Abstract:
The structural framing system comprises a steel beam that supports flooring components interconnected through the addition of a solidifying material such as poured concrete. A structural framing system is created by anchoring steel beams to vertical columns, spanning floor sections between the steel beams, pouring concrete into the interior of the beams and contacting the flooring components, and then forming a rigid joint between the steel beam, floor sections and columns through the addition of a bonding layer.

Description:
RELATED APPLICATION 
     The present application claims priority to U.S. Provisional Application Ser. No. 60/254,278 entitled “Composite Structural Framing System” filed on Dec. 8, 2000. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to building construction and more specifically to a composite steel and concrete framing system that forms a substantially monolithic support structure. 
     BACKGROUND OF THE INVENTION 
     In the field of building construction, specifically the erection of multi-story buildings, the framing system constitutes the essential load-bearing structure that provides the stability and structural integrity of the building. The typical multi-story framing system consists of a plurality of stacked vertical columns interconnected with horizontal support beams. Typically, vertical columns and horizontal beams are composed of either steel, precast concrete, or formed-in-place concrete. Further, the horizontal beams typically support flooring sections of precast concrete, metal, or formed-in-place concrete. The framing system is designed to support well in excess of the anticipated loads developed by the structure itself and all live loads placed thereon. The forces generated by these loads are largely borne by the horizontal beams, the vertical columns and the connection members that join the beams and columns. 
     One known method of erecting a framing system is to pour concrete in place, utilizing suitable forms, to produce vertical columns, horizontal beams and floor sections. Pouring concrete in place has the advantage of producing buildings which are strong, highly rigid, durable and highly fire resistant. However, this method requires the use of labor intensive forms and complicated temporary supports which are expensive, easily destroyed and impede efficient work flow. 
     Another known method of erecting a framing system is to assemble precast concrete columns, beams and floor sections. This method has the advantage of rapid erection, with little need for temporary supports. However, precast concrete buildings tend to be less rigid than poured-in-place concrete buildings and have other inherent structural limitations. Still another often practiced method of erecting a framing system is to assemble steel columns and beams with steel or concrete floor sections. This method also has the advantage of rapid erection when steel precast concrete floor sections are used. Similar to the framing system assembled of precast concrete, steel buildings have inherent structural limitations. Most notably, these known framing systems are limited by the forces borne by the connecting members—typically the weakest elements of the framing system. 
     Presently, no framing system provides a support structure which is both highly rigid and fire resistant as found with a poured-in-place system while easy to assemble as found with a steel system. Thus, there exists a need for a highly rigid and fire resistant framing structure which may be erected without temporary forms and complicated supports while overcoming the limitations found in connecting members. 
     SUMMARY OF THE INVENTION 
     The present invention addresses the shortcomings described above by providing a system of horizontal composite beams supported by vertical columns, which support flooring components such as precast planks or metal deck sections that receive poured concrete. A pourable bonding layer, such as a plasticized or cementitious material that hardens, tops the flooring components and bonds the flooring components, composite beams and columns. Each composite beam comprises a steel beam and interior of plasticized or solidifying material such as poured concrete. In the preferred embodiment, the steel beam includes a bottom plate, adjacent containment sides fortified by strap bars, studs, and horizontal support members. The horizontal support members provide a support surface for the floor components. Alternatively, the individual elements of the steel beam may be formed as a single, substantially monolithic unit. Reinforcing members such as rebar and post tensioned cables provide additional force bearing capacity to the composite beam. 
     In erecting the preferred framing system, concrete vertical columns are provided, each with at least one receiving saddle for supporting the end of a steel beam. The steel beams are raised and the flooring components, which span between adjacent steel beams, are set. Concrete is then poured to fill the interior of the steel beam; the strap bars act to resist the outward forces created by the wet concrete and the studs act to bond the cured concrete to the steel beam. Sufficient concrete is poured to fill the steel beam, flow into the hollow cores of precast floor planks, and rise to the upper surface of the planks. Alternatively, concrete is poured to fill the steel beam and added to fill a deck component to create a subfloor. Concrete can continue to be added to form a bonding layer and to fill all voids in or around the columns, thereby creating a substantially monolithic layer. Some blocking may be necessary at the columns to stop seepage of the concrete or bonding layer while the concrete is wet. 
     In a preferred embodiment, the composite beam is adapted for use along the perimeter of a horizontal level. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     The accompanying drawings, which are incorporated in and form a part of the specification, illustrate preferred embodiments of the present invention and, together with the description, disclose the principles of the invention. In the drawings: 
     FIG. 1 is a top view illustrating a typical section of the flooring system of a preferred embodiment, including precast floor sections; 
     FIG. 2 is a cross-sectional view which illustrates a preferred embodiment of the composite beam; 
     FIG. 3 is a cross-sectional view of a preferred composite beam supporting the perimeter of a flooring system; 
     FIG. 4 is a cross-sectional view of a column and two preferred beams illustrating a preferred connection between a column and beam; 
    
    
     DETAILED DESCRIPTION 
     As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention. 
     Referring to the drawings wherein like elements are designated by like numbers, FIG. 1 illustrates a top view of the composite structural framing system  10 . Generally speaking,,the system  10  consists of flooring components  12  that are supported by vertical columns  14  and horizontal composite beams  16 . Vertical columns  14  are located as necessary to support the composite beams  16 . Each vertical column  14  is typically connected to and supports at least one composite beam  16 . The composite beams  16  support floor components  12  which may be, by way of illustration and not limitation, precast hollow core planks or metal deck sections which receive poured concrete. As explained in detail below, a pourable bonding layer  20  tops the flooring components  12  to join the flooring components, the composite beams  16 , and columns  14  to create a rigid joint. By way of example and not limitation, the bonding layer  20  is a plasticized material, such as concrete, that hardens to provide improved structural integrity between the discrete framing components. 
     FIG. 2 is a cross-sectional view of a preferred embodiment of a composite beam  16  supporting precast floor components  12 . In this embodiment, composite beam  16  includes an exterior steel beam  22  sheath and solidifying material  24 . In this embodiment, the steel beam  22  includes a bottom plate  26 , containment sides  28 , reinforcement means  30 , joining means  32  and horizontal support surfaces  34 . Containment sides  28  are attached to the bottom plate  36 , by welding or other means, and extend upwardly. FIG. 2 illustrates the containment sides  28  attached along the outer edges  36  of the bottom plate, but may be attached inward away from the outer edges to form one or more lower support surfaces (not shown). Horizontal support members are attached to the containment sides  28  along they uppermost edge  38  to form a support surface  34 , by welding or other means. These members may extend inwardly towards the center of the beam  22  or outwardly away from the beam. The horizontal support members provide a support surface  34  for the floor components  12 . It will be understood that horizontal support members may be oriented on either face of the containment side  28  and at various elevations, the location being merely a decision choice. It is also contemplated that the support surface  34  provided by the support members may be formed by merely thickening the uppermost edge  38  to a suitable width. 
     In the illustrated embodiment, reinforcement means  30  are attached at one end to the inside face of a containment side  28  and at the opposite end to the inside face of a second containment side. Placed approximately four feet on-center, one purpose of the reinforcement means  30  is to restrain the containment sides  28  from lateral movement. By way of example and not limitation, the reinforcement means  30  illustrated are strap bars. It will be understood that equally suitable reinforcement means includes but is not limited to well known restraining/reinforcement devices such as but not limited to strap bars, interior or exterior mounted ribs, fins, stiffening plates, angles and bands. Various reinforcement means may be positioned at differing locations. In the illustrated embodiment, joining means  32  are attached to the bottom plate approximately one foot on-center, one purpose of the joining means  32  is to anchor the cured concrete to the steel beam  22 . By way of example and not limitation, the joining means  32  illustrated are studs. It will be understood that equally suitable joining means includes but is not limited to well known shear/joining devices such as but not limited to studs, ribs, fins, anchor bolts and rebar. Various joining means may be positioned at differing locations. Further, an abundance of reinforcement means may serve the combined function of reinforcing devices and joining devices. 
     In the illustrated embodiment, the bottom plate  26 , containment sides  28 , reinforcement means  30 , joining means  32 , and horizontal support surfaces  34  are formed from forged or standard rolled shape steel. Nevertheless, it is contemplated that as a design choice, steel may be substituted with other materials that meet minimum performance characteristics. It is also contemplated that the individual elements of the steel beam  22  enumerated above may be formed as a single, substantially monolithic unit. 
     The steel beam  22  supports the bottom surface of the floor component  12  with the horizontal support surfaces  34 . Reinforcing members  40  may be added to provide additional force bearing capacity to the composite beam  16 , and are located according to design criteria. Reinforcing members  40  may be well known reinforcing members such as rebar or post tensioned cables. 
     In erecting the framing system  10 , the foundation (not shown) and vertical columns  14  are constructed according to the methods well known by those skilled in the art. In the illustrated embodiment, the columns are concrete, either precast or poured in place and are provided with a receiving saddle  44 , best shown in FIG.  4 . The saddles  44 , which are approximately the height of the composite beam  16  approximately 1″ wider and approximately 3″ deep, receive and support the end of the composite beam  16 . The end of each composite beam  16  maybe further secured to the column by methods well known to those skilled in the art. It is contemplated that a plurality of columns  14  are erected which receive and support steel beams  22 . Any temporary intermediate supports required may now be installed. The steel beams  22  then receive and support flooring components  12 , such as precast concrete planks or metal decking, along the horizontal supports  34 . 
     FIG. 2 best illustrates flooring components  12 , supported by a steel beam  22 , which in turn is supported by columns  14 . Next, in the process of erecting the framing system  10  a solidifying material  24 , such as but not limited to concrete, is poured into the steel beam  22  where it fills the cavity created by the bottom plate  26  and sides  28 . The reinforcement means  30  act to resist the outward forces created by the wet concrete and the joining means  32  act to anchor the cured concrete to the steel beam  22 . Sufficient concrete  24  is poured to fill the steel beam  22 , flow into the hollow cores of the precast floor planks  12 , and rise to the upper surface of the planks. Alternatively, concrete  24  is poured to fill the steel beam  22  and added to fill a metal deck flooring component to create a finished subfloor. It is contemplated that concrete  24  can continue to be added to form the bonding layer  20  and to fill any voids in or around the columns  14 . In other words, the solidifying material  24  and bonding layer  20  may be of the same plasticized material. The bonding layer  20  creates a substantially monolithic layer which connects and unites each horizontal level of flooring components  12 , composite beams  16  and columns  14  together to form a rigid joint. By way of illustration and not limitation, the solidifying mixture  24  illustrated is poured concrete. It will be understood that equally suitable solidifying means include but are not limited to well known plastic bonding materials that solidify to realize increased performance characteristics such as cement, grout, Gyp-creteo®, and similar performance enhanced concretes. 
     During erection of the framing system  10 , the steel beam  22  initially provides temporary support to the floor components  12 . Thereafter, the steel beam  22  acts as a form to accept the concrete  24 . Finally, the steel beam  22  becomes an integral part of the composite beam  16 . Some of the advantages realized by providing the steel beam  22  include: the virtual elimination of temporary shoring, the virtual elimination of temporary forms, and isolating concrete pouring to a single critical step per horizontal level. Some of the advantages realized by providing the composite beam  16  include a structural beam with greatly improved performance characteristics in spans of at least sixty feet in length, and a substantially more rigid frame  10  by interlocking the flooring components  12 , composite beams  16  and columns  14  of each horizontal level together with a bonding layer  20 . Individually and together these advantages reduce construction related expenses and time. 
     FIG. 3 depicts a preferred embodiment of a perimeter composite beam  50  adapted for use along the perimeter of a horizontal level. The composite beam  50  includes an exterior containment side  52  that extends upwardly from the bottom plate  26 . In the illustrated embodiment, the upper edge  38  terminates and returns at the elevation of the bonding layer  20 . It will be understood that the configuration, even the existence, of the return position  54  is a design choice and may be replaced with a horizontal support  34  for the purpose of attaching walls, windows, rails or other building components. The remaining components illustrated in FIG. 3, together with their advantages, are substantially identical to the steel beam  22  and composite beam  16  described above. 
     FIG. 4 illustrates a cross-section of a typical concrete column  14  supporting one end each of two steel beams  22 . Flooring components  12  are also shown supported by the steel beams  22 . The vertical column  14  illustrated is a poured in place concrete column, constructed in a manner well known by those skilled in the art. It is also contemplated that the column  14  may be configured with precast concrete or a steel beam. The support column  14  illustrated includes two receiving saddles  44  to support the steel beams  22 . The location and number of receiving saddles  44  is a design choice, as is any additional attachment means between the beam  22  and column  14 . 
     From the configuration of the horizontal level illustrated in FIG. 4, the next step in constructing the framing system is to pour solidifying material  24  into the steel beam  22  and pour the bonding layer  20 . The selection of solidifying material  24  and bonding layer  20  is a design choice governed by structural design criteria and construction timing requirements. It will be understood that some blocking (not shown) may be necessary around the columns  14  to stop seepage of the material  24  or bonding layer  20  and that few temporary intermediate supports will be required to support the steel beam  22  while the concrete is wet, but the need for intermediate supports is ultimately a design choice. 
     While various embodiments of this invention have been described above, these descriptions are given for purposes of illustration and explanation. Variations, changes, modifications, and departures from the systems and methods disclosed above may be adopted without departure from the spirit and scope of this invention.