WO2024082065A1

WO2024082065A1 - Single-piece structural composite floor joist

Info

Publication number: WO2024082065A1
Application number: PCT/CA2023/051396
Authority: WO
Inventors: Hossein KAMALABADI
Original assignee: Kamalabadi Hossein
Priority date: 2022-10-21
Filing date: 2023-10-20
Publication date: 2024-04-25

Abstract

A single-piece joist comprises a top chord defining a top section having a pair of distal ends, and a pair of opposed top angled sections comprising proximal ends, extending downwardly and inwardly from a respective one of the pair of distal ends of the top section. A bottom chord defines a bottom section having a pair of distal ends, and a pair of opposed bottom angled sections comprising proximal ends, extending upwardly and inwardly from a respective one of the pair of distal ends of the bottom section. A web portion extends between the top chord and the bottom chord, the web portion connected at an upper end to the proximal ends of the pair of opposed top angled sections, and connected at a lower end to the proximal ends of the pair of opposed bottom angled sections.

Description

SINGLE-PIECE STRUCTURAL COMPOSITE FLOOR JOIST

TECHNICAL FIELD

[0001] The technical field generally relates to a structural floor joist, and more particularly to a single-piece structural floor joist.

BACKGROUND

[0002] Joists are placed on floors of buildings during construction to provide support in the floor and to distribute load to vertical support columns. Traditional floor joists are made of a top chord and a bottom chord which are fabricated separately then connected, such as by welding, to web members. This causes stress concentrations at spots which have been welded, while also adding to manufacturing time and cost.

[0003] There is therefore still a need for a joist that overcomes at least some of the drawbacks of what is known in the field, such as the above-mentioned drawbacks that may result from connecting joist portions.

SUMMARY

[0004] In one aspect, there is provided a single-piece joist including a top chord, a bottom chord and a web portion extending between the top chord and the bottom chord. The top chord includes a top section having a pair of distal ends, and a pair of opposed top angled sections extending downwardly and inwardly from a respective one of the pair of distal ends of the top section to enter into contact at a proximal end of the pair of opposed top angled sections. The bottom chord defines a bottom section having a pair of distal ends, and a pair of opposed bottom angled sections extending upwardly and inwardly from a respective one of the pair of distal ends of the bottom section to enter into contact at a proximal end of the pair of opposed bottom angled sections. The web portion is connected at an upper end to the proximal end of the pair of opposed top angled sections, and connected at a lower end to the proximal end of the pair of opposed bottom angled sections.

[0005] In some embodiments, the bottom chord has a triangular profile.

[0006] In some embodiments, the top chord can include a vertical section extending upwardly from the top section of the top chord to confer an arrow profile to the top chord. Optionally, the top chord can further include an anchoring structure for providing anchoring in concrete during installation, the anchoring structure extending upwardly from one of the vertical section and the top section. Further optionally, the anchoring structure comprises an I-beam profile.

[0007] In some embodiments, the web portion has a thickness corresponding to twice a thickness of at least one of the horizontal and angled sections of the top chord or bottom chord.

[0008] In some embodiments, the top chord defines a top hollow channel.

[0009] In some embodiments, the bottom chord defines a bottom hollow channel.

[0010] In some embodiments, the top section of the top chord comprises at least one horizontal segment that is horizontally extending. For example, the top section of the top chord comprises two horizontal segments spaced apart from one another, each one extending on a respective side of an axis of symmetry S. Optionally, each horizontal segment has a length of at least 3” for receiving a structural member in abutment thereon.

[0011] In some embodiments, the web portion has a plurality of openings being spaced apart from one another in a longitudinal direction.

[0012] In another aspect, there is provided a method of manufacture for producing the single-piece joist as defined herein, the method comprising forming the single-piece joist from a single material component. [0013] In some embodiments, the single material component can be a single sheet of material, and the forming of the single-piece joist can comprise coldforming the single sheet of material. For example, the cold-forming of the single sheet of material is performed at a temperature ranging from -10°C to 100°C. For example, the cold-forming comprises bending and punching the single sheet of material.

[0014] In some embodiments, the forming of the single-piece joist can comprise extruding the single material component according to a given profile.

[0015] In yet another aspect, there is provided a composite section including a first single-piece joist and a second single-piece joist being as defined herein, a structural member extending between the first and second single-piece joists and abutting at least a portion of the top section of the first and second single-piece joists; and a floor slab extending above the structural member.

[0016] In some embodiments, the structural member can be a metal deck.

[0017] In some embodiments, the floor slab can be a concrete slab being formed upon pouring concrete over the structural member and first and second single-piece joists.

[0018] While the joist will be described in conjunction with example embodiments, it will be understood that it is not intended to limit the scope of the joist and related techniques to such example embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included as defined by the present description. The objects, advantages and other features of the present joist and related techniques will become more apparent and be better understood upon reading of the following non-restrictive description, given with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Embodiments of a floor joist and related method of manufacture are represented in and will be further understood in connection with the following figures.

[0020] FIG. 1 illustrates a top perspective view of a floor joist, in accordance with one embodiment.

[0021] FIG. 2 illustrates a top perspective view of the floor joist of FIG. 1 , when assembled with a steel deck on each side of the floor joist and when fixed to a horizontal structural member (I-beam).

[0022] FIG. 3 illustrates a top perspective view of an assembled section having three spans of the floor joist shown in FIG. 1 , assembled with a steel deck on each side of the floor joists and with a section of concrete poured thereon while each floor joist is fixed to a respective horizontal structural member.

[0023] FIG. 4 illustrates a side view of the assembly of FIG. 3 taken along the line 4-4.

[0024] FIG. 5 illustrates a front cross-sectional view of the assembly of FIG. 4 showing the floor joist of FIG. 1 with the steel decks and concrete section taken along the line 5-5.

[0025] FIG. 6 illustrates a close-up perspective view of the assembly of FIG. 3.

[0026] FIG. 7 illustrates a front cross-sectional view of a floor joist according to another embodiment.

[0027] FIG. 8 illustrates a top perspective view of the floor joist of FIG. 7. DETAILED DESCRIPTION

[0028] The present techniques that are described herein relate to a single piece structural composite floor joist, a method of manufacture thereof and assemblies including at least one floor joist. Various aspects of the techniques will be described in further detail below.

[0029] It will be appreciated that, for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements or steps. In addition, numerous specific details are set forth in order to provide a thorough understanding of the exemplary embodiments described herein. However, it will be understood by those of ordinary skill in the art, that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. Furthermore, this description is not to be considered as limiting the scope of the embodiments described herein in any way but rather as merely describing the implementation of the embodiment described herein.

[0030] There is provided a structural floor joist that is formed from a single material component, being for example a single sheet of material, such as metal. Referring to FIG. 1 , there is provided a section of a single-piece floor joist 10 in accordance with one example embodiment. The expression “single-piece” should be understood as the floor joist being made of one continuous piece of material, e.g., a single sheet of metal, and being formed without having to rely on any fastening or welding means, e.g., by cold-forming the sheet of metal into the floor joist. The floor joist 10 has a top chord 20, a bottom chord 50 and a web portion 80 extending between the top chord 20 and bottom chord 50. In the illustrated embodiment, the bottom chord 50 is substantially shaped like a triangle, while the top chord 20 is substantially shaped like an arrow. The web portion 80 is a substantially planar section of the floor joist 10. In some embodiments, as seen in Figure 1 , the web portion 80 may have a plurality of openings 81 spaced apart from one another along a longitudinal direction between two ends of the floor joist 10 to reduce the weight of the floor joist 10, or for perm itting piping and/or wiring to pass therethrough. Optionally, the openings may be punched or machined. Alternatively, although not illustrated, it is noted that the web portion of the floor joist may be solid throughout the web portion.

[0031] Upon comparing the two example embodiments shown in Figures 1 and 8, one can see that the single sheet of material can be formed according to a same given profile in different ways, such that certain portions/parts may have a thickness that differs from one embodiment to another embodiment. For example, one can see that the web portion 80 shown in Figure 1 includes a double layer of material and thus has a doubled thickness in comparison to a thickness of the web portion 800 of the joist 100 shown in Figure 8 being formed of a single layer of material. It is thus noted that the position of the distal and proximal end portions of the single sheet of material can vary and be selected in accordance with a strength that is desired for certain portions/parts of the joist. Figure 8 shows distal and proximal ends of the sheet of material being positioned at respective top chord 200 and bottom chord 500 of the joist 100.

[0032] Referring to FIG. 5, positional descriptions of the floor joist 10 are provided with respect to a vertical axis or plane V, a horizontal axis or plane H, and an axis or plane of symmetry S. It is understood that the positional descriptions such as “top”, “bottom”, “up” and “down” are provided only for ease of description along the vertical axis V. The floor joist 10 is symmetric with respect to the axis/plane of symmetry S that can correspond to the vertical axis/plane V. In the embodiment shown, the axis of symmetry S extends parallel to the web portion 80 and in a same plane. The floor joist 10 will be described in part with respect to the terms “inwardly” or “outwardly”, also “distal” or “proximal”, an inward/proximal position being proximate the axis of symmetry S, with an outward/distal position being spaced away therefrom. [0033] A non-limitative embodiment of the top chord 20 will now be described, as shown in Figure 5. The top chord 20 comprises a pair of opposed top angled sections 22, a top section 24, a vertical section 26, and an anchoring structure 30 which is embodied by an I-beam section. The top section 24 comprises two horizontal segments 21 spaced apart from one another, each one extending on a respective side of the axis of symmetry S and having a pair of distal ends 23. The top section 24 is configured to support a load which can be mounted thereon, for example on the horizontal segments 21 , as will be described in more detail below.

[0034] Each one of the pair of opposed top angled sections 22 of the top chord 20 extends downwardly and inwardly from a respective one of the pair of distal ends 23 of the top section 24 and enters into contact with the other one of the pair of opposed top angled sections 22 at a proximal end 29 of the opposed top angled sections 22 to an upper end 82 of the web portion 80. In the illustrated embodiment, each one of the two horizontal segments 21 extends substantially along the horizontal axis H from the respective distal end 23 towards the vertical section 26. In the illustrated embodiment, the vertical section 26 comprises two vertical segments 27 which extend upwardly from a respective one of the horizonal segments 21 of the top section 24. The two vertical segments 27 terminate at an upper end thereof at a junction with the I-beam section 30. More particularly, the upper end of each vertical segment 27 of the vertical section 26 is contiguous to a distal end of a bottom flange 32 of the I-beam section 30.

[0035] As shown in FIG. 1 , in addition to the bottom flange 32, the I-beam 30 comprises a top flange 36 and a central web 34 extending vertically between the bottom flange 32 and the top flange 36. The I-beam section 30 defines, on each lateral side thereof, a recess 31 delimited by the top flange 36, the bottom flange 32, and the central web 34.

[0036] As will be described in further detail below, with reference to FIGS. 3 to 5, the vertical section 26 allows for alignment of support structures (or structural members), such as steel decks 70, mounted onto the floor joist 10 by providing a surface for steel decks to abut against. Alternatively, the support structures may comprise metal bars mounted between two adjacent floor joists and a surface, such as a sheet of wood or metal, supported by the metal bars for supporting concrete thereon. The anchoring structure 30, such as the I-beam section, provides a connection between the floor joist 10 and concrete poured thereon, as will be described in more detail below. The interaction between the floor joist 10 and the concrete results in a composite section having improved properties in compression/tension, in comparison to a section consisting only of concrete or metal. It is appreciated that the shape of the anchoring structure 30 can vary from the I-beam. In the illustrated embodiment, the anchoring structure 30 is shaped like an I-beam to provide an improved moment of inertia, thus providing a better connection to the concrete. Other shapes which permit interlocking with concrete poured thereon/therein may also be envisaged.

[0037] Referring to the embodiment shown in Figures 7 and 8, the forming of the joist 100 from the sheet of material can be chosen to provide a continuous surface (without rupture in the sheet of material) to the anchoring structure 300, such as the shown I-beam profile.

[0038] Alternatives to the embodiment shown in the figures can be foreseen. For instance, and without being limitative, the top section 24 can comprise a single horizontal segment extending between the pair of spaced-apart distal ends 23, or one or more segments, each one extending on a respective side of the axis of symmetry S. Furthermore, although in the embodiment shown the vertical section 26 comprises two vertical segments 27, it is appreciated that the vertical section 26 can comprise a single vertical segment extending upwardly, or multiple angled/vertical segments. In another embodiment, the top chord 20 can be free of at least one of the vertical sections 26 and the anchoring structure 30. For instance, the anchoring structure 30 can extend upwardly from the top section 24, i.e., the top chord 20 is free of vertical section 26. [0039] Therefore, a combination of the angled sections 22, the top section 24, the vertical section 26, and the bottom flanges 32 of the I-beam 30, on both lateral sides of the floor joist 10, delimit a hollow elongated top channel 40 extending longitudinally through the top chord 20 of the floor joist 10. In a cross-section view, the hollow elongated channel 40 is substantially shaped like a downwardly oriented arrow and has a closed shape. In other words, a cross-sectional shape of the hollow elongated top channel 40 is entirely delimited by sections/segments of the floor joist 10. It is understood that the arrow shape is a variation of a triangular shape, although other variations of the triangular shape may also be used. In another possible implementation (not shown), the hollow elongated top channel 40 may be shaped substantially like a triangle. It is noted that a triangular/arrow shape may confer an improved moment of inertia relative to standard floor joist profiles with horizontal flanges. The triangular/arrow shape also serves to stiffen the top chord 20, helping to prevent local buckling at the top chord 20 when the top chord 20 is under a compressive load.

[0040] One possible advantage of the arrow-shaped hollow elongated top channel 40 is that the top section 24 may provide support to structural members mounted thereon, as shown in FIGS. 3 to 6. More particularly, FIGS. 3, 5 and 6 show one floor joist 10 supporting two decks 70, one on each lateral side of the floor joist 10. More particularly, each one of the decks 70 is supported by a respective horizontal segment 21 of the top section 24 of the top chord 20. As will be described in more detail below, a plurality of floor joists 10 can be configured in a spaced-apart, substantially parallel configuration and decks, such as steel decks 70, can be mounted thereon with one deck extending between two spaced-apart and adjacent floor joists 10 for construction purposes, such as building construction. In one non-limitative embodiment, each one of the horizontal segments 21 has at least 3” of length (or bearing) for receiving a structural member, such as a deck, thereon.

[0041] Returning to FIG. 5, a non-limitative embodiment of the bottom chord 50 will now be described. The bottom chord 50 comprises a bottom section 52 having a pair of distal ends 53. In the illustrated embodiment, the bottom section 52 comprises a lower segment 54 extending between the pair of distal ends 53. Alternatively, the bottom section 52 may comprise one or more lower segments extending between the pair of distal ends 53, substantially horizontally or at an angle with respect to the horizontal axis.

[0042] The bottom chord 50 also comprises a pair of opposed bottom angled sections 55. Each one of the pair of opposed bottom angled sections 55 extends upwardly and inwardly from a respective one of the pair of distal ends 53 of the bottom section 24 and enters into contact with the other one of the pair of opposed bottom angled sections 55 at a proximal end 57 of the pair of opposed bottom angled sections 55 to a lower end 84 of the web portion 80.

[0043] A combination of the angled sections 55 and the lower segment 54, on both lateral sides of the floor joist 10, delimit a hollow elongated bottom channel 60 extending longitudinally through the bottom chord 50 of the floor joist 10. In a cross-section view, the hollow elongated channel 60 is substantially shaped like a triangle and has a closed shape, i.e. , in cross-section, its shape is entirely delimited by sections/segments of the floor joist 10. Alternatively, the hollow elongated channel 60 may be shaped substantially like an arrow, similar to the top chord 20, or another variation of a triangle. As mentioned previously, the triangular/arrow shape may confer an improved moment of inertia relative to standard floor joist profiles comprising an I-beam profile with planar horizontal flanges (not shown). Although, in the illustrated embodiment, the top chord 20 and the bottom chord 50 have substantially similar widths along the horizontal axis H, alternatively they may have different widths. For example, the top chord 20 may have a greater width than the bottom chord 50, or alternatively the bottom chord 50 may have a greater width than the top chord 20.

[0044] In the embodiment shown in Figure 7, the bottom chord 500 of the joist 100 is seen to include a rupture in the continuity of the surface as an end portion of the sheet of material is used to form and close the bottom chord 500 at a lower end 840 of the web portion 800. Similarly, the top chord 200 is seen to include another rupture in the continuity of the surface as the other end portion of the sheet of material is used to form and close the top chord 200 at an upper end 820 of the web portion 800.

[0045] Referring to FIGS. 2 and 3, there is shown one floor joist 10 supported at an end thereof by a structural member 110. It is appreciated that the floor joist 10 can be supported at both ends by two spaced-apart structural members 110. Referring to FIG. 2, when supporting a steel deck 70, the vertical section 26 may further be configured to be aligned laterally with the steel deck 70, with the bottom flange 32 of the I-beam section 30 being aligned with top sections 72 of the steel deck 70. In the non-limitative embodiment shown, the steel deck 70 further includes bottom sections 74 and angular sections 76. The bottom sections 74 are spaced apart from one another, with a respective one of the top sections 72 extending between two adjacent ones of the bottom sections 74, thereby defining elongated recesses 78 between adjacent ones of the top sections 72. Adjacent ones of the top and bottom sections 72, 74 are connected to one another via angular sections 76. The combination of the top sections 72 and the bottom sections 74 of the steel deck 70 define respectively a topmost surface and a bottommost surface of the steel deck 70. The bottom sections 74 of the deck 70 are abutted against the top section 24 of the top chord 20 when engaged together. It is appreciated that the shape of the steel deck 70 can vary from the embodiment shown. Furthermore, it is appreciated that the deck 70 can be made of another material than steel. For instance, the deck 70 can be made of any suitable metal or non-metal material providing the required mechanical properties.

[0046] With reference to FIGS. 2 and 3, the steel deck 70 can be configured to be at least partially covered with concrete to fill the elongated recesses 78 defined between adjacent ones of the top sections 72. Accordingly, concrete 90 can be poured onto the steel deck 70 to cover, at least partially, the top sections 72, bottom sections 74, and angular sections 76. When engaged together, the vertical section 26 is configured to be aligned with the steel deck 70 with the top sections 72 being substantially aligned with the bottom flanges 32 of the I-beam 30. Thereby, concrete 90 poured onto the steel deck 70 fills the recesses 31 of the I- beam 30, as shown in FIG. 5. Therefore, the I-beam 30 can be embedded in the concrete 90 poured over the decks 70.

[0047] In the non-limitative embodiment shown in FIG. 3, the concrete slab (as exemplified from section 90) can extend continuously over two adjacent ones of the decks 70 with one floor joist (10a, 10b or 10c) extending in between for supporting both decks 70 and the concrete slab.

[0048] Referring to FIG. 5, if the top sections 72 of the steel deck 70 were located at a height exceeding the height of the vertical section 26, for example, the recesses 31 of the I-beam 30 could be covered at least partially by the steel deck 70, thereby preventing concrete from filling these recesses 31.

[0049] In some non-limitative embodiments, as shown in FIGS. 3 to6, a concrete slab supported by the steel deck 70 and the floor joist(s) (10, 10a, 10b, 10c) may additionally comprise a wire mesh 92 for additional reinforcement of the concrete 90, for example to provide cracking resistance and/or tensile resistance.

[0050] In order to make a standard floor joist, a top chord, bottom chord and web portion(s) are generally separately fabricated, then fixedly attached together by a suitable means, such as welding or fasteners. There is rather provided herein a method to manufacture the structural floor joist as defined herein, wherein the method includes forming the structural floor joist as a single-piece component, for example from a single sheet of metal.

[0051] In some implementations, the floor joist 10 may be fabricated using Cold-Formed Steel (CFS), eliminating the need for skilled labor (e.g., welders) during manufacture. For example, a production line of Computer Numerically Controlled (CNC), manufacturing devices may be able to produce the floor joist 10 described herein in a form that may be ready for shipping (e.g., to a construction site) without the need for skilled labor to process the joists. As the name suggests, CFS may be formed at “cold” temperatures, for example at a temperature ranging between -10°C and 100°C, such as at room temperature (20°C), and otherwise at temperatures significantly lower than required during production of “hot rolled” steel (on the order of 1 ,000°C). A CFS production line may also be simpler, and therefore more cost-effective, than a “hot rolled” steel production line.

[0052] An additional benefit of the floor joist 10 of the present disclosure is that by removing welding or fasteners from the top and bottom chords, point stresses are eliminated and a more equal load distribution is provided. Accordingly, cracks propagating at points where stresses are greatest (e.g., weld points) are less likely with the proposed floor joist 10, leading to enhanced performance. Furthermore, as described above, the top section 24 of the top chord 20 of the floor joist 10 is configured to receive and a support a deck or a floor thereon. The vertical section 26 of the top chord 20 of the floor joist 10 additionally prevents lateral movement of the deck or the floor supported by the top section 24 when the deck or floor is placed between two fixed floor joists 10. Therefore, the combination of the top section 24 and vertical section 26 eliminates the need for studs to fixedly attach the floor joist 10 to the deck or the floor and then to the concrete poured thereon, if any. When the recesses 31 are filled with concrete 90, the I-beam 30 of the top chord 20 grounds the floor joist 10 into concrete during construction, preventing vertical movement thereof.

[0053] Referring to FIG. 5, the I-beam 30 of the top chord 20 is embedded in the concrete 90 poured over the deck 70 and thereby substantially prevents movement of the floor joist 10 once the concrete is set. Moreover, the I-beam 30 eliminates the need for any shoring, props, or temporary support for spans of various lengths during construction. In one possible and non-limitative implementation, a steel deck up to twenty-five (25) feet may be simply supported between adjacent and spaced-apart floor joists 10 between two horizontal structural members 110, as shown in FIGS. 3 and 6. [0054] In accordance with an example embodiment of the method of manufacture of the floor joist 10, the floor joist 10 can be fabricated starting from a sheet metal that is then manipulated by machinery, such as CNC machinery via bending and punching, to produce a desired profile, such as the profile shown in FIGS. 1 and 5. In accordance with this example embodiment, the floor joist 10 is made from a single sheet of metal. Each of the left/right side with respect to the axis of symmetry S can be further formed from the same sheet of metal. As a result, due to the fact that the sheet metal is shaped and bent to correspond to the left and right sides of the floor joist 10, the web portion 80 has a thickness corresponding to two juxtaposed layers of sheet metal. Consequently, the web portion 80 has twice the thickness of the horizontal and angled sections of the top chord 20 and bottom chord 50. This double layer of sheet metal at the web portion 80 increases the shear capacity of the floor joist 10.

[0055] Also due to the fact that the sheet metal is shaped and bent to correspond to the left and right sides of the floor joist 10, the top chord 20 and the bottom chord 50 can define hollow elongated channels 40, 60 reducing an overall weight of the single-piece joist 10 while maintaining its resistance to mechanical constraints. Due to the shaping of the sheet of material in accordance with the configuration of the sections of the joist 10 defined herein, the bottom hollow channel 60 can have a triangular profile for the bottom chord 50 and the top hollow channel 40 can have an arrow profile for the top chord 20. As mentioned above, it is appreciated that the elongated channels 40, 60 can have other cross-sectional shapes.

[0056] It should be understood that a change in the method of manufacture of the joist can lead to making non-hollow top and bottom chords. For example, the method may include an extrusion of material in accordance with the general profile of the joist described herein, thereby for example producing a triangular bottom chord which is thus not hollow. [0057] It is envisaged that the gauge, or thickness, as well as the height of the sheet of steel may also be modified depending on the design loads that the floor joist 10 will be expected to support. Naturally, a greater thickness (corresponding to a lower gauge) will result in a stronger floor joist. Similarly, a greater height of the joist 10 will result in a stronger floor joist. A benefit of a cold-formed floor joist 10 produced according to the present disclosure is that the floor joist 10 may be produced at a manufacturing facility and sent to a construction site without the need for additional treatment, such as cutting or welding, of the floor joist 10 at the construction site. This compares favorably, for example, to hot-rolled steel where production facilities may be less capable of adapting their output to the particular requirements of a given construction project. For example, referring to FIG. 3, it is envisaged that multiple spans may be prefabricated in the manufacturing facility and sent to the construction site as an assembled composite section 100. In the non-limitative example shown in FIG. 3, the assembled composite section 100 comprises three floor joists 10a, 10b, 10c assembled to two steel decks 70a, 70b (corresponding to a three-span composite section) placed between the floor joists 10c, 10b, 10c, with concrete 90 poured thereon and wire mesh 92 in the concrete 90 for additional reinforcement. The assembled composite section 100 may be mounted on site to horizontal structural members 110 (I-beams in the illustrated embodiment) to provide a structure for a floor. Prefabricating the assembled composite section 100 provides the benefit of speeding up construction on site. It is envisaged that, alternatively, the composite assembled section 100 may comprise only the floor joists 10a, 10b, 10c being assembled to steel decks 70a, 70b with concrete poured on site. Alternatively, less or more than three spans may be assembled at a time.

[0058] Steps of the method of manufacture of the joist may be implemented by being performed or completed manually, automatically, or a combination thereof.

[0059] The term “method” may refer to manners, means, techniques and procedures for accomplishing a given task including, but not limited to, those manners, means, techniques and procedures either known to, or readily developed from known manners, means, techniques and procedures by practitioners of the art to which the invention belongs.

[0060] The descriptions, examples, methods and materials presented in the claims and the specification are not to be construed as limiting but rather as illustrative only.

[0061] It will be appreciated that the steps of the method described herein may be performed in the described order, or in any suitable order.

[0062] It should be understood that any one of the above-mentioned aspects of joist, method of manufacture thereof and use thereof may be combined with any other of the aspects thereof, unless two aspects clearly cannot be combined due to their mutual exclusivity. For example, the various structural features of the joist described herein-above, herein-below and/or in the appended Figures, may be combined with any of the general steps of the method and use descriptions appearing herein and/or in accordance with the appended claims.

Claims

1 . A single-piece joist comprising: a top chord defining: a top section having a pair of distal ends, and a pair of opposed top angled sections extending downwardly and inwardly from a respective one of the pair of distal ends of the top section to enter into contact at a proximal end of the pair of opposed top angled sections, a bottom chord defining: a bottom section having a pair of distal ends, and a pair of opposed bottom angled sections extending upwardly and inwardly from a respective one of the pair of distal ends of the bottom section to enter into contact at a proximal end of the pair of opposed bottom angled sections; and a web portion extending between the top chord and the bottom chord, the web portion connected at an upper end to the proximal end of the pair of opposed top angled sections, and connected at a lower end to the proximal end of the pair of opposed bottom angled sections.

2. The single-piece joist of claim 1 , wherein the bottom chord has a triangular profile.

3. The single-piece joist of claim 1 or 2, wherein the top chord further comprises a vertical section extending upwardly from the top section of the top chord to confer an arrow profile to the top chord.

4. The single-piece joist of any one of claims 1 to 3, wherein the top chord further comprises an anchoring structure for providing anchoring in concrete during installation, the anchoring structure extending upwardly from one of the vertical section and the top section. The single-piece joist of claim 4, wherein the anchoring structure comprises an I-beam profile. The single-piece joist of any one of claims 1 to 5, wherein the web portion has a thickness corresponding to twice a thickness of at least one of the horizontal and angled sections of the top chord or bottom chord. The single-piece joist of any one of claims 1 to 6, wherein the top chord defines a top hollow channel. The single-piece joist of any one of claims 1 to 7, wherein the bottom chord defines a bottom hollow channel. The single-piece joist of any one of claims 1 to 8, wherein the top section of the top chord comprises at least one horizontal segment that is horizontally extending. The single-piece joist of claim 9, wherein the top section of the top chord comprises two horizontal segments spaced apart from one another, each one extending on a respective side of an axis of symmetry S. The single-piece joist of claim 9 or 10, wherein each horizontal segment has a length of at least 3” for receiving a structural member in abutment thereon. The single-piece joist of any one of claims 1 to 11 , wherein the web portion has a plurality of openings being spaced apart from one another in a longitudinal direction. A method of manufacture for producing the single-piece joist as defined of any one of claims 1 to 12, the method comprising forming the single-piece joist from a single material component. The method of manufacture of claim 13, wherein the single material component is a single sheet of material, and the forming of the single-piece joist comprises cold-forming the single sheet of material. The method of manufacture of claim 14, wherein the cold-forming of the single sheet of material is performed at a temperature ranging from -10°C to 100°C. The method of manufacture of claim 14 or 15, wherein the cold-forming comprises bending and punching the single sheet of material. The method of claim 13, wherein the forming of the single-piece joist comprises extruding the single material component according to a given profile. A composite section comprising: a first single-piece joist and a second single-piece joist being as defined in any one of claims 1 to 12; a structural member extending between the first and second single-piece joists and abutting at least a portion of the top section of the first and second single-piece joists; and a floor slab extending above the structural member. The composite section of claim 18, wherein the structural member is a metal deck. The composition section of claim 18 or 19, wherein the floor slab is a concrete slab being formed upon pouring concrete over the structural member and first and second single-piece joists.