The invention relates generally to prefabricated building components. More specifically, the invention relates to a precast, prestressed concrete truss suitable for use as a load bearing wall in building construction.
Load bearing walls of buildings are constructed from a variety of materials including wood, steel, and concrete. The type of material that is used depends upon numerous factors, including, for example, the cost of the material, the anticipated loads on the material, the size of the building, the ease with which the building can be constructed using the material, and the strength of the material.
Wood frame construction is commonly used. The use of wood is attractive because it is generally cheaper than equivalent steel and concrete construction. However, wood frame construction is generally limited to buildings having about four stories or less. Further, the use of wood consumes valuable environmental resources, and is generally not as fire resistant as the counterpart steel and concrete alternatives. Steel is also commonly used for both single level and multi-level buildings.
Concrete has many advantageous properties that make it suitable for building construction. For example, concrete has excellent fire protection properties. In addition, concrete has excellent durability, as well as favorable vibration and sound transmission characteristics.
The use of concrete to form load bearing walls is known. One example is disclosed by Fintel et al. in “Staggered Transverse Wall Beams For Multistory Concrete Buildings—A Detailed Study”, Portland Cement Association, Skokie, Ill. (circa. 1968). The concrete walls disclosed in this publication are cast-in-place structures, where the concrete is poured at the building site to form the walls.
The construction industry has seen an increasing use of prefabricated building components for constructing buildings. Prefabricated building components permit faster erection times, and can reduce the number of construction personnel at the building site, thereby resulting in an overall reduction in building costs.
However, current concrete construction, whether prefabricated or cast-in-place, requires a uniform gridwork of closely spaced columns, including interior columns, to support the floor elements of the building. The interior columns extend through functional space within the building, including living space and parking space, thereby interfering with the use and function of that space within the building.
There is a continuing need for prefabricated concrete building components that reduce or eliminate the use of interior columns. There is also a need for prefabricated concrete building components that can be economically used in multi-level building that are, for example, higher than four stories.
The invention relates to a precast, prestressed concrete truss that spans between exterior columns and forms an interior or exterior load bearing wall of a building. By spanning between exterior columns, the use of interior columns can be reduced and/or eliminated. The truss is preferably configured for use as an interior wall, but it can also be configured for use as an exterior wall.
Many different types of buildings can be constructed using trusses according to the invention. The trusses can be used in single level or multi-level buildings. The trusses have particular benefits in buildings that are higher than four stories. However, the trusses can also be used to construct buildings that are less than four stories, particularly where the benefits of concrete add sufficient value over counterpart wood frame construction to offset the higher cost of using concrete. Examples of the types of buildings that can be constructed using trusses according to the invention include hotels, motels, assisted living facilities, condominiums, and apartments.
In one aspect of the invention, a precast, prestressed concrete truss is provided. The truss comprises a top chord, a bottom chord, and a plurality of web members interconnecting the top chord and the bottom chord. The top chord, the bottom chord, and the web members are integrally formed from concrete, and prestressed reinforcing members are embedded in the concrete of the top and bottom chords to apply stress in the top and bottom chords. In addition, the truss has at least one opening between two adjacent truss members and between the top and bottom chord, with the opening having dimensions sufficient to form a corridor passage in a building in which the truss is used.
In another aspect of the invention, a precast, prestressed concrete truss is provided. The truss comprises a top chord, a bottom chord, and at least one web member interconnecting the top chord and the bottom chord. The top chord, the bottom chord, and the web member are integrally formed from concrete, and prestressed reinforcing members are embedded in the concrete of the top and bottom chords to apply a stress in the top and bottom chords. In addition, the top and bottom chords are each adapted to support planks that form a floor and/or a ceiling in a building in which the truss is used.
In yet another aspect of the invention, a building comprises a plurality of walls, with at least one of the walls comprising a precast, prestressed concrete truss that includes a top chord, a bottom chord, and a plurality of web members interconnecting the top chord and the bottom chord. The top chord, the bottom chord, and the web members are integrally formed from concrete, and the top and bottom chords are each adapted to support planks that form a floor and/or a ceiling in the building. Prestressed reinforcing members are embedded in the concrete of the top and bottom chords to apply a stress in the top and bottom chords. Further, the truss includes at least one opening through it.
In still another aspect of the invention, a method of constructing a building comprises providing a plurality of precast, prestressed concrete trusses. Each truss includes a top chord, a bottom chord, and a plurality of web members interconnecting the top chord and the bottom chord. Further, the top chord, the bottom chord, and the web members are integrally formed from concrete, and the top and bottom chords are each adapted to support planks that form a floor and/or a ceiling in the building. Prestressed reinforcing members are embedded in the concrete of the top and bottom chords to apply a stress in the top and bottom chords. In addition, the truss includes at least one opening through it. The method also includes erecting exterior support columns, and installing the trusses as load bearing walls in the building, with each end of each truss supported by one of the exterior support columns.
These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages and objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying description, in which there is described a preferred embodiment of the invention.
A precast, prestressed concrete truss 10 according to one embodiment of the invention is illustrated in
The truss 10 is precast in that it will typically be fabricated at a location remote from the intended building site, shipped to the building site, and then installed in the building as needed. The truss 10 could also be fabricated at or adjacent the building site provided the building site has suitable manufacturing capability to fabricate the truss 10.
The truss 10 is configured to form a load bearing wall in a building in which the truss is used. The wall is preferably an internal wall as illustrated in
With reference to
As illustrated in
The web members 12 each include a first side surface 18 and a second side surface 20 defining a thickness tw therebetween. In the embodiment illustrated in
Each web member 12 also includes a height hw between the bottom of the top chord 14 and the top surface of an enlarged portion of the bottom chord 16. The height hw is generally constant from one end 13 of the truss 10 to the other end 15, as best seen in
With reference to
The protrusion of the side surfaces 22, 24 beyond the sides 18, 20 of the web members 12 creates a first ledge 26 and a second ledge 28 on a top surface of the enlarged square portion defined by the top chord 14. The ledges 26, 28 support concrete planks (to be later described) that are used to form the floors and ceilings in the building. Preferably, each side surface 22, 24 projects beyond the respective side surface 18, 20 of the web members 12 the same distance d1. The enlarged square portion of the top chord 14 also includes a height htc measured from a downwardly facing surface of the top chord 14 to the top surface of the enlarged square portion of the top chord, as illustrated in
The top chord 14 also includes a flange 30 that projects upwardly from the top surface of the enlarged square portion. For long trusses, for example the truss 10 having a length lt of about 45 feet to about 70 feet as described above, the flange 30 provides added strength to the top chord 14 to help maintain the rigidity of the top chord 14 and the truss 10. The flange 30 also helps to separate the planks 40 which are described in detail below. The flange 30 has a thickness tf that is substantially equal to the thickness tw of the web members 12, and a height hf from the top surface of the enlarged square portion of the chord 14 to the top surface of the flange 30. In the illustrated embodiment, the height hf is between about 7.0 and about 11.0 inches.
With continued reference to
The protrusion of the side surfaces 32, 34 beyond the sides 18, 20 of the web members 12 creates a first ledge 36 and a second ledge 38 on a top surface of the enlarged square portion defined by the bottom chord 16. The ledges 26, 28 support the concrete planks 40. Preferably, each side surface 32, 34 projects beyond the respective side surface 18, 20 of the web members 12 the same distance d2. The enlarged square portion of the bottom chord 16 also includes a height hbc measured from the top surface of the enlarged square portion of the bottom chord 16 to a bottom surface of the bottom chord, as illustrated in
As described above, the web members 12 preferably extend between the top and bottom chords 14, 16. However, at the location(s) of the truss 10 where an opening is formed, as discussed further below, the bottom chord 16 includes a flange 39 that projects upwardly from the top surface of the enlarged square portion of the chord 16 between adjacent web members 12. The flange 39 provides added strength to the bottom chord 16 at the location(s) where an opening is formed. The dimensions of the flange 39 are identical to the dimensions of the flange 30 on the top chord 14, and are not further described in detail.
The ledges 26, 28, 36, 38 are used to support precast, hollow-core concrete planks 40 that form a floor and/or a ceiling. Precast, hollow-core concrete planks are known in the art. With reference to
The planks can be supported by the top and bottom chords in other manners as well. For example, steel plates could be embedded in the top and bottom chords at the time of manufacture, or otherwise be attached to the top and bottom chords, with the plates projecting from the chords to support the planks thereon. Further, the support scheme shown in
Returning to
The members 42 preferably comprises strands, for example steel cable or carbon fiber strands. Alternatively, the members 42 can comprise steel bars. In the illustrated truss 10, the members 42 comprise strands of steel cable, with the top chord 14 illustrated as including eight strands, two of which are disposed in the flange 30, and the bottom chord 16 illustrated as including fourteen strands, two of which are positioned so that they extend through the flanges 39 and the lowermost portions of the web members 12. A larger or smaller number of strands could be used, depending upon, for example, the desired load bearing capacity of the truss. Each of the strands in the illustrated embodiment has a diameter of about 0.5 inches. However, other strand diameters, either smaller or larger than about 0.5 inch, could be used.
The members 42 are preferably embedded in the concrete during casting of the truss 10. The truss 10 is cast in a mold using concrete casting techniques known to those of skill in the art. When forming the truss 10, the members 42 are placed under tension by applying a tension force to each end of the strands. The high strength concrete is then poured into the mold. Once the concrete is cured, the tension force on the members 42 is released, so that the members 42 apply a compression force to the top and bottom chords 14, 16 of the truss 10. In the illustrated truss, the compression force applied by the members 42 is about 25,000 pounds each. However, other compression force values could be used.
Although not illustrated, the truss 10 also preferably includes reinforcing elements, for example metal reinforcing bars, embedded in the concrete of the web members 12 and the chords 14, 16. The location and configuration of the reinforcing elements will vary based upon, for example, the anticipated loading on the truss 10 during use. The design and placement of reinforcing elements in concrete is well known in reinforced concrete design. A person of skill in the art, having read this specification, would be able to design the truss 10 with suitable reinforcement.
Turning to
The opening 44 is preferably formed between the chords 14, 16 and between adjacent web members 12. In the illustrated embodiment, the opening 44 extends from the bottom chord 16 to the top chord 14. However, the opening 44 need not extend completely between the chords 14, 16. The opening 44 could extend only partially the distance between the top and bottom chords 14, 16.
The opening 44 has a length lo and a height ho and is generally rectangular in shape. The length and height of the opening 44 can vary depending upon, for example, the desired size of the corridor and local building codes. For a corridor passage, it is expected that the length lo will be at least about 48 inches, and the length lo could be as large as about 10 feet or more. In addition, for a corridor passage, the height ho will typically be at least about 80 inches, and the height ho can be as large as about 9 feet or more. If the opening 44 is to form a passageway other than for a corridor, such as for a doorway or a window, the length lo and height ho dimensions would likely be different.
Additional openings 46a, 46b can also be formed in the truss 10. The openings 46a can form, for example, a corridor or walkway passageway in those instances when, for example, the corridor of the building is angled so that the central openings 44 are not aligned or when the corridor turns a corner. The openings 46b are generally in locations where there is unnecessary concrete that is not needed for the truss 10 to function properly. The openings 46b reduce the weight of the truss 10 and reduce the amount of concrete that is used, thereby reducing material costs. The openings 46b, as well as the openings 46a, could also be used to accommodate mechanical and electrical components in the building, such as ducting and wiring.
Once the columns 52 are anchored in place, the trusses 10 are installed so that each end of each truss is supported by the columns 52, as illustrated in
After the trusses are in place, the planks 40 can then be installed. Floor 1, which can be, for example, a hotel lobby, is defined between a floor 54 and the planks 40 supported by the bottom chord 16 of the truss 10 on Floor 2. The floor 54, which may be a precast double-tee, is preferably installed after the columns 52 have been erected. The planks 40 supported by the bottom chord 16 of the truss 10 on Floor 2 thus form a ceiling for Floor 1. For Floor 2, the planks 40 supported by the bottom chord 16 form a floor, while the planks 40 supported by the top chord 14 form a ceiling for Floor 2. For Floor 3, the planks 40 supported by the top chord 14 of the truss on Floor 2 form a floor, while the planks 40 supported by the bottom chord of the truss on Floor 4 form a ceiling for Floor 3. Because the planks 40 form a ceiling for one floor and a floor for the next floor immediately above, the trusses 10 can alternate every other floor as shown.
Once the planks 40 are in place, exterior, non-load bearing walls 58 of the building 50 are then installed, as shown in
A concrete slab 55 can be poured at any convenient time in the building process, for example after the planks 40 are installed, to produce a surface suitable for underground parking.
Other floor configurations are possible. Because load bearing walls, like the trusses 10, are difficult to remove, they are generally permanent. However, the relatively large space defined between the trusses allows relatively easy reconfiguration of the floor layout by reconfiguring the non-permanent, non-load bearing walls. Therefore, with the trusses 10, buildings can be constructed where the space between the trusses 10 on a floor can be left open. A person intending to occupy the space can then have the floor configured in the desired way by having non-permanent interior walls installed. Thereafter, changes to the floor layout can be made by reconfiguring the non-permanent interior walls.
The trusses 10 are shown in
When used to form an exterior load bearing wall, the trusses 100 will be configured slightly different than the trusses 10 in
Returning to
An alternative embodiment of a truss 200 is illustrated in
In another alternative embodiment of a truss 250, illustrated in
The above specification and examples provide a complete description of the manufacture and use of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.
This application is a Continuation of application Ser. No. 10/360,355, filed on Feb. 6, 2003, now U.S. Pat. No. 7,010,890.
Number | Name | Date | Kind |
---|---|---|---|
1273344 | Evers | Jul 1918 | A |
1340291 | Pratt | May 1920 | A |
1418297 | Goodrich | Jun 1922 | A |
1538293 | Loyeau | May 1925 | A |
1543848 | Henderson | Jun 1925 | A |
1764134 | Young | Jun 1930 | A |
1928748 | Young | Oct 1933 | A |
1938887 | Young | Dec 1933 | A |
1990001 | Rutten | Feb 1935 | A |
1990156 | Young | Feb 1935 | A |
2004991 | Klotz | Jun 1935 | A |
2043697 | Deichmann | Jun 1936 | A |
2049926 | Rafter | Aug 1936 | A |
2151267 | Finsterwalder | Mar 1939 | A |
2435998 | Cueni | Feb 1948 | A |
2786349 | Coff | Mar 1957 | A |
3074209 | Henderson | Jan 1963 | A |
3323263 | Adams | Jun 1967 | A |
3349527 | Bruns | Oct 1967 | A |
3362121 | Weber | Jan 1968 | A |
3530626 | Mezes | Sep 1970 | A |
3577504 | Lipski | May 1971 | A |
3686819 | Atkinson | Aug 1972 | A |
3712008 | Georgiev et al. | Jan 1973 | A |
3722159 | Kessler | Mar 1973 | A |
3732650 | Gwilliam et al. | May 1973 | A |
3772835 | Cox et al. | Nov 1973 | A |
3800490 | Conte | Apr 1974 | A |
3818671 | Matsushita et al. | Jun 1974 | A |
3824754 | Fatosme et al. | Jul 1974 | A |
3834681 | Fordyce et al. | Sep 1974 | A |
3844081 | Bergvall et al. | Oct 1974 | A |
3894370 | Parazader | Jul 1975 | A |
3898757 | Gentert | Aug 1975 | A |
4048769 | van der Lely et al. | Sep 1977 | A |
4144686 | Gold | Mar 1979 | A |
4187652 | Bobrovnikov et al. | Feb 1980 | A |
4282619 | Rooney | Aug 1981 | A |
4282690 | Meheen | Aug 1981 | A |
4457118 | Bowen | Jul 1984 | A |
4513465 | Schambeck | Apr 1985 | A |
4583336 | Shelangoskie et al. | Apr 1986 | A |
4649588 | Taylor | Mar 1987 | A |
4653237 | Taft | Mar 1987 | A |
4700519 | Person et al. | Oct 1987 | A |
5161340 | Wetton | Nov 1992 | A |
5195204 | Muller et al. | Mar 1993 | A |
5305572 | Yee | Apr 1994 | A |
5444913 | Nyitray | Aug 1995 | A |
5491861 | Penuela | Feb 1996 | A |
5655349 | Ghali et al. | Aug 1997 | A |
5671573 | Tadros et al. | Sep 1997 | A |
5727272 | Peter | Mar 1998 | A |
5761862 | Hendershot et al. | Jun 1998 | A |
5782047 | De Quesada | Jul 1998 | A |
5806264 | Boot | Sep 1998 | A |
5867963 | Hershey | Feb 1999 | A |
6073413 | Tongiatama | Jun 2000 | A |
6568139 | Bot | May 2003 | B2 |
6915615 | Won | Jul 2005 | B2 |
7010890 | DeSutter | Mar 2006 | B2 |
20010039773 | Bot | Nov 2001 | A1 |
20030182883 | Won | Oct 2003 | A1 |
20040216249 | El-Badry | Nov 2004 | A1 |
20060272267 | Mentado-Duran | Dec 2006 | A1 |
Number | Date | Country |
---|---|---|
0 188 395 | Jul 1986 | EP |
1 031 420 | Mar 1953 | FR |
1 031 420 | Jun 1953 | FR |
2 532 352 | Mar 1984 | FR |
10-159173 | Jun 1998 | JP |
410159173 | Jun 1998 | JP |
2000-291192 | Oct 2000 | JP |
Number | Date | Country | |
---|---|---|---|
20060059803 A1 | Mar 2006 | US |
Number | Date | Country | |
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Parent | 10360355 | Feb 2003 | US |
Child | 11253989 | US |