Modular joist shoe

Abstract

The present invention provides a modular end shoe for a cold-rolled sheet steel joist having a Z-shaped shear connector top chord or a C or Z-shape in non-composite construction, comprising a bearing surface for bearing on a support for the joint end, and means for connecting the bearing surface to the web and top chord of the joist and fastening means connecting the modular end shoe to the top chord and to the web.

Description

FIELD OF INVENTION

[0001] The present invention relates to a modular joist shoe for use with a cold-rolled sheet steel joist both composite and non-composite.

BACKGROUND OF THE INVENTION

[0002] Canadian Patent 885,156 issued on Nov. 9, 1971 taught the use of a cold-rolled sheet steel joist in a composite steel and concrete floor system, the joist having a Z-shaped top chord providing a shear connector between the steel joist and the concrete slab in which the top chord is embedded.

[0003] The problem in using a cold-rolled steel joist is that instead of the joist being supported on an end shoe connected to the top chord, the joist must be supported on the bottom chord. Such support is less stable during construction and concreting stages than if the joist is supported at the top chord. It also requires filling in the void between joist and bearing surface and bottom of slab or roof.

[0004] The present invention is directed to the provision of a modular end shoe for attachment to a cold-rolled steel joist of the type disclosed in the prior Canadian patent and standard C and Z-shaped joist, thereby greatly increasing the utility of the cold-rolled joist and its stability during construction stages during the erection of form work and concrete placement and prior to the concrete developing its ultimate strength.

[0005] The end shoe of the present invention enables completed joist to be fabricated on site merely by cutting the joist to the correct span length, and attaching the end shoes to the joist.

[0006] The joist when fabricated can then be supported with the usual roll bar or spanner bar equipment as taught in Canadian Patent 885,156 and other relevant prior art.

SUMMARY OF THE INVENTION

[0007] In accordance with the present invention, a modular end shoe for a cold-rolled sheet steel joist having a Z-shaped shear connected top chord comprises a bearing surface for bearing on a support for the joint end, and means for connecting said bearing surface to the web and top chord of the joist and fastening means connecting said modular end shoe to said top chord and to said web.

[0008] In another aspect the invention also includes an L-shaped vertical member adapted to be positioned adjacent the web and extending over the bearing surface, a clamping plate for bearing against the web of the joist on the side opposite to the L-shaped member, and connecting means joining the L-shaped member and the plate to the web and a back strap forming the bearing surface of the end shoe extending over said L-shaped member, and connecting means connecting the back strap to the top chord.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] A better understanding of the invention may be obtained by reading the detailed description of the invention below, in conjunction with the following drawings, in which:

[0010] FIG. 1 is a perspective view of a cold-rolled sheet metal joint for use with the end shoe of the invention,

[0011] FIG. 2 is a cross-section through a composite floor constructed using cold-rolled sheet metal joist;

[0012] FIG. 3 is a perspective view of the modular end shoe in accordance with the invention,

[0013] FIG. 4 is a side view of the modular shoe,

[0014] FIGS. 5A, 5B and 5C are respectively a side elevation, end and top view of the back strap of the modular joist,

[0015] FIG. 6 is a front view of the modular shoe;

[0016] FIG. 7 is a cross section of the cold-rolled sheet joist of the prior art,

[0017] FIG. 8 illustrates the modular end shoe connected to the sheet metal joist,

[0018] FIG. 9 illustrates the sheet metal joist with a pair of modular end shoes resting on supports for supporting the joist,

[0019] FIG. 10 illustrates the modular end shoe connected to a Z-shaped joist, and

[0020] FIG. 11 illustrates the modular end shoe connected to a C-shaped joist.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0021] FIGS. 1 and 2, labelled “Prior Art” illustrate a known cold-rolled sheet metal joist as taught by Canadian Patent 885,156. In FIG. 1, the joist is indicated generally at 10, and consists of a bottom chord 11 in a generally flattened oval or rectangular shape, a vertical web or flange 12, and a generally Z-shaped top chord 13. Openings 16 are provided in the web through which spanner bars are inserted for stabilizing the web during construction phases. In FIG. 2, top chords 13 are embedded in the concrete slab 17 which is reinforced by metal mesh 18. As discussed, during the erection phase, such a sheet metal joist must be supported at its ends by resting the bottom chord 11 on a suitable support. This has limited the development and use of the sheet metal joist to restricted applications which temporary supports and bridging can be utilized.

[0022] The present invention as shown in FIGS. 3 through 9 provides a means for permitting a sheet metal joist with modular end shoes to be used in direct replacement for long span open web joists. In addition, the use of these modular end shoes permits the joist to be custom fabricated on site, the end shoes attached and the joist placed and utilized as one would normally use an open web joist.

[0023] Referring to FIG. 3, there is shown in perspective view a modular end shoe 30 which consists of a back strap having a top portion 31, a sloping component 32, an end portion 33, a bearing surface 34, and a positioning surface 35. An L-shaped vertical plate 36 is welded to the back strap 31 and a clamping plate 37 is welded to the vertical leg 35 of the back strap.

[0024] FIG. 4 illustrates the modular end shoe 30 with the top component of the back strap 31, the angle component 32, the end portion 33, the load bearing portion 34 and the vertical positioning portion 35. Conveniently, the back strap is a single piece bent to the configuration illustrated and providing the connection of all of the components. The vertical plate 36 and the clamping plate 37 are also illustrated. The dotted portion 38 indicates positions through which self-drilling and tapping screws (not shown) can be secured.

[0025] For purposes of further clarification, FIGS. 5A, 5B and SC illustrate the back strap as finally formed and prior to attachment to the plate 36 and the attachment of the clamping member 37.

[0026] FIG. 6 is an end on view of the modular shoe prior to installation of the end shoe on the end of the joist. The dotted portions on the flange 40 on the plate 36 and the flange 41 on the clamping plate 37 indicate possible positions for welding the plate 36 and the plate 37 to the back strap portion 35.

[0027] FIG. 7 is a cross-section of the cold-rolled sheet metal joist 17 for which the modular end shoe of FIG. 6 is intended to be applied.

[0028] FIG. 8 illustrates the joist 70 in section mounted in the modular shoe 30. The web and the chord of the joist are connected to the end shoe by self-drilling and tapping screws.

[0029] As illustrated in FIG. 9, an end shoe is attached to each end of the joist 70, the joist being shown as broken in the center to save space. Each end shoe 30 is supported typically by an I-beam wall, or other masonry support and a plurality of like joists are positioned on the supports with spacer bars mounted in the openings of the joist to stabilize the joist during the concreting phase of the composite floor construction.

[0030] FIGS. 9 and 10 show the use of the end shoe with Z and C-shaped joists, the joist being attached to its end shoe as before, either by screws or other suitable means.

[0031] Thus a sheet metal joist can now be utilized in exactly the same way as an open web joist has been previously.

[0032] When joists of standard lengths are required it may be desirable to install the end shoes in the fabricating plant and ship the completed joist to the job site ready for installation. It will also be appreciated by those skilled in the art that the end shoe can be attached to the joist by welding or clinching if installed at a location where facilitates exist for such procedures.

[0033] A person understanding the above-described invention may now conceive of alternative designs, using the principles described herein. All such designs which fall within the scope of the claims appended hereto are considered to be part of the present invention.

Claims

1. A modular end shoe for attachment to a sheet steel joist having a Z-shaped top chord and a vertical web comprising:

a bearing surface for transmitting load to a support,

means for connecting said bearing surface to the web and top chord of the joist, including fastening means joining said connecting means to said top chord and web.

2. An end shoe as defined in claim 1, wherein said means for connecting said bearing surface to the top chord and web of said joint comprises an L-shaped vertical member adapted to be positioned adjacent and fastened to the web, and extending over and connected to the bearing surface.

3. An end shoe as defined in claim 2, wherein said bearing surface is formed by a back strap and extending over said L-shaped member and said top chord and fastened thereto, and said fastening means includes means for fastening said portion of said back strap extending over said top chord to said top chord.

4. An end shoe as claimed in claim 2, including a clamping plate attached to the back strap and parallel and spaced from said L-shaped member, and positioned to permit the web of said joist to be positioned between the L-shaped member and the clamping plate, and fastening means extending through said clamping plate, said web and said L-shaped member.

5. An end shoe as in claim 4 wherein said fastening means is a plurality of self drilling, self-tapping screws.

6. A sheet steel joist having a modular end shoe as defined in claim 1 on each end thereof.