WO2002020910A1

WO2002020910A1 - Khonsar replaceable energy-dissipating structural connection

Info

Publication number: WO2002020910A1
Application number: PCT/GB2000/003397
Authority: WO
Inventors: Seyed Vahid Khonsari
Original assignee: Imperial College Innovations Limited
Priority date: 2000-09-04
Filing date: 2000-09-04
Publication date: 2002-03-14
Also published as: AU2000268598A1

Abstract

A replaceable energy-dissipating structural connection for connecting structural elements of a structure, comprising : first and second attachment members each including attachment surfaces for attachment to structural elements of a structure; and first and second ductile energy-dissipating members connecting the attachment member, wherein the first and second energy-dissipating members are configured to have different relative states of loading on loading the structural connection to cause relative rotation of the attachment members about a rotation axis, and deform, and thereby dissipate energy, on loading the structural connection above a critical value. With this construction, damage to the structural elements of a structural connections, thereby allowing easy repair of the structure by replacement of the structural connections.

Description

KHONSAR REPLACEABLE ENERGY-DISSIPATING STRUCTURAL CONNECTION

The present invention relates to an energy-dissipating structural connection for connecting structural elements of a structure, in particular a beam-to-column connection for connecting a beam to a column and a brace connection for connecting a brace element to a beam or a column, such as to dissipate energy on overloading of the structure. In one embodiment the structure could be the skeletal structure of a construction, such as a building, which could suffer from overloading as, for example, experienced in earthquakes or explosions. Multi-storey buildings and towers are examples of large-scale building structures in which structural connections of the present invention find application.

Structural connections currently exist for connecting structural elements, for example, the beams and columns, of structures. The currently-used structural connections are, however, simple connections which are not configured to dissipate energy from an overloaded structure. Any limited ability of those structural connections to dissipate energy is provided essentially only by the ductility of the material, usually mild steel, of the structural connections. As such, the overloading of a structure incorporating existing structural connections leads to destruction of both the structural connections and the structural elements.

It is thus an aim of the present invention to provide a replaceable energy-dissipating structural connection which dissipates energy from a structure when overloaded. Such structural connections, when incorporated in a structure loaded beyond normal service loads, act to absorb and hence dissipate energy sacrificially in preference to damaging the structural elements.

In this way, in the event of a structure being overloaded as a result, for example, of an earthquake or an explosion, the damage to the structure is confined to the structural connections. In confining the damage to the structural connections, repair of the structure is much simpler as the structural connections can be replaced separately from the much larger load-bearing structural elements. Also, by enabling the structural connections to be fabricated as components which are separate to the structural elements of a structure and can be fixed by means which do not alter the material properties, such as by connecting bolts or rivets, the structural connections can easily be heat treated to control the material properties thereof. For example, where the structural connections are fabricated as welded steel components, it is well known that the welding operations, in particular the rapid cooling of the welds and the heat-affected zones, can induce residual stresses and lead to the development of the brittle martensitic phase. Thus, heat treatment is desirable both to relieve any residual stresses and to provide for the transformation of the brittle martensitic phase to a ductile phase. Also, where the structural connections are fabricated as aluminium-based extrusions, the structural connections can desirably be heat treated by way of tempering. As will be appreciated, such heat treatment would not be practical where, as is conventional, the structural connections are welded to the structural elements.

Accordingly, the present invention provides an energy-dissipating structural connection for connecting structural elements of a structure, comprising: first and second attachment members each including attachment surfaces for attachment to structural elements of a structure; and first and second ductile energy-dissipating members connecting the attachment members, wherein the first and second energy- dissipating members are configured to have different relative states of loading on loading the structural connection to cause relative rotation of the attachment members about a rotation axis, and deform, and thereby dissipate energy, on loading the structural connection above a critical value.

Preferably, the first and second energy-dissipating members are configured to be in respective states of tension and compression on loading the structural connection.

In one embodiment at least one of the first and second energy-dissipating members extends substantially orthogonally to the rotation axis. Preferably, the first and second energy-dissipating members extend substantially orthogonally to the rotation axis.

In another embodiment at least one of the first and second energy-dissipating members extends substantially parallel to the rotation axis.

Preferably, the first and second energy-dissipating members extend substantially parallel to the rotation axis.

Preferably, at least one of the first and second energy-dissipating members is provided by a tubular section.

More preferably, the first and second energy-dissipating members are provided by tubular sections.

In another embodiment the structural connection comprises an element which extends orthogonally to the rotation axis, with one end region of the element providing the first energy-dissipating member and the other end region of the element providing the second energy-dissipating member.

Preferably, the element comprises a tubular section.

In one embodiment the attachment surfaces are parallel.

In another embodiment the attachment surfaces have a non-parallel relationship such that, when one of the attachment members is attached to a structural element, the attachment surface of the other attachment member is upwardly inclined so as to present a surface which can be engaged by another self-supporting structural element.

Preferably, the attachment members comprise embracing plates. Preferably, the structural connection farther comprises a hinge section which defines the rotation axis about which the attachment members are relatively rotatable and is configured to support shear loading of the structural connection.

More preferably, the hinge section is configured to allow relative lateral movement of the attachment members upon deformation of the energy-dissipating members.

Preferably, the structural connection comprises a plurality of first energy-dissipating members and a plurality of second energy-dissipating members.

In one embodiment the structural connection is fabricated as a metal extrusion.

In one preferred embodiment the structural connection is fabricated as an aluminium- based extrusion.

Preferably, the aluminium-based extrusion is heat treated, more preferably tempered.

In another embodiment the structural connection is fabricated as a metal casting.

In one preferred embodiment the structural connection is fabricated as an aluminium- based casting.

Preferably, the aluminium-based casting is heat treated, more preferably tempered.

In another preferred embodiment the structural connection is fabricated as a steel casting.

Preferably, the steel casting is heat treated, more preferably annealed.

In a further embodiment the structural connection is fabricated as a synthetic material extrusion. In a yet further embodiment the structural connection is fabricated as a synthetic material casting.

Preferably, the structural connection is fabricated as a fibre-reinforced composite casting.

In a still further embodiment the structural connection is fabricated as a welded structure.

In one preferred embodiment the structural connection is fabricated as a welded steel structure.

Preferably, the welded steel structure is heat treated, more preferably annealed.

The present invention also extends to a structure, in particular a skeletal structure, incorporating structural connections as above-described.

In one embodiment the structural elements comprise ones of beams and columns.

In another embodiment the structural elements comprise ones of bracing elements of a bracing system and at least one of beams and columns.

Preferably, the structural elements comprise ones of bracing elements of a bracing system and beams and columns.

In one preferred embodiment the bracing system comprises an inverted V bracing system.

In another preferred embodiment the bracing system comprises an X bracing system.

In a further embodiment the structural elements comprise ones of bracing elements and at least one of beams and columns of an eccentrically braced frame. Preferably, the structural elements comprise ones of bracing elements and beams and columns of an eccentrically braced frame.

Preferably, ones of the bracing elements are connected in offset relation such that a bending moment is applied to the respective structural connections on loading the same.

This structural connection is a KHONSAR™ structural connection.

Preferred embodiments of the present invention will now be described hereinbelow by way of example only with reference to the accompanying drawings, in which:

Figure 1(a) illustrates a side view of a structural connection in accordance with a first embodiment of the present invention;

Figure 1(b) illustrates one face view of the structural connection of Figure 1(a), with one of the attachment members removed;

Figure 1(c) illustrates the other face view of the structural connection of Figure 1(a), with the other of the attachment members removed;

Figure 2(a) illustrates a side view of an arrangement comprising I-section beams connected to an I-section column by the structural connections of Figure 1(a);

Figure 2(b) illustrates a pian view of the arrangement of Figure 2(a);

Figure 3(a) illustrates a side view of an arrangement comprising I-section beams connected to a rectangular hollow section column by the structural connections of Figure 1(a);

Figure 3(b) illustrates a plan view of the arrangement of Figure 3(a); Figure 4(a) illustrates a side view of an arrangement comprising I-section beams connected to a circular hollow section column by the structural connections of Figure

1(a);

Figure 4(b) illustrates a plan view of the arrangement of Figure 4(a);

Figure 5(a) illustrates a side view of an arrangement comprising concrete beams connected to an I-section column by the structural connections of Figure 1(a);

Figure 5(b) illustrates a plan view of the arrangement of Figure 5(a);

Figure 6(a) illustrates a side view of an arrangement comprising I-section beams connected to a concrete column by the structural connections of Figure 1(a);

Figure 6(b) illustrates a plan view of the arrangement of Figure 6(a);

Figure 7(a) illustrates a side view of an arrangement comprising concrete beams connected to a concrete column by the structural connections of Figure 1(a);

Figure 7(b) illustrates a plan view of the arrangement of Figure 7(a);

Figure 8(a) illustrates a side view of a test structural connection;

Figure 8(b) illustrates one face view of the structural connection of Figure 8(a), with one of the attachment members removed;

Figure 8(c) illustrates the other face view of the structural connection of Figure 8(a), with the other of the attachment members removed;

Figure 9 illustrates a side view of a T-shaped test assembly comprising I-section beam sections connected to an I-section column section by the structural connections of Figure 8(a), as mounted in a testing rig; Figure 10 illustrates a mechanistic model of the test assembly of Figure 9;

Figure 11 illustrates the load-deflection diagrams of the column sections of first and second test assemblies;

Figure 12 illustrates the moment-rotation diagrams of an 'average' structural connection of the first and second test assemblies;

Figures 13 to 20 illustrate structural connections as modifications of the structural cormection of Figure 1(a);

Figure 21(a) illustrates a side view of a structural cormection in accordance with a second embodiment of the present invention;

Figure 21(b) illustrates one face view of the structural cormection of Figure 21(a), with one of the attachment members removed;

Figure 21(c) illustrates the other face view of the structural connection of Figure 21(a), with the other of the attachment members removed;

Figure 22(a) illustrates a side view of a structural connection in accordance with a third embodiment of the present invention;

Figure 22(b) illustrates one face view of the structural connection of Figure 22(a), with one of the attachment members removed;

Figure 22(c) illustrates the other face view of the structural connection of Figure 22(a), with the other of the attachment members removed;

Figure 23(a) illustrates a side view of a structural cormection in accordance with a fourth embodiment of the present invention; Figure 23(b) illustrates a sectional view (along section I-I) of the structural connection of Figure 23(a);

Figure 23(c) illustrates a sectional view (along section II-II) of the structural connection of Figure 23(a);

Figure 24 illustrates a side view of an arrangement comprising a structural connection in accordance with a fifth embodiment of the present invention connecting a beam to a column;

Figure 25(a) illustrates a side view of a structural connection in accordance with a sixth embodiment of the present invention;

Figure 25(b) illustrates a sectional view (along section I-I) of the structural connection of Figure 25(a);

Figure 25(c) illustrates a sectional view (along section II-II) of the structural connection of Figure 25(a);

Figure 25(d) illustrates a side view of an arrangement comprising the structural connection of Figure 25(a) connecting a beam to a column;

Figure 26(a) illustrates a side view of an arrangement comprising a structural connection in accordance with a seventh embodiment of the present invention connecting a beam to a column;

Figure 26(b) illustrates a pian view of the arrangement of Figure 26(a);

Figure 27(a) illustrates a side view of an arrangement comprising a structural connection in accordance with an eighth embodiment of the present invention connecting a beam to a column;

Figure 27(b) illustrates a plan view of the arrangement of Figure 27(a); Figure 28(a) illustrates a side view of an arrangement comprising a structural connection in accordance with a ninth embodiment of the present invention connecting a beam to a column;

Figure 28(b) illustrates a plan view of the arrangement of Figure 28(a);

Figure 29(a) illustrates a side view of an arrangement comprising a structural connection in accordance with a tenth embodiment of the present invention connecting a beam to a column;

Figure 29(b) illustrates a plan view of the arrangement of Figure 29(a);

Figure 30(a) illustrates a side view of a structural cormection in accordance with an eleventh embodiment of the present invention;

Figure 30(b) illustrates a sectional view (along section I-I) of the structural connection of Figure 30(a);

Figure 30(c) illustrates a sectional view (along section II-II) of the structural connection of Figure 30(a);

Figure 30(d) illustrates a side view of an arrangement comprising the structural connection of Figure 30(a) connecting a beam to a column;

Figure 31(a) illustrates a side view of a structural connection in accordance with a twelfth embodiment of the present invention;

Figure 31(b) illustrates a sectional view (along section I-I) of the structural connection of Figure 31(a);

Figure 31(c) illustrates a sectional view (along section II-II) of the structural connection of Figure 31 (a); Figure 31(d) illustrates a side view of an arrangement comprising the structural connection of Figure 31 (a) connecting a beam to a column;

Figure 31 (e) illustrates a plan view of the arrangement of Figure 31 (d) ;

Figure 32(a) illustrates a side view of a structural cormection in accordance with a thirteenth embodiment of the present invention;

Figure 32(b) illustrates a sectional view (along section I-I) of the structural connection of Figure 32(a);

Figure 32(c) illustrates a sectional view (along section II-II) of the structural connection of Figure 32(a);

Figure 32(d) illustrates an enlarged view of the hinge section of the structural connection of Figure 32(a);

Figure 33 illustrates an enlarged view of a modified hinge section for the structural cormection of Figure 32 ;

Figure 34 illustrates an enlarged view of another modified hinge section for the structural connection of Figure 32;

Figure 35(a) illustrates a side view of a structural connection in accordance with a fourteenth embodiment of the present invention;

Figure 35(b) illustrates a sectional view (along section I-I) of the structural connection of Figure 35(a);

Figure 35(c) illustrates a sectional view (along section II-II) of the structural connection of Figure 35(a); Figure 36(a) illustrates a side view of a structural connection in accordance with a fifteenth embodiment of the present invention;

Figure 36(b) illustrates a sectional view (along section I-I) of the structural connection of Figure 36(a);

Figure 36(c) illustrates a face view of the structural connection of Figure 36(a);

Figure 36(d) illustrates a side view of an arrangement comprising the structural connection of Figure 36(a) connecting a beam to a column;

Figure 37(a) diagrammatically illustrates a multi-storey construction comprising a skeletal structure of interconnected beams and columns and an inverted V bracing system, the bracing elements of which are connected by the structural connections of Figure 27;

Figures 37(b) and (c) illustrate in enlarged scale side and end views of the connection of one structural connection of the skeletal structure of Figure 37(a);

Figure 38(a) diagrammatically illustrates another multi-storey construction comprising a skeletal structure of interconnected beams and columns and an inverted V bracing system, the bracing elements of which are connected by the structural connections of Figure 29;

Figures 38(b) and (c) illustrate in enlarged scale side and end views of the connection of one structural connection of the skeletal structure of Figure 38(a);

Figure 39(a) diagrammatically illustrates a further multi-storey construction comprising a skeletal structure of interconnected beams and columns and an inverted V bracing system, the bracing elements of which are connected by slightly modified structural connections of Figure 32; Figures 39(b) and (c) illustrate in enlarged scale side and end views of the connection of one structural cormection of the skeletal structure of Figure 39(a);

Figure 40(a) diagrammatically illustrates a yet further multi-storey construction comprising a skeletal structure of interconnected beams and columns and an X bracing system, the bracing elements of which are connected by slightly modified structural connections of Figure 32; and

Figures 40(b) and (c) illustrate in enlarged scale side and plan views of the connection of one structural connection of the skeletal structure of Figure 40(a).

Figures 1(a) to (c) illustrate a structural cormection C in accordance with a first embodiment of the present invention.

The structural connection C comprises first and second attachment members 1, 3, in this embodiment embracing plates disposed in parallel relation, for attachment to structural elements of a structure, in particular a skeletal structure, a hinge unit 5 defining a rotation axis about which the first and second attachment members 1, 3 are relatively rotatable, and first and second energy-dissipatmg members 7, 9, each having a lateral dimension substantially the same as the spacing of the attachment members 1, 3 and being fixed to both the first and second attachment members 1, 3 on opposed sides of the rotation axis. The energy-dissipating members 7, 9 comprise ductile tubular sections, in this embodiment of circular section, the longitudinal axis of which extends parallel to the central, horizontal axis of the structural connection C. The hinge section 5 comprises a first arm 11 which includes a through hole 12 and is fixed to the first attachment member 1, second and third arms 13, 14 which each include opposed through holes 15, 16 and are fixed in spaced relation to the second attachment member 3 to receive the first arm 11 therebetween, and a hinge pin 17 which extends through the through holes 12, 15 , 16 in the first to third arms 11, 13, 14 and defines the rotation axis. With this construction, the energy-dissipating members 7, 9 are in use loaded, substantially diametrically, such that one of the energy-dissipating members 7, 9 is under tension and the other of the energy-dissipating members 7, 9 is under compression depending on the bending moment which is being transferred by the structural connection C.

In this embodiment the structural connection C is fabricated by welding steel, preferably mild steel, components and annealing the welded connection to relieve any residual stresses and transform any brittle phase to a ductile phase. By selection of the geometric parameters and material characteristics of the energy-dissipating members 7, 9, the structural connection C can be configured to exhibit the required rigidity under service loads, but yet fail, and in so doing dissipate significant energy, on being overloaded.

In use, these structural connections C are used to interconnect the structural elements of a structure, which structural elements typically comprise ones of metal, for example steel, concrete or wooden beams and columns.

Figures 2(a) and (b) illustrate first and second structural connections Cl, C2 connecting first and second I-section steel beams 21, 23 to the opposed sides of an I- section steel column 25.

Figures 3(a) and (b) illustrate first and second structural cormections Cl, C2 connecting first and second I-section steel beams 21, 23 to the opposed sides of a rectangular hollow section (RHS) steel column 25.

Figures 4(a) and (b) illustrate first and second structural connections Cl, C2 connecting first and second I-section steel beams 21, 23 to the opposed sides of a circular hollow section (CHS) steel column 25 including outer stiffeners 27, 29 to stiffen the column 25 at the point of connection to the first attachment members 1 , 1 of the structural connections Cl, C2.

Figures 5(a) and (b) illustrate first and second structural connections Cl, C2 connecting first and second concrete beams 21, 23 to the opposed sides of an I-section steel column 25. Figures 6(a) and (b) illustrate first and second structural connections Cl, C2 connecting first and second I-section steel beams 21, 23 to the opposed sides of a concrete column 25.

Figures 7(a) and (b) illustrate first and second structural connections Cl, C2 connecting first and second concrete beams 21, 23 to the opposed sides of a concrete column 25.

Under service loads, the structural connections Cl, C2 exhibit sufficient rigidity that the attachment members 1, 3 of the respective structural connections Cl, C2 each maintain a substantially parallel relationship, with ones of the energy-dissipating members 7, 9 of the structural connections Cl, C2 being under tension and the others of the energy-dissipating members 7, 9 being under compression depending on the bending moment of the beams 21, 23.. However, when the structure is overloaded, the bending moment of the beams 21, 23 relative to the column 25 is such as to cause the deformation and hence failure of the energy-dissipating members 7, 9, with the ones of the energy-dissipating members 7, 9 under tension being elongated and the others of the energy-dissipating members 7, 9 under compression being crushed. This plastic deformation of the energy-dissipatmg members 7, 9 dissipates the energy associated with the overload, thereby maintaining the beams 21, 23 undamaged. Where the deformation of the energy-dissipating members 7, 9 is limited and the energy- dissipating members 7, 9 could dissipate further energy, the structural connections C can remain in service, but where the deformation exceeds a predetermined limit such that the energy-dissipating members 7, 9 could dissipate no further energy, the structural connections C are replaced.

Characteristics of the structural connection C of the above-described embodiment will be exemplified with reference to the following non-limiting Example.

Example

A test structural connection C, as illustrated in Figures 8(a) to (c), was first fabricated by welding steel components. All of the dimensions in Figures 8(a) to (c) are in millimetres. The welded connection was then annealed to relieve any residual stresses and transform any brittleness as induced by the welding operations. In this Example, the annealing process was performed in an annealing furnace and comprised the steps of gradually heating the welded connection to 650 °C, maintaining the structural connection at that temperature for 2 hours and allowing the structural connection to cool down slowly at the cooling rate of the annealing furnace. In this test structural connection C, the attachment members 1, 3, the hinge section 5 and the energy- dissipating members 7, 9 were formed of mild steel. Also, the attachment members 1, 3 and the hinge section 5 were formed of large sections to exhibit a high degree of rigidity, and thus negligible deformation under load, so that the deflection of the test structural connection C is that of and attributable to the energy-dissipating members 7, 9.

The bending behaviour of the test structural connection C was tested in first and second tests using first and second identical T-shaped test assemblies as illustrated in

Figure 9. A mechanistic model of the test assemblies is illustrated in Figure 10. Each of the test assemblies is a symmetrical system comprising first and second beam sections 31, 33 each including end plates 35, 37, in these test assemblies IPB140 (DIN standard) wide flange sections having a length of 600 mm, connected to the opposed sides of a column section 39, in these test assemblies an IPB160 (DIN standard) wide flange section having a length of 315 mm, by first and second test structural connections Cl, C2. Again, in order to greatly simplify analysis, heavy sections were used for the beam and column sections 31, 33, 39 as well as the end plates 35, 37 of the beam sections 31, 33 and high strength connecting bolts. With this configuration, deformation of the beam and column sections 31, 33, 39, the end plates 35, 37 and the connecting bolts is negligible, thus allowing the total deflection measured to be attributed to that caused by the rotation of the structural connections Cl, C2.

The testing rig for measuring the bending moment of the test assemblies comprises a rigid platform which includes first and second rollers spaced 1200 mm apart on which the test assemblies are located, and a loading mechanism for applying a load P along the centre line of the column section 39. In each of the tests, the test structural cormections Cl, C2 were tested to the point of failure of the energy-absorbing members 7, 9, the first energy-dissipating members 7, 7 being in compression and the second energy-dissipating members 9, 9 being under tension. In the first test, owing to imperfections in the test assembly, believed to be mainly geometric, the deformation process gradually deviated from the symmetric state and the beam sections 31, 33 did not rotate symmetrically. Thus, the results obtained from the first test represent average values of the first and second test structural connections Cl, C2. In the second test, symmetry of the test assembly was maintained during the test. Thus, the results obtained from the second test are believed to be more accurate.

The load-deflection diagrams of the column sections 39 of the first and second test assemblies as obtained from the first and second tests are illustrated in Figure 11. From Equations 1 and 2 as set out hereinbelow, as derived from the mechanistic model illustrated in Figure 10, and attributing the deflection under the applied loads and moments to the energy-dissipating members 7, 9 of the test structural connections Cl, C2, the moment-rotation diagrams of an 'average' structural cormection for each of the test assemblies can be determined. These moment-rotation diagrams are illustrated in Figure 12.

tan a - H => a = arctan H

D D (1)

M = P.D

2 (2)

Where:

a is the angle of rotation of the structural connection, and also that of each beam section

D is the horizontal projection of the part of one beam section and the structural connection as bounded by the respective supporting roller and the rotation axis of the structural connection II

H is the vertical displacement of the column section, and also the vertical projection of the part of one beam section and the structural connection as bounded by the respective supporting roller and the rotation axis of the structural connection M is the moment transferred by the structural connection

P is the vertical load applied at the top of the column section

From the moment-rotation diagrams, the total energy dissipated by the 'average' structural connection C can be determined; this dissipated energy being the integral of the area bounded by the plot of the respective moment-rotation diagram. The determined values of the dissipated energy for the 'average' structural connections C of the test assemblies are given in Table 1 hereinbelow. As will be noted, the determined values of dissipated energy are comparable with the documented energy- dissipating capacities of end plate connections, but significantly, in those end plate connections, the beams and columns are damaged by deformation. The final rotations after rebound and the maximum, but not final, moments of the 'average' structural connections C of the test assemblies are also given in Table 1. As a point of note, it is the fluctuating nature of the moment-rotation diagrams of the test structural connections Cl, C2 which causes the maximum moment to be different from the final moment.

Table 1: Maximum/final rotations, moments and total absorbed energy of an 'average' structural connection C of the first and second test assemblies and two documented end plate connections.

On testing the present structural connections Cl, C2, the damage was confined to the energy-dissipating members 7, 9 and none of the beam sections 31, 33, the end plates 35, 37, the column section 39 or the connecting bolts were damaged by way of permanent inelastic deformation. Thus, energy dissipation was provided entirely by the energy-dissipating members 7, 9. This confinement of the damage to the structural connections Cl, C2 enables repair of a damaged structure by requiring replacement of only the damaged structural connections Cl, C2, and damage is confined to the structural connections Cl, C2 even when the beam sections 31, 33, the end plates 35, 37, the column section 39 and the connecting bolts are formed from the usual, less stiff, smaller and practical sections.

Figures 13 to 20 illustrate structural connections C which are modifications of the structural connection C of the above-described first embodiment. These structural connections C differ only in the construction of the energy-dissipating members 7, 9.

In these modified structural connections C, energy-dissipating members 7, 9 having tubular sections with at least one other than circular are utilised; these geometric shapes including square, rectangular and hexagonal. Further, the structural connections C include first and second energy-dissipating members 1 , 9 of different construction, rectangular and hexagonal as illustrated in Figure 17, square and hexagonal as illustrated in Figure 18, circular and hexagonal as illustrated in Figure 19 and circular and rectangular as illustrated in Figure 20. By selection of the geometric shape and material characteristics of the energy-dissipating members 7, 9, the rigidity, the moment and the energy-dissipating capacity of the structural cormection C can be controlled.

Figures 21(a) to (c) illustrate a structural connection C in accordance with a second embodiment of the present invention.

This structural connection C is substantially identical to the structural connection C of the above-described first embodiment, and thus, in order to avoid unnecessary duplication of description, only the differences will be described in detail.

This embodiment differs only in the construction of the hinge section 5, in that at least one of the through hole 12 in the first arm 11 on the first attachment member 11 or the through holes 15, 16 in the second and third arms 13, 14 on the second attachment member 3 comprise slots extending orthogonal to the respective attachment member 1, 3. With this construction, the attachment members 1, 3 are, upon deformation of the energy-dissipating members 7, 9, free to move laterally, but relative vertical sliding movement is constrained so as to accommodate a high shear loading. Operation is the same as for the above-described first embodiment.

Figures 22(a) to (c) illustrate a structural connection C in accordance with a third embodiment of the present invention.

This structural connection C is similar to the structural connection C of the above- described first embodiment, and thus, in order to avoid unnecessary duplication of description, only the differences will be described in detail.

This embodiment differs only in the omission of the hinge section 5. With this construction the attachment members 1, 3 are able to move laterally and slide vertically relative to one another. Operation is the same as for the above-described first embodiment, with the rotation axis being located between the energy-dissipatmg members 7, 9.

Figures 23(a) to (c) illustrate a structural connection C in accordance with a fourth embodiment of the present invention.

This structural connection C is similar to the structural connection C of the above- described third embodiment, and thus, in order to avoid unnecessary duplication of description, only the differences will be described in detail.

This embodiment differs only in the structure of the energy-dissipating members 7, 9. In this embodiment the energy-dissipating members 7, 9 each comprise first and second elongate, arcuate elements 7a, 9a, 7b, 9b disposed in opposed relation such as to define tubular sections, with each of the elongate elements 7a, 9a, 7b, 9b including a stiffening rib 38 extending along the length thereof. Operation is the same as for the above-described third embodiment, with the rotation axis being located between the energy-dissipating members 7, 9. Figure 24 illustrates a structural connection C in accordance with a fifth embodiment of the present invention connecting first and second structural elements of a skeletal structure, in this embodiment a column 45 and a beam 47 including an end plate 49.

^' This structural connection C is similar to the structural connection C of the above- described third embodiment, and thus, in order to avoid unnecessary duplication of description, only the differences will be described in detail.

This embodiment differs only in the energy-dissipating members 7, 9 each being of different dimension and the non-parallel relationship of the attachment surfaces of the attachment members 1, 3. In this embodiment the second, lower energy-dissipating member 9 is of larger dimension than the first, upper energy-dissipating member 7, and the attachment surface of the second attachment member 3 to which a beam 47 is connected is upwardly inclined relative to the vertical when the structural connection C is connected to a column 45. By providing the energy-dissipating members 7, 9 to be of different dimension and material properties, the structural connection C can be adapted to meet particular loading requirements. Further, the configuration of this structural connection C, in providing an upwardly-inclined beam attachment surface, is particularly advantageous in that, by first fitting the structural cormections C to the columns 45, the beams 47 are self-supporting when lowered into position. In this way, the beams 47 can be connected to the structural cormections C without requiring any separate support. Operation is the same as for the above-described third embodiment, with the rotation axis being located between the energy-dissipatmg members 7, 9.

Figures 25(a) to (d) illustrate a structural connection C in accordance with a sixth embodiment of the present invention connecting- first and second structural elements of a skeletal structure, in this embodiment a column 45 and a beam 47 including an end plate 49.

This structural connection C is similar to the structural cormection C of the above- described third embodiment, and thus, in order to avoid unnecessary duplication of description, only the differences will be described in detail. This embodiment differs only in including first and second groups, in this embodiment pairs, of energy-dissipating members 7, 9 disposed in spaced relation and extending parallel to the horizontal axis of the structural connection C. Operation is the same as for the above-described third embodiment, with the rotation axis being located between the first and second groups of energy-dissipating members 7, 9.

Figures 26(a) and (b) illustrate a structural cormection C in accordance with a seventh embodiment of the present invention connecting first and second structural elements of a skeletal structure, in this embodiment a column 45 and a beam 47 including an end plate 49.

The structural connection C comprises first and second attachment members 51, 53, in this embodiment embracing plates disposed in parallel relation, attached respectively to the column 45 and the end plate 49 of the beam 47, and first and second energy- dissipating members 57, 59 disposed in spaced relation and extending along the central, vertical axis of the first and second attachment members 51, 53. The energy- dissipating members 57, 59 comprise ductile tubular sections, in this embodiment of circular section. With this construction, the attachment members 51, 53 are configured to rotate about a rotation axis located between the orthogonally-directed energy- absorbing members 57, 59, with the energy-dissipating members 57, 59 being loaded, substantially diametrically, such that one of the energy-dissipating members 57, 59 is under tension and the other of the energy-dissipating members 57, 59 is under compression depending on the bending moment of the beam 47.

In this embodiment the structural connection C is fabricated as a metal, particularly an aluminium-based, extrusion. By selection of the geometric parameters and material characteristics of the energy-dissipating members 57, 59, the structural connection C is configured to exhibit the required rigidity under service loads, but yet fail, and in so doing dissipate significant energy, on being overloaded. In being a separate component, the structural connection C of this embodiment can be heat treated, for example tempered where an aluminium-based extrusion. Under service loads, the structural connection C exhibits sufficient rigidity that the attachment members 51, 53 maintain a substantially parallel relationship, with one of the energy-dissipating members 57, 59 being under tension and the other of the energy-dissipating members 57, 59 being under compression depending on the bending moment which is being transferred by the structural connection C. However, when the skeletal structure is overloaded, the bending moment of the beam 47 relative to the column 45 is such as to cause the deformation and hence failure of the energy- dissipating members 57, 59, with the one of the energy-dissipating members 57, 59 under tension being elongated and the other of the energy-absorbing members 57, 59 under compression being crushed. This plastic deformation of the energy-dissipating members 57, 59 dissipates the energy associated with the overload, thereby maintaining the column 45 and the beam 47 undamaged. Where the deformation of the energy-dissipating members 57, 59 is limited, the structural connection C can remain in service, but where the deformation exceeds a predetermined limit as to render the structural connection C ineffective, the structural connection C is replaced.

Figures 27(a) and (b) illustrate a structural connection C in accordance with an eighth embodiment of the present invention.

This structural connection C is similar to the structural connection C of the above- described seventh embodiment, and thus, in order to avoid unnecessary duplication of description, only the differences will be described in detail.

This embodiment differs only in that the energy-dissipating members 57, 59 are provided by a single element, in this embodiment a continuous tubular section, which extends along the central, vertical axis of the structural cormection C. With this construction, the energy-dissipating members 57, 59 are provided by the end regions of the tubular section, and the attachment members 51, 53 are configured to rotate about a rotation axis located at substantially a mid point of the tubular section, with the energy-dissipating members 57, 59 being loaded, substantially diametrically, such that one of the energy-dissipating members 57, 59 is under tension and the other of the energy-dissipating members 57, 59 is under compression depending on the bending moment of the beam 47. Operation is the same as for the above-described seventh embodiment, with the rotation axis being located at substantially the mid point of the tubular section defining the energy-dissipatmg members 57, 59.

Figures 28(a) and (b) illustrate a structural connection C in accordance with a ninth embodiment of the present invention connecting first and second structural elements of a skeletal structure, in this embodiment a column 45 and a beam 47 including an end plate 49.

This embodiment differs only in including first and second groups, in this embodiment pairs, of energy-dissipating members 57, 59 disposed in spaced relation and extending parallel to the vertical axis of the structural connection C. Operation is the same as for the above-described seventh embodiment, with the rotation axis being located between the first and second groups of energy-dissipating members 7, 9.

Figures 29(a) and (b) illustrate a structural connection C in accordance with a tenth embodiment of the present invention.

This structural connection C is similar to the structural connection C of the above- described ninth embodiment, and thus, in order to avoid unnecessary duplication of description, only the differences will be described in detail.

This embodiment differs only in that respective ones of the groups of energy- dissipating members 57, 59 are provided by the same elements, in this embodiment continuous tubular sections, which extend along axes parallel to the vertical axis of the structural cormection C. With this construction, the energy-dissipating members 57, 59 are provided by the end regions of the tubular sections, and the attachment members 51, 53 are configured to rotate about a rotation axis located at substantially a mid point of the tubular sections, with the energy-dissipating members 57, 59 being loaded, substantially diametrically, such that one of the groups of energy-dissipating members 57, 59 is under tension and the other of the groups of energy-dissipating members 57, 59 is under compression depending on the bending moment of the beam 47. Operation is the same as for the above-described ninth embodiment, with the rotation axis being located at substantially the mid points of the tubular sections defining the energy-dissipating members 57, 59.

Figures 30(a) to (d) illustrate a structural connection C in accordance with an eleventh embodiment of the present invention connecting first and second structural elements of a skeletal structure, in this embodiment a column 45 and a beam 47 including an end plate 49.

This embodiment differs only in being provided as a plurality of, in this embodiment two, parts. The first and second attachment members 1, 3 are each provided as a plurality, in this embodiment two, separate sections la, 3a, lb, 3b, with respective ones of the sections la, 3a, lb, 3b being connected to respective ones of the energy- dissipating members 7, 9. The configuration of this structural connection C is advantageous in that the spacing of the parts thereof, and hence the spacing of the energy-dissipating members 7, 9, can be set according to the expected bending moment of the beam 47. Also, fabrication of the structural connection C is facilitated as each of the parts has the same configuration, allowing, for example, the parts to be formed as an extrusion from a single die. Operation is the same as for the above- described third embodiment, with the rotation axis being located between the first and second groups of energy-dissipating members 7, 9.

Figures 31 (a) to (e) illustrate a structural connection C in accordance with a twelfth embodiment of the present invention connecting first and second structural elements of a skeletal structure, in this embodiment a column 45 and a beam 47 including an end plate 49. This structural connection C is similar to the structural connection C of the above- described ninth embodiment, and thus, in order to avoid unnecessary duplication of description, only the differences will be described in detail.

This embodiment differs only in being provided as a plurality of, in this embodiment two, parts. The first and second attachment members 51, 53 are each provided as a plurality, in this embodiment two, separate sections 51a, 53a, 51b, 53b, with respective ones of the sections 51a, 53a, 51b, 53b being connected to respective ones of the energy-dissipating members 57, 59. The configuration of this structural connection C is advantageous in that the spacing of the parts thereof, and hence the spacing of the energy-dissipating members 57, 59, can be set according to the expected bending moment of the beam 47. Also, fabrication of the structural connection C is facilitated as each of the parts has the same configuration, allowing, for example, the parts to be formed as an extrusion from a single die. Operation is the same as for the above- described ninth embodiment, with the rotation axis being located between the first and second groups of energy-dissipating members 57, 59.

Figures 32(a) to (d) illustrate a structural connection in accordance with a thirteenth embodiment of the present invention.

The structural connection C comprises first and second attachment members 61, 63, in this embodiment embracing plates disposed in parallel relation, for attachment to structural elements of a structure, in particular a skeletal structure, a hinge unit 65 defining a rotation axis about which the first and second attachment members 61, 63 are relatively rotatable, and first and second energy-dissipating members 67, 69, each having a lateral dimension substantially the same as the spacing of the attachment members 61, 63 and being fixed to the first and second attachment members 61, 63 on opposed sides of the rotation axis. The energy-dissipating members 67, 69 comprise ductile tubular sections, in this embodiment of circular section. The hinge section 65 comprises a first arm 71, in this embodiment formed integrally as part of the first attachment member 61, which includes a recess, in this embodiment a part-circular recess, located in part about the central, horizontal axis of the structural connection C, a second arm 73, in this embodiment formed integrally as part of the second attachment member 63, which includes a recess, in this embodiment a part-circular recess, located in part about the central, horizontal axis of the structural cormection C, and a hinge pin 77 which is located between the recesses in the first and second arms 71, 73 and extends along the central, horizontal axis -of the structural connection C. With this construction, the energy-dissipating members 67, 69 are loaded, substantially diametrically, such that one of the energy-dissipating members 67, 69 is under tension and the other of the energy-dissipating members 67, 69 is under compression depending on the bending moment which is being transferred by the structural connection C. This structural connection C also advantageously accommodates a high, downward shear loading by virtue of the provision of the hinge section 65. Downward shear loading is the dominant shear loading arising from the gravitational loading.

In this embodiment the structural connection C is fabricated as a metal, particularly aluminium-based, extrusion, with the hinge pin 77 being provided as a separate pin. By selection of the geometric parameters and material characteristics of the energy- dissipating members 67, 69, the structural connection C is configured such as to exhibit the required rigidity under service loads, but yet fail, and in so doing dissipate significant energy, on being overloaded. In being a separate component, the structural connection C of this embodiment can be heat treated, for example tempered where an aluminium-based extrusion.

In use, structural connections C are used to interconnect the structural elements of a structure, in particular a skeletal structure, which structural elements typically comprise ones of metal, for example steel, concrete or wooden beams and columns.

Under service loads, the structural connections C exhibit sufficient rigidity that the attachment members 61, 63 maintain a substantially parallel relationship, with ones of the energy-dissipating members 67, 69 of the structural connections C being under tension and the others of the energy-dissipating members 67, 69 being under compression depending on the bending moments which are being transferred by the structural cormections C. However, when the structure is overloaded, the bending moment of the beams relative to the columns is such as to cause the deformation and hence failure of the energy-dissipating members 67, 69, with the ones of the energy- dissipating members 67, 69 under tension being elongated and the others of the energy-dissipating members 67, 69 under compression being crushed. This plastic deformation of the energy-dissipating members 67, 69 dissipates the energy associated with the overload, thereby maintaining the beams and columns undamaged. Where the deformation of the energy-dissipating members 67, 69 is limited, the structural connections C can remain in service, but where the deformation exceeds a predetermined limit as to render the structural connections C ineffective, the structural connections C are replaced.

Figures 33 and 34 illustrate the hinge sections 65 of structural connections C which are modifications of the structural cormection C of the above-described thirteenth embodiment. These structural connections C differ only in the construction of the hinge section 65 which allow for relative lateral movement of the attachment members 61, 63 upon deformation of the energy-dissipating members 67, 69. In the modification of Figure 33, the recesses in the arms 71, 73 are shallow arcuate recesses which allow for limited relative lateral movement of the attachment members 61, 63 about the pin 77. In the modification of Figure 34, the recesses in the arms 71, 73 are elongate recesses which allow for relative lateral movement of the attachment members 61, 63 about the pin 77 as bounded by the movement of the pin 77 in the recesses.

Figures 35(a) to (c) illustrate a structural connection C in accordance with a fourteenth embodiment of the present invention.

This structural connection C is similar to the structural connection C of the above- described twelfth embodiment, and thus, in order to avoid unnecessary duplication of description, only the differences will be described in detail.

This embodiment differs only in the structure of the energy-dissipating members 67, 69. In this embodiment the energy-dissipating members 67, 69 each comprise first and second elongate, arcuate elements 67a, 69a, 67b, 69b disposed in opposed relation such as to define tubular sections, with each of the elongate elements 67a, 69a, 67b, 69b including a stiffening rib 78 extending along the length thereof. Operation is the same as for the above-described thirteenth embodiment, with the rotation axis being located between the energy-dissipating members 67, 69.

Figures 36(a) to (d) illustrate a structural connection C in accordance with a fifteenth embodiment of the present invention.

This structural connection C is very similar to the structural connection C of the above-described thirteenth embodiment, and thus, in order to avoid unnecessary duplication of description, only the differences will be described in detail.

This embodiment differs only in the manner of the connection of the second attachment member 63 to a structural element. The first attachment member 61 is connected similarly to a structural element, in this embodiment a column 93, by connecting bolts, but, differently to the above-described thirteenth embodiment, the second attachment member 63 includes first and second flanges 95, 97 by which the second attachment member 63 is connected to a structural element, in this embodiment a beam 99, by connecting bolts. This construction advantageously avoids the need for an end plate to be welded to the end of the beam 99. As mentioned hereinabove, welding can give rise to defects, such as cracking, and thus avoiding the need for welding is advantageous. In this embodiment the structural connection C is an extruded body. However, the provision of connecting flanges finds equal application in welded structural connections C, with the connecting flanges being welded prior to annealing. Operation is the same as for the above-described thirteenth embodiment, with the rotation axis being located at the hinge pin 77 of the hinge section 65.

Figures 37(a) to (c) illustrate a multi-storey construction comprising a skeletal structure of interconnected beams 101 and columns 103 and an inverted V braced or chevron braced system, the braces 105 of which are connected by the structural connections C of the above-described eighth embodiment to respective ones of the beams 101.

As illustrated, the structural connections C are connected to the mid points of respective ones of the beams 101, with the first attachment members 51 being connected through respective connecting blocks 111 to the bracing elements 105 and the second attachment members 53 being connected respectively to the mid points of the beams 101. The connection points of the bracing elements 105 to the connecting block 111, in this embodiment as provided by hinge pins 113, 115, are offset in relation of the rotation axis of the structural connection C in order to ensure that a bending moment is applied to the structural connection C on loading the skeletal structure.

Figures 38(a) to (c) illustrate a multi-storey construction comprising a skeletal structure of interconnected beams 101 and columns 103 and a chevron braced system, the braces 105 of which are connected by the structural connections C of the above- described tenth embodiment to respective ones of the beams 101.

Figures 39(a) to (c) illustrate a multi-storey construction comprising a skeletal structure of interconnected beams 101 and columns 103 and a chevron braced system, the braces 105 of which are connected by slightly modified structural connections C of the above-described thirteenth embodiment to respective ones of the beams 101.

The structural cormection C is very similar to the structural connection C of the above- described thirteenth embodiment, and thus, in order to avoid unnecessary duplication of description, only the differences will be described in detail. This embodiment differs only in the configuration of the hinge section 65. In this embodiment the first arm 71 on the first attachment member 61 includes a head 107, in this embodiment a rounded head, and the second arm 73 on the second attachment member 63 includes a recess 109, in this embodiment a rounded recess, in which the head 107 on the first arm 71 is engaged such as to allow relative rotation, but prevent relative sliding and thereby support shear loading, of the attachment members 61, 63. Operation is the same as for the above-described thirteenth embodiment, with the rotation axis being located at the junction of the head 107 on the first arm 71 and the recess 109 in the second arm 73. This structural connection C does, however, advantageously support shear loading in both possible sliding directions of the attachment members 61, 63.

As illustrated, the structural connections C are connected to the mid points of respective ones of the beams 101, with the first attachment members 61 being connected through respective connecting blocks 111 to the bracing elements 105 and the second attachment members 63 being connected respectively to the mid points of the beams 101. The connection points of the bracing elements 105 to the connecting block 111, in this embodiment as provided by hinge pins 113, 115, are offset in relation of the rotation axis of the structural connection C in order to ensure that a bending moment is applied to the structural connection C on loading the skeletal structure.

Figures 40(a) to (c) illustrate a multi-storey skeletal comprising a skeletal structure of interconnected beams 101 and columns 103 and an X bracing system, the braces 105 of which are connected to the upper ends of respective ones of the columns 103 at the junctions with the beams 101 by the same structural connections C as utilised in the chevron braced system described hereinabove in relation to Figures 39(a) to (c).

As illustrated, the structural connections C are connected to the upper ends of respective ones of the columns 103 at the junctions with the beams 101, with the first attachment members 61 being connected through respective connecting blocks 111 to the bracing elements 105 and the second attachment members 63 being connected respectively to the upper ends of the columns 103. The connection points of the bracing elements 105 to the connecting block 111, in this embodiment as provided by hinge pins 113, are offset in relation of the rotation axis of the structural connection C in order to ensure that a bending moment is applied to the structural connection C on loading the skeletal structure.

Finally, it will be understood that the present invention has been described in relation to its preferred embodiments and can be modified in many different ways without departing from the scope of the invention as defined by the appended claims.

In the preferred embodiments the energy-dissipating members 7, 9; 57, 59; 67, 69 are tubular sections. Those energy-dissipating members 7, 9; 57, 59; 61, 69 can, however, be formed of any section which in combination with the material exhibits the necessary ductility to dissipate energy from the structure in which the structural connections C are incorporated.

In another modification, the energy-dissipating members 7, 9; 57, 59; 67, 69 can include a resilient material, such as a rubber, or a crushable energy-absorbing material, such as a foam. In the preferred embodiments, where the energy-dissipating members 7, 9; 57, 59; 67, 69 comprise tubular sections, those tubular sections can be packed with such materials. The provision of a resilient material has the effect of increasing the energy-dissipating capacity of the structural connections C in altering the mode of collapse of the energy-dissipating members 7, 9; 57, 59; 67, 69 to a more efficient mode providing greater energy dissipation, and also delaying the onset of the permanent deformation of the energy-dissipating members 7, 9; 57, 59; 67, 69 by virtue of the resilience of the resilient material. The provision of a crushable energy- absorbing material has the effect of increasing the energy-dissipating capacity of the structural connections C by virtue of the resistance to crushing of the crushable material and the dissipation of energy in crushing, and also in altering the mode of collapse of the energy-dissipating members 7, 9; 57, 59; 67, 69 to a more efficient mode providing greater energy dissipation. In a further modification, the structural connections C, in particular the energy- dissipating members 7, 9; 57, 59; 67, 69, can be encased in a fire-protecting agent to prevent the structural connections C being destroyed in the event of a fire.

Further, in the described embodiments, connecting bolts are used as the connecting means for connecting the structural connections C to structural elements. It should, however, be understood that any other connecting means, such as rivets, can be used.

Still further, in the described embodiments, certain of the structural connections C are described as having been fabricated by welding and others by extrusion. It should, however, be understood that the structural connections C can be fabricated by any fabrication technique, for example welding, bonding, extrusion and casting. Also, the materials can be any of metals, for example steel and aluminium alloys, plastics and composites, for example fibre-reinforced composites. Whilst plastics may not, for example, be a suitable material for structures which are subjected to very high loadings, such as the structural elements of a building structure, such materials could find application in more lightly-loaded systems, such as smaller scale engineering structures.

Claims

1. An energy-dissipating structural connection for connecting structural elements of a structure, comprising: first and second attachment members each including attachment surfaces for attachment to structural elements of a structure; and first and second ductile energy-dissipating members connecting the attachment members, wherein the first and second energy-dissipating members are configured to have different relative states of loading on loading the structural connection to cause relative rotation of the attachment members about a rotation axis, and deform, and thereby dissipate energy, on loading the structural connection above a critical value.

2. The structural connection of claim 1, wherein the first and second energy- dissipating members are configured to be in respective states of tension and compression on loading the structural connection.

3. The structural connection of claim 1 or 2, wherein at least one of the first and second energy-dissipating members extends substantially orthogonally to the rotation axis.

4. The structural connection of claim 3, wherein the first and second energy- dissipating members extend substantially orthogonally to the rotation axis.

5. The structural connection of claim 1 or 2, wherein at least one of the first and second energy-dissipating members extends substantially parallel to the rotation axis.

6. The structural connection of claim 5, wherein the first and second energy- dissipating members extend substantially parallel to the rotation axis.

7. The structural connection of any of claims 1 to 6, wherein at least one of the first and second energy-dissipating members is provided by a tubular section.

8. The structural connection of claim 7, wherein the first and second energy- dissipating members are provided by tubular sections.

9. The structural connection of claim 1 or 2, comprising a section which extends orthogonally to the rotation axis, with one end region of the section providing the first energy-dissipating member and the other end region of the section providing the second energy-dissipating member.

10. The structural connection of claim 9, wherein the section comprises a tubular section.

11. The structural connection of any of claims 1 to 10, wherein the attachment surfaces are parallel.

12. The structural connection of any of claims 1 to 10, wherein the attachment surfaces have a non-parallel relationship such that, when one of the attachment members is attached to a structural element, the attachment surface of the other attachment member is upwardly inclined so as to present a surface which can be engaged by another self-supporting structural element.

13. The structural connection of any of claims 1 to 12, wherein the attachment members comprise embracing plates.

14. The structural connection of any of claims 1 to 13, further comprising a hinge section defining the rotation axis about which the attachment members are relatively rotatable and being configured to support shear loading of the structural connection.

15. The structural connection of claim 14, wherein the hinge section is configured to allow relative lateral movement of the attachment members upon deformation of the energy-dissipating members.

16. The structural connection of any of claims 1 to 15, comprising a plurality of first energy-dissipatmg members and a plurality of second energy-dissipating members.

17. The structural cormection of any of claims 1 to 16, as fabricated as a metal extrusion.

18. The structural connection of claim 17, as fabricated as an aluminium-based extrusion.

19. The structural connection of claim 18, where heat treated, preferably tempered.

20. The structural connection of any of claims 1 to 16, as fabricated as a metal casting.

21. The structural connection of claim 20, as fabricated as an aluminium-based casting.

22. The structural connection of claim 21, where heat treated, preferably tempered.

23. The structural connection of claim 20, as fabricated as a steel casting.

24. The structural connection of claim 23, where heat treated, preferably annealed.

25. The structural connection of any of claims 1 to 16, as fabricated as a synthetic material extrusion.

26. The structural connection of any of claims 1 to 16, as fabricated as a synthetic material casting.

27. The structural connection of claim 26, as fabricated as a fibre-reinforced composite casting.

28. The structural connection of any of claims 1 to 16, as fabricated as a welded structure.

29. The structural connection of claim 28, as fabricated as a welded steel structure.

30. The structural connection of claim 29, where heat treated, preferably annealed.

31. A structure, in particular a skeletal structure, incorporating structural connections of any of claims 1 to 30.

32. The structure of claim 31, wherein the structural elements comprise ones of beams and columns.

33. The structure of claim 31, wherein the structural elements comprise ones of bracing elements of a bracing system and at least one of beams and columns.

34. The structure of claim 33, wherein the structural elements comprise ones of bracing elements of a bracing system and beams and columns.

35. The structure of claim 33 or 34, wherein the bracing system comprises an inverted V bracing system.

36. The structure of claim 33 or 34, wherein the bracing system comprises an X bracing system.

37. The structure of claim 31, wherein the structural elements comprise ones of bracing elements and at least one of beams and columns of an eccentrically braced frame.

38. The structure of claim 37, wherein the structural elements comprise ones of bracing elements and beams and columns of an eccentrically braced frame.

9. The structure of any of claims 33 to 38, wherein ones of the bracing elements are connected in offset relation such that a bending moment is applied to the respective structural connections on loading the same.