Technical Field

[0001] Embodiments generally relate to arch structures, structures comprising arch structures, and associated methods of construction.

Background

[0002] Arch structures are sometimes used in building structures, such as to support a roof or floor, for example. They are also used in non-building structures, such as to support a bridge deck, for example.

[0003] Arch structures can be useful for spanning large distances with high structural efficiency. However, they usually require a high camber and occupy a large vertical space. Therefore, typical arch structures may not be suitable for some applications with height restrictions or limited vertical space. Arch structures can also be difficult to fabricate and erect on-site when large spanning members are required.

[0004] It is desired to address or ameliorate one or more shortcomings or

disadvantages associated with existing arch structures and/or methods of construction or to at least provide a useful alternative thereto.

[0005] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application.

[0006] Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. Summary

[0007] The embodiments described herein generally relate to arch structures, structures comprising arch structures, and associated methods of construction.

[0008] Some embodiments relate to an arch structure for supporting a structural load, the arch comprising:

a set of first members configured to form a first arch element;

a set of second members configured to form a second arch element;

a set of first connections, an end of each first member being connected to an end of an adjacent one of the first members by one of the first connections;

a set of second connections, an end of each second member being connected to an end of an adjacent one of the second members by one of the second connections; a set of third connections, an end of each first member being connected to an adjacent one of the second members at or near a midpoint of the adjacent second member by one of the third connections; and

a set of fourth connections, an end of each second member being connected to an adjacent one of the first members at or near a midpoint of the adjacent first member by one of the fourth connections;

wherein the sets of third and fourth connections transfer forces between the sets of first and second members such that the first and second arch elements support each other to stabilise the arch structure, and

wherein one or more of the sets of first, second, third and fourth connections comprise pinned connections, each pinned connection comprising a pin and two or more connectors, each connector defining a bore configured to receive part of the pin, and each connector being connected to one of the first or second members.

[0009] The bore of each connector may be defined by a concave cylindrical surface configured to surround and contact part of the pin.

[0010] In some embodiments, each of the first and second connections may comprise the pinned connections. In some embodiments, each of the third and fourth connections may comprise the pinned connections. In some embodiments, each of the first, second, third and fourth connections may comprise the pinned connections.

[0011] In some embodiments, the first and third connections associated with each first member may be formed by a single one of the pinned connections, and the second and fourth connections associated with each second member may be formed by a single one of the pinned connections.

[0012] In some embodiments, each of the first and second connections may comprise fixed connections. In some embodiments, each of the third and fourth connections may comprise fixed connections.

[0013] In some embodiments, the fixed connections may comprise welded joints. In some embodiments the fixed connections may comprise fixing plates and mechanical fasteners.

[0014] In some embodiments, each end of the first arch element may be aligned with each respective end of the second arch element with respect to the central plane of the arch structure. In some embodiments, each end of the first arch element may be offset from each respective end of the second arch element in a direction parallel to the central plane of the arch structure.

[0015] In some embodiments, the arch structure may further comprise one or more tension elements extending between ends of the arch structure configured to resist axial thrust in the arch structure.

[0016] In some embodiments, the first and second arch elements may share a common central plane. In some embodiments, a central plane of the first arch element may be parallel with, but spaced from a central plane of the second arch element.

[0017] Some embodiments relate to a structure comprising an arch structure according to any one of the embodiments described herein. [0018] Some embodiments, relate to a structure comprising a plurality of arch structures according to any one of the embodiments described herein.

[0019] In some embodiments, at least two of the plurality of arch structures may be arranged such that the central plane of each arch structure is spaced from and parallel to the central plane of the other arch structure. In some embodiments, at least two of the plurality of arch structures may be aligned in a direction perpendicular to the central plane of each of the arch structures.

[0020] In some embodiments, ends of the arch structures may be mounted on respective supports via pinned connections. The supports comprise may comprise walls, blade walls, columns, piers, foundations or footings. The supports may resist axial thrust in the arch structure. In some embodiments the ends of each arch structure may be disposed at or near ground level. In some embodiments, the ends of each arch structure may be disposed at an elevated level above ground level. Blade walls may particularly well suited for resisting axial thrust in the arch structure for applications where the ends of the arch structure are supported above ground level.

[0021] Some embodiments relate to a method of constructing an arch structure or structure according to any one of the embodiments described herein.

Brief Description of Drawings

[0022] Embodiments are described in further detail by way of reference to the accompanying drawings, in which:

[0023] Figures 1A to 1C are schematic diagrams of an arch structure according to some embodiments;

[0024] Figure 2 is an exploded perspective view of a pinned connection according to some embodiments; [0025] Figure 3 is an exploded perspective view of a pinned connection according to some embodiments;

[0026] Figure 4A is a side view of a structure comprising an arch structure according to some embodiments;

[0027] Figures 4B to 4D show various views of a pinned connection of the arch structure of Figure 4A;

[0028] Figures 4E and 4F show various views of a pinned connection mounting the arch structure of Figure 4 A to a support, according to some embodiments;

[0029] Figure 5A is a side view of a structure comprising an arch structure according to some embodiments;

[0030] Figures 5B to 5D show various views of a pinned connection of the arch structure of Figure 5 A; and

[0031] Figures 5E and 5F show various views of a pinned connection mounting the arch structure of Figure 5 A to a support, according to some embodiments.

Description of Embodiments

[0032] Embodiments generally relate to arch structures, structures comprising arch structures, and associated methods of construction.

[0033] Referring to Figures 1A to 1C, an arch structure 100 is shown schematically according to some embodiments. The arch structure 100 comprises a plurality of members 110 connected to each other by a plurality of connections 120 to form the arch structure 100. The arch structure 100 may define a bow-shaped curve extending between two ends 101. The members 110 may comprise substantially straight, elongate beams which are arranged to form the bow-shaped curve of the arch structure 100. In some embodiments, some or all of the members 110 may be curved. [0034] The arch structure 100 may be installed in a building structure such as a building to support a roof or floor, for example, or may be installed in a non-building structure such as a bridge to support a bridge deck, for example. The arch structure 100 may usually be arranged such that the ends 101 are positioned at the lowest level of the arch structure 100 with the rest of the arch extending upwards. In some embodiments, the arch structure 100 may be installed such that it is aligned with a vertical plane. In some embodiments, the arch structure 100 may be installed at an incline with respect to the vertical or even in an inverted orientation with the ends 101 positioned at the highest level of the arch structure 100. However, for the purposes of describing the construction, installation, and mechanics of the arch structures of the present disclosure, it will be assumed that the arch structures are arranged with the ends at the lowest level of the arch structure and the rest of the arch extending upwards such that the central plane of the arch structure is aligned with a vertical plane.

[0035] When referring to a central plane of an arch structure or arch element herein, it should be understood that the term "central plane" refers to a plane of curvature of the arch structure or arch element. Furthermore, any reference to in-plane forces, moments or movement should be understood to mean parallel to and within the central plane of the relevant arch structure or arch element.

[0036] In some embodiments, a plurality of arch structures 100 may be installed in a building or non-building structure to support one or more structural loads. For example, a plurality of arch structures 100 may be arranged in parallel such that central planes of the arch structures 100 are parallel to and spaced from each other, and parallel projections of the arch structures 100 are aligned.

[0037] The arch structure 100 may comprise a set of first members 112 configured to form a first arch element 102 (shown as a solid line in Figures 1A to 1C), and a set of second members 114 configured to form a second arch element 104 (shown as a dashed line in Figures 1A to 1C). The first arch element 102 defines a bow-shaped curve extending between two ends 106 and the second arch element 104 defines a bow- shaped curve extending between two ends 108. The ends 106, 108 of the first and second arch elements 102, 104 may be positioned alongside or coincident with each other as shown in Figure 1A, or in some embodiments, may be offset from each other as shown in Figure IB.

[0038] In some embodiments, a central plane of the first arch element 102 may be co- aligned and co-planar with a central plane of the second arch element 104. That is, the first and second arch elements 102, 104 may share a common central plane. In some embodiments, a central plane of the first arch element 102 may be parallel with, but spaced from a central plane of the second arch element 104. That is, with the arch elements 102, 104 extending alongside each other in offset planes.

[0039] A set of first connections 122 may be configured such that an end of each of the first members 112 is connected to an end of an adjacent one of the first members 112 by one of the first connections 122. A set of second connections 124 may be configured such that an end of each of the second members 114 is connected to an end of an adjacent one of the second members 114 by one of the second connections 124. A set of third connections 126 may be configured such that an end of each of the first members 112 is connected to an adjacent one of the second members 114 at or near a midpoint of the adjacent second member 114 by one of the third connections 126. A set of fourth connections 128 may be configured such that an end of each of the second members 114 is connected to an adjacent one of the first members 112 at or near a midpoint of the adjacent first member 112 by one of the fourth connections 128.

[0040] The sets of third and fourth connections 126, 128 may be configured to transfer forces between the sets of first and second members 112, 114 such that the first and second arch elements 102, 104 support each other to stabilise the arch structure 100. For example, if a gravity load is applied to an end of one of the first members 112 part way along the arch structure 100 (as shown by force arrow 130 in Figure 1A), the force will be transferred to an adjacent second member 114 via one of the third connections 126 at or near a midpoint of the adjacent second member 114. The force will then be transferred through the adjacent second member 114 to one or more adjacent first members 112 via one or more of the fourth connections 128. [0041] In this way, the force will be transmitted along the arch structure 100 through the members 110 and connections 120 to the ends 106, 108, and dissipated over the arch elements 102, 104. The arch elements 102, 104, support and stabilise each other and transfer structural loads to the ends 106, 108 where the forces are transmitted into the ground via foundations, walls, columns, piers or other structures.

[0042] This arrangement of force dissipation is similar to the principles employed in Leonardo da Vinci's self-supporting arch bridge and the Rainbow bridge of the Song Dynasty. However, the arch structures of the present disclosure differ from those bridges in that one or more of the first, second, third and fourth sets of connections comprise pinned connections. In some embodiments, each of the first and second connections 122, 124 may comprise the pinned connections. In some embodiments, each of the third and fourth connections 126, 128 may comprise the pinned

connections. In some embodiments, each of the first, second, third and fourth connections 122, 124, 126, 128 may comprise the pinned connections.

[0043] The use of pinned connections is important because it allows in-plane forces to be transmitted through the pinned connections without transmitting in-plane moments or torque through the pinned connections, which means that forces from structural loads are dissipated as bending stress across the length of each member 110 instead of being concentrated at the connections 120 and the ends of the members 110.

[0044] Each pinned connection may comprise a pin and two or more connectors, each connector defining a bore configured to receive part of the pin. The bore of each connector may be defined by a concave cylindrical surface configured to surround and contact part of the pin. Each connector may be connected to a corresponding one of the members 110 connected by the pinned connection. That is, each connector may be connected to one of the first or second members 112, 114. The pin of each pinned connection may extend laterally with respect to the arch structure 100 and

perpendicular to the central plane of the arch structure 100. That is, a longitudinal axis or axis of rotation of the pin may be substantially horizontal and substantially perpendicular to a longitudinal axis of the arch structure 100, or out of plane with respect to Figures 1A to 1C. Exemplary pinned connections are described in further detail below.

[0045] In some embodiments, the first and third connections 122, 126 associated with each first member 112 may be formed by a single one of the pinned connections, and the second and fourth connections 124, 128 associated with each second member 114 may be formed by a single one of the pinned connections. That is, some pinned connections may act as both the first and third connections 122, 126 with each pinned connection configured to connect adjacent ends of the first members 112 to each other as well as to an adjacent second member 114 at or near a midpoint of the adjacent second member 114, and some pinned connections may act as both the second and fourth connections 124, 128 with each pinned connection configured to connect adjacent ends of the second members 114 to each other as well as to an adjacent first member 112 at or near a midpoint of the adjacent first member 114.

[0046] For example, each pinned connection may comprise a pin and three connectors, each connector defining a bore configured to receive part of the pin. The bore of each connector may be defined by a concave cylindrical surface configured to surround and contact part of the pin.

[0047] For pinned connections forming the first and third connections 122, 126, two of the connectors may be connected to adjacent ends of adjacent first members 112, and the third connector may be connected to an adjacent second member 114 at or near a midpoint of the second member 114. The three connectors may be connected by a pin received in the bores of each of the three connectors to form the first and third connections 122, 126.

[0048] For pinned connections forming the second and fourth connections 124, 128, two of the connectors may be connected to adjacent ends of adjacent second members 114, and the third connector may be connected to an adjacent first member 112 at or near a midpoint of the first member 112. The three connectors may be connected by a pin received in the bores of each of the three connectors to form the second and fourth connections 124, 128.

[0049] As the connectors receive and surround the pins, the pinned connections can resist relative forces between members 110 connected by the pinned connection in any direction perpendicular to the longitudinal axis of the pin (i.e., in-plane forces). This means that the arch structure 100 can resist dynamic uplift forces, which may be present due to aerodynamic or seismic loads, as well as downwardly acting gravity loads.

[0050] It should be appreciated that in practice, the pinned connections may provide some resistance to relative moments between members 110 connected by the pinned connections due to friction between the pin and the concave cylindrical surfaces of the connectors or friction between abutting surfaces of the connectors, for example.

However, for the purposes of structural analysis it is generally considered that pinned connections do not resist moments.

[0051] The arrangement of members 110 and connections 120 in the arch structure 100, and other arch structures described herein, allows large distances to be spanned with a relatively low camber or curvature compared to conventional arch structures. This allows relatively low profile arch structures to be used in building and non- building structures where there are height restrictions, or where an arch structure with a low height is required. The arch structures described herein may also be designed to be more structurally efficient and require less material to span a certain distance and support a certain structural load. The use of pinned connections may also simplify construction of the arch structure 100 and enable fast erection of the structure on site.

[0052] The arch structure 100 may comprise a generally elongate arcuate form with a camber of any suitable curve, such as parabolic, hyperbolic, circular or elliptical, for example. When the arch structure 100 is under compression, such as when it is supporting a gravity load as in Figure 1A, for example, there will be a force acting to flatten out the arch structure 100 and arch elements 102, 104 and separate the ends 101, 106, 108. That is, the force will act to separate the ends 101 of the arch structure 100. The force will also act to separate the ends 106 of the first arch element 102, and it will also act to separate the ends 108 of the second arch element 104. This force is known as axial thrust, and its magnitude depends on the design of the arch structure 100 as well as the structural loads acting on the arch structure 100. The direction of axial thrust is shown by force arrows 135 in Figure 1C.

[0053] Depending on the application, the ends 106, 108 may be connected to any one of a number of different supports, such as foundations, piers, walls, columns, blade walls, or other structural elements, for example, which may be grounded to resist the axial thrust. In some embodiments, the ends 106, 108 may be connected to the supports via pinned connections.

[0054] In some embodiments, a tension element 140 may be connected to and extend between the ends 106, 108 as shown in Figure 1C to resist axial thrust. The tension element 140 may comprise a rope or cable which is unable to support any compressive load along its longitudinal axis, or in some embodiments, the tension element 140 may comprise a rod, beam, or strut which is able to support a compressive load along its longitudinal axis. In some embodiments, the arch structure 100 may be prestressed by tensioning the tension element 140 by strand-jacking, for example. In some

embodiments, a number of tension elements 140 may extend between and connect opposing branches of the arch structure 100 at different levels to control stress distribution in the arch structure 100.

[0055] The members 110 may be formed of any suitable materials having strength and stiffness characteristics which are sufficient to support the design loads of a given application. For example, the members 110 may be formed of any one or more of: metal, metal alloy, steel, structural steel, high tensile steel, aluminium, timber, engineered timber, LVL timber, plastic, polymer, and composite materials.

[0056] The members 110 may comprise any suitable cross-sectional profile, such as: solid round section, hollow round section, solid square section, hollow square section, solid rectangular section, hollow rectangular section, hollow box section, flanged section, I-section, T-section, U-section, C-section, or Z-section, for example. In some embodiments, the cross-sectional profile of the members 110 may comprise a composite profile which may include a combination of two or more suitable cross- sectional profiles, such as two or more of the profiles listed above, for example. In some embodiments, the cross-sectional profile may vary along the length of the members 110 or may be different in different members 110 within the arch structure 100. In some embodiments, the members 110 may comprise a plurality of beams arranged in parallel. The plurality of beams may be arranged with spaces between the beams.

[0057] The connections 120 may be formed of any suitable materials having strength and stiffness characteristics which are sufficient to support the design loads of a given application. For example, the connections 120 may be formed of any one or more of: metal, metal alloy, steel, structural steel, high tensile steel, aluminium, timber, engineered timber, LVL timber, plastic, polymer, and composite materials.

[0058] Referring to Figure 2, an exemplary pinned connection 220 is shown, according to some embodiments, in an exploded perspective view. Connection 220 is an example of a pinned connection between adjacent arch elements 202, 204, which could be used for one or more of the third and fourth sets of connections 126, 128 referred to in relation to Figures 1A to 1C.

[0059] Two members 212 of a first arch element 202 are shown with their respective ends welded to each other and to a first connector 222. An adjacent member 214 of a second arch element 204 is shown with a second connector 224 welded to the member 214 at or near a mid-point of the member 214.

[0060] The first connector 222 includes a first aperture or bore 226 defined by a first concave cylindrical surface 228 configured to surround, receive and contact part of a pin 230. The pin 230 comprises a cylindrical body 232 defining a convex cylindrical surface 234. The second connector 224 includes a second aperture or bore 236 defined by a second concave cylindrical surface 238 configured to surround, receive and contact part of the pin 230.

[0061] The pin 230 may be received in the first and second bores 226, 236 of the first and second connectors 222, 224 to form the pinned connection 220, with the convex cylindrical surface 234 of the pin 230 mating with the first and second concave cylindrical surfaces 228, 238 of the first and second connectors 222, 224, such that forces are transmitted between the first and second connectors 222, 224 via the pin 230. The cylindrical body 232 may have a diameter similar to or less than diameters of the first and second bores 226, 236 to provide a close fitting connection.

[0062] In some embodiments, the connection 220 may further comprise a washer or spacer ring 240 configured to receive and surround part of the pin 230 and be positioned between the connectors 222, 224 to restrict direct contact between the connectors 222, 224.

[0063] In some embodiments, the connection 220 may further comprise end plates 242 configured to be connected to respective ends of the pin 230, such as by welding, for example, to restrict removal of the pin 230 from the connectors 222, 224. The end plates 242 may comprise circular discs and may have diameters larger than the diameters of the bores 226, 236.

[0064] The end plates 242 may be welded to respective ends of the pin 230 once the pin 230 has been inserted into the bores 226, 236 to connect the connectors 222, 224. In some embodiments, the pin 230 may be formed with one end plate 242 attached to one end of the pin 230 prior to insertion into the bores 226, 236, and the other end plate 242 may be fixed to the other end of the pin 230 after the connection 220 has been formed.

[0065] During construction, the connection 220 may be assembled by arranging the pin 230 and first and second connectors 222, 224 in coaxial alignment along a pin axis 244, such that central axes of rotation of the pin body 232 and first and second bores 226, 236 are in alignment with the pin axis 244 and the convex cylindrical surface 234 of the pin is parallel with the concave cylindrical surfaces 228, 238 of the connectors 222, 224. The pin 230 may then be inserted into the bores 226, 236 such that the concave cylindrical surfaces 228, 238 of the connectors 222, 224 surround and contact respective parts of the convex cylindrical surface 234 of the pin 230.

[0066] The end plates 242 may then be fixed to the pin 230 to restrict movement of the pin 230 along the pin axis relative to the connectors 222, 224. In some

embodiments, the washer 240 may be placed between the connectors 222, 224 prior to insertion of the pin 230, and the pin 230 may be inserted through the washer 240 as well as the connectors 222, 224.

[0067] As discussed above, the pinned connection 220 may transmit in-plane forces perpendicular to the pin axis 244 and restrict relative in-plane translation between the members 212, 214 connected by the connection 220. However, the pinned connection 220 may not transmit in-plane moments about the pin axis 244 or restrict relative in- plane rotation between the members 212, 214 connected by the connection 220.

Although, as also discussed above, some resistance to moments may occur due to friction between the convex cylindrical surface 234 of the pin 230 and the concave cylindrical surfaces 228, 238 of the connectors 222, 224.

[0068] Referring to Figure 3, an exemplary pinned connection 320 is shown, according to some embodiments, in an exploded perspective view. Connection 320 is an example of a pinned connection between ends of adjacent members 310 of an arch element, which could be used for one or more of the first and second sets of connections 122, 124 referred to in relation to Figures 1A to 1C.

[0069] Two members 312 of a first arch element 302 are shown with their respective ends fixed to a first connector 322 and a second connector 324, respectively. The first and second connectors 322, 324 may be fixed to the respective ends of the members 312 by welding, bonding, or mechanical fasteners, such as bolts, brackets, rivets, screws or nails, for example. An adjacent member 314 of a second arch element 304 is shown connected to the respective ends of the members 312 at or near a mid-point of the member 314.

[0070] The first connector 322 includes a first aperture or bore 326 defined by a first concave cylindrical surface 328 configured to surround, receive and contact part of a pin 330. The pin 330 comprises a cylindrical body 332 defining a convex cylindrical surface 334. The second connector 324 includes a second aperture or bore 336 defined by a second concave cylindrical surface 338 configured to surround, receive and contact part of the pin 330.

[0071] The pin 330 may be received in the first and second bores 326, 336 of the first and second connectors 322, 324 to form the pinned connection 320, with the convex cylindrical surface 334 of the pin 330 mating with the first and second concave cylindrical surfaces 328, 338 of the first and second connectors 322, 324, such that forces are transmitted between the first and second connectors 322, 324 via the pin 330. The cylindrical body 332 may have a diameter similar to or less than diameters of the first and second bores 326, 336 to provide a close fitting connection.

[0072] In some embodiments, the connection 320 may further comprise a washer or spacer ring (not shown) configured to receive and surround part of the pin 330 and be positioned between the connectors 322, 324 to restrict direct contact between the connectors 322, 324.

[0073] In some embodiments, the connection 320 may further comprise end plates 342 configured to be connected to respective ends of the pin 330, such as by welding, for example, to restrict removal of the pin 330 from the connectors 322, 324. The end plates 342 may comprise circular discs and may have diameters larger than the diameters of the bores 326, 336.

[0074] The end plates 342 may be welded to respective ends of the pin 330 once the pin 330 has been inserted into the bores 326, 336 to connect the connectors 322, 324. In some embodiments, the pin 330 may be formed with one end plate 342 attached to one end of the pin 330 prior to insertion into the bores 326, 336, and the other end plate 342 may be fixed to the other end of the pin 330 after the connection 320 has been formed.

[0075] During construction, the connection 320 may be assembled by arranging the pin 330 and first and second connectors 322, 324 in coaxial alignment along a pin axis 344, such that central axes of rotation of the pin body 332 and first and second bores 326, 336 are in alignment with the pin axis 344 and the convex cylindrical surface 334 of the pin is parallel with the concave cylindrical surfaces 328, 338 of the connectors 322, 324. The pin 330 may then be inserted into the bores 326, 336 such that the concave cylindrical surfaces 328, 338 of the connectors 322, 324 surround and contact respective parts of the convex cylindrical surface 334 of the pin 330.

[0076] The end plates 342 may then be fixed to the pin 330 to restrict movement of the pin 330 along the pin axis relative to the connectors 322, 324. In some

embodiments, a washer may be placed between the connectors 322, 324 prior to insertion of the pin 330, and the pin 330 may be inserted through the washer as well as the connectors 322, 324.

[0077] As discussed above, the pinned connection 320 may transmit in-plane forces perpendicular to the pin axis 344 and restrict relative in-plane translation between the members 312, 314 connected by the connection 320. However, the pinned connection 320 may not transmit in-plane moments about the pin axis 344 or restrict relative in- plane rotation between the members 312, 314 connected by the connection 320.

Although, as also discussed above, some resistance to moments may occur due to friction between the convex cylindrical surface 334 of the pin 330 and the concave cylindrical surfaces 328, 338 of the connectors 322, 324.

[0078] In some embodiments, each connector 322, 344 may comprise a plurality of connector plates 350 connected to a member end plate 352, as shown in Figure 3. This may allow stress developed in the connection 320 to be distributed across the end plate 352 and transmitted to the member 312. The connector plates 350 may be arranged in parallel and each define a bore and concave cylindrical surface to receive, surround and contact part of the pin 330, as described above. The connector plates 350 may be evenly spaced and welded to the end plate 352, and may be arranged such that the connector plates 350 of the first and second connectors 322, 324 can be interleaved to align the bores of the connectors 322, 324.

[0079] As well as being connected to each other via the pinned connection 320, the ends of the members 312 may be fixedly connected to the adjacent member 314 of arch element 304 by fastening plates 360. The fastening plates 360 may be configured to be fastened to outer surfaces of the members 312, 314 to connect the members 312, 314. In some embodiments, the fastening plates may be welded or bonded to the members 312, 314. In some embodiments, the fastening plates may be fixed to the members 312, 314 by mechanical fasteners 364, such as bolts, rivets, screws or nails, for example. This type of connection may be used for one or more of the third and fourth sets of connections 126, 128 described in relation to Figures 1A to 1C. Or in embodiments where the third and fourth sets of connections 126, 128 comprise pinned connections, fastening plates may be used for one or more of the first and second sets of connections 122, 124.

[0080] The members 312, 314 shown in Figure 3 each comprise a plurality of parallel spaced beams 362. The beams 362 of members 312 are interleaved with the beams 362 of member 314, which allows for a symmetrical stress distribution as the arch elements 302, 304 are co-aligned with a common central plane perpendicular to the pin axis 344. In some embodiments, as shown in Figure 3, the fastening plates 360 may connect each of the beams 362 of the of the members 312 of the first arch element 302 to an adjacent one of the beams 362 of the member 314 of the second arch element 304.

[0081] Referring to Figure 4A, an arch structure 400 is shown supporting part of a structure 470, according to some embodiments. The structure 470 may comprise a building structure, such as a warehouse, for example, or a non-building structure, such as a bridge, for example. The arch structure 400 may be configured to support a structural element 472 such as a bridge deck, or a roof or floor of a building, for example. The arch structure 400 may be mounted on supports 474 which may comprise walls, blade walls, columns, piers, or foundations, for example.

[0082] The arch structure 400 comprises similar elements to those described in relation to arch structure 100, and similar components are given similar reference numerals. The arch structure 400 comprises a plurality of members 410 connected to each other by a plurality of connections 420 to form the arch structure 400. The arch structure 400 may define a bow-shaped curve extending between two ends 401. The members 410 may typically comprise substantially straight, elongate beams arranged to form the bow-shaped curve of the arch structure 400.

[0083] The arch structure 400 may comprise a set of first members 412 configured to form a first arch element 402, and a set of second members 414 configured to form a second arch element 404. The first arch element 402 defines a bow-shaped curve extending between two ends 406 and the second arch element 404 defines a bow- shaped curve extending between two ends 408. The ends 406, 408 of the first and second arch elements 402, 404 may be positioned alongside or coincident with each other and mounted to supports 474.

[0084] A set of first connections 422 may be configured such that an end of each of the first members 412 is connected to an end of an adjacent one of the first members 412 by one of the first connections 422. A set of second connections 424 may be configured such that an end of each of the second members 414 is connected to an end of an adjacent one of the second members 414 by one of the second connections 424. A set of third connections 426 may be configured such that an end of each of the first members 412 is connected to an adjacent one of the second members 414 at or near a midpoint of the adjacent second member 414 by one of the third connections 426. A set of fourth connections 428 may be configured such that an end of each of the second members 414 is connected to an adjacent one of the first members 412 at or near a midpoint of the adjacent first member 412 by one of the fourth connections 428. [0085] The sets of first and second connections 422, 424 may comprise pinned connections similar to pinned connection 320 described in relation to Figure 3. The sets of third and fourth connections 426, 428 may comprise fastener plate connections similar to the fastener plates 360 described in relation to Figure 3. An exemplary pinned connection 420 is shown in Figures 4B to 4D.

[0086] Connection 420 is an example of a pinned connection between ends of adjacent members 410 of an arch element, which may be used in each of the first and second sets of connections 422, 424. Two members 412 of the first arch element 402 are shown with their respective ends fixed to a first connector 492 and a second connector 494, respectively, which are connected by a pin 430 which is held in place by end plates 442 as described in relation to connection 320.

[0087] As discussed above, the pinned connection 420 may transmit in-plane forces perpendicular to a pin axis 444 and restrict relative in-plane translation between the members 412, 414 connected by the connection 420. However, the pinned connection 420 may not transmit in-plane moments about the pin axis 444 or restrict relative in- plane rotation between the members 412, 414 connected by the connection 420.

[0088] Each connector 492, 494 may comprise a plurality of connector plates 450 connected to a member end plate 452, as shown in Figure 4D. This may allow stress developed in the connection 420 to be distributed across the end plate 452 and transmitted to the member 412. The connector plates 450 may be arranged in parallel and each define a bore and concave cylindrical surface (as described in relation to connection 320) to receive, surround and contact part of the pin 430. The connector plates 450 may be evenly spaced and welded to the end plate 452, and may be arranged such that the connector plates 450 of the first and second connectors 492, 494 can be interleaved to align the bores of the connectors 492, 494.

[0089] The first connector 492 may comprise three connector plates 450a, 450b, 450c, and the second connector 494 may also comprise three connector plates 450d, 450e, 450f. Different numbers of connector plates 450 may be used in different applications, such as one, two, three, four, five or more connector plates 450. In some embodiments, the connector plates 450 may be configured such that when the connectors 492, 494 are connected, adjacent pairs of the interleaved connector plates 450 are in contact with each other as shown in Figure 4D. That is, with connector plates 450a and 450d in contact, connector plates 450b and 450e in contact, and connector plates 450c and 450f in contact.

[0090] In some embodiments, the pairs of connector plates may also be separated from one another with washers or spacer rings 440, as shown in Figure 4D. For example, connector plate 450d may be spaced from connector plate 450b by spacer ring 440a, and connector plate 450e may be spaced from connector plate 450c by spacer ring 440b. In some embodiments, all of the connector plates 450 may be isolated from each other by spacer rings or washers 440. The spacer rings or washers 440 may comprise hollow cylindrical forms with a central aperture configured to receive the pin 430.

[0091] As well as being connected to each other via the pinned connection 420, the ends of the members 412 may be fixedly connected to the adjacent member 414 of arch element 404 by fastening plates 460. The fastening plates 460 may be configured to be fastened to outer surfaces of the members 412, 414 to connect the members 412, 414, as described in relation to connection 320. This type of connection may be used for the third and fourth sets of connections 426, 428.

[0092] The members 412, 414 shown in Figures 4B to 4F each comprise a plurality of parallel spaced beams 462. The beams 462 of members 412 are interleaved with the beams 462 of member 414, which allows for a symmetrical stress distribution as the arch elements 402, 404 are co-aligned with a common central plane perpendicular to the pin axis 444. The fastening plates 460 may connect each of the beams 462 of the of the members 412 of the first arch element 402 to an adjacent one of the beams 462 of the member 414 of the second arch element 404. In some embodiments, the connector plates 450 may be aligned with the beams 462. [0093] As shown in Figures 4E and 4F, the ends 406, 408 may be connected to the supports 474 by pinned connections 480 similar to pinned connections 320, 420.

Pinned connections 480 may comprise a first connector 482 similar to connectors 322, 492, a second connector 484 similar to connectors 324, 494, and a pin 486 similar to pins 330, 430 with end plates 488. The a first connector 482 may be fixed to both ends 406, 408 at each end 406, 408 of each arch element 402, 404, and a second connector 484 may be fixed to each the support 474 to thereby connect the ends 406, 408 to the supports 474. In embodiments where the arch structure 400 is mounted with ends 401 disposed at an elevated level above ground level, the supports 474 should be configured to resist axial thrust in the arch structure 400 and transmit the axial thrust into the ground. The supports 474 may comprise blade walls as shown in Figure 4E with a central plane of each blade wall substantially aligned with the central plane of the arch structure 400.

[0094] As discussed above, the beams 462 of adjacent members 412, 414 may be interleaved such that the first and second arch elements 402, 404 are co-aligned with a common central plane. In some embodiments, a similar arrangement may be achieved using cut-outs or recesses in one or both sets of members 412, 414 to allow the members 412, 414 to extend around or through each other such that the first and second arch elements 402, 404 are co-aligned with a common central plane. In other embodiments, the first and second arch elements 402, 404 may be arranged alongside each other and aligned with two respective central planes parallel to and spaced from each other.

[0095] This arrangement allows the camber of the arch structure 400 to be reduced. For example, the members 412, 414 at the ends 406, 408 may extend away from the horizontal at an angle in the range of about 10° to 60°, optionally about 15° to 45°, optionally about 15° to 30°, optionally about 15° to 20°. As mentioned above, this allows arch structures to be formed with a large span and low height, which may be advantageous in certain applications. [0096] Referring to Figure 5A, an arch structure 500 is shown supporting part of a structure 570, according to some embodiments. The structure 570 may comprise a building structure, such as a warehouse, for example, or a non-building structure, such as a bridge, for example. The arch structure 500 may be configured to support a structural element 572 such as a bridge deck of a bridge, or a roof or floor of a building, for example. The arch structure 500 may be mounted on supports 574 which may comprise walls, blade walls, columns, piers, foundations or footings, for example.

[0097] The arch structure 500 comprises similar elements to those described in relation to arch structure 100, and similar components are given similar reference numerals. The arch structure 500 comprises a plurality of members 510 connected to each other by a plurality of connections 520 to form the arch structure 500. The arch structure 500 may define a bow-shaped curve extending between two ends 501. The members 510 may typically comprise substantially straight, elongate beams arranged to form the bow-shaped curve of the arch structure 500.

[0098] The arch structure 500 may comprise a set of first members 512 configured to form a first arch element 502, and a set of second members 514 configured to form a second arch element 504. The first arch element 502 defines a bow-shaped curve extending between two ends 506 and the second arch element 504 defines a bow- shaped curve extending between two ends 508. The ends 506, 508 of the first and second arch elements 502, 504 may be positioned alongside each other and mounted to supports 574.

[0099] A set of first connections 522 may be configured such that an end of each of the first members 512 is connected to an end of an adjacent one of the first members 512 by one of the first connections 522. A set of second connections 524 may be configured such that an end of each of the second members 514 is connected to an end of an adjacent one of the second members 514 by one of the second connections 524. A set of third connections 526 may be configured such that an end of each of the first members 512 is connected to an adjacent one of the second members 514 at or near a midpoint of the adjacent second member 514 by one of the third connections 526. A set of fourth connections 528 may be configured such that an end of each of the second members 514 is connected to an adjacent one of the first members 512 at or near a midpoint of the adjacent first member 512 by one of the fourth connections 528.

[0100] The sets of first and second connections 522, 524 may comprise fixed connections by welding, bonding, or mechanical fasteners, such as bolts, brackets, rivets, screws or nails, for example. The sets of third and fourth connections 526, 528 may comprise pinned connections similar to pinned connection 220 described in relation to Figure 2. An exemplary pinned connection 520 is shown in Figures 5B to 5D.

[0101] Connection 520 is an example of a pinned connection between ends of adjacent members 510 of an arch element, which may be used in each of the first and second sets of connections 522, 524. Two members 512 of the first arch element 502 are shown with their respective ends welded to each other and to a first connector 592. An adjacent member 514 of a second arch element 504 is shown with a second connector 594 welded to the member 514 at or near a mid-point of the member 514. The first and second connectors 592, 594 are connected by a pin 530 which is held in place by end plates 542 as described in relation to connection 220.

[0102] The first and second connectors 592, 594 each comprise a plurality of connector plates 550 fixed to the members 512, 514. Each connector plate 550 includes an aperture configured to receive a hollow cylindrical pipe element 552 which is fixed to the connector plates 550 to form each connector 592, 594. The pipe elements 552 may be welded to the connector plates 550, which may in turn be welded to the members 512, 514. The pipe elements 552 may comprise internal concave cylindrical surfaces (not shown) similar to the concave cylindrical surfaces 228, 238 described in relation to connection 220.

[0103] The pin 530 may be received in the pipe elements 552 to form the pinned connection 520, with a convex cylindrical surface of the pin 530 mating with the concave cylindrical surfaces of the pipe elements 552, such that forces are transmitted between the first and second connectors 592, 594 via the pin 530 as described in relation to connection 220.

[0104] In some embodiments, the connection 520 may further comprise a washer or spacer ring 540 configured to receive and surround part of the pin 530 and be positioned between the connectors 592, 594 to restrict direct contact between the connectors 592, 594 as described in relation to connection 220.

[0105] In some embodiments, the connection 520 may further comprise end plates 542 configured to be connected to respective ends of the pin 530, such as by welding, for example, to restrict removal of the pin 530 from the connectors 592, 594 as described in relation to connection 220.

[0106] As shown in Figures 5E and 5F, the ends 506, 508 may be connected to the supports 574 by pinned connections 580 similar to pinned connection 480 described in relation to Figures 4E and 4F. Pinned connections 580 may comprise a first connector 582 similar to connector 482, a second connector 584 similar to connector 484, and a pin 586 similar to pin 486 with end plates 588. The first connector 582 may be fixed to both ends 506, 508 at each end 506, 508 of each arch element 502, 504, and the second connector 584 may be fixed to each support 574 to thereby connect the ends 506, 508 to the supports 574.

[0107] The members 512, 514 may comprise a rectangular hollow section or box section. The first connectors 582 may be fixed to open ends of the members 512, 514 or may be fixed to an end plate (not shown) of each member 512, 154. The members 512, 514 are shown arranged alongside each other. However, in some embodiments, one set of members 512, 514 may have a smaller width than the other set of members 512, 514, and the wider members 512, 514 may define apertures configured to allow passage of the narrower set of members 512, 514 allowing the first and second arch elements 502, 504 to be co-aligned with a common central plane. As mentioned above, this may allow arch structures to be formed with a lower camber and lower height while maintaining a large span, which may be advantageous in certain applications. [0108] It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.