The present invention pertains to concrete construction of buildings or other structures. In particular, the sustainable form-inclusion system described herein is designed to replace concrete not needed in the building structure, while using waste material that might otherwise be placed in landfills. In framed structures, the inclusion system is placed in areas of the structure that are dominated by bending rather than shear behavior. Concrete typically placed in these areas, either cast-in-situ or precast, provides little or no structural benefit, only adding weight to the structure. The present inclusion system preferably uses recycled material assembled and incorporated into the structure, with little or no additional energy required to reconfigure the material before placement in the structure.
Structures have been constructed, and are being constructed daily, with concrete. These structures are constructed on-grade as well as being suspended in framed structures. These structures must be designed to resist gravity loads as well as loads caused by wind and seismic events. In many areas of the structure, concrete is placed during the process of building, but because of the location where the concrete is placed, the concrete provides no structural benefit.
Precast long-span framing systems frequently use shapes for framing elements that optimize the structure. This can be accomplished by T-shaped framing elements or slab systems with hollow cores. The hollow core planking system Spancrete Hollowcore Plank uses open sections along the length of the structural element to eliminate the need for concrete in center areas of the section while reducing weight.
Inclusion systems have been introduced into both on-grade structures and framed structures. In many cases, lost forms are introduced. These forms mostly consist of elements that frame voids where concrete is not required. The framing for these voids has included framed wood, fabricated Styrofoam or similar materials, and some plastics. In these cases, raw materials are used to create the inclusion.
Other systems have introduced inclusions into the structure during the casting process. These inclusions have consisted of products such as “Sonovoid”—a capped Sonotube system. Other systems such as Bubbledeck include preformed, fabricated balls that require a considerable amount of embodied energy to create the inclusion elements.
What is needed is an environmentally sustainable form-inclusion system. That need is satisfied by the present invention.
The present invention is an environmentally sustainable form-inclusion system that can be utilized in concrete structures, and in other structures as well. The sustainable form-inclusion system can be incorporated into steel and/or composite reinforced concrete structures, either suspended or constructed on-grade.
The inclusion system may be placed in structures that are or cast-in-situ or are partially or wholly precast. The inclusion system is placed to eliminate concrete where it is not required for the structure, and to utilize waste products that might otherwise be placed in landfills.
In many structures, there are areas that require little or no concrete, with the concrete being placed only for ease of construction. In addition, in order to achieve long structural spans without vertical support (at columns or walls), beams and girders are typically used for framing. Flat reinforced concrete slabs usually span between framing members. These structures require a considerable amount of material and labor to construct, each requiring special formwork systems to be assembled and disassembled. These framing members usually create obstacles in occupied structures, particularly related to building service system distribution and clear heights for ceilings. In addition, future space partitions are difficult to incorporate because of geometric coordination.
The present sustainable form-inclusion system provides voids within the structure, allowing for flat-formed bottoms to the structure while creating a built-in framing system without the rigorous effort of fabricating internal forms. Long-span structural conditions can be achieved with total structural depth less than that for a conventionally framed beam and slab structure. As with beam and slab construction, the present sustainable form-inclusion structure may incorporate conventional mild reinforcing steel and/or high-strength pre-stressed cables.
The present sustainable form-inclusion system may be arranged in various geometries within the concrete structure. In a framed structure, the inclusion system may be placed either in a two-way cellular layout or a one-way continuous cell layout, or a combination of both. In a two-way slab system, the concrete placed in two intersecting middle strips of the structure, generally the central area of the structure located halfway between vertical supports, is an area primarily subject to bending, with a small magnitude of shear due to gravity and superimposed loads. This area requires concrete to provide bonding and continuum for reinforcing steel and only a minimal amount of shear resistance, since the shear load is nearly non-existent. The present inclusion system is placed with high concentration in these areas. On the other hand, in this same system, concrete is essential for the structure in a two-way slab framing system near vertical supports. Here shear is highest, and concrete is required to transfer load from the frame system to the vertical support. The inclusion system is placed with relatively low concentration in these areas. In a similar manner, the sustainable form-inclusion system can be placed in one-way slab or beam systems, where the highest concentrations of the form-inclusion are located in areas of low shear forces, typically located away from supports, with the lowest concentrations near supports where shear is the highest.
The reduction in the structure's weight not only reduces the amount of concrete, but also reduces the amount of reinforcing steel or pre-stressing cables required. In addition, the structural demand to resist gravity loads is reduced. Since the weight is reduced, there is a reduction in seismic mass. Applied lateral loads from seismic events are less. The demand on vertical load carrying elements, such as columns and walls, is less. The demand on the foundation systems are also less, leading to less material required for construction. The present form-inclusion system can be placed in framed floor slabs, beams, columns, walls, fills, structures on grade, etc.
The fill used in the present inclusion system can include, but is not limited to, plastic bottles, bags, waste Styrofoam, packing materials, rubber tires, and other similar waste materials. These materials may be compressed or assembled into controlled shapes. The shapes of these forms can be spherical, square, rectangular, cylindrical; similar to spherical, square, rectangular, or cylindrical; or any other. Waste materials may be collected and assembled into these forms without reconfiguration. Plastic water bottles with caps create an internal air chamber with only partial compression when hydrostatic load due to concrete placement is applied, and can be assembled into units of an engineered geometry, tied, and placed in the structure. Plastics, rubber tires, or similar materials can be partially compressed, bundled, and wrapped in plastic or shrink-wrapped for placement in the structure. The plastic wrapping, shrink wrap, or similar process, maintains the general shape of the inclusion system, and prevents concrete from entering the inclusion system during the concrete pour.
The present light-weight inclusion system has the tendency to become buoyant during the placement of concrete. Therefore, the inclusion system must be restrained vertically during concrete pours, whether the pour is performed on-site or in precast plants. This restraint is achieved by using form-ties or similar devices commonly used in concrete construction.
Fire rating of suspended concrete framing systems is achieved through providing minimum concrete cover to all reinforcing, and by providing an overall framed assembly that meets fire rating requirements.
These and other more detailed and specific objects and features of the present invention are more fully disclosed in the following specification, reference being had to the accompanying drawings, in which:
As seen in
Accordingly, with the introduction of the sustainable form-inclusion system 10 into structures, optimum structural efficiency is achieved while using materials that might otherwise be placed in landfills. Materials are placed in engineered locations and densities to allow the required forces to transfer within the structure. Because the recycled material's density is considerably less than the reinforced concrete's density, the demand on the structure is reduced. Therefore, less structural concrete and steel reinforcing is required for the framed structure, and less structural concrete, reinforcing, and combination of concrete, reinforcing, and structural steel is required for vertical and lateral load-resisting structural elements, including but not limited to columns and walls. Since the mass of the structure is significantly reduced, the demand on the structure's lateral load-resisting system subjected to seismic loads is also reduced. The demand on the foundation system is also less, therefore requiring less structural materials to resist the imposed loads.
It will be understood that the above-described arrangements of apparatus and methods described above are merely illustrative of applications of the principles of this invention, and many other embodiments and modifications may be made without departing form the spirit and scope of the invention as defined in the claims.
For example, the sustainable form-inclusion system 10 described herein may be incorporated into other configurations of framed structures, including slabs spanning in one direction to beam framing consisting of reinforced concrete or structural steel. In addition, framed reinforced concrete slab systems may be supported on reinforced walls or columns consisting of structural steel or a combination of structural steel and concrete. The present sustainable form-inclusion system 10 can be used in reinforced concrete wall construction, in reinforced concrete or post-tensioned beams, and in structures used for roadway construction, such as roads and bridges.
The present sustainable form-inclusion system 10 may use alternate placement configurations based on structural framing conditions and demands. Alternate placements of the sustainable form-inclusion system embodiment 30 may be used in a column strip 14 and/or a middle strip 16 of the structure. The overall configuration does not have to be rectilinear, but may be radial or irregularly spaced. Reinforced concrete or post-tensioned beam framing may be used to span between reinforced concrete columns 12. This framing can include sustainable form-inclusion system embodiments 30. Reinforced concrete walls can be used to support the framed structure in lieu of the reinforced concrete columns 12, with these walls including sustainable form-inclusion system embodiments 30. Alternate recycled materials can be used as filler within sustainable form-inclusion system embodiments 30, including glass, rubber tires, Styrofoam, fiberglass, etc.
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