Patent Application
20140090332
This disclosure relates to cold rolled steel joists and in particular unitary steel joist that are for use with a concrete slab.
Cold rolled steel joists are becoming more popular. Heretofore, where cold rolled steel joist is a unitary steel joist they were designed to be used as bottom chord bearing joists. In general a unitary steel joist is not designed to be used as a top chord bearing type joist. Accordingly it would be advantage to provide a unitary steel joist assembly that can be used in a composite steel joist/concrete assembly, with increased end reaction load capacity capabilities.
The present disclosure relates to a steel joist assembly for use in association with a concrete slab and being adapted to form a composite steel joist including a steel joist and a pair of end connectors. The steel joist has a top portion with a generally planar top surface and a planar web generally orthogonal to the generally planar top surface. An end connector is attached at each end of the steel joist. Each end connector has a strut and a diagonal member. The strut has a generally planar bottom surface which is attached to a portion of the generally planar top surface of the steel joist and the diagonal member is attached at one end thereof to the strut and at the other end thereof to a portion of the planar web of the steel joist.
The end connector may further include a shoe attached to the distal end of the strut. The strut may be a pair of generally L-shaped members arranged back to back and each having an upper lip extending outwardly. The diagonal member may be a generally L-shaped member. The pair of generally L-shaped members may each have a plurality of holes formed therein adapted to receive reinforcing bars.
The steel joist assembly may further include a steel deck attached to the generally planar top surface of the steel joist. The deck may be attached with a plurality of screws and the screws have a multi-shear connectors attached thereto which extend upwardly. The multi-shear connectors may have a bottom portion, a back portion, a sloped portion and two side portions wherein the bottom portion rests on the deck, the back portion extends upwardly from the bottom portion, the side portions extend inwardly from the back portion and the sloped portion is sloped inwardly from the back portion whereby the side portions and sloped portions are shaped to receive a reinforcing bar.
The steel joist may be a unitary steel joist. The steel joist may have a generally vertical planar web; a generally horizontal bottom flange extending outwardly on each side of the planar web, the bottom flange having a double thickness; a generally horizontal top flange extending outwardly on each side of the planar web, the top flange having a double thickness; a bottom wing extending outwardly from one side of the planar web; a bottom planar web portion extending between the bottom flange and the bottom wing; a top wing extending outwardly from one side of the planar web; a top planar web portion extending between the top flange and the top wing; and whereby the planar web, the bottom flange, the top flange, the bottom wing, the bottom planar web portion, the top wing and the top planar web portion are made from a unitary piece of steel.
A steel joist system for use in association with a concrete slab to form a composite steel joist system includes a plurality of steel joists and a deck attached to the plurality of steel joists. The deck may be attached with a plurality of screws and the screws may have a multi-shear connectors attached thereto which extends upwardly. The multi-shear connectors may have a bottom portion, a back portion, a sloped portion and two side portions wherein the bottom portion rests on the deck, the back portion extends upwardly from the bottom portion, the side portions extend inwardly from the back portion and the sloped portion is sloped inwardly from the back portion whereby the side portions and sloped portions are shaped to receive a reinforcing bar. The steel joist system may further include a plurality of reinforcing bars extending through the end connectors and extending through the multi-shear connectors. The steel reinforcing bars may form a perimeter around a predetermined floor area. Wire mesh may be placed on top of the reinforcing bars.
A multi-shear connector includes a bottom portion, a back portion, a sloped portion and two side portions wherein the bottom portion rests on the deck, the back portion extends upwardly from the bottom portion, the side portions extend inwardly from the back portion and the sloped portion is sloped inwardly from the back portion whereby the side portions and sloped portions are shaped to receive a reinforcing bar.
A composite steel joist assembly includes a plurality of steel joists, a dovetail deck, and a concrete slab. Each joist has a top portion with a generally planar top surface and a planar web generally orthogonal to the generally planar top surface;
each joist having a pair of end connectors, one attached at each end of the steel joist and extending outwardly therefrom. The dovetail deck is attached to the plurality of steel joists. The concrete slab is poured into and around the dovetail deck.
Further features will be described or will become apparent in the course of the following detailed description.
The embodiments will now be described by way of example only, with reference to the accompanying drawings, in which:
Referring to figure s 1 to 4, the steel joist assembly is shown generally at 10. Steel joist assembly 10 includes a steel joist 12 and a pair of end connectors 14. The end connectors 14 could work with any steel joist having a generally planar top surface and a planar web generally orthogonal to the bottom surface. The end connectors 14 may be used with any I beam shaped joists, alternatively they could be used with C-shaped joists. Accordingly, the end connectors are not applicable to open webbed steel joists. In an embodiment shown herein steel joists 12 are unitary steel joist as described in U.S. application Ser. No. 12/942,714, filed Nov. 9, 2010 and entitled Unitary Steel Joist and having the same inventors as shown herein. Steel joist 12 has a top flange 16, bottom flange 18 and a planar web 20 therebetween. The top flange 16 has a generally planar top surface.
The planar web 20 is a generally vertical. A generally horizontal bottom flange 18 extends outwardly on each side of the planar web 20. The bottom flange 18 has a double thickness. The generally horizontal top flange 16 extends outwardly on each side of the planar web 20. The top flange 16 has a double thickness. A bottom wing extends outwardly from one side of the planar web. A bottom planar web portion extends between the bottom flange and the bottom wing. A top wing extends outwardly from one side of the planar web. A top planar web portion extends between the top flange and the top wing; and the planar web, the bottom flange, the top flange, the bottom wing, the bottom planar web portion, the top wing and the top planar web portion are made from a unitary piece of steel.
End connector 14 includes a strut 24 and a diagonal member 26. The strut 24 has a generally planar bottom surface 28 which is attached to a portion of the generally planar top surface 22 of the steel joist 12. The diagonal member 26 is attached at one end thereof to the strut 24 and at the other end thereof to a portion of the planar web 20 of the steel joist 12.
In an embodiment shown herein the strut 26 is a pair of generally L-shaped members 28 arranged back to back and each having an upper lip 30 extending outwardly. Similarly the diagonal member 26 is a generally C- shaped member. The strut 26 have a plurality of holes 32 formed therein adapted to receive reinforcing bars 34.
The End connector 14 may further include a shoe 36 attached to the distal end of the strut 24. In an embodiment shown herein the shoe 36 is an L-shaped member.
The steel joist assembly including a steel deck attached to the generally planar top surface of the steel joist. In an embodiment the steel deck 38 is a corrugated steel deck having generally a trapezoidal shape.
The steel deck is held in place with a plurality of screws 40 or welds. In the embodiment shown therein multi-shear connectors 42 are connected to the screws 38 and extend upwardly over the deck 38. Referring to
Referring to
An alternate deck 62 is shown in
In one embodiment the unitary steel joists 12 are cambered for dead load deflection.
There are a number of advantages that are realized by the composite steel joist system shown herein. For example end connectors 14 that sit flush with the supporting member 64, as shown in
The multi-shear connectors 42 can function alone without reinforcing bar and provide shear bond capacity between the steel joist 12 and the concrete slab 60. Alternatively the multi-shear connectors may be used in conjunction with reinforcing bar 34 which is “a high chair” for reinforcing mesh 54 and allows for the installation of a reinforcing bar 34 to reinforce the concrete slab 60. In addition the strut provides for a coordinated method of locating a short reinforcing bar at the joist end support to increase shear capacity at the joists most vulnerable location and provides a method to transfer loads from the joist end to the perimeter beam.
Generally speaking, the systems described herein are directed to a steel joist assembly and a steel joist system. Various embodiments and aspects of the disclosure will be described with reference to details discussed below. The following description and drawings are illustrative of the disclosure and are not to be construed as limiting the disclosure. Numerous specific details are described to provide a thorough understanding of various embodiments of the present disclosure. However, in certain instances, well-known or conventional details are not described in order to provide a concise discussion of embodiments of the present disclosure.
As used herein, the terms, “comprises” and “comprising” are to be construed as being inclusive and open ended, and not exclusive. Specifically, when used in the specification and claims, the terms, “comprises” and “comprising” and variations thereof mean the specified features, steps or components are included. These terms are not to be interpreted to exclude the presence of other features, steps or components.
As used herein, the term “exemplary” means “serving as an example, instance, or illustration,” and should not be construed as preferred or advantageous over other configurations disclosed herein.
As used herein, the terms “about” and “approximately” are meant to cover variations that may exist in the upper and lower limits of the ranges of values, such as variations in properties, parameters, and dimensions. In one non-limiting example, the terms “about” and “approximately” mean plus or minus 10 percent or less.
As used herein, the term “substantially” refers to the complete or nearly complete extent or degree of an action, characteristic, property, state, structure, item, or result. For example, an object that is “substantially” enclosed would mean that the object is either completely enclosed or nearly completely enclosed. The exact allowable degree of deviation from absolute completeness may in some cases depend on the specific context. However, generally speaking the nearness of completion will be so as to have the same overall result as if absolute and total completion were obtained. The use of “substantially” is equally applicable when used in a negative connotation to refer to the complete or near complete lack of an action, characteristic, property, state, structure, item, or result.
| Number | Date | Country | |
|---|---|---|---|
| 61707331 | Sep 2012 | US |
