Technical Field

[0001] The present disclosure generally relates to structural components used in the building industry. More specifically, the disclosure relates to joining of the structural components together.

Background

[0002] Steel girders are commonly used to construct structural frameworks in the building industry. An example of a common steel girder is an I-beam which has a transverse cross-section with the shape of the letter T .

[0003] The I-beam can be joined to other I-beams by means of a connection such as a splice connection. Splice connections consist of at least one plate (or bracket) and fasteners that are passed through holes in the plate and the I-beam being joined. The fasteners can consist of nuts and bolts or rivets. The process of connecting beams using splice connections may be time consuming and may limit the orientations in which the I-beams can be connected.

[0004] 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; 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; or could have been understood, regarded as relevant or reasonably expected to have been combined by a person skilled in the art.

Summary

[0005] Some embodiments relate to a method of joining structural members together for use in building construction. The method comprises:

- cooling a projection on a male connection portion of a first structural member, such that the cooled projection thermally contracts so that it can be located in a

complimentary recess defined by a female connection portion of a second structural member;

- locating the cooled projection in the recess;

- thermally expanding the cooled projection while the cooled projection is located in the complimentary recess.

The thermal expanding cold bonds at least a portion of the projection with at least a portion of the recess, to thereby join the first and second structural members together.

[0006] In some embodiments, the method comprises cooling the projection below a lower temperature that is less than ambient temperature. In some embodiments, the lower temperature is -150°C.

[0007] In some embodiments, the method comprises cooling the projection with a refrigeration system. In some embodiments, the method comprises cooling the projection with a cryogenic substance. In some embodiments, the cryogenic substance is either liquid nitrogen or solid carbon dioxide. In some embodiments, the cryogenic substance is received in a reservoir defined by the male connection portion.

[0008] In some embodiments, the step of thermally expanding comprises heating at least the male connection portion with a source of heat and the source of heat is above ambient temperature. In some embodiments, thermally expanding comprises allowing the male connection portion to heat up to an ambient temperature.

[0009] Some embodiments relate to a system of interconnected structural members for building construction. The system comprises:

a first structural member comprising a first body and a male connection portion located on the first body, the male connection portion comprising a projection; and

a second structural member comprising a second body and a female connection portion located on the second body, the female connection portion defining a complimentary recess receiving the projection, wherein, at least a portion of the projection is cold bonded with at least a portion of the recess; wherein, the projection was cooled to thermally contract, thereby enabling the projection to be fitted into to the recess, and wherein, the projection was thermally expanded, while fitted in the complimentary recess, to thereby join the first and second structural members together.

[0010] In some embodiments, the first body and the second body are elongate in shape.

[0011] In some embodiments, the male connection portion is located at one extreme end of the first body and the female connection portion is located at one extreme end of the second body.

[0012] In some embodiments, the first body further comprises a second female connection portion at a location separated from the male connection portion and the second female connection portion is identical to the female connection portion on the second structural member; and the second body further comprises a second male connection portion at a location separated from the female connection portion and the second male connection portion is identical to the male connection portion on the first structural member.

[0013] In some embodiments, the male connection portion further comprises a reservoir for receiving a cryogenic substance.

[0014] In some embodiments, the projection of the male connection portion has a cross-section comprising a concave section adjacent to and continuously connected to a convex section. In some embodiments, the projection is multi-faceted and defines 5 or more facets. In some embodiments, the projection has a polygonal cross-section selected from the group of: squares, rectangles, pentagons, hexagons, heptagons or octagons.

[0015] 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. Brief Description of Drawings

[0016] Embodiments are described in further detail below, by way of example, with reference to the accompanying drawings briefly described below:

[0017] Figure 1A is a top view of a system of interconnectable structural components according to some embodiments;

[0018] Figure IB is a top view of the system of interconnectable structural components from Figure 1A shown interconnected;

[0019] Figure 2 is a top view of a system of interconnectable structural components according to some embodiments;

[0020] Figure 3 is a top view of a system of interconnectable structural components according to some embodiments;

[0021] Figure 4A is a top view of a structural component;

[0022] Figure 4B is a perspective view of the structural component shown in Figure 4A;

[0023] Figure 5 A is a top view of a system of interconnectable structural components according to some embodiments;

[0024] Figure 5B is a top view of another system of interconnectable structural components according to some embodiments; and

[0025] Figure 6 is a flow diagram of a method for joining structural components. Detailed Description

[0026] The present disclosure generally relates to structural components used in the building industry. More specifically, the disclosure relates to joining of the structural components together.

[0027] With reference to Figures 1A and IB, there is provided a system 100 of interconnectable structural members that can be used in building construction. The system includes a first structural member 120 and a second structural member 140. The first structural member 120 includes a first body 122 that includes a male connection portion 124 that is attached to the first body 122. The second structural member 140 includes a second body 142 that includes a female connection portion 144.

[0028] Male connection portion 124 comprises at least a male part 125 that can be cooled so that it thermally contracts. This enables at least a portion of the cooled male part 125 of the male connection portion to be fitted to a recess 146 defined by the female connection portion 144. The male part 125 can be thermally expanded while fitted in the recess 146 so that at least a part of the external surface 127 of male part 125 is cold bonded to at least a part of an internal wall 147 defining the recess 146 to thereby join the first and second structural members 120, 140 together.

[0029] In some embodiments, the male part 125 comprises a projection on the male connection portion 124. In some embodiments, the male part 125 solely consists of the projection on the male connection portion 124.

[0030] The male connection portion 124 is shown as being attached to the first structural member 120 and the female connection portion 144 is shown as being integrally formed with the second structural member 140. However, in some embodiments the male connection portion 124 is integrally formed with the first structural member 120. In some embodiments the female connection portion 144 is formed as a separate component from the second structural member 140 and is attached to the second structural member 140. Examples of how the male and female connection portions 124, 144 may be attached to the first or second structural members 120, 140 respectively include welding, or use of fasteners such as bolts or screws. When fasteners are used for attachment, the structural members 120, 140 and/or connection portions 124, 144 may include suitable apertures, internally threaded recesses, and/or flanges to enable the connection portions 124, 144 to be attached to the first or second structural members 120, 140.

[0031] The male connection portion 124 can be located anywhere on the first body 122 provided that it can be fitted to a female connection portion 144 on the second body 142 as described earlier. Similarly, the female connection portion 144 can be located anywhere on the second body 142 provided that it can receive a male connection portion 124.

[0032] In some embodiments, the internal surface 147 that defines a recess 146 is shaped to complement a cooled male part 125 by enabling it to be received in the recess 146. The surface 147 is shaped such that a substantial amount of it can be in intimate contact with an external surface 127 of the male part 125. The recess 146 has a female lateral dimension D _f and the male part 125 has a male lateral dimension D _m . When the male part 125 is the same temperature as the female part 145, the male lateral dimension D _m is larger than the female lateral dimension D _f . When the male part 125 is cooled with respect to the female part 145 to a lower temperature TL _, the male lateral dimension D _m is equal to the female lateral dimension D _f . When the male part 125 is cooled below the lower temperature T _L , the male lateral dimension D _m is less than the female lateral dimension D _f and the male part 125 can be fitted into the recess 146.

[0033] In some embodiments, the male parts 125 and recess 146 may be shaped as cylinders and the lateral dimensions D _m , D _f may be the diameter of the cylinder. In some embodiments, the male part 125 and recess 146 may be shaped as rectangular prisms extending along a longitudinal axis along the length of the body of the structural member. The lateral dimensions D _m , D _f may be the length of a transverse side of the prism.

[0034] Referring to Figure 2, a system 200 of interconnectable structural components according to some embodiments is shown. The system 200 comprises a first structural member 220 with a first body 222 and a second structural member 240 with a second body 242. The male connection portion 224 is attached to the first body 222 and is shaped such that the external surface area 227 of the male part 225 is curved. The male part 225 is shaped such that it has a cross-section with a concave section 228 adjacent to and continuously connected to a convex section 229 and the maximum diameter of the male part 225 is defined as the male lateral dimension D _m . The female connection portion 244 is attached to the second body 242 and an internal surface 247 defines a recess 246 that is shaped to complement the shape of the male connection portion when it has been cooled. Recess 246 has a maximum diameter that defines the lateral female dimension D _f .

[0035] Advantageously, the inclusion of curved surfaces such as defined by the concave section 228 and the convex section 229 may assist in guiding the male part 225 into the complementarily shaped recess 246.

[0036] As described earlier, the male lateral dimension D _m is larger than the lateral female dimension D _f when the male and female connection portions are at the same temperature.

[0037] In some embodiments, the male lateral dimension D _m and lateral female dimension D _f are in the range of 50 mm to 300 mm. In other embodiments, the male lateral dimension D _m and lateral female dimension D _f are in the range of 125 mm to 250 mm. In some embodiments, the male lateral dimension D _m and lateral female dimension D _f are larger than 50 mm and/or less than 300 mm.

[0038] In other embodiments, the connection portions may have other shapes with surface areas that are larger than a cylinder of the same diameter. The connection portions may be multi-faceted, for example defining more than 5 facets. The connection portions may, for example, have a hexagonal transverse cross-section. The large surface area advantageously provides a large surface area for cold bonding between the external surface 227 of the male part 225 and the internal surface 247 of the recess 246 as described in further detail below. [0039] In some embodiments, the male connection portion 224 is integrally formed with the first structural component 222 and the female connection portion 244 may be integrally formed with the second structural component 242.

[0040] Referring to Figure 3, a system 300 of interconnectable structural components is provided. The system 300 comprises a first structural component 320 and a second structural component 340. The second structural component 340 may be identical to the second structural component 140. The first structural component 320 comprises male connection portion 324 which defines a reservoir 330 for receiving and holding a coolant. The male connection portion 324 may otherwise be the same as male connection portion 124. The coolant may be a cryogenic substance such as liquid nitrogen or solid carbon dioxide (dry ice) and the reservoir 330 may be specifically configured to receive the cryogenic substance. A section 331 of the male connection portion 324 that defines the reservoir 330 is in thermal contact with the male part 325. Section 331 may include an aperture 332 for receiving the coolant and reservoir 330 is shaped to retain the coolant. The coolant may, for example be pouring through the aperture 332 into the reservoir 330. So, as section 331 is cooled by the coolant, male part 325 is also cooled as they are in thermal contact with each other. In other embodiments, the male connection portion 224 may define a reservoir identical to reservoir 330.

[0041] In other embodiments, the aperture 332 and reservoir 330 are shaped to receive a cold finger of a refrigeration system. The cold finger can then make thermal contact with an internal surface of section 331 within the reservoir 330 to thereby cool section 331 and the male part 325.

[0042] Although the aperture 332 is shown as being circular it may take any suitable shape to allow coolant to enter the reservoir 330. The aperture 332 may be sized to be smaller than at least one dimension of the reservoir 330 in the direction parallel to the plane of the aperture 332. The section 331 thereby defining a lip to assist in retaining the coolant within the reservoir 330. [0043] In the embodiment shown, the section 331 forms part of male part 325.

However, in some embodiments, the male part 325 may be a projection on the male connection portion 324 and is separate from section 331. Referring to Figures 4A and 4B, there is shown a structural member 421 that comprises at least one male connection portion 424 and at least one female connection portion 444. The structural member 420 comprises a body 422 with an elongate shape and the male connection portion 424 is located at one end 422a of the body. The female connection portion 444 is located on the body 422 at another end 422b that is spatially separated from an end 422a where the male connection portion 424 is located. As best seen in Figure 4B, the body 422 may be shaped as a universal beam with a cross-section in the shape of the letter T .

[0044] In some embodiments, since the structural members 421 comprise both male and female connection portions 424, 444, a plurality of structural members 421 can be provided as the first structural members 420 and second structural members 440 in a system of interconnectable structural members 400. The system 400 is then otherwise identical to the previously described systems of interconnectable structural members 100, 200 or 300.

[0045] Referring to Figure 5 A, in some embodiments a first structural member 521 is provided comprising a plurality of male connection portions 524 on a first body 522. A second structural member 540 for each of the male connection portions 524 can be joined to the first structural member 521. The male connection portions 524 may be identical to the male connection portion 124, 224, 324 or 424. The second structural member 540 may be identical to the second structural member 140, 240, 340 or 440 so that the recess complements the shape of the male connection portion 524.

[0046] Referring to Figure 5B, in some embodiments a second structural member 541 is provided comprising a plurality of female connection portions 544 on a second body 542. A first structural member 520 for each of the female connection portions 544 can be joined to the second structural member 541. The female connection portions 544 may be identical to the male connection portion 144, 244, 344 or 444. The first structural member 520 may be identical to the second structural member 120, 220, 320 or 420 so that the male connection portion 524 complements the shape of the female connection portion 544. As described earlier, the female connection portion 544 may be either integrally formed in the second body 542 or separately formed and attached to the second body 542.

[0047] Referring to Figure 6, there is also provided a method 600 of joining structural members together for use in building construction. The method comprises, at 610, cooling a male part of a male connection portion of a first structural member such that the cooled male part thermally contracts so that it can be fitted into a complimentary recess in a female connection portion of a second structural member. The method 600 further comprises: locating the cooled male part in the complimentary recess, at 620; and thermally expanding the cooled male part while the cooled male part is located in the complimentary recess, at 630. The thermal expanding cold bonds at least a portion of the male part projection with at least a part of the recess, to thereby join the first and second structural members together.

[0048] The method 600 may be performed using any one of the previously described structural components. For simplicity, the method will be described in relation to the system of interconnectable structural components 100. In some embodiments, the male part 125 of the male connection portion 124 is a male part 125 which may be shaped as a projection on the male connection portion 124 as described earlier. The male and female connection portions 124, 125 may also be the same as any one of the male and female connection portions described earlier.

[0049] In order for the cooled male part 125 to be fitted into the complimentary recess 146 and for subsequent thermal expansion of the male part 125 to result in cold bonding, the female connection portion 144 must be at a higher temperature than the cooled male part 125.

[0050] In some embodiments, the step of cooling may comprise the use of a closed cycle cryogenic refrigeration system. The refrigeration system may comprise a cold finger with a tip that is cooled to cryogenic temperatures. The tip may be placed into thermal contact with the male part 125 in order to cool the male part 125. The tip may be placed into direct contact with the male part 125 or it may be placed in contact with another part of the male connection portion 124 such as part of a reservoir 330 defined by the male connection portion 324 as described above.

[0051] In some embodiments, the step of cooling may comprise the use of a male connection portion having a reservoir 330 and aperture 332 as described earlier. The step of cooling may comprise use of a coolant such as a cryogenic substance. The cryogenic substance may, for example, be liquid nitrogen or solid carbon dioxide (dry ice) and can be poured, decanted or inserted through the aperture 332 into the reservoir 330. The step of cooling may comprise receiving the cryogenic substance in a reservoir defined by the male connection portion 324 described earlier. The sections 331 of the male connection portion 324 that define the reservoir 330 are in thermal contact with the male part 325 and so, as these sections 331 are cooled by the cryogenic substance, the male part 325 can also be cooled.

[0052] In some embodiments, the step of cooling may comprise cooling the male part 125 to an average temperature below a lower temperature of -150°C. There may be non-uniform cooling of the male part 125 and therefore some parts of the male connection portion 124 may be at a temperature that is above the lower temperature.

[0053] In an exemplary embodiment, if the male part is a projection with a symmetrical shape the projection can be described with a diameter D. When the projection is cooled, the change in the diameter can be modelled as a linear thermal contraction. The diameter at the lower temperature T _L (D _L ) can be expressed as:

D _L = D _a (l + a(T _L -Tj) where, a thermal expansion coefficient a is taken to be constant, T _a is the ambient temperature and D _a is the male lateral dimension at ambient temperature T _a . As an example, the male part 125 may be formed from a steel alloy with a thermal expansion coefficient a taken to be constant at a value of 13 x 10 ^"6 /°C. Therefore, for a diameter D _a of 180 mm at an ambient temperature T _a of 30°C, cooling to a lower temperature of -150°C (~ 123 K) would result in a diameter D _L of about 179.58 mm at the lower temperature T _L . This is a fractional change of about 0.23%. If the female connection portion 144 remains at the ambient temperature of 30°C and has a recess 146 with a diameter larger than about 179.59 mm, it should be possible to locate the male part 125 into the recess 146 if it has been cooled below the lower temperature T _L .

[0054] In some embodiments, the cooled male part 125, 225, 325 is thermally expanded as a result of the male part 125 coming into thermal contact with part of the warmer female connection portion 124 such as the internal wall 147.

[0055] In other embodiments, at least one of the male connection portion 124, 224,

324 and female connection portion 144, 244, 344 are heated to a temperature above the ambient temperature. This can advantageously reduce the amount of time required to join the first and second structural members together by cold bonding.

[0056] Following thermal expansion of the cooled male part 125, 225, 325, the male part 125, 225, 325 and female part 145, 245,345 may be in thermal equilibrium. In this expanded state, the male part 125, 225, 325 exerts a pressure against the internal walls 147, 247 defining the recess 146, 246. In some embodiments, the male part 125, 225,

325 and recess 146, 246 are sized so that the pressure exerted is less than the yield strength of the material that the male and female connection portions 124, 144 are fabricated from. This means that the male and female connection portions are not deformed during connection or when connected.

[0057] A combination of the pressure exerted by the male part and friction between the external surface 127, 227 of the male part 125, 225 and the internal surface 147, 247 of the female part 145, 245 results in a bonding force that strongly resists the separation of the first and second structural members 120, 140 or 220, 240 after they have been joined. Cold welding of metal surfaces may also bond the surfaces 127 and 147 (or 227 and 247). Cold welding occurs because the atoms in the surface are brought into close proximity. This may occur when the male part 125, 225 is forced onto the internal surface 147, 247 of the recess 146, 246 under pressure resulting from the thermal expansion described above. It is particularly likely for cold welding to occur if the surfaces 127, 147, 227, 247 are smooth. The method of joining structural members as described may therefore be useful for building construction.

[0058] In an example, for a diameter D for the male connection portion of 183 mm and a recess with diameter 182.7 mm, it is calculated that a pressure of 164 MPa is exerted following thermal expansion of the male connection. This is less than the yield strength of most steel alloys. The described method may therefore be used to join structural components without deformation of the structural components.

[0059] 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.