US20090205285A1

US20090205285A1 - Composite floor systems and apparatus for supporting a concrete floor

Info

Publication number: US20090205285A1
Application number: US12/031,877
Authority: US
Inventors: James F. Jendusa
Original assignee: Lightweight Structures LLC
Current assignee: Lightweight Structures LLC
Priority date: 2008-02-15
Filing date: 2008-02-15
Publication date: 2009-08-20

Abstract

An apparatus for supporting a concrete floor and a composite floor system constructed therewith comprises form panels supported between a plurality of joists, the joists including a shear connector at least partially embedded in the concrete slab of the floor system. Each of the joists may be formed of a double channel structural member, including a top chord to which the shear connector is secured, a bottom chord and a reinforced web.

Description

BACKGROUND

The present invention relates generally to building components and more particularly to an apparatus for supporting a concrete floor and composite floor systems constructed therewith.
Many commercial buildings and some larger, multi-story residential complexes, such as apartment buildings or condominiums, utilize concrete floor decking or concrete floors in their construction. Concrete floor decking has also become increasingly popular in residential and smaller constructions over the last decade. Concrete floor support systems have several advantages over traditional decking materials, such as strength, rigidity, durability, mold resistance, sound attenuation, suitability for in-floor radiant heating and the availability of decorative concrete finishes.
Traditional concrete flooring systems were adapted from commercial construction, and generally constructed by spanning steel or wood joists between structural walls or primary structural members, spacing or bridging the joists with rebar or blocking members to provide lateral support to the joists, and laying plywood, steel, aluminum, or fiberglass decking on or between the joists and pouring a thick concrete layer over the decking. The resulting flooring systems are heavy and require significant time to install. Further, in order to bear the additional weight of the decking and concrete layer during curing, the decking panels must be shored (or braced), adding to the cost of the systems. In smaller constructions, such as residential applications, these traditional systems were generally too expensive and logistically challenging to install.
Further, in application, conventional concrete flooring systems are subject to significant horizontal and vertical forces, and in particular, horizontal shear occurring along the longitudinal top of primary and secondary joist members. Indeed, these systems ultimately fail because of loss of interfacial force in the shear span.
Composite concrete floor support systems offer a solution to traditional concrete floor systems. Composite systems utilize steel joists having a top chord or portion that is embedded into the poured concrete deck. The top chord then forms a shear connector to prevent slippage from occurring between the concrete slab and the joist, due to horizontal shear along the joist, which can reduce the amount of reinforcement required over the traditional systems.
Various forms of shear connectors have been developed, including elongated studs welded to the top chord of the joist member. The studs are embedded in the concrete, thereby transferring horizontal shear forces from the slab to the beam. However, these studs are welded to the joist after the joist has been connected to the structure during erection, requiring significant labor and time, and they can be hazardous to crew members after installation, but before the concrete has been poured. Other types of shear connectors include, joists having an irregular or S-shaped tap chord, such as the Hambro™ joist, or alternatively, a shear connector of the type disclosed in U.S. Pat. No. 7,013,613 to Boellner et al., which teaches an extended length shear connector including protrusions and indentations on the surface thereof
Regardless of the shear connector used in the prior art systems described above, these systems still require reinforcement of the concrete layer. In particular, rebar (reinforcing bar), metal mesh, decking or cross braces are placed over or in between the joists to reinforce the concrete layer before the concrete is poured. Accordingly, this type of composite system, while having increased strength over non-composite systems, can be heavy and expensive due to the added cost of reinforcement material. However, rebar and other metal reinforcements are subject to corrosion and deterioration of the floor. Further, in systems where the reinforcement is positioned on top of the top chord or shear connector, these systems are subject to failure due to tearing of the deck near the shear connector.
In addition, many of the prior art systems require removable framing systems to be in place before construction and removed after the concrete has cured, adding to the cost of installation of these types of composite systems.
Accordingly, there is a need for a lighter floor support system for use with concrete floor decking, in particular, for use in above-grade and residential constructions, while also offering decreased costs and ease of installation on-site.

SUMMARY

A composite flooring system and method for supporting a concrete flooring system in accordance with one embodiment of the present invention can be used in situations where conventional wood, masonry, or light gauge steel framing materials are used. The system includes a plurality of joist assemblies having a shear connector secured thereto, the joist assemblies arranged in a spaced apart and substantially parallel configuration, with a panel supported between each pair of adjacent joist assemblies, and a concrete layer provided over the panel and shear connector components.
The joist assembly includes a first frame member having a top flange, a web portion and a bottom flange and a second frame member of mirror image construction. The frame members are arranged in a back-to-back fashion, providing the joist assembly with a two layered and reinforced web portion. The web portions of each of the frame members include a plurality of space-apart clips and tabs which can secure a support angle in place on the web portion of the frame member along the length thereof for supporting sections of polystyrene foam in between the frame members. The web portions of each of the frame members can also include openings to permit plumbing, electrical wiring, ductwork or other building utilities to run through the support system.
A shear connector is secured to the top chord of each joist assembly and extends the entire length thereof The shear connector extends vertically upwards from the top chord of the joist, having an arcuate end or bend. This bend provides additional surface area to which the concrete layer may bond and can be used to stiffen the shear connector. The shear connector also includes a plurality of openings that also provide additional surface area of contact between the shear connector and the concrete layer, further strengthening the resulting steel-concrete composite flooring system. The shear connector can include attachment portions including downwardly extending tabs for engaging slots provided in the top chord of the joist assembly. By providing a shear connector with attachment tabs and a top chord with corresponding attachment slots, the time it takes to assemble the joist and shear connector members is minimized.
The system may also include a method for supporting a concrete floor by providing at least two joist assemblies, as described above, and each having a shear connector secured to the top chord thereof, and permanently securing at least one foam panel between a pair of adjacent joist assemblies. The method can include forming a composite floor of the present invention by additionally pouring a layer of concrete over the foam panel and to a height above the top of the shear connector.
The composite floor system and methods for supporting a concrete floor eliminate the need for reinforcement provided within the concrete layer, such as rebar, metal mesh or cross braces, thus rendering the system lighter, easier to install and less expensive. In addition, without the necessity to reinforce the concrete, the concrete layer is more suitable for installation of radiant heating systems. Furthermore, construction processes are simplified because cross blocking, special tools and skills required for framing the system during the curing period are not require due to the reduced weight of the system, and the drilling and cutting associated with traditional wood products are all unnecessary. Further, the system provides a composite concrete floor that does not require framing material to be removed, significantly shortening set up and construction time.
The composite concrete floor support systems disclosed herein have all the advantages of concrete flooring system, such as strength, rigidity, durability, mold resistance and sound attenuation, with the added benefit of utilizing a foam insulation layer to provide a durable and energy-efficient construction. Because of benefits, such as sound attenuation, impact resistance, and high R-value, the foam layer enhances the advantages of the concrete decking to provide a lighter, more durable composite system over traditional composite concrete flooring systems.
Various other features, objects, and advantages of the invention will be made apparent to those skilled in the art from the accompanying drawings and detailed description thereof

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a composite floor system of the present invention, with a concrete layer shown in shadow;

FIG. 2 is a partial perspective view of a joist assembly for use in the composite floor system illustrated in FIG. 1;

FIG. 3 is a partial side view of a channel member used in constructing the joist assembly illustrated in FIG. 2;

FIG. 4 is a sectional view of the channel member illustrated in FIG. 3, taken along the line 4;

FIG. 5 is a partial side view of a shear connector used in the composite floor system illustrated in FIGS. 1 and 2;

FIG. 6 is a sectional view of the shear connector illustrated in FIG. 5, taken along the line 5;

FIG. 7 is an end view of a support angle used in constructing the joist assembly illustrated in FIG. 2;

FIG. 8 is a partial side view of a forming panel used in the composite floor system illustrated in FIGS. 1 and 2;

FIG. 9 is an exploded side view of the composite floor system illustrated in FIGS. 1 and 2, illustrating construction of the joist assembly and panel components; and

FIG. 10 is a side view of the composite floor system illustrated in FIGS. 1, 2 and 9, illustrating the joist assembly and foam panel components, and including a layer of concrete, completing the composite floor system.

FIG. 11 is a partial perspective view of an alternative embodiment of a joist assembly for use in a composite floor system of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 through 10 illustrate one embodiment of a system 30 for supporting a concrete deck or concrete floor in accordance with the present invention. In its simplest form, the floor support system 30 includes at least one panel 32, supported between at least one pair of joist members or assemblies, indicated generally at 34, and a concrete layer 35. As will be readily apparent from the following description, the floor support system is not limited to any particular construction application and can be utilized in grade level or above-grade projects, and in both small and large flooring and/or roofing projects. In addition, the floor support system 30 is compatible with a number of different shoes, hangers and/or connectors, ensuring the system is properly secured to primary structural members such as walls, primary girders, beams, trusses or foundation members, as will be recognized by those skilled in the art.
Turning first to FIGS. 1-4, each joist assembly 34 comprises first and second C-shaped channel or frame members 36 and 38, respectively, of mirror image construction, arranged in a back-to-back fashion. The channel member 36 includes a top flange 40, a bottom flange 42 and a web portion 44 therebetween. Likewise, the channel member 38 includes a top flange 46, a bottom flange 48 and a web portion 50. The channel members are preferably constructed of steel, but other metals, alloys, composite materials or any material of sufficient strength as determined by required engineering standards may be used to form the channel members 36 and 38.
The web portion 44 of the channel member 36 includes a plurality of clips 52 and corresponding tabs 56. The clips 52 are located near the top of the web portion 44 and are spaced apart along the length 47 of the channel member 36. As best illustrated in FIG. 3, each of the tabs 56 is vertically aligned with one of the clips 52 for retaining a support angle 59 (shown in FIGS. 7, 9 and 10). The clips 52 and tabs 56 can be stamped or punched within the web portion 44, leaving an aperture within the web, or alternatively, the clips and the tabs can be secured to or otherwise provided within the web portion.
The support angle 59 includes a leg 66 that is inserted into the clips 52 and a leg 68 that rests on the tabs 56, securing the support angle 59 along the length of the channel 36. The legs 66 and 68 may further be secured to the channel member 36 by welding or using screws, rivets, pins or another fastener that secures the support angle in place.
Similarly, the web portion 50 of the channel member 38 includes a plurality of clips 54 and corresponding tabs 58. The clips 54 are located near the top of the web portion 50 and are spaced apart along the length 49 of the channel member 38. Each of the tabs 58 is vertically aligned with one of the clips 54 for retaining a support angle 61 (shown in FIGS. 7, 9 and 10). The clips 54 and tabs 58 can be stamped or punched within the web portion 50, leaving an aperture within the web, or alternatively, the clips and the tabs can be secured to or otherwise provided within the web portion.
The support angle 61 includes a leg 70 that is inserted into the clips 54 and a leg 72 that rests on the tabs 58, securing the support angle 61 along the length of the channel 38. The legs 70 and 72 may further be secured to the channel member 38 by welding or using screws, rivets, pins or another fastener that secures the support angle in place.
It will be appreciated by those skilled in the art that the clips and tabs provided within the web portions of each of the channel members may be replaced by another support mechanism that adequately retains the support angles in place. Such a mechanism can include using screws, rivets, pins or alternatively by welding the support angle to the channel members.
The web portions 44 and 50 of each of the channel members 36 and 38 also include a plurality of apertures 60 and 62, respectively, to permit plumbing, electrical wiring, ductwork or other building utilities to run through the support system. As will be recognized by those skilled in the art, the size of the channel members 36 and 38, including but not limited to, the span of their corresponding web portions 44 and 50, the number of clips 52 and tabs 56 provided, and the size and number of apertures 60 and 62 provided within the web portions 44 and 50, will depend on the given construction application, and is determined by, among other factors, the span of the flooring system to be installed, loading considerations of the floor, use and location of the building and applicable ANSI, ASTM, and/or governmental design and safety standards.
As best illustrated in FIGS. 2, 9 and 10, the joist assembly 34 is formed by arranging the channel members in a back-to-back fashion. The top flange 40 of the channel member 36 is horizontally aligned with the top flange 46 of the channel member 38, forming top chord 80 of the joist assembly 34. The bottom flange 42 of the channel member 36 is horizontally aligned with the bottom flange 48 of the channel member 38, forming bottom chord 82 of the joist assembly 34. As illustrated in the Figures, in this arrangement, the web portions 44 and 50 of the channel members are aligned and apertures 60 and 62 along the length of each of the channel members are also aligned.
It will be appreciated from FIG. 10, that the joist assembly 34 includes a two-layered or reinforced web comprising both the web portions 44 and 50. Once positioned in this manner, the channel members 36 and 38 can be secured together, if required, by welding or using bracket, screws, clips, rivets, pins or another fastener.
As best shown in FIGS. 1, 2, 9 and 10, a shear connector 84, is secured to the top chord 80 of each of the joist assemblies 34. The shear connector 84 is preferably constructed of steel or another material capable forming a sufficient bond with the concrete layer 35, resulting in the required composite action/strength. As best illustrated in FIG. 6, the shear connector 84 extends the entire length of each of the joist assemblies, and has a substantially vertical portion, indicated generally at 90, and a plurality of attachment portions, indicated generally at 86 and 88, extending horizontally away from the bottom 92 of the vertical portion 90.
The attachment portions 86 and 88 are short, substantially planar members formed on alternating sides of the vertical portion 90. Each of the attachment portions 84 and 86 includes downwardly extending tabs 94 and 96, respectively, for engaging the top chord 80 of the joist assembly 34. In particular, the top chord 80 is provided with a plurality of spaced apart slots 102 and 104 (shown in FIG. 9) for receiving the tabs 94 and 96, respectively, on each of the alternating attachment portions 84 and 86. Once positioned in this manner, the tabs 94 and 96 may be secured within the slots 102 and 104, if required, by using adhesives or welds, or using fasteners, such as screws, clips, rivets or pins. Although the attachment portions 84 and 86 are illustrated having two tabs on each segment, it will be recognized that more than two tabs may be provided, and a corresponding number of slots will be provided within the top chord 80 of the joist assembly 34.
The vertical portion 90 of the shear connector 84 includes an arcuate end or bend 110 located at the top thereof This bend 110 can be used to stiffen the vertical portion 90 of the shear connector and also provides additional surface area to which the concrete layer 35 may bond. The bend 110 can be formed in either direction, as is not limited to the direction indicated in FIG. 6. Consistent with the broader aspects of the present invention, the bend 110 can be replaced with another extension or protuberance that provides at least the same amount of contact surface area for bonding with the concrete layer 35. In addition, the vertical portion 90 also includes a plurality of openings 100 formed along the length 98 of the shear connector 84. These openings also provide additional surface area of contact between the shear connector 84 and the concrete, further strengthening the resulting steel-concrete composite flooring system.
Turning now to FIG. 8, and with reference to FIGS. 1, 9 and 10, each panel 32 is a substantially planer member, having top and bottom surfaces 112 and 114, respectively, a thickness 115 and opposing ends 116 and 118. The ends of each of the panels 32 are configured to be supported by the support angles 61 and 59 between two adjacent joist assemblies 34, as best illustrated in FIG. 1. Preferably, each end 116 and 118 is provided with a notch or groove 120 and 122, respectively, for receiving at least a portion of each of the adjacent support angles 61 and 59. The panel 32 is preferably constructed of polystyrene or polyisocyanurate insulation foam, however, plywood, oriented strand board or particle board may also be used. The size of the panels 32, including the length, thickness 115 and span 117 is determined by spacing of the joist assemblies 34, the material of panel 32 and applicable design standards, as recited herein.
An alternative embodiment of the present invention is shown in FIG. 11. In this embodiment, stiffeners 130 are incorporated at the ends of a joist 34. The stiffeners 130 extend in a vertical direction between the top 80 and bottom 82 chords of the joists 34, and the legs of the stiffeners 130 may be bolted or otherwise secured to the joists 34. The stiffeners 130 provide increased stiffness an reinforcement at the ends of the joists 34.
As illustrated in FIGS. 8-9, and also in FIGS. 1 and 10, the composite flooring system 30 of the present invention is constructed by providing at least two joist assemblies 34, each having a shear connector 84 secured to the top chord 80 thereof, and securing the panel 32 between the joist assemblies by inserting the leg 68 of the support angle 59 into the groove 122 on the end 118 of the panel 32, and by inserting the leg 72 of the support angle 61 into the groove 120 on the end 116 of an adjacent panel 32. The panels 32 may be additionally secured to each joist member using an adhesive, such as epoxy or a polymeric adhesive, sufficient to securely bond the panel 32 to the joist assembly 34.
The concrete layer 35 is poured on top of the panels 32, to a height above the bend 110 in the shear connector 84. The panels 32 remain in place after the concrete layer cured. The amount of concrete utilized, and therefore the height of the concrete layer is determined, at least in part, by the particular type of concrete utilized, the particular construction application, the ultimate live and dead loads, including the weight of additional flooring, the size of the joist assemblies utilized, and the type of panel selected. It will be appreciated that materials other than concrete, such as concrete-fiberglass composites, or treated concrete materials can be used for the layer 35.
It can be seen that the composite floor system 30 and methods of the present invention provides a lighter and compact composite floor support system compared to conventional composite systems by eliminating the need for concrete reinforcement. By including foam panels 32 that remain in place after construction of the system, in combination with a joist assembly 34 that includes a reinforced web portion (the web portions 44 and 50 of the channel members) and a shear connector 84 provided with a plurality of openings 100 to increase the surface area for contact with the concrete layer, the composite system of the present invention does not require use of rebar or other concrete reinforcements. Without regard to any particular theory or mode of installation, the present invention provides a composite system 30 that utilizes a novel construction, allowing the concrete 35 and foam panels 32 to act as a compression flange, distributing horizontal shear forces from the slab to the primary structural members. As such, by eliminating the need for concrete reinforcement, the present invention can provide a less expensive and easier to assemble system.
While the invention has been described with reference to preferred embodiments, those skilled in the art will appreciate that certain substitutions, alterations and omissions may be made to the embodiments without departing from the spirit of the invention. Accordingly, the foregoing description is meant to be exemplary only, and should not limit the scope of the invention as set forth in the following claims.

Claims

1. An apparatus for supporting a concrete floor comprising:

a plurality of joist assemblies, each joist assembly having a top and a bottom and comprising a first frame member having a first top flange, a first web portion and a first bottom flange, a second frame member having a second top flange, a second web portion and a second bottom flange, the second frame member arranged such that the second web portion contiguously contacts the first web portion;

a plurality of continuous shear connectors, each shear connector having a vertical portion with a bottom secured to the top of one of the plurality of joist assemblies, the vertical portion having a length and a top with an arcuate end; and

a plurality of panels, each panel supported between a pair of adjacent joist assemblies of the plurality of joist assemblies.

2. The apparatus of claim 1, wherein the web portions of each of the first and second frame members of each of the joist assembly include a support mechanism for supporting one of the panels between a pair of adjacent joist assemblies of the plurality of joist assemblies.

3. The apparatus of claim 2, wherein the support mechanism comprises an angle component extending outwardly from the web portions of each of the first and second frame members.

4. The apparatus of claim 3, wherein the support mechanism further comprises a set of clips and tabs formed within the web portions of each of the first and second frame members, each tab vertically aligned with one of the clips for supporting the angle component.

5. The apparatus of claim 1, wherein the first and second web portions of each of the first and second frame members further include a plurality of openings formed for accommodating building utilities.

6. The apparatus of claim 1, wherein the joist assemblies and the shear connectors are constructed of steel.

7. The apparatus of claim 1, wherein the panel is constructed of a foam material.

8. An apparatus for supporting a concrete floor comprising:

a least one pair of joist assemblies, each joist assembly having a top chord, a bottom chord and a web portion therebetween;

a least one pair of continuous shear connectors, each shear connector having a bottom secured to the top chord of the joist assembly, a top having an arcuate shape and a vertical portion extending therebetween, the vertical portion including a plurality of openings formed therein; and

at least one panel supported between adjacent joist assemblies.

9. The apparatus of claim 8, wherein the web portion of each joist assembly comprises a plurality of apertures formed therein.

10. The apparatus of claim 8, wherein the web portion of each joist assembly has first and second surfaces and wherein each of the first and second surfaces includes a support mechanism, wherein the support mechanisms on adjacent joist assemblies are configured to support the at least one panel therebetween.

11. The apparatus of claim 8, wherein each joist assembly comprises a first frame member having a first top flange, a first web portion and a first bottom flange, a second frame member having a second top flange, a second web portion and a second bottom flange, the second frame member arranged such that the second web portion contiguously contacts the first web portion.

12. The apparatus of claim 11, wherein the bottom of each shear connector comprises a plurality of horizontal attachment portions, at least one of the horizontal attachment portions configured to secure to the first top flange of the first frame member and at least one other of the horizontal attachment portions configured to secure to the second top flange of the second frame member.

13. The apparatus of claim 8, wherein the joist assemblies and the shear connectors are constructed of steel and the panel is constructed of at least one layer of foam material.

14. A method of supporting a concrete floor comprising:

providing a pair of adjacent joist assemblies, each joist assembly having a top chord, a bottom chord and a web portion therebetween;

providing each joist assembly with a continuous shear connector having an arcuate top portion adapted to be embedded in the concrete floor, a vertically extending middle portion including a plurality of apertures formed therein and a bottom portion;

securing the bottom portion of the continuous shear connector to the top chord of each joist assembly; and

permanently securing a panel between the adjacent joist assemblies.

15. A composite floor comprising:

two or more joist assemblies;

one or more shear connectors secured to one or more of the joist assemblies, each shear connector having a bottom portion, a vertically extending middle portion including a plurality of apertures formed therein, an a top portion having an arcuate shape;

one or more panels supported between the joist assemblies, wherein the panels are permanently secured between the joist assemblies;

a concrete layer poured over the panels to a height above the shear connector such that middle portion and top portion of shear connector are embedded in the concrete layer when the concrete layer cures.

16. A shear connector adapted for securing to a joist and embedding in a concrete layer poured over panels connected to a plurality of joists to form a composite floor, the shear connector comprising:

a bottom portion secured to the joist;

a top portion having an arcuate shape, the top portion adapted to be embedded in the concrete layer; and

a middle portion extending between the bottom portion and the top portion, the middle portion including a plurality of openings formed therein and adapted to be embedded in the concrete layer.