the gradient.
Characteristic F(δ) of the sandwich structure is a hysteretical on the route n, o, p.. r, n, which continues with non-linear elastic increasing extensions on routes n, s and p_, t which provide the disipation of a large quantity of energy at low and average loads within the displacements range corresponding to the δ δ3 segment. High values of the forces occur from E, to F2 and respectively from F3 to FA , at small increments of the displacements in δ ,δ2 segment and δ3,δ4 segment respectively as to a pre - set
displacement δλ and δ3 segment respectively, with the maintenance of the sandwich structure integrity and large capacity of reaction.
Characteristic F(δ) may be practically accomplished in any form, limitted only by the location of the mediane curve n - o - in a range confined by the lines (θ,α) and (θ,β) respectively, which create a small angle with the coordinate axes, usually below
5° and the disipated energy in one cycle may have high values, e. g. 40% - 60% of the elastic energy evaluated on the mediane curve n - o - p..
In this case the sandwich structures are generally suited for paralel installation in order to obtain large forces F for prescribed pre-set displacement δ , in order to provide the overtaking of permanent static loads with imposed elastic displacements.
According to the invention, the sandwich structure in another constructive alternative, has the package A pre-stressed by means of a peripherial lower deforming part, 9, having the surfaces u, y and w outer plane, average convex or concave and internal concave or convex related to the set A2 and may have or not a peripherical holes, x, of the same size and coaxial with the holes, c, and a central hole al, coaxial with hole a. The part, 9, may hav§ a paralel or tapered position as to paskstge A, with the same base angle like package A. ' ><
According to this alternative, the sandwich structures are suitable for reverse installation with the part 9 in contact and large displacements may be obtained towards the values of δ^δ^f
According j fte invention, the sandwich struetureyl another constructive alternative, has the package A fastened or not by means of a peripherial deforming upper part, 10, made from deforming materials, which may be or not provided with peripherical holes, b|, of the same size and coaxial with holes, c. The part 10 may have a paralel or tapered position as to package A, with the same base angle like package A.
In this case, the sandwich structures are generally suit for installation in series with the parts 6, 9 and 10 in contact in order to obtain large displacement δ for prescribed pre - set forces F as well as to take over the displacements from thermal expansions with small variations of the load;
According to this alternative the sandwich structures are generally suited for installation in series in order to obtain very large displacements δ[,δ2 * for small variations force F .
According to the invention, in a first constructive alternative the device for the control of structure behaviour is made up of some sandwich structures, B, that include the package A and part 5 and 6 and 7 and 8 or some sandwich structures, C, including the package A and parts 6, 8 and 9 or some sandwich structure D including the package A and part 6, 9 and 10, installed by a central rod, 11 , and peripherial rods, 12, elastic or rigid. The sandwich structures B or C or D are central pre-stress via the nuts, 13, at the upper part of rod 11 and the lower end of the rods, 11, is attached to the deforming part, 5, usually by a weld, 14, or a lock thread and also are peripherial pre- stress by lower and upper nuts, 15, and 16, screwed at the rod ends, 12, which press an upper end part, 17, with peripherical holes, c, which are coaxial with holes c and a central hole cT coaxial with hole a through which the rod 11 pass and another lower end part, 18, with peripherial holes e[, coaxial with holes c in which the rods 12 are fixed and a central hole f in which a bolt, 19 is usually fastened by a weld, 20, and which is provided with a central hole, g\
Function of the selected constructive solution, parts 5, 6, 7, 8, 9, which are in direct contact, may be separated or united in a single body with the adjacent part.
.The sølufon to fasten the device is preferably fb means of a bolt 19, to the support structure, not illustred in figures, and the rod, 11 , is fastened to a structure, system, equipment or pipe network by nuts or belt type support, not illustrated in figures.
By the application of a force ^ on the rod, 11, the rod 19 remaining fifed, the .lyforpp is taken over by the distortion of iet ^pdwich structures B and/or C and/or ift .,-..* f-;.?afg|aj -value δ and force F is uniformly cfefjfl ted between elastic blades 1 and 3. -bAf .χ f Function of the number of elastic blades 1 and 3 in a sandwich structure B or C ? or D and of the geometry of surfaces f, g, k the device can develop a large range of hysteresis characteristics F(δ) up to a pre-set displacement δl and δ3 which are continued with an non-linear encreasing elastic extension; beyond that limit the device is having the behaviour of an elastic body with very high stiffness.
According to this alternative, the device can take over static forces with pre - set stiffness and displacement on which dynamic loads may overlap and be damped, but it does not allow displacements from thermal expansions with constant and small reaction forces.
According to another constructive alternative, the device has between the elastic blade 1 and outer washer 4, a gap IV usually between 1 - 100 mm and a gap W
between the elastic blade 3 and inner washer 2, usually equal to IV. In case of devices having the cross - section of a rectangular or elipse shape, the gap IV and W have, usually, different values on different directions.
As per this alternative, the device allows large displacements in normal plane on the symetry axis, such as, from thermal expansions with constant pre - set reaction force, given by the pre - stress between Set A1 and A2 of package A by nuts 13.
As per another constructive alternative, the device is made up of two subansamblies, E, each of them including the structures B and/or C and/or D, rods 11 , 12 welding, 14, and end part, 17, symetrically arranged as to a mediane plane and pre - stressed by nuts 15 and 16.
According to this alternative, the device is fixed by one of rods 11 directly on the support structure and can allow larger non-linear geometric elastic deformation and can support large static loads on which large dynamic loads may overlap and be damped.
According to another constructive alternative the device has some lugs 21 with holes, Y attached to rods 11.
As per this alternative the device can be easily inserted into a large range of structures elements such as' b-iέacings, in order to control distortion and limitted to prescribed set values.
According to another constructive alternative, the device has a central elastic rod, 22, fixed in, the hole g^ which, along with rods 12 are nade of a high elasticity material and th nV, jV and (V exterior plane,
and the part 17 has a surface jV central convex on upper side and a threaded bolt 28 with a central hole f in which rod 22 accommodates, is fixed in hole d\ The end part 17 is pre-stressed by means of a set of elastic blades 3 using waέhers 24 that penetrate the enlarged holes c. A bushing 24 that penetrates the holes b is mounted on bolt 23 and a set of sandwich structures D is installed between end parts 17 and 18.
As per this constructive alternative, the device is spatially operating with characteristics of pre - set stiffness and damping for each direction.
On axial direction, all sandwich structures D are connected in series, developing a non - linear force - displacement characteristic of the required shape by the mounting of package A with a different numer of blades 1 and 3 distorted on parts 6 and 9, with the surfaces e, f, g with different geometries*
In a radial plane, the device is operating by the relative controlled displacement by rods 12 and 22 between sets A1 and A2, obtaining both an elastic force and a damp energy due to the friction in blades 1 and 3.
According to another constructive alternative the box device, is made up of some devices G including any of the alternatives devices mentioned above, with the remark that it does not allow the application of the construction alternative devices with lugs 21, installed in paralel between some lower and upper plates 25 and 26, usually in the shape of a circle, elipse or square, by means of nuts 27 and 28 and washers 29 and 30, stiffened by a lattice of lower and upper profiles 31 and 32.
Plates 25, 26 and profiles 31 , 32 are provided with some concentric holes s and some skirts 33 and 34 provided with some slots t. are attached to plates 25, 26 outside. The skirts 33 and 34 overlap in the central area and make a circular space iV in which it is possible to instal a deforming body 35. To the skits 33 and 34 the lower and upper, lugs 36 and 37, are fixed and provided with lateral holes and w| and lower and upper holes and x|_and _, hooks 38 and 39, also provided with holes g and W both of them uniformly distributed on the circumference.
In this constructive alternative, the obtained device dan take over very large axial static loads generally vertical position on which tridimensional dynamic loads may overlap and be damped and it can be employed to isolate heavy equipments and machines.
Lt:AA--
:. According to another constructive alternative the invention, the column- devie
;i
§.
of some box devices H
G, plates 25 and 26, nuts 27 a f * 28, washers 29 and 30, profiles 31 and 32, skirts 33 and 34, body 35 and lugs 36 and 37, hooks 38 and 39, installed in series by means of screws 40, washers 41 and nuts 42 that are mounted through the slots V and/or through fastening the adjacent lugs 36 and 37.
As per this constructive alternative, the device column may develop very large dynamic displacements on any directions and it can be employed to control the dynamic behaviour of structures and very heavy equipments, especially by their isolation.
The devices which include the sandwich structures B or/and C and/or D may be pre-stressed so that, in the installation position, packages A has a deformed tapered position with a base angle of max. 10°, function of the size of the ratio between the shear force and the normal force applied on the devices, and the magnitude of the reaction force which is oposing to the displacement in the normal plane of the symetry
axis, such as, the displacements due to thermal expansions of the pipes in pipe networks supported by such devices.
The network of devices for the control of a structure or system behaviour as per the invention usually consists, in the formation in the most loaded areas of a structure or some system squares K with controlled deforming diagonals L which are made up of some devices M which include lugs 21 installed in series or in paralel and some profiles 43 and fastening strips 44 and gusset plates 45.
For an existing structure made up of reinforced concrete columns, 46, and beams 47, the network of devices can be employed in consolidating the structure and it consists of the installation at the ground floor and upper levels of some coatings 48, for the joint between columns 46 and beams 47 connected amoung themselves by means of corners, 49, anchored by fastening steel - made strips, 50.
Squares K are symmetrically arranged on the building sides and/or inside the building and can be done employing a part of the existing elements structure. The device network may also include the installation of devices between the component substructure of a building. *
' ■ a The network of devices fogthe control *of a structure behaviour tikes over and ^ disipates the shocks, vibrations and seismics energy in the elastic range of a building structure behaviour and it may be employed both with new and existing buildings, without affecting the building operability and/or architecture.
When reachi g the maximum distortion value fonϊwbiGh the building structure does not develof**| t^s,tic hinges,: e. g. 4 %o of a inter-stof-e f άight as"felative lateral displacement with reinforced concrete frame structures, the stiffness of the devices encreases very much, providing, after this displacement, very high forces for very low displacements, forces which are required to maintain the building stability.
As per another constructive alternative of the invention, the network of devices for the control of a building or an equipment or a machine behaviour consists of the installation between a general basemat 51 and equipment or machine or building or between the super-structure of a building which is separated from its consolidated below-structure, of some columns devices N consisting of base devices H, bolts 40, washers 41 and nuts 42 among which bracings L connected to the upper side of a columns devices N and lower part of adjacent columns devices N, are mounted.
According to this constructive alternative, the obtained network is capable to take over very large static loads on which high dynamic loads may overlap with high
displacements and damps on any directions such as the seismic loads which it overtakes and damps, providing thus the control of the building behaviour by isolating it against the source of shocks, vibrations and earthquakes.
By the employment of such a network, one can also obtain an efficient isolation of equipment and heavy machines, historical monuments against shocks, vibrations and earthquakes, without affecting their historical value and art value as well as of all new and existing buldings of any type.
The network of devices to take over and damp the loads for the control of pipe network behaviour as per another constructive alternative of the invention, consists of the installation between a pipe type structure 53 and a support steel structure 54, or a support concrete structure 55, of some supports O or P or R which include a device G and some fastening elements of saddle type, 56 and clamps, 57, prestressed on pipe 53 by means of nuts 58, or a threaded rod 59, attached and prestressed on pipe 53, by means of a nut 60, 61 so that another saddle type part 61 , is pressing on pipe 53.
In this case, supports R are installed dimetrically oposed to pipe 53 or in a star- arrangement as to pipe 53. Support Q may be installed below or over the pipe.
According to this constructive alternative, th obtained network is capable to take over static loads, thermal expansions and dynamic loads, accomplishing a balance of forces between pipe 53 and supports O or/and P or/and R, at a level as low as possible. The casing device in another constructive alternative, the sandwich structure B and/or C and/or D and the. device , which do not include the elastic centa |pd 22, are fastened in a casing 62 or 63. In,^;^ 62 a sandwich structure D is prestr^e^and it is interpositioned or not, between elastic blades 3 which have hole b of the same size like hole a. Casing 62 is provided with a inside shoulder a^ at the bottom side, which is fastening a outside shoulder IV[ located at the part 9.
On top, casing 62 is fastened by a weld 64 at part 6 after structure D has been prestressed accomplishing a deforming of package A with a base angle of max 10°, function of the size of the static loads and the ratio between the normal force and shear force which the sandwich structure D must take over.
In the central holes a, b, tf, bl, a bushing guide 65 is setting to allow the installation of the same device on various bolt sizes, not shown in figures.
In casing 63 some sandwich structures B and/or C and/or D are prestressed by fixing the casing 63 by welds 66 and 67 to the parts 17 or 18, case in which the
sandwich structures B and/or C and/or D no longer have the peripherial holes c, d, j, I, m, x, tV and them are no longer prestressed with rods 12.
Rod 11 may be guided by a bushing guide 68 fastened in the part 17 and guided by a bushing guide 69, fastened to a part 70 which is screwed into part 18 and locked by a nut 71.
Part 70 is also used to press the sadwich structure B and/or C and/or D by pressing it on a shoulder c of rod 11. A hook 72 is attached to part 18 for catching.
As per this alternative the device may also operate like a constant load support in case that the number of blades 1 and 3 of the sandwich structure B and/or C and/or D are progressively encreased.
According to another constructive alternative of the casing device a support part 73 provided with holes \Λ for possitioning is attached to rod 11. In thes case the casing device can be used to support heavy equipment or machines.
All casing devices have a simpler structure, smaller size and weights, lower costs, better resistance in aggressive media, higher reliability, yet rendering the same performances and characteristics like the devices without casi g.