Composite joist floor system

The composite joist floor system includes joists supporting metal decking and a stand-off fasteners are spaced along the length of the joist Each fastener has an upper portion with a through hardness between HRB 70 and HRC 40 and a lower portion having a threaded portion with a through hardness of between HRB 70 and HRC 40 and a thread-forming portion adjacent the threaded portion with at least a HRC 50 hardness and failure torque to thread-forming torque of at least 3.0 and a drive torque at least 20% less than a thread-forming torque, and a fluted lead portion adjacent the thread-forming portion with a nominal diameter between 70 and 95% of major diameter of the threaded portion adapted to form a fastener opening. These stand-off fasteners extend into and are encapsulated by a cementitious slab supported by the metal decking to form a composite floor system.

BACKGROUND AND SUMMARY OF THE INVENTION

Large scale, multi-story buildings are typically constructed of steel and concrete. Floors in such buildings may be composite floor systems assembled by spanning wide flange beams with spaced-apart steel joists and installing typically corrugated metal decking over the joists. The decking forms a lateral surface onto which a cementitious slab can be placed and cured. Generally, the underside of the beams or lower chords of the joists form the framework from which ceilings may be supported. The composite floor construction is typically achieved by using welded shear studs, or partial extension of the joist upper chord, extending above the form or metal deck into the cementitious slab. Flooring system designs must also be mindful of fire safety, acoustics, and vibration considerations.

Such composite floor systems have been designed in the past to address one or more of these issues individually. These prior designs have included some systems that integrated the joist and deck assembly with the cementitious slab to provide a composite floor system. This integral structure was assembled by providing self-drilling studs with a threaded portion to be in threaded engagement with the deck and underlying joists. A length of each stud extended above the metal decking and was encased in the cementitious slab, and resisted and transmitted horizontal shear forces which develop between the cementitious slab and the supporting joist structure. See U.S. Pat. No. 5,605,423. These composite floor systems were an improvement, but still had drawbacks in that the floor systems were time consuming and difficult to install. There was still a need for a composite floor system that was rapidly and safely installed with fewer building errors to provide a floor system with improved erectability and economy for the same or greater load bearing capacity.

Disclosed is an improved composite joist floor system comprising a first support structure, a second support structure, a plurality of joists spaced apart and extending from the first support structure to the second support structure, decking supported by the plurality of joists, and a plurality of stand-off fasteners adapted to be fastened through the decking to the plurality of joists, each stand-off fastener of carbon steel comprising a lower portion and an upper portion where the lower portion has a clamping part capable of clamping the decking to the joist, the lower portion having a threaded portion adjacent the clamping part with a through hardness of between HRB 70 and HRC 40 and having the lower portion of the fastener with a failure torque to thread-forming torque of at least 3.0 and a drive torque at least 20% less than a thread-forming torque, a thread-forming portion adjacent the threaded portion of at least HRC 50 hardness adapted to enable the fastener to form threads in an upper chord of a joist, and a fluted lead portion adjacent the thread-forming portion of at least HRC 50 hardness with a nominal diameter between 80 and 95% of major diameter of the threaded portion adapted to form a fastener opening in an upper chord of a joist, and the upper portion of the stand-off fasteners have a through hardness of between HRB 70 and HRC 40 and when installed, at least a portion of the upper portion of each stand-off fastener extends significantly above the decking. The composite floor system is completed by providing a cementitious slab supported by the decking and encapsulating the upper portion of each stand-off fastener extending above the decking. The threaded portion of the fastener may extend to within 1.5 of a thread pitch of the clamping part of the fastener.

The threaded portion of each stand-off fastener may meet a specification selected from the group consisting of ASTM A307, ASTM A325, ASTM A354, and ASTM A490 specification or a specification selected from the group consisting of SAE J429 Grade 2, SAE J429 Grade 5, and SAE J429 Grade 8.

The stand-off fasteners of the composite joist floor system may have a drive torque no more than 50% of a thread-forming torque. In any case, the lower drive torque enables the fasteners to be rapidly installed through the deck and into a joist upper chord with low consumption by battery powered tools with a worker in a short time, with the thread forming torque in forming the threads in the deck and joist following drilling of the fastener opening and the seating torque desired for the fastener being the controlling torques in positioning the fastener. This low power consumption and labor saving installation is enabled by the nominal diameter fluted lead portion of the fastener adapted to form a fastener opening in an upper chord of a joist between 80 and 95% of major diameter of the threaded portion or between 80 and 98% of major diameter of the threaded portion. Additionally, the failure torque of the fastener is more than three (3) times the thread-forming torque and may be more than four (4) times the thread-forming torque so that the prospect of the fastener failing and lessening the load capability of the composite floor system is avoided. The thread-forming torque of each stand-off fastener may be no more than 100 inch-pounds.

The failure torque is substantially more than the seating torque of the fastener. The threaded portion of each stand-off fastener may have a seating torque of at least 80 inch-pounds, or between 80 and 450 inch-pounds to provide the proper seating torque, depending on the size of the stand-off fastener and type and properties of the decking, joist and other support material into which the stand-off fasteners are threaded. The threaded portion of each stand-off fastener may also have a thread angle of less than 50°, or may have a thread angle between 45 and 60° Alternately or in addition, the threaded portion may include back-tapered threads for ease of installation. The back-taper of the threaded portion may be between 0.0005 and 0.0025 inch per inch of length or between 0.001 and 0.003 inch per inch of length.

The thread-forming portion of each stand-off fastener may be between 3 and 7 thread pitches in length to provide desired thread-forming torque. To further improve the speed of assembly and improve the load carrying capacity of the composite floor the shape of the thread-forming portion of the stand-off fastener may be selected from the group consisting of bilobular, trilobular, quadlobular and pentalobular. Of these the quadlobular shape has been found to date to give the best performance in thread forming. In any event, these lobar shapes of the thread-forming portion of the fastener control the thread-forming torque and drive torque to facilitate assembly of the composite floor system and reduce failures in installation of the stand-off fasteners and improve the load carrying capacity of the assembled composite floor system.

In addition, the fluted lead portion of the stand-off fastener may have a milled point to reduce the failure rate of the stand-off fastener. Pinch point may be provided on the fluted lead portion of the stand-off fastener, but we have found the fasteners made with a milled point are more reliable and result in less failures of the stand-off fastener, reducing assembly time and cost and producing an assembled composite floor assembly with greater load capacity.

Another aspect of the present composite floor system is the threaded portion of the fastener has a through hardness of between HRB 70 and HRC 40, while the fluted lead portion and most if not all of the thread-forming portion has a hardness of at least HRC 50. Such through hardness on the threaded portion of the fastener enables the composite floor system to support higher loads as the fastener interacts with the cementitious slab and avoids cracking and fracturing of the fastener. The threaded portion of each stand-off fastener may be of at least HRC 33 through hardness and up to five threads adjacent the thread-forming portion may be hardened to at least HRC 50 hardness. To further facilitate assembly of the composite floor system, the fluted lead portion may be of at least HRC 54 hardness or of at least HRC 50 induction hardness. The upper portion of the stand-off fasteners have a through hardness of between HRB 70 and HRC 40 to provide ductility in the upper portion of the fastener to reduce cracking in the fasteners in operation in a cementitious slab of the composite joist floor system.

In addition, the clamping portion of the lower portion of each stand-off fastener of composite joist floor system may comprise a fastener drive head positioned to be used in installing the stand-off fastener and the upper portion of the stand-off fastener is sized to permit the stand-off fastener to be installed into the decking. A SEMS anchor or stake anchor may be positioned on the upper portion of the stand-off fastener sized to permit the stand-off fastener to be installed into the decking and a joist upper chord and the SEMS anchor or stake anchor engage in the cementitious slab on installing of the fastener and placement of the cementitious slab. Optionally, the stand-off fastener may include threads adjacent the end of upper portion of the fastener configured to couple to a reinforcing member such as rebar or some other member that will effectively extend the length of the stand-off fastener. These embodiments further improve the composite floor system by further reducing failures in positioning the fasteners, and at the same time reducing the time to assemble the floor system. Stand-off fasteners utilizing the SEMS anchor or stake anchor also are easy to produce and improve the load carrying capacity of the composite floor system at the same time.

The decking may comprise corrugated steel decking defining altering peaks and valleys, where the stand-off fasteners are installed in the valleys of the corrugated steel decking, and where adjacent stand-off fasteners along a joist are separated by at least one valley of the corrugated steel decking. Alternatively or in addition, the decking may comprise corrugated steel decking defining altering peaks and valleys, and at least two adjacent stand-off fasteners are located in the same valley of the corrugated steel decking.

Also disclosed is a wall panel system comprising a metal base adapted to support placement of a cementitious material, a plurality of stand-off fasteners for fastening at spaced locations along the base, each stand-off fastener of carbon steel comprising a lower portion and an upper portion where the lower portion has a threaded portion, a thread-forming portion adjacent the threaded portion adapted to enable the fastener to form threads in the base, and a fluted lead portion adjacent the thread-forming portion with a nominal diameter between 70 and 95% of major diameter of the threaded portion adapted to form a fastener opening in the base, and where, when installed, at least a portion of the upper portion of each stand-off fastener extends significantly above the base; and a cementitious slab formed on the base and encapsulating the upper portion of each stand-off fastener extending above the base to form a desired wall surface of the panel system.

The lower portion of the fasteners of wall panel system may have a threaded portion with a through hardness of between HRB 70 and HRC 40 and the lower portion of the fastener has failure torque to thread-forming torque of at least 3.0 and a drive torque at least 20% less than a thread-forming torque. The stand-off fastener may have a drive torque no more than 50% of a thread-forming torque. In addition, the thread-forming portion adjacent the threaded portion of a wall panel system has at least HRC 50 hardness adapted to enable the fastener to form threads in the base, and a fluted lead portion adjacent the thread-forming portion of at least HRC 50 hardness. The threaded portion of each stand-off fastener may be of at least HRC 33 through hardness and up to five threads adjacent the thread-forming portion may be hardened to at least HRC 50 hardness. The fluted lead portion may have at least HRC 54 hardness. The upper portion of the stand-off fasteners have a through hardness of between HRB 70 and HRC 40 to provide ductility in the upper portion of the fastener to reduce cracking in the fasteners in operation in a cementitious slab of the wall panel system.

These wall panel systems are typically assembled with the lower portion of the stand-off fasteners drilled and threaded into the metal base. The base may comprise corrugated metal decking assembled and fastened to wall studs. In any case, temporary or permanent side walls may surround the metal base and support the concrete during placing and curing of the cementitious slab. The wall may extend above the upper portion of the stand-off fasteners so the surface of the cementitious slab provides a desired wall surface for the panel system without upper portions of the fasteners showing through. In this way a composite wall panel can be assembled that can be lifted into place. The wall panel system has the metal base, cementitious slab and stand-off fasteners as an integral wall system that can provide a desired wall surface where cracking of the cementitious slab is inhibited if not eliminated. The wall panel system may be used either as an inside wall system or an outside wall system as explained in more detail below with reference to the drawings.

To facilitate assembly and avoid assembly defects, the clamping portion of the lower portion of each stand-off fastener may comprise a fastener drive head positioned to be used in installing the stand-off fastener, with the upper portion of the stand-off fastener sized to permit the stand-off fastener to be installed into the base. An SEMS anchor or stake anchor may be positioned on the upper portion of the stand-off fastener sized to permit the stand-off fastener to be fastened into the base, with the SEMS anchor or stake anchor (threaded or unthreaded) engaging in the cementitious slab on installing of the fastener and placement of the cementitious slab. These embodiments provide for easier installation, while improving the quality and integrity of composite wall panel system assembled.

Alternatively, a fastener drive head may be positioned on the upper portion of each stand-off fastener adapted to be used in fastening the stand-off fastener to the base and to engage in the cementitious slab on installing of the fastener and placement of the cementitious slab. In this embodiment, SEMS anchor is part of the lower portion of each stand-off fastener and adapted to engage the base and the cementitious slab on placement of the cementitious slab.

To facilitate assembly of the wall panels, the thread-forming portion of each stand-off fastener has a shape selected from the group consisting of bilobular, trilobular, quadlobular and pentalobular.

For the wall panel systems, the threaded portion of each stand-off fastener may meet a specification selected from the group consisting of ASTM A307, ASTM A325, ASTM A354, and ASTM A490 specification or a specification selected from the group consisting of SAE J429 Grade 2, SAE J429 Grade 5, and SAE J429 Grade 8.

As with the composite floor systems, the fluted lead portion of the stand-off fastener may have a milled point to reduce the failure rate of the stand-off fastener. Pinch point may be provided on the fluted lead portion of the stand-off fastener, but as previously observed, we have found the fasteners made with a milled point are more reliable and result in less failures of the stand-off fastener, reducing assembly time and cost and producing an assembled composite floor assembly with greater load capacity

DETAILED DESCRIPTION OF THE DRAWINGS

Composite Joist Floor Systems

The composite joist floor systems described herein are generally assembled at the building site and provide structural support for floors and/or ceilings of the building. In general, pluralities of steel joists are positioned laterally spaced apart supported at either end by the building's primary support structures. Such building support structures may include but are not limited to: I-beams and H-beams, joist girders, masonry walls, concrete walls, cold-formed wall studs, and/or wood load bearing wall studs. In any case, the steel joists span the open areas within the building's main structure to provide support for the floors or ceilings, or both. Importantly, the present invention provides a plurality of varying component floor system designs and design approaches. These various designs may use a combination of joist depth, chord size, joist spacing, flexible stand-off fastener size and spacing, and various corrugated steel deck profiles to create flooring systems that are light in weight, have generally decreased material costs, labor costs, and construction costs, assembled largely without construction errors, and offer improved strength and load bearing capacity.

Typical steel joists of the composite joist floor systems described herein have spans ranging from eight (8) to fifty (50) feet and depths ranging from eight (8) to fifty (50) inches. In addition to variations in the size and spacing of the joist, the number and pattern of the stand-off fasteners, the configuration of the corrugated steel decking, the connections between the flooring system and the support beam, as well as other design elements contribute to lighter weight, materially reduced construction errors, and added strength and load bearing capacity for the composite floor system.

Referring to the drawings,FIGS. 1 and 2illustrate a partial perspective view, with portions broken-away, and a partial cross-sectional side view, respectively, of a composite joist floor system100in accordance with an embodiment of the present invention. As illustrated inFIGS. 1 and 2, and as described above, the composite joist floor system100generally includes a plurality of laterally, spaced apart joists110supported on their ends by a supporting wall or beam, such as a wall structure101comprising steel wall studs as shown inFIGS. 1 and 2. The joist110, in combination with other joists, walls, or beams (not shown); supports a cementitious slab120on corrugated steel decking180. The corrugated steel decking180is typically, but not necessarily positioned such that the corrugations run substantially perpendicular to the joist110. Importantly, a plurality of stand-off fasteners130are drilled through the corrugated steel decking180into the upper chord of joist110. The lower portion of each stand-off fastener130connects the corrugated decking180to the joist110, and the upper portion of each stand-off fastener130extends some distance above the corrugated decking180. In this way, when cementitious material is placed over the corrugated steel decking180, the stand-off fasteners130are encapsulated within the cementitious slab to form a composite joist floor system, once the concrete is cured. As will be described in greater detail below, this composite joist floor system allows for structures that can be assembled substantially error-free at much lower cost and to be stronger, lighter, and/or safer composite floor system. The term “concrete” here can be any of a number of cementitious materials or materials with properties similar to cementitious materials as may be accepted by governing building codes and/or desired in the particular embodiment.

As illustrated inFIGS. 1 and 2, in an exemplary embodiment, each joist110comprises an upper chord112and a lower chord111. The upper chord112and the lower chord111are joined together by a web118extending there between. In the illustrated embodiment, the web118has an open web configuration comprising one or more of rod, angle, or cold-formed “C” shaped members119that extend between and are coupled to the upper chord112and the lower chord111. In the illustrated embodiment of the invention, the web118is made primarily from a single round solid rod119bent into a zigzag or sinusoidal-like pattern having one or more peaks alternating with valleys. In such an embodiment, the upper chord112is welded (or otherwise coupled) to the peaks in the bent rod119and the lower chord111is welded (or otherwise coupled) to the valleys in the bent rod119. These rods119may be of a low carbon steel composition which is generally used for rebar in reinforcing concrete.

In the illustrated embodiment, the upper chords112and lower chords111may be each formed from two L-shaped metal members positioned back-to-back (also sometimes referred to as “angle irons,” although the angle members described generally are steel and not iron).FIG. 1illustrates an embodiment where two angles113and114are placed on either side of the bent rod119forming the open web, and joined to the valleys in the bent rod119to form the lower chord111. Similarly, two angles115and116are placed on either side of the bent rod119and joined to the peaks in the bent rod119to form the upper chord112. The webs118are shown herein as bent rod119, but can be almost any cross-sectional shape. So that the composite joist floor system100is relatively light in weight, the L-shaped members forming the upper chord112and the lower chord111typically have relatively thin cross sections.

As further illustrated inFIGS. 1 and 2, the joist110includes a rod-shaped “end diagonal”117at each end of the joist for transferring forces between the joist110and the supporting wall structure101. The “end diagonal”117may be L-shaped angles or cold-formed “C”-shaped sections suitable for heavier floor loadings. One end of the end diagonal117is joined to the lower chord111at or near a nearest joint of the web and the other end of diagonal117joined to the upper chord112at or near to the seat or joist shoe170. In some embodiments, the lower chord111of the joist110may include a ceiling extension190that extends the lower chord111such that the lower chord111ends proximate the wall structure101or beam if desired. Such an extension190may be provided as support for a ceiling195hung from the lower chord111.

As described above, corrugated steel decking180is positioned over the joist110and with each decking section generally spanning two or more adjacent joists. The corrugated steel decking180may be painted, galvanized or otherwise coated as desired. Standard corrugated steel decking generally comes in the form of sheet sections in widths of 32, 33, or 36 inches. Besides coming in a variety of widths, standardized corrugated steel decking sections also comes in a number of different profiles and thicknesses, depending on the application. The type of corrugated steel decking primarily illustrated herein is 1.0 inch deep steel decking, although other types of decking may be used depending upon the application. The steel used in the steel decking and joist may be made by electric arc furnace from generally 70% recycled materials.

As illustrated inFIGS. 1 and 2, the corrugated steel decking180is generally positioned such that the corrugations run laterally to the joist110span. As described in detail below with reference toFIGS. 4A,4B and4C, stand-off fasteners130are such to provide rapid and safe assembly of the composite joist floor system that is more potentially error-free and can support large loads. Stand-off fasteners130are drilled through the corrugated decking180and the flanges of the upper chord112, with the upper portion of the stand-off fasteners encapsulated in the concrete. The stand-off fasteners130transfer horizontal shear forces between the cementitious slab120and the joist upper chord of the joist110allowing the two structures to act more like a single unit. The composite structure may be significantly stronger and/or material and labor may be reduced in the floor system over non-composite systems. The cementitious floor slab120is designed with sufficient cementitious materials to provide the load bearing capacity of the composite floor system.

In some embodiments, the cementitious slab120is strengthened by placing reinforcing such as welded wire fabric125or other types of reinforcing over the corrugated steel decking180. When the cementitious slab120is placed over the corrugated steel decking180, the welded wire fabric125and the upper portion of the stand-off fasteners130are encapsulated within the cementitious slab120. The concrete is then smoothed so as to form a floor of the building. In some embodiments, ties or lifts are used to hold the welded wire fabric125in desired location above the corrugated steel decking180as the cementitious slab120is placed.

The composite joist floor system100described above provides many advantages over the traditional non-composite and composite floor systems. In non-composite floor systems, the joist and the cementitious slab share load based on the relative stiffness of each component and act substantially independently to support the bearing loads on the composite joist floor system. In previous composite joist floor systems, the steel joist, metal decking, and cementitious slab act as a composite and the system is relatively thin compared to its span (i.e., the length of the joist) where ease of installation and potential errors in the installation are a focus. Such composite joist floor system required additional large labor costs and requires anticipating potential broken and defectively installed stand-off fasteners. As such, prior composite joist floor systems were designed with more or heavier components to provide the same safety factors as needed for error-free assembly and installation of the composite floor systems. In contrast, the composite joist floor system described herein can be assembled and installed with low labor costs while reducing potential errors in installation. These factors, and because the stand-off fastener can be more effective to produce a composite floor system with high load bearing capacity, the overall cost of the composite joist floor system can be reduced and at the same time safer composite joist floor systems capable of higher load bearing capacity can be produced.

To explain, the cementitious slab120carries compression and the lower chord111of the joist110carries tension. As such, the design moment is based on the concrete strength, the steel strength, and the shear transfer between them. The stand-off fasteners130function as a shear transfer mechanism in the composite joist floor system and are the focus in the operation of the overall composite floor system. In this way, the material used in the structure can be reduced to reduce weight and costs depending on the effectiveness of the stand-off fasteners. Alternatively, the size and strength of the upper chord112can be reduced and transitioned to increase the size and strength of the lower chord111to achieve significant increases in load capacity without an increase in the amount of material in the joist. Therefore, in some embodiments of the present invention, the upper chord112of the joist110is smaller than the lower chord111or is formed from lower strength material compared to the material used to form the lower chord111.

Returning toFIGS. 1 and 2, as described above the end of the joist110is supported by a beam, a wall, or other structural support member. In the illustrated example, the end of the joist110is supported by the wall structure101comprising cold formed steel wall studs. The end of the upper chord112has a shoe170for transferring forces from the joist110to the wall101. In the illustrated embodiment, the shoe170is made up of a pair of metal L-shaped angles positioned back-to-back and welded beneath the upper chord angles115and116. Configured as such, the angles115and116that make up the upper chord112and the angles115and116that make up the joist shoe170combine to form an I-beam like bearing connection. The end of the end diagonal117is positioned between the shoe angles171and172and serves as a spacer between the shoe angles. In this regard, the shoe angles171and172are welded to the end diagonal117in addition to being welded to the upper chord angles115and116.

The lower surface of the joist shoe170rests upon and is supported by the wall structure101. As illustrated inFIG. 2A, a load distribution member168or header and/or a wall track167or plate may be positioned between the wall studs and the joist shoe170to distribute force along the length of the wall101. In other embodiments, as illustrated inFIGS. 1 and 2B, a distribution member168may not be used.

As further illustrated inFIGS. 1 and 2, in some embodiments of the composite joist floor system100, the corrugated steel decking180does not extend significantly over the wall structure101or other supporting member. In this way, when the cementitious slab120is placed over the steel decking180, the concrete may flow into the region above the supporting wall101and forms cementitious composite beam121with encapsulated stand-off fastener131in the wall structure that is integral with the cementitious slab120. The concrete in the region121also encapsulates the ends of the upper chords112of each joist110and the ends of each joist shoe170, and functions to assist the load transfer of the joist shoes170to the upper portion of the wall structure101. The concrete in the region forms a cementitious beam121extending over the wall structure101lateral to the joists110. This cementitious beam helps to collect and distribute forces being transferred between the walls and the floor so there is no need for an additional load distribution element such as load distribution member168. As illustrated inFIGS. 1 and 2, a z-shaped closure150and a pour stop160are used to contain the concrete within the region121over the upper portion of the wall structure101. The composite joist floor system100with the integral cementitious beam121in the upper portion of the wall structure101as illustrated inFIGS. 1 and 2may lead to improved fire-safety ratings, improved acoustic attenuation, and most importantly, a stronger and more economical overall building structure.

In the embodiment illustrated inFIG. 2A, a pour stop160is used to prevent the cementitious slab120from flowing beyond the plane of the supporting wall101as the cementitious slab120is being placed and cured. The pour stop160has a lower lateral flange161and an upwardly extending face162. The lateral flange161rests on a tubular distribution member168and optionally may be coupled to the distribution member168by, for example, a stand-off fastener131. The pour stop160is positioned such that the upwardly extending face162is substantially within the same plane of the backside of the wall structure101so that the upwardly extending face162of the pour stop160prevents the concrete from flowing beyond this plane into the building exterior. The pour stop160may have an upper lip163in the upwardly extending face162that curves or is otherwise bent inward and downward toward the joist110. The lip163prevents the upwardly extending face162of the pour stop160from becoming separated from the cementitious slab120and, therefore, prevents moisture from entering between the pour stop upwardly extending face162and the cementitious slab120. Alternatively in some embodiments, the pour stop160may not include the lip163. In one exemplary embodiment, the height of the pour stop160is sized such that a 2.5 to 3-inch deep 3000 pounds per square inch minimum compressive strength cast-in place cementitious slab120is created over the corrugated steel decking180.

Opposite the pour stop160, a z-shaped closure150is provided. In combination with the joist110and the corrugated steel decking180, the z-shaped closure150functions to contain the concrete within the region121above the wall structure101.FIGS. 3A,3B,3C and3D illustrate a portion of a z-shaped closure150in accordance with an embodiment of the present invention. As illustrated inFIG. 3, the z-shaped closure150has a generally upwardly extending face152, with upper flange153extending away from the wall structure101, and a generally lateral lower flange151extending in a direction opposite from the upper flange153. In the illustrated embodiment, the upwardly extending face152has a cutout154at one end. The cutout154has the shape of approximately one-half of an I-beam. This cutout154is configured to fit around at least one side of the I-beam formed by the combination of the upper chord112and the joist shoe170, as illustrated inFIGS. 1 and 2. As also illustrated inFIGS. 1 and 2, the upwardly extending face152of the z-shaped closure extends upwards above the upper chord112so that the upper flange153extends above a peak or peaks in the corrugated steel decking180. Stand-off fasteners131, welds, pneumatic pins, or a variety of other fasteners may be used to couple the lower flange151to the supporting wall. Fasteners133, welds, pneumatic pins, or a variety of other fasteners may be used to couple and the upper flange153to a peak or peaks in the corrugated steel decking180.

As illustrated inFIG. 3C, in some embodiments of the invention, the lower flange151is configured such that, before the z-shaped closure150is installed in the composite floor system100, the lower flange151may have an angle with the upwardly extending face152that is greater or lesser than 90 degrees with a tapered or forward angle to provide a desired set for the z-shaped member when installed. For example, the z-shaped closure illustrated inFIG. 3Cforms a 100-degree angle between the upwardly extending face152and the lower flange151. When such a z-shaped closure150is installed in the floor system100, the z-shaped closure150may be pressed into position such that the angle between the upwardly extending face152and the lower flange151is reduced to an angle closer to 90 degrees. When the z-shaped closure150is installed in this manner, the resilient bias of the z-shaped closure150will press the lower flange151against the upper portion of the wall structure101and, thereby, create a better seal between the wall structure101and the z-shaped closure150than would have otherwise been formed using a z-shaped closure manufactured to have a 90-degree angle or other desired angle between the upwardly extending face152and the lower flange151. Alternatively, where space on the upper portion of the supporting wall is limited, the lower flange151may be shortened as desired for the application and fasteners used to attach the z-shaped closure to the supporting wall.

The stand-off fasteners130of carbon steel as shown inFIGS. 4A through 4Ehave the upper portion140having a desired length and the lower portion141, where the lower portion has a clamping part146capable of clamping the decking180to the joists110. As shown inFIG. 4A, a fastener head147may be part of the clamping part146, or be a separate head147that is part of upper portion140as shown inFIGS. 4B and 4C. In any case, the fastener head of each stand-off fastener is adapted to be used in installing the stand-off fastener130and to engage in the cementitious slab120on installing of the fastener and placing the cementitious slab.

The lower portion141of the fastener130includes a threaded portion142adjacent the clamping part146having a hardness between about Rockwell B-Scale hardness (HRB) 70 and Rockwell C-Scale hardness (HRC) 40 through hardness, and includes a thread-forming portion143adjacent the threaded portion142of at least HRC 50 hardness adapted to enable the fastener to engage with formed threads in decking180and joist upper chords112. The lower portion141of the stand-off fasteners130may include a self-drilling end portion comprising the fluted lead portion144adjacent the thread-forming portion143of at least HRC 50 hardness with a nominal diameter between about 80 and 98% of the major diameter of the threaded portion142adapted to form a fastener opening. The fluted lead portion144drills through the decking180and flange of the upper chord of joists110during installation, and the thread-forming portion143forms threads in the bore of the drilled fastener opening for the threaded portion142to engage the decking180and the upper chord of joists110. The stand-off fastener130is seated by clamping part146to clamp with the threads engaging the corrugated steel decking180to joists110. Alternatively, the fluted lead portion144may have a nominal diameter between about 80% and 95% of the major diameter of the threaded portion142.

The threaded portion142has a major diameter, the diameter of the fastener at the tip of the thread, and a minor diameter, the diameter of the fastener at the root of the thread. The threaded portion142has a desired thread pitch, the distance from one thread tip to the adjacent thread tip along the length of the threads. The stand-off fastener130typically has a major diameter between ⅜ and ¼ inch.

The upper portion140may have a through hardness between about HRB 70 and HRC 40. In one alternative, the upper portion140may have a through hardness between about HRC 25 and HRC 34. Alternatively, at least a portion of the upper portion140has a through hardness between about HRB 70 and HRB 100. In one alternative, at least a portion of the upper portion140has a through hardness between about HRC 19 and HRC 30. In one alternative, at least a portion of the upper portion140has a through hardness between about HRC 26 and HRC 36. In yet another alternative, at least a portion of the upper portion140has a through hardness between about HRC 33 and HRC 39.

In one alternative, at least a portion of the threaded portion142has a through hardness between about HRC 25 and HRC 34. In one alternative, at least a portion of the threaded portion142has a through hardness between about HRB 70 and HRB 100. In one alternative, at least a portion of the threaded portion142has a through hardness between about HRC 19 and HRC 30. In one alternative, at least a portion of the threaded portion142has a through hardness between about HRC 26 and HRC 36. In yet another alternative, at least a portion of the threaded portion142has a through hardness between about HRC 33 and HRC 39. Adjacent the threaded portion142, thread-forming portion143has a hardness greater than about HRC 50, and may be greater than about HRC 54. Up to five threads of the threaded portion142adjacent thread-forming portion143may be hardened to at least HRC 50 or at least HRC 54.

To further improve the speed of assembly and improve the load carrying capacity of the composite floor the shape of the thread-forming portion143of the stand-off fastener130may be selected from the group consisting of bilobular, trilobular, quadlobular and pentalobular. Of these the quadlobular shape has been found to date to give the best performance in thread forming. In any event, these lobar shapes of the thread-forming portion143of the fastener130control the thread-forming torque to facilitate assembly of the composite floor system100and reduce failures in installation of the stand-off fasteners130and improve the load carrying capacity of the assembled composite floor system100.

In further explanation, the thread-forming portion143includes a plurality of relief recesses145spaced around the thread-forming portion143to segment the thread-forming portion into a desired number of lobes139forming the bilobular, trilobular, quadlobular, pentalobular, or other cross-sectional shape. For example, five relief recesses145may be spaced as desired around the thread-forming portion143to segment the thread-forming portion143into five lobes139forming the pentalobular cross-section shown inFIG. 4E, and four relief recesses145may be spaced as desired around the thread-forming portion143to segment the thread-forming portion143into four lobes139forming the quadlobular cross-section also shown inFIG. 4E. The relief recesses145may be longitudinal recesses provided along the axial direction of the fastener. In one alternative, the width of the relief recesses145may be wider toward the fluted lead portion forming the triangular shape as shown inFIG. 4D. The relief recesses145may extend into the threads of the fastener130to about the minor diameter. Alternatively, the relief recesses145may extend into the fastener130deeper than the minor diameter, such as to a depth between about 80% and 99% of the minor diameter. In yet another alternative, the relief recesses145may extend into the threads of the fastener130to a depth between the major diameter and the minor diameter, such as to a depth between about 101% and 120% of the minor diameter. Each relief recess145may be about one thread pitch in width. Alternatively, the relief recesses145may be between about 0.8 and 4 thread pitches wide. In one alternative, the width of the relief recesses145may be between about 30% and 70% of the formula (π×major diameter/number of lobes) as desired to provide desired separation between the lobes139. In yet another alternative, the width of the relief recesses145may be between about 40% and 65% of the formula (π×major diameter/number of lobes). For example, in one application having 4 lobes (quadralobular), the width of the relief recesses may be approximately 60% of the formula (π×major diameter/number of lobes). In another example, in one application having 2 lobes (bilobular), the width of the relief recesses may be approximately 50% of the formula (π×major diameter/number of lobes). The relief recesses145of the thread-forming portion143may be between about 3 to 7 thread pitches in axial length. Alternatively, the relief recesses145of the thread-forming portion143may be between 2 and 5 thread pitches in axial length. Depending upon the size of the fastener, the thread-forming portion143may be between about 0.06 and 0.5 inches in length, and has failure torque to thread-forming torque of at least 3.0 and may be at least 4.0.

The fluted lead portion144may have a swaged or pinched point, a milled point, or a combination of both. The milled point alone, or in combination with preformed swaged or pinched point, is generally desired to ensure effectiveness of the fluted lead portion144in drilling through the decking and upper chord of the joist. The length of the fluted lead portion144may be longer than the thickness of the metal decking and the flange of the upper chord of the joist. It may be useful to provide the fluted lead portion144having an axial length between about 1.1 and 2.0 times the thickness of the metal decking and the flange of the upper chord of the joist. The fluted lead portion144may be a Type1, Type2, Type3, Type4, Type5, or a variation thereof.

The stand-off fastener130has a drilling torque to rotate the fluted lead portion144into and forming the fastener opening. Additionally, the drive torque of the threaded portion142is at least 20% and may at be at least 50% less than the thread-forming torque. In one alternative, the drive torque is less than 30% of the thread-forming torque. The thread-forming torque of each stand-off fastener may be no more than 100 inch-pounds. Alternatively, the drive torque is between about 5% and 50% of the thread-forming torque. To reduce driving torque, the threaded portion142may include back-tapered threads, and may have a thread angle less than 60°. Alternatively, the thread angle may be less than 50°. In yet another alternative, such thread angle may be between 45 and 50°. Reducing the thread angle also reduces the thread pitch and reduces the minor diameter. Back-tapered threads as used herein means that the major diameter of the threaded portion142adjacent the thread-forming portion143has a back-taper such that the major diameter is larger than the major diameter adjacent the clamping part146. In certain embodiments, the back-taper of the major diameter may be between about 0.0005 and 0.0025 inch per inch of axial length. Alternatively, the back-taper may be between about 0.001 and 0.003 inch per inch of length.

The failure torque is substantially more than the seating torque of the fastener130, which is more than the thread-forming torque. The threaded portion142of stand-off fastener130may have a seating torque of at least 80 inch-pounds, or between 80 and 450 inch-pounds, or greater, to provide the proper seating torque, depending on the size of the stand-off fastener130and type and properties of the decking, joist and other support material into which the stand-off fasteners130are threaded.

The threaded portion142of the fastener130may extend to within 1.5 of a thread pitch of the clamping part146of the fastener. The threaded portion142of the stand-off fastener130may provide a strip torque of at least 80 inch-pounds measured using a fastener having a major diameter of about ¼ inch with the fluted lead portion144having at least one diameter within nominal diameter between about 80% and 95% of the major diameter and installed in decking180and the upper chord of the joist110having a combined material thickness about 0.125 inch (about 3.2 millimeter). The threaded portion may have a failure torque between about 80 and 450 inch-pounds. Alternatively, the threaded portion has strip torque of between 80 and 350 inch-pounds measured using a ¼ inch diameter fastener130with the fluted lead portion144having at least one diameter within nominal diameter between about 80% and 95% of the major diameter and installed in a first and second building member having a combined material thickness of about 0.125 inch (about 3.2 millimeter). Alternatively, the threaded portion has a failure torque between 350 and 900 inch-pounds measured using a ⅜ inch fastener with the fluted lead portion192having at least one diameter within nominal diameter between about 80% and 98% of the major diameter and installed in a building member having a material thickness of about 0.25 inch (about 6.4 mm).

The threaded portion142may comply with fastener standards such as ASTM A307, ASTM A325, ASTM A354, ASTM A490, SAE J429 Grade 2, SAE J429 Grade 5, SAE J429 Grade 8, or other fastener standards. Portions of the lower portion141of the stand-off fastener130may be selectively hardened, such as the fluted lead portion144, and the thread-forming portion143to a hardness of at least HRC 50. Additionally, between about 1 and 5 threads of the threaded portion142adjacent the thread-forming portion143may be hardened to at least HRC 50. By hardening only a portion of the lower portion141to at least HRC 50, the threaded portion142making the bolted connection retains physical properties as desired in compliance with ASTM A307, ASTM A325, ASTM A354, ASTM A490, SAE J429 Grade 2, SAE J429 Grade 5, SAE J429 Grade 8 or other selected fastener standards. Typically, the stand-off fasteners130are made with a medium carbon steel, medium carbon alloy steel, or a weathering steel in conformance with the desired fastener standard.

As shown inFIG. 4A, the clamping part146of the lower portion141of each stand-off fastener130may include the fastener drive head adapted to be used in installing the stand-off fastener130, with the upper portion140of the stand-off fastener130sized to permit the stand-off fastener130to be installed into the decking180and the joist110. In this configuration, an anchor member148may be provided on the upper portion140for engagement and encapsulation in the cementitious slab120. The anchor member148may be a SEMS washer, or may be a press-fit member. As used herein, SEMS means a washer or other anchor or member held captive on the fastener where the dimension of the fastener on each side of the SEMS washer being larger than the washer hole prevents the SEMS washer from coming off. Optionally, as shown inFIG. 4A, the stand-off fastener130may include threads138adjacent the end of upper portion140of the fastener configured to couple to a reinforcing member such as rebar or some other member that will effectively extend the length of the stand-off fastener. In one alternative shown inFIGS. 4B and 4C, the clamping part146may be a SEMS washer. Alternatively, the clamping part146may be an integral flange. The clamping part146may include serrations (not shown) adjacent the threaded portion142to engage the surface of the upper surface of the metal decking180, or other building member during installation. These embodiments improve the composite floor system by further reducing failures in positioning the fasteners, and at the same time reducing the time to assemble the floor system. The SEMS anchors or stake anchors are easy to produce and improve the load transfer capacity of the stand-off fasteners at the same time.

The resulting assembly improves the speed of assembly as well as improves the load carrying capacity of the composite joist floor system. The fastener130facilitates assembly of the composite floor system100and reduce failures in installation of the stand-off fasteners130increasing the load capacity of the assembled composite floor.

As described above and illustrated inFIGS. 1 and 2, the composite floor system is completed by providing cementitious slab120supported by the decking180and encapsulating the upper portion140of each stand-off fastener130extending above the decking a plurality of stand-off fasteners130installed through at least some of the valleys in the corrugated steel decking180and through a flange of the upper chord112. Because of the features of the stand-off fastener, the composite floor systems can be installed with low labor costs to form a composite floor system with reduced installation errors and an improved load bearing capacity. As further illustrated, a portion of each stand-off fastener130continues to extend upwards above the corrugated steel decking180after the stand-off fastener130is fully installed through the decking180and the upper chord112. The stand-off fastener130has a lower collar149that functions to secure the corrugated steel decking180to the upper chord112. In this way, the stand-off fasteners130are connected to the metal decking180and joist upper chord112to the cementitious slab120with few defective installations, improving the installation time as well as load bearing capacity of the assembled composite floor system. In other words, these stand-off fasteners130cause the cementitious slab120to function with the upper chord of the composite joist system100with a much larger load carrying capacity.

In order for the stand-off fasteners130to more evenly transfer the horizontal shear loads along the length of the composite steel joist, the upper portion140of the stand-off fasteners130have a through hardness of between HRB 70 and HRC 40 to provide ductility. As the upper portion of the stand-off fasteners bends, shear load is shared with stand-off fasteners located throughout the length. However, in addition to being ductile enough to share the shear loads without breaking, the fluted lead portion144of lower portion141of stand-off fastener130must also have a hardness of at least HRC 50 to allow it to drill through the corrugated steel decking180and the upper chord112of the joist110. To accommodate both design requirements, the stand-off fastener130is specially heat treated so that the lower fastener portion of the stand-off fastener130has sufficient hardness for drilling while the upper portion remains sufficiently ductile.

FIGS. 5 and 6graph testing the threading-forming and threaded portion of simulated stand-off fasteners. The graph plots installation torque over time being threaded into a pre-drilled pilot hole to negate effects of the fluted lead portion in a test plate of two sheet thicknesses inFIG. 5and one plate thickness inFIG. 6. As the thread-forming portion is driven into the pilot hole, the thread-forming torque is the largest torque used to rotate the thread-forming portion of the stand-off fastener into the pilot hole forming threads in the pilot hole. After the head makes contact with the test plate, further rotation advances the threaded portion into the threaded fastener opening with increasing torque as the head clamps the members against the threads formed in the pilot hole. The operator stops tightening the fastener at a seating torque as desired lower than the failure torque187. The seating torque is selected as desired between the drive torque and the failure torque. For some applications, the selected seating torque is greater than the thread-forming torque. Alternatively, for some applications the selected seating torque may about 80% of the failure torque. The drive torque186is the torque right before the torque rise to a seating torque, as shown inFIGS. 5 and 6. Continued rotation of the fastener may further increase the torque needed to turn the fastener until the connection fails at the failure torque187. The failure mode typically is determined by the thickness of the metal decking and the flange of the upper chord of the joist and the major diameter of the fastener130. When metal decking180and the flange of the upper chord of the joist110in which threads are formed are thin materials such as less than 14 gauge, or less than 16 gauge, the materials of metal decking and the flange of the upper chord may deform or fracture adjacent the fastener and the fastener ultimately strips-out at the failure torque. The failure torque187generally refers to strip torque in materials of thinner thickness. For certain material thicknesses, the fastener will fracture at the failure torque.

Shown in the graph ofFIG. 5is the installation torque over time of five samples identified as manufacturer's samples ETC040 having a major diameter of ¼ inch installed at 175 revolutions per minute into pilot holes corresponding to the fluted lead portion into two steel sheets having a combined thickness of about 0.060 inch (about 1.5 millimeters). The thread-forming torque185as shown in the graph ofFIG. 5is less than about 20 inch-pounds. The drive torque186, before the torque rises to seating and then failure, is less than about 6 inch-pounds. In one sample, the failure torque187is greater than 40 inch-pounds. For certain samples, the failure torque is greater than 50 inch-pounds, and one sample greater than about 60 inch-pounds. The failure torque187shown inFIG. 5is a strip torque. The ratio of strip torque to thread-forming torque for the stand-off fasteners may be at least 3.0 and the ratio of strip torque to drive torque is greater than 6.0 with metal sheets with a combined thickness of 0.060 inch (about 1.5 millimeters) and the pilot hole corresponding to the nominal diameter of the fluted lead portion144between 80 and 95% of major diameter. Alternatively, the ratio of strip torque to thread-forming torque may be at least 3.0 and the ratio of strip torque to drive torque is greater than 6.0 when the first and second steel members have a combined thickness of 0.060 inch (about 1.5 millimeter) and the nominal diameter of the fluted lead portion144is between 70 and 95% of major diameter. Alternatively, the ratio of strip torque to drive torque may be greater than 10, and may be as high as 25 to 50, or more, when the combined thickness of the decking and upper joist flange is 0.12 inch and the fluted lead portion having at least one diameter within nominal diameter between 80 and 95% of major diameter.

Shown in the graph ofFIG. 6is the installation torque over time for the threaded portion and thread-forming portion of the stand-off fastener130. Five test samples identified as manufacturer's samples 360-80901-60 having a major diameter of ⅜ inch installed at 175 revolutions per minute into pilot holes corresponding to the fluted lead portion in a ¼ inch thick plate. The thread-forming torque185as shown in the graph ofFIG. 6is less than about 200 inch-pounds. The drive torque186, before the torque rises to seating, is less than about 25 inch-pounds. The failure torque187is greater than 600 inch-pounds. For certain samples, the failure torque187is greater than 700 inch-pounds, and one sample greater than about 900 inch-pounds. The failure torque187shown inFIG. 5is a strip torque for4of the5samples. The trace identified as “A” inFIG. 6shows a drop to 0 inch-pounds after reaching the failure torque because fastener A fractured at the failure torque. The ratio of failure torque to thread-forming torque is at least 3.0 and the ratio of failure torque to drive torque is greater than 10 when the steel members have a thickness of 0.25 inch (about 6.35 millimeter) and the pilot hole having at least one diameter within nominal diameter between 85 and 90% of major diameter. The ratio of failure torque to drive torque may be as high as 50 to 100, or more, when the second building member having a thickness of 0.25 inch and the fluted lead portion having at least one diameter within nominal diameter between 80 and 98% of major diameter.

Specifically,FIGS. 7A through 7Dillustrate 1.0 C-type steel decking having a width W.FIG. 7Aillustrates W/3 spacing where each width of corrugated steel decking180contains three fasteners130.FIG. 7Billustrates W/4 spacing where each width of corrugated steel decking180contains four stand-off fasteners130.FIG. 7Cillustrates W/5 spacing where each width of corrugated steel decking180contains five stand-off fasteners130.FIG. 7Dillustrates W/6 spacing where each width of corrugated steel decking180contains six stand-off fasteners130.

As illustrated inFIG. 1, stand-off fasteners130may drill through the upper flange of the upper chord112on alternating sides of the web118. To illustrate, the quantity of stand-off fasteners may be provided in the patterns as shown fromFIG. 7AthroughFIG. 7Dfor composite joist floor systems provide higher horizontal shear transfer and thus higher floor capacities.

FIGS. 8-11illustrate variations of the embodiment of the composite joist floor system described above inFIGS. 1-2. More particularly,FIG. 8illustrates a composite joist floor system100in accordance with an embodiment of the present invention where the supporting member for supporting the end of the joist110includes a structural steel beam103.

FIG. 9illustrates a composite joist floor system100in accordance with an embodiment of the present invention where the supporting member for supporting the end of the joist110includes a masonry wall101, such as a concrete block or a brick wall. In such an embodiment, the masonry wall101may include a concrete-filled channel127running through the uppermost blocks or bricks in the wall101so that masonry fasteners may be inserted into the concrete to hold, for example, the pour stop160or the joist shoe170in place, so that the forces from the cementitious floor slab120are more evenly distributed throughout the wall structure101. As also illustrated inFIG. 9, the concrete-filled channel127may have rebar126provided therein for reinforcing the concrete in the channel.FIG. 9also illustrates another embodiment where the corrugated steel decking180has an adjacent stand-off fasteners130′ located in the same valley of the corrugated steel decking as stand-off fastener130.

FIG. 10illustrates a composite joist floor system100in accordance with an embodiment of the present invention where the supporting member for supporting the end of the joist110includes a concrete wall101.FIG. 11illustrates a composite joist floor system100in accordance with an embodiment of the present invention where the supporting member for supporting the end of the joist110includes a wall structure101comprising wood studs. In such an embodiment, the wood stud wall structure may include a wood top plate and/or the load distribution member168to distribute the force from the cementitious slab120throughout the wall structure101. As illustrated, all of the floor systems shown inFIGS. 8-11utilize many of the same structures and configurations describe above with reference toFIGS. 1-2.

FIG. 12illustrates a sectional side view of composite joist floor system100showing how an I-beam103to support the ends of two joists110on opposite sides of the beam103extending in opposite directions in accordance with an embodiment of the present invention. Similar to the joist described above with respect toFIGS. 1 and 2, each joist110illustrated inFIG. 12may include an upper chord112and a lower chord111separated by an open web formed from one or more rod-like members119. At the end of each joist110, a diagonal end member117extends from the lower chord111near the first web connection to the end of the upper chord112adjacent the joist shoe170. Shoes170are attached to the ends of the upper chords112to form an I-beam configuration at the end of each joist110. The bottom surface of each shoe170is supported by the upper surface of the beam103.

In the illustrated embodiment, the ends of the joists are configured such that they extend less than halfway across the beam103, thereby creating a gap between the ends of the opposing joists. In illustratedFIG. 12, the ends of the opposing joists110are seated on the beam103at approximately the same location along the beams axis. In other embodiments, however, the opposing joists110may be staggered along the axis of the beam103.

As further illustrated byFIG. 12, each joist110supports corrugated steel decking180. The corrugated steel decking180is positioned such that the corrugations run lateral to the joists110. The corrugated steel decking180is also positioned such that the corrugated steel decking180on either side of the beam103ends at or before the beam103. By ending the corrugated steel decking180at or before the beam103, an opening is created above the beam103that exposes the top of the beam, the ends of the upper chords, and the ends of the joist shoes. Stand-off fasteners130are also are installed in above the beam103so that when cementitious material is placed over the corrugated steel decking180to form the slab120, the cementitious material is permitted to flow into the opening above the beam103to create a composite distribution/collector beam121extending above the steel beam103, with the stand-off fasteners the ends of the upper chords and the joist shoes encapsulated in the cementitious slab120. Z-shaped closures150are positioned on either side of the beam103to form the wall forms of a channel that the concrete is placed into and, thus, form the walls of the cementitious distribution/collector beam121.

More specifically, each z-shaped closure has a lower flange151that rests atop the steel beam103. A fastener, weld, powder actuated fastener, pneumatic pin, or a variety of other fasteners may be used to couple each horizontal lower flange to the steel beam103. The upwardly-extending upper flanges153of the z-shaped closures extend away from the beam103and at least a portion of each upper flange153rests atop a peak or peaks of the corrugated steel decking180. A fastener133may be used to couple upper flange153to a respective peak in the corrugated steel decking180. Each z-shaped closure150further includes a vertical face152extending between the upper flange153and lower flange151to form the upwardly-extending walls of the channel121. As described above with respect toFIG. 3, the upwardly-extending faces152have cutouts154that allow the closures150to fit around the contours of the I-beam103created by the ends of the upper chords112and the joist shoes170.

As described above with respect to theFIGS. 1 and 2, stand-off fasteners130are positioned through the corrugated steel decking180and the upper chords112of the joist110in at least some of the valleys of the corrugated steel decking180. In some embodiments, stand-off fasteners130are also threaded through the flanges of the upper chords112proximate the ends of the upper chords112in the region above the steel beam103.

FIG. 13illustrates a sectional side view of a composite joist floor system100showing where the corrugated steel decking180is supported at its edge by a wall structure101that runs along the joists110. The wall structure101may, for example, comprise a plurality of steel studs. The wall structure101includes the cold-formed wall track167along the upper portion of the wall to distribute forces from the composite joist floor to the load bearing wall studs. A stand-off fastener130may be drilled through a valley in the corrugated decking180and into the cold-formed wall track167to couple the edge of the cementitious floor slab120to the wall101. In some embodiments, the stand-off fastener130may be a stand-off fastener as described above with respect toFIG. 4A4B or4C.

As further illustrated inFIG. 13, the corrugated steel decking180may, in some embodiments, only extend over a portion of the supporting wall101so that the un-cured cementitious slab120can flow over the edge of the corrugated steel decking180and onto the upper portion of the cold-formed wall track167to form a cementitious beam121in the upper portion of the wall structure. If the composite floor is to end at the edge of the wall structure101, a pour stop160, such as the pour stop described above with respect toFIGS. 1 and 2, may be used to contain and form the un-cured cementitious slab120during cementitious material placement.

As further illustrated, one or more stand-off fasteners131may be drilled through the cold-formed wall track167in the region over the wall structure101beyond the edge of the corrugated steel decking180. As will be described in greater detail below, using stand-off fasteners131in this manner at the upper portion of the wall structure101or other supporting members can provide significant structural advantages. For example, in some embodiments, the upper portion of the wall structure101is the cold-formed wall track167, or cold-formed steel section, connecting a plurality of cold-formed steel wall studs. Optionally, the load distribution member168may be provided at the upper portion of the wall structure101such as shown inFIG. 2A. The stand-off fasteners131installed along the top of the wall in the cold-formed steel wall track167or load distribution member168transfer forces between the cementitious slab120and the upper portion of the wall structure101allowing the two structures to act more like a single unit. As such, the structure may be significantly stronger and/or material and labor may be reduced in the floor system. Furthermore, as will also be described in greater detail below, stand-off fasteners131installed at the tops of shear walls may also have significant structural advantages with regard to transferring horizontal diaphragm forces from the floor to the shear wall.

InFIG. 13, the wall structure101is the proper height to directly support the edge of the corrugated steel decking180. In other embodiments, however, z-shaped closures may be used at the inside edge of the wall to support the corrugated steel decking180. In this way, a larger cementitious material distribution/collector beam can be created in the upper portion of the wall structure that can provide various structural advantages and improve the structure's fire safety rating. For example,FIG. 14Aillustrates a partial cross-sectional view of a composite joist floor system100where an external masonry wall101that is substantially parallel to the floor joist110supports the edge of the corrugated steel decking180using a z-shaped closures150to support the edge of the corrugated steel decking180, in accordance with an embodiment of the present invention. Alternatively or additionally, the stand-off fasteners131may be used to fasten the pour stops160and z-shaped closures150to the wall structure, reducing material and labor costs.

More particularly, the z-shaped closure150comprises a generally lateral lower flange151that is coupled to the upper portion of the wall structure101by, for example, a masonry fastener134. The z-shaped closure150further comprises an upper flange153that abuts and supports the lower side of the edge of the corrugated steel decking180. Fasteners133may be used to couple the valleys in the corrugated steel decking180to the upper flanges153of the z-shaped closure150. An upwardly-extending face152extends between the upper and lower flanges and forms the wall forms of the cementitious beam121.

Since the wall101is an external wall, a pour stop160is used to form the exterior wall of the cementitious slab120and beam121. The pour stop160comprises a lower flange161and an upwardly-extending face152. The lower flange,161may be coupled to the upper portion of the wall structure101by, for example, a masonry fastener134. It should be appreciated that the length of the upwardly-extending faces of the pour stop160and the z-shaped closure150determine the size of the cementitious distribution/collector beam121over the wall structure101and the distance that this beam121extends beneath the decking180. Therefore, the pour stops160and z-shaped closures150can be varied to change the structural characteristics of the composite floor system100depending on the design requirements. The pour stops160and z-shaped closures150can also be used to alter the noise attenuating and fire containing properties of the structure. Furthermore, when the supporting structure101is a masonry wall such as inFIG. 14A, the height of the pour stop160and z-shaped closure150can be selected so that the height of the resulting cementitious beam121matches the masonry course height or some desired multiple thereof.

FIG. 14Billustrates an interior structural wall101extending generally parallel to the floor joists110. Since the wall structure101supports corrugated decking180on each side of the wall101, two z-shaped closures150are used to support the decking180, respectively, and to create the channel forms for the cementitious distribution/collector beam121above the wall101. Typically fire caulking is required at the upper portion of a structural wall101or some other fire stop must be installed in the corrugations of the metal decking180between the decking and wall in order to meet the proper fire safety design requirements. However, the pour stops160and z-shaped closures150can also be varied to provide the cementitious distribution/collector beam121over the wall structure101as desired to alter the noise attenuating and fire containing properties of the structure. The z-shaped closures150may be used to create a cementitious material beam121that is large enough and creates enough of a fire barrier so that additional fire proofing may not be required at the juncture between the floor and the demising wall. Additionally, stand-off fasteners (not shown) may be positioned into the upper portion of the wall structure to form a composite beam in the wall structure to provide structural support for the building. This can save significant time and cost during construction of the building structure.

Flush Seat Configuration for Composite Joist Floor System

FIG. 15illustrates a partial cross-sectional side view of a composite joist floor system100where the joist110is supported by a wall structure101running laterally to the joist110in accordance with another embodiment of the present invention. The configuration of the joist110and the joist shoe170are generally similar to the joists and joist shoes described above, however, the composite joist floor system100uses a “flush seat” configuration to support the end of the joist110. A flush seat is a metal plate positioned directly on the structural support, where the metal plate may be bent to better seat the joist on the wall structure under load.

Referring toFIG. 15, in the flush seat configuration of the composite joist floor system100the upper chord112is secured such that it is substantially directly on the upper portion of the supporting member101, with or without an intermediate distribution member168or header positioned at the upper portions of a supporting wall101. The flush seat configuration includes a generally flat main plate201that is welded to the upper surface of the end of the upper chord112. The horizontal plate201extends beyond the end of the upper chord112so that a portion of the plate201rests upon the upper portion of surface of the distribution member168or directly on the wall structure101. In the illustrated embodiment, a substantially downwardly-extending plate202extends downward from the main plate201at a location on the main plate201just beyond the end of the upper chord112. The downwardly-extending plate202extends downward typically to just below the lower surface of the joist shoe170. Typically, the downwardly-extending plate202extends downward between about ⅛ inch and ½ inch below the lower surface of the joist shoe170. The joist shoe170is welded to the joist such that it extends slightly (e.g., ¼ of inch) beyond the end of the upper chord112. This slight extension of the joist shoe170allows the downwardly-extending plate202to be welded to the horizontal plate201without interfering with the end of the joist upper chord112. The downwardly-extending plate202is welded with an upwardly extending weld and a lateral weld to the bottom of the joist shoe170to support the vertical load on the joist shoe170and to minimize eccentricity on the joist end.

In the flush seat configuration illustrated inFIG. 15, the corrugated steel decking180extends over the main plate201and ends after it extends approximately half way (or, for example, at least 1.5 inches) across the supporting wall101. As also illustrated, in some embodiments, the stand-off fasteners130may be installed into the joist upper chord112near the flush seat and positioned closer to each other than the typical spacing of the stand-off fasteners along the joist110.

FIG. 16illustrates another embodiment of a flush seat configuration where two opposing joists110are supported by the same steel I-beam103. In the illustrated composite joist floor system100, the main plates201, the downwardly-extending plates202, and the joist shoes170are each configured similar to the corresponding plates and shoes described above with reference toFIG. 15. InFIG. 16, however, the corrugated steel decking180extends from the first joist110completely over the beam103to the second joist110. By reducing the space or height consumed by the joist above the structural beam103, more space or height may be allocated for the structural beam103allowing for the use of a beam with a greater depth, reduced weight, and corresponding lower cost. Alternatively, the space saved by the flush seat may allow for a greater useable area between a floor and ceiling for ducting, plumbing, wiring, or other building systems.

FIG. 17illustrates another flush seat configuration of the composite joist floor system100where the flush bearing seat200is configured specifically for a masonry-type support member, such as a block wall structure, in accordance with an embodiment of the present invention. Specifically, the portion of the main plate201extending beyond the downwardly-extending plate202is bent downward. In this way, the main plate201is pre-bent to concentrate the downward force more toward the center of the cementitious material channel127rather than toward the upper inside of the top block in the masonry wall101.

Diaphragm Attachment Using Stand-Off Fasteners

FIGS. 18A and 18Billustrate a top view and a partial cross-sectional view, respectively, of a composite floor system100in accordance with an embodiment of the present invention. Specifically,FIGS. 18A and 18Billustrate how the composite floor system100may be configured to transfer horizontal diaphragm shear forces188from the cementitious slab120to the primary support structures, such as a cold-formed steel shear-wall101, in accordance with an embodiment of the present invention. In addition to transferring horizontal diaphragm loads188from the cementitious slab120to the wall structure, the techniques described herein also provide for the transfer of other forces between the two structures. For example, the force exerted by wind blowing against an exterior wall can be transferred from the wall structure101to the cementitious slab120more efficiently using the systems described herein. The corrugated decking180and the cementitious slab120are not shown inFIG. 18Afor clarity.

As illustrated inFIGS. 18A and 18B, in addition to the friction between the cementitious slab120and the upper portion of the wall101, embodiments of the present invention use two primary techniques for transferring diaphragm shear forces188from the cementitious slab120to the wall structure101. In some embodiments of the present invention both techniques are used together, while in other embodiments of the present invention only one or none of the techniques may be used. In the first technique, the joist shoes170are attached to the top of the wall101by stand-off fasteners131. By securing the ends of the joists110to the upper portion of the wall structure101and by using the stand-off fasteners130to couple the joist110to the cementitious slab as described above, the shear forces are transferred from the slab120into the joist110by the stand-off fasteners130and then from the joist110into the wall structure101by the stand-off fastener130to attach the joist110to the wall structure101.

As illustrated inFIG. 18B, in one embodiment of the composite joist floor system100, the joist shoes170extend over the supporting wall101beyond the end of the joist upper chord112so that there is sufficient room for the stand-off fasteners131to be drilled and threaded through the joist shoe170and into the upper portion of the wall structure101. In some embodiments, stand-off fasteners are used to fasten the joist shoes170to the wall structure101.

In a second technique for transferring horizontal diaphragm forces from the cementitious slab120to the wall structure101, stand-off fasteners131, which may be the same size as or a different size from the stand-off fasteners130installed through the decking180and joists110, are installed in the upper portion of the wall structure101(or load distribution member, wall track, or header, as the case may be) as desired. The stand-off fasteners131function to transfer the diaphragm shear forces188from the cementitious slab120to the wall structure101. As described above with reference to stand-off fastener130, the stand-off fasteners131are heat treated in such a way that the lower portion of the stand-off fastener131has a greater hardness than the upper portion of the fastener.

FIG. 18Aillustrates an exemplary embodiment of the invention where a single row of stand-off fasteners131are installed in the upper portion of wall structure101. In other embodiments, more than one row of stand-off fasteners131may be installed into the upper portion of the wall structure101when desired. Where more than one row of stand-off fasteners130are used, the rows may be aligned and have the same fastener spacing such that each stand-off fastener131is installed next to a corresponding stand-off fastener in the other row(s). In other embodiments, the rows may be configured such that they are not aligned and/or have different fastener spacing such that the stand-off fasteners131are staggered relative to the stand-off fasteners131in the other row(s) as desired for the particular embodiment.

FIG. 19illustrates a side section view of a portion of the composite floor system100at an external wall that is positioned along the floor joists110, in accordance with an embodiment of the present invention. As illustrated inFIG. 19, two rows of stand-off fasteners131are installed in the upper portion of the wall structure101to transfer horizontal diaphragm forces from the cementitious slab120to the external wall101. As described above, although two side-by-side rows of stand-off fasteners131are illustrated in theFIG. 19, in other embodiments any number of rows may be used and the rows may be staggered relative to each other.

AlthoughFIGS. 18 and 19illustrate external walls, the stand-off fasteners131can also be used in a similar manner to transfer diaphragm forces from the cementitious slab120to interior walls or support beams, as the case may be. In this regard,FIG. 20illustrates an interior support wall101in which stand-off fasteners131have been installed into the upper portion of the wall structure101to transfer diaphragm forces from the cementitious slab120to the wall structure101in accordance with an embodiment of the present invention.

FIG. 20illustrates an interior structural wall101extending generally parallel to the floor joists110. Since the wall structure101supports corrugated decking180on each side of the wall101, two z-shaped closures150are used to support the decking180, respectively, and to create the channel forms for the cementitious distribution/collector beam121above the wall101. As discussed above with reference toFIG. 14B, typically fire caulking is required at the upper portion of the structural wall101or some other fire stop must be installed in the corrugations of the metal decking180between the decking and wall in order to meet the proper fire safety design requirements. However, in this configuration, the pour stops160and z-shaped closures150can be varied to provide the cementitious distribution/collector beam121over the wall structure101as desired to alter the noise attenuating and fire containing properties of the structure. The z-shaped closures150may be used to create a cementitious material beam121that is large enough and creates enough of a fire barrier so that additional fire proofing may not be required at the juncture between the floor and the demising wall. As shown inFIG. 20, stand-off fasteners may be positioned into the upper portion of the wall structure for to form a composite beam in the wall structure to provide structural support for the building. This can save significant time and cost during construction of the building structure. Additionally, the stand-off fasteners131may be used to fasten the pour stops160and z-shaped closures150to the wall structure as shown inFIG. 20, reducing material and labor costs.

Furthermore, although the figures illustrate installation of the stand-off fasteners into cold-formed steel wall studs and steel distribution plates or wall tracks, the stand-off fasteners may be similarly used in support structures made of other materials. For example, standoff fasteners may be used at the upper portion of masonry wall structures or wood-framed wall structures. In such embodiments, the stand-off fasteners may be modified such that the stand-off fasteners have threads and hardnesses that are tailored to meet the requirements of the material being used for the support structure. Exemplary stand-off fasteners specifically configured for installation into wood or masonry support structures are described in greater detail below.

Composite Cold-Formed Steel Joist Floor System

In some embodiments of the present invention, various different types of cold-formed steel floor joists are used in addition to or as an alternative to open web steel joists. For example,FIGS. 21A,21B and21C illustrate three different exemplary cold-formed steel floor joists110,110, and110that can be used in the present composite joist floor system. In each of these embodiments, stand-off fasteners130as illustrated above inFIG. 4A,4B or4C are installed through the corrugated steel decking180and into the cold formed steel floor joist110and function to pull the decking180against the joists110. The upper stand-off portion of the fasteners130are then encapsulated in the cementitious slab120providing a composite structure that increases the stiffness and load carrying capacity of the composite floor system floor.

Composite Wall Panel System

Referring toFIG. 22, a composite wall panel300comprising a metal base301adapted to support placement of a cementitious material320, and a plurality of stand-off fasteners330for fastening at spaced locations along the base301, each stand-off fastener of carbon steel comprising a lower portion341and an upper portion340. As shown inFIG. 22A, the lower portion341has a threaded portion342, a thread-forming portion343adjacent the threaded portion342adapted to enable the fastener330to form threads in the base301, and a fluted lead portion344adjacent thread-forming portion343with a nominal diameter between 80 and 98% of major diameter of the threaded portion342adapted to form a fastener opening in the base301. When installed, at least a portion of the upper portion340of each stand-off fastener330extends significantly above the base301, and a cementitious slab320formed on the base301and encapsulating the upper portion340of each stand-off fastener extending above the base301to form a desired wall surface of the panel system300.

The wall panel system300has the metal base301, cementitious slab320and stand-off fasteners330as an integral wall system that can provide a desired wall surface where cracking of the cementitious slab is inhibited if not eliminated. The wall panel system300may be used either as an inside wall system or and outside wall system as explained in more detail below with reference to the drawings. The cementitious slab320may have any surface desired either for inside walls or outside walls. The metal base301may be corrugated metal decking as shown inFIG. 22, and the stand-off fasteners330may be fastened through the base301to a flange311of metal wall studs310. Also reinforcing325such as welded wire fabric or other reinforcing may provide further strengthening and durability for the cementitious slab320.

The wall panel system300may be formed by providing the metal base301and a support structure302such as a support structure302comprising cold-formed steel wall studs310and installing the fasteners330through the base301and through the flanges311of the wall studs310while the support structure302is laying down. Alternatively, the support structure302may comprise other structural members such as girts, beams, or other supporting members as desired. Temporary side wall pour stops360may be placed around the periphery of the base301positioned by fasteners333to the support structure302. The temporary side pour stops generally extend above the upper end of the stand-off fasteners330installed in the base301, so that the outer surface of the cementitious slab320has a smooth surface or some other desired surface decorative or functional service with the upstanding stand-off fasteners totally embedded in the cementitious slab320. The temporary side pour stops360are then typically removed as shown inFIG. 23; however, the side pour stops may be used as part of the finish wall panel system300as shown inFIG. 24. In any case, once the concrete forming the cementitious slab320is cured, the panel is brought upright and assembled in place in the building structure as shown inFIGS. 24 and 25. The pour stops360may be shaped and positioned such that when the wall panels are assembled, a gap is provided between the cementitious slab and the adjacent cementitious slab or other structure as shown inFIG. 23. Additionally, the side pour stops360may be formed to provide a chamfer362on the edge of the cementitious slab320as shown inFIG. 22such that multiple wall panel systems300can be assembled butted together in the building structure with the chamfers362forming a groove adapted to be filled with sealing material315. Optionally, a backer rod309may be provided as a backing for the sealing material315as shown inFIG. 23.

The stand-off fasteners330may be an embodiment of the stand-off fasteners illustrated inFIG. 4A,4B or4C. The lower portion341of the fasteners330of the wall panel system may have a threaded portion342, thread-forming portion343and fluted lead portion344. Threaded portion342may have a through hardness of between HRB 70 and HRC 40 and the lower portion341of the fastener330may have a failure torque to thread-forming torque ratio of at least 3.0 and a drive torque at least 20% less than a thread-forming torque. The stand-off fastener may have a drive torque no more than 50% of a thread-forming torque. In addition, the thread-forming portion343adjacent the threaded portion342of a wall panel system300has at least HRC 50 hardness adapted to enable the fastener to form threads in the base301, and a fluted lead portion344adjacent the thread-forming portion343of at least HRC 50 hardness. The upper portion340of the stand-off fasteners have a through hardness of between HRB 70 and HRC 40 to provide ductility in the upper portion340of the fastener330to reduce cracking in the fasteners in operation in a cementitious slab320of the wall panel system300. The threaded portion342of each stand-off fastener330may be of at least HRC 33 through hardness and up to five threads adjacent the thread-forming portion343may be hardened to at least HRC 50 hardness. The fluted lead portion344may have at least HRC 54 hardness.

To facilitate assembly and avoid assembly defects, the clamping portion346of the lower portion341of each stand-off fastener330may comprise a fastener head347adapted to be used in installing the stand-off fastener330, with the upper portion340of the stand-off fastener330is sized to permit the stand-off fastener330to be installed into the base301. A SEMS anchor348or stake anchor may be positioned on the upper portion340of the stand-off fastener330sized to permit the stand-off fastener330to be fastened into the base301, with the SEMS anchor348or stake anchor as shown inFIG. 4Aengaging in the cementitious slab320on installing of the fastener330and placement of the cementitious slab320. These embodiments provide for easier and less time consuming installation, while improving the quality and integrity of composite wall panel system assembled.

Alternatively, a fastener head may be positioned on the upper portion340of each stand-off fastener330adapted to be used in fastening the stand-off fastener330to the base301and to engage in the cementitious slab320on installing of the fastener330and placement of the cementitious slab320. In this embodiment, a SEMS anchor348may be part of the lower portion341of each stand-off fastener330and adapted to engage the base301and the cementitious slab320on placement of the cementitious slab320.

To facilitate assembly of the wall panels300, the thread-forming portion343of each stand-off fastener330has a shape selected from the group consisting of bilobular, trilobular, quadlobular and pentalobular.

For the wall panel systems300, the threaded portion of each stand-off fastener330may meet a specification selected from the group consisting of ASTM A307, ASTM A325, ASTM A354, and ASTM A490 specification or a specification selected from the group consisting of SAE J429 Grade 2, SAE J429 Grade 5, and SAE J429 Grade 8.

As with the composite floor systems100, the fluted lead portion344of the stand-off fastener330may have a milled point to reduce the failure rate of the stand-off fastener330. A pinch point may be provided on the fluted lead portion344of the stand-off fastener330, but as previously observed, we have found the fasteners made with a milled point are more reliable and result in less failures of the stand-off fastener, reducing assembly time and cost and producing an assembled composite wall assembly with greater load capacity.

As shown inFIG. 23, the wall panel systems300may be assembled together in a building structure using abutting wall studs310and310′ of adjacent wall panels. The composite wall systems can be assembled together by fasteners.

As shown inFIG. 24, the wall panel systems may be assembled in a building structure with the wall panel fastened to the building structure by fasteners331. The support structure302may comprise cold-formed steel wall studs310with the wall studs310fitted into a lower distribution track364and upper distribution track361. As shown inFIG. 24, the wall panel300may be fastened to the building structure through the lower distribution track364using the masonry fastener331. Optionally, a bearing pad or bearing strip322may be positioned between the cementitious slab320of the wall panel300and the building structure, such as a Korolath™ bearing strip. Additionally, the sealing material315may be positioned between the wall panel300and the building structure.

As shown inFIG. 25, the composite wall system300of the present invention may be an outside wall of a building structure. The composite wall system300may be used as the support structure of the joist110supporting a roofing material366. Alternatively, the composite wall system300may be used as the support structure of a joist110supporting the composite floor system similar to that shown inFIG. 15. These are, however, examples. It is recognized that the composite wall system300may used to assemble outside building walls embodying the present composite floor system100, as well as any other building structure that may be desired by a designer.