Patent Application
20050188638
The present invention relates to the construction of buildings such as large open span buildings. The present invention more particularly relates to composite floor systems and a novel design for joists used in such a floor system and installation of such joists.
Many multi-story commercial buildings and some multi-story residential buildings are constructed primarily of steel and concrete. In many instances, the floors in these multi-story buildings may be constructed by spanning steel joists between structural walls or beams and laying a supporting material such as plywood, metal pan or other type of decking material along or near the top portions of such joists. This supporting material forms a support structure or surface onto which concrete is poured. Generally, the lower chords of the joists form the framework from which ceilings are hung.
Composite floor systems have been employed in multi-story building construction for many years and improvements are constantly being sought, both in the materials used in the composite floor systems and the methodologies used to erect the buildings that incorporate composite floor systems. The development and sophistication of these structural systems has gradually extended to encompass many varieties of steel and concrete floor construction, the result of which has been to measurably reduce the cost of steel framing for multi-story buildings in the industry.
It will also be appreciated that the purposes of composite floor construction are to save considerable steel weight and cost, as well as to reduce depth and deflection. In view of the foregoing, it should be appreciated that it would be desirable to provide additional methodologies for constructing various types of composite floor systems that are simpler and less expensive to install, using existing materials and components to the extent possible.
The composite floor system of the present invention comprises a plurality of joists at least partially embedded in the concrete slab of the floor system. In the most preferred embodiments of the present invention, each of the joists is formed from a single piece of cold rolled sheet metal and, in at least one orientation, exhibits a substantially “Z-shaped” or “C-shaped” cross section along a longitudinal axis. In addition, for certain applications, a novel mounting bracket may be affixed to each end of the joists to provide for an underslung installation.
The present invention will hereinafter be described in conjunction with the appended drawing figures, wherein like numerals denote like elements, and:
The present invention relates to a composite floor system and parts and formwork therefore and erecting method for use in the construction of buildings such as large open span commercial or residential buildings. The present invention is particularly concerned with composite floor systems made from steel and concrete with a novel method of attaching joists used in such a floor system.
Referring now to
While support structures 110 and 115 are depicted as a block wall and an I-beam respectively, it should be understood that these are merely representative of the types of support structures that may be utilized in conjunction with the present invention. In practice, support structures 105 and 115 may be any type of structure capable of supporting the load of composite floor system 100, including columns, load-bearing interior walls, etc. Apertures 165 are provided for the installation of various utilities such as electrical lines, plumbing pipes and other similar purposes.
Once joists 160 are in place, removable spanner bars 170 are inserted into the body portion of joists 160 by inserting the ends of spanner bars 170 into apertures 135. Apertures 135 are most preferably spaced equidistant along the body portion of joists 160 so that cooperating pairs of apertures 135 can be aligned to receive alternate ends of removable spanner bars 170. The location and number of removable spanner bars 170 used for supporting a given concrete slab 110 can be determined by performing load analysis calculations for composite floor system 100.
With the appropriate number of removable spanner bars 170 in place, support platform 140 can be installed. Support platform 140 rests on and is supported by removable spanner bars 170. Support platform 140 provides a form for defining the bottom of concrete slab 110 and also provides stability to the overall structure prior to the pouring of concrete slab 110.
After support platform 140 has been completed, reinforcing material 190 is placed over the top of joists 160. Reinforcing material 190 is typically a welded wire mesh and is provided to add additional strength and stability to concrete slab 110 and will be embedded within concrete slab 110. Finally, concrete slab 110 can be poured in place over support platform 140 and reinforcing material 190. Support platform 140, in concert with joists 160, removable spanner bars 170 and support structures 105 and 115, support concrete slab 110 while it hardens and cures. After an appropriate period of time, such as approximately one or two days, spanner bars 170 and support platform 140 can be stripped from joists 160. Concrete slab 110 may be further reinforced in the usual way to carry all loads between any vertical walls and columns.
It should be noted that, after positioning joists 160 as shown in
Referring now to
Reinforcing material 220 is a welded wire fabric or rebar mat placed over the upper chords of joists 230, prior to the pouring of concrete slab 210. In the most preferred embodiments of the present invention, reinforcing material 220 is a welded wire fabric with a mesh-like appearance. However, it should be noted that any other reinforcing material capable of developing the required structural capacity may be used as well. Reinforcing material 220 is typically draped over the upper chords of joists 230 and hangs in a catenary-like shape between the joists to provide the most effective reinforcement. Reinforcing material 220 is completely encased with the boundaries of concrete slab 210.
Support platform 260 is suspended on spanner bars 270 prior to the pouring of concrete slab 210. Support platform 260 is used as a form for defining the bottom surface of concrete slab 210. Support platform 260 also provides a degree of lateral stability to the structure of composite floor system before concrete slab 210 is poured. After concrete slab 210 has been poured and allowed to cure for an appropriate amount of time, spanner bars 270 are removed by using handles 240 and support platform 260 may be stripped from concrete slab 210 and may be reused in subsequent concrete pouring operations. Hat channel 250 is attached to joists 230 and ceiling 280 is attached to hat channel 250.
With the composite floor system of the present invention, it is possible to utilize standard-sized materials to form the support structure for the concrete slab. For example, the spacing of joists 230 may be advantageously fixed at approximately four-foot centers, thereby enabling the use of readily available and inexpensive standard 4′ by 8′ sheets of plywood for support platform 260. It should also be recognized that, in accordance with contemporary construction practice, such plywood panels would be treated with a release coating, such as oil, to avoid adherence of concrete slab 210 to plywood used in support platform 260. Such a release coating enables the ready stripping of support platform 260 beneath concrete slab 210 with a minimum loss of formwork due to accidental destruction. Alternatively, support platform 260 may be constructed from typical steel pan formwork or some other material known to those skilled in the art that provides sufficient strength to support concrete slab 210.
Referring now to
Reinforcing material 320 is a welded wire fabric or rebar mat placed over the upper chords of joists 330, prior to the pouring of concrete slab 310. In the most preferred embodiments of the present invention, reinforcing material 320 is a welded wire fabric with a mesh-like appearance. However, it should be noted that any other reinforcing material capable of developing the required structural capacity may be used as well. Reinforcing material 320 is typically draped over the upper chords of joists 330 and hangs in a catenary-like shape between the joists to provide the most effective reinforcement. Reinforcing material 320 is completely encased with the boundaries of concrete slab 310.
Support platform 360 is suspended on spanner bars 370 prior to the pouring of concrete slab 310. Support platform 360 is used as a form for defining the bottom surface of concrete slab 310. Support platform 360 also provides a degree of lateral stability to the structure of composite floor system before concrete slab 310 is poured. After concrete slab 310 has been poured and allowed to cure for an appropriate amount of time, spanner bars 370 are removed by using handles 340 and support platform 360 may be stripped from concrete slab 310 and may be reused in subsequent concrete pouring operations.
Referring now to
Next, a plurality of removable spanner bars are positioned between each pair of joists (step 430). Then, the support platform for the concrete slab is positioned on top of the removable spanner bars (step 440). As previously mentioned, the support platform may be any material capable of supporting the load of the concrete slab. After the support platform is in place, the reinforcing material is positioned by draping it over the upper chords of each of the joists (step 450). The reinforcing material is typically a welded wire mesh material well known to those skilled in the art. Once the reinforcing material has been positioned, the concrete slab can be poured over the support platform and allowed to cure (step 460). Finally, after the concrete slab has been allowed to sufficiently cure, the removable spanner bars and the support platform can be stripped from the underside of the concrete slab (step 470).
Referring now to
Body portion 510 is shaped similar to a piece of steel angle with a 90° bend at the midpoint. Horizontal bearing plate 520 is attached to body portion 510 by welding or other suitable attachment methods. Horizontal bearing plate 520 serves to distribute the load of any joists attached to mounting bracket 500 over a larger surface area, thereby minimizing any undesirable load concentrations that may result in structural failure. Horizontal bearing plate 520 typically rests on a load bearing structure such as a wall.
Wall or beam attachment apertures 530 are used to securely attach mounting bracket 500 to the top of a supporting or load-bearing structure, such as a wall or a beam, if required. While bolts or screws may be inserted through apertures wall or beam attachment apertures 530, thereby attaching mounting bracket 500 to a wall or beam, in certain applications mounting bracket 500 will be welded in place and apertures 530 will not be used.
Upper chord attachment apertures 540 are used to securely attach the upper chord of a joist to mounting bracket 500. As with wall or beam attachment apertures 530, bolts or screws may be inserted through upper chord apertures 530, thereby securely attaching mounting bracket 500 to the upper chord of a joist. It is anticipated that the upper chord of the joist may be welded to mounting bracket 500 in certain applications.
Web attachment apertures 560 are used to secure the body of a joist to mounting bracket 500. As previously explained in conjunction with upper chord attachment apertures 540 and wall or beam attachment apertures 530, bolts or screws may be inserted through web apertures 560, thereby attaching the body portion of a joist to mounting bracket 500. Once again, it is anticipated that mounting bracket 500 will be welded directly to the joist for certain applications. Mounting bracket is connected to a joist and the joist is then positioned as shown and described in
Referring now to
Body portion 620 defines a plurality of body apertures 650. Body apertures 650 are used to support spanner bars that, in turn, are used to support the decking material that will form the surface for the concrete slab when the concrete is poured in place. The spanner bars may be inserted to support the plywood or other material suspended between a plurality of joists 600 and to stabilize the plurality of joists 600 prior to the pouring of the concrete slab. Optional aperture 695 may be used to provide for the installation of utilities such as electrical and plumbing lines.
Upper chord 630 defines a plurality of apertures 640 spaced along the length of upper chord 630. Apertures 640 are positioned horizontally in upper chord 630 and allow the portion of the concrete above upper chord 630 to be connected with the portion of the concrete slab beneath upper chord 630. Apertures 640 are concrete-engaging mechanisms that act as an additional shear transfer mechanism. Much of the interface shear is accomplished by the combination of the concrete and steel reinforcement gripping and adhering to the embedded portion of upper chord 630, upper flange 635, and the upper portion of body 620. Lower chord 660 may also have apertures 640 formed therein. In the most preferred embodiments of the present invention, upper chord 630 is entirely encased within the concrete slab during the pouring of the concrete slab. Optional apertures 695 are provided for the installation of various utilities such as electrical lines, plumbing pipes and other similar purposes.
As shown in
In the most preferred embodiments of the present invention, joist 600 is completely formed of a single piece of cold rolled sheet metal, but may be fabricated in many other ways and additionally reinforced, if necessary. Apertures 640 and 650, along with optional aperture 695 can be created as part of the overall manufacturing process and any of the various methods for creating apertures known to those skilled in the art may be used. Alternatively, instead of apertures 640, upper chord 630 may be fabricated with other concrete-engaging mechanisms such as a series of “dimples” or other protrusions that would further assist in firmly fixing upper chord 630 into a concrete slab.
Referring now to
Upper chord 730 defines a plurality of apertures 740 equally spaced along upper chord 730. Apertures 740 allow the portion of the concrete above upper chord 730 to be connected with the portion of the concrete slab beneath upper chord 730. Apertures 740 are concrete-engaging mechanisms that act as an additional shear transfer mechanism. Lower chord 760 may also have apertures 740 formed therein. In the most preferred embodiments of the present invention, upper chord 730 is entirely encased within the concrete slab during the pouring of the concrete slab. Optional apertures 795 are provided for the installation of various utilities such as electrical lines, plumbing pipes and other similar purposes.
As shown in
In the most preferred embodiments of the present invention, joist 700 is completely formed of a single piece of cold rolled sheet metal, but may be fabricated in other ways and additional reinforcement may be added as needed. Apertures 740, 750 and 795 can be created as part of the overall manufacturing process and any of the various methods for creating apertures known to those skilled in the art may be used. Alternatively, instead of apertures 740, upper chord 730 may be fabricated with other concrete-engaging mechanisms such as a series of “dimples” or other protrusions that would further assist in firmly fixing upper chord 730 into a concrete slab.
Referring now to
Referring now to
While certain preferred exemplary embodiments have been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that these preferred embodiments are only examples and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description provides those skilled in the art with a convenient roadmap for implementing the preferred exemplary embodiments of the invention. It should be understood that various changes may be made in the function and arrangement of elements described in the exemplary preferred embodiments without departing from the spirit and scope of the invention as set forth in the appended claims.
This application is a continuation-in-part of U.S. patent application Ser. No. 10/177,070, now pending, which application is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10177070 | Jun 2002 | US |
| Child | 11116652 | Apr 2005 | US |
