The present invention relates generally, to construction material, and more specifically, to a composite I-beam member used for light-framed construction.
This application claims the benefit of priority as a continuation-in-part to U.S. patent application Ser. No. 13/772,338, filed on Feb. 21, 2013, entitled COMPOSITE I-BEAM MEMBER, by WeiHong Yang, which claims the benefit of priority as a continuation-in-part to U.S. patent application Ser. No. 13/225,518, filed on Sep. 5, 2011, entitled COMPOSITE GUARDRAIL POSTS AND COMPOSITE FLOOR I-JOIST, by WeiHong Yang, and to U.S. patent application Ser. No. 12/804,601, filed on Mar. 19, 2010, entitled STEEL-WOOD COMPOSITE STRUCTURE WITH METAL JACKET WOOD STUDS AND RODS, by WeiHong Yang, the contents of each being hereby incorporated by reference in its entirety.
I-beams are shaped like the letter āIā to maximize the moment of inertia, which in turn maximizes its resistance to bending and deflection when used as a beam or floor joist. It is well known that I-beams are the most efficient structural members when subjected to bending, and they are widely used in both light-framed and heavy-duty constructions.
In light-framed construction, support for structures is conventionally provided by members composed of a single material, predominantly either wood or metal. These single-material members are often vulnerable to failure due to characteristics of the material. For examples, while wood is weak in tension and very vulnerable to fire and termite; a metal stud has inherent problems of pre-mature failure due to weak connection and local buckling. Conventional steel I-beams can be very heavy. Furthermore, use of certain materials can have a negative effect on the environment. For example, inefficient use of timber wastes trees, a valuable natural resource. Also, timber is often treated for use in exterior construction which can add pollutants to the environment. In another example, pressure treated wood produces a large volume of waste water with pollutants.
In heavy duty construction, composite techniques are often used to achieve higher structural performance. A composite structure combines different materials together to form a new structure. Since it fully utilizes the potential of individual materials, the advantages of composite structures have been well recognized in the engineering community during the past decades.
However, past applications, such as concrete-filled steel tubes and composite floor decks, mostly involve combining steel and concrete in various forms, and are primarily used in commercial buildings and infrastructures.
What is needed is to introduce composite techniques in light-framed construction to allow for lighter and stronger I-beam members.
The above needs are met by an apparatus, system, method and method of manufacture for a composite I-beam member.
In one embodiment, a confined top flange comprises a wooden core and a metal jacket wrapped around an outer perimeter of the wooden core and two inner side walls of an rectangular channel slotted along the longitudinal direction within the wooden core. The metal jacket is pre-stressed to confine the wooden core, providing a two-way lateral interaction. The two-way lateral interaction can be normal to the interface between the metal jacket and the wooden core and, when subjected to compression, provide an amount of support to the top flange surpassing the sum of amount of support provided by the metal jacket and the wooden core when being used separately.
A confined bottom flange comprising substantially a mirror image of the composite top flange. When subjected to tension, the metal jacket alone is capable to provide adequate tensile force to counteract the compressive force of the top flange.
A web board, either a regular wooden board or a composite laminated board, can have a top edge portion inserted into and locked with the confined top flange and a bottom edge portion inserted into and locked with the confined bottom flange using metal connectors. In one embodiment, the metal connectors can penetrate an entire width of the composite top and bottom flanges at, for example, the mid-height of inner side walls of the slotted channel. In other embodiments, the metal connectors can penetrate partially into the composite top and bottom flanges at either horizontal or diagonal directions. In one embodiment, localized composite action at the connection between the laminated web and confined flange can increase the capacity of the dowel connection significantly. This composite action is similar to the two-way lateral interaction of the flange, but at a localized region around each metal connector. In this case, the confinement effect is originated from the pre-compression of the metal connector, not the metal jacket. For example, tightening of a nut to a pre-compression when the metal connector is a bolt.
When the shear demand is small, in an embodiment, the web board comprises a wooden board. As the shear demand increases, the capacity provided by wooden board may become inadequate, then composite laminated web can be used to increase capacity and ductility under shear loading. When the shear demand is moderate, one-sided composite laminated board (i.e. a wooden board bonded on one side by one metal cover) may be adequate. However, when additional shear capacity is still needed for certain heavy duty application, sandwiched composite laminated web (i.e. a wooden board sandwiched between two metal covers, possibly made of light gauged sheet metal) can be employed to achieve highest composite performance.
For the composite laminated web, the wooden board provides lateral support to the metal sheet and prevent it from pre-mature lateral buckling, so that the metal sheet can develop the full tensile potential of the metal material, which is so-called one-way lateral interaction. The one-way interaction can also be normal to an interface between the outer metal sheets and the inner wooden board. When it is a wooden board, shear capacity is provide 100% by wooden board; when it is one-sided composite laminated board, the shear capacity is provided by both the metal sheet and the wooden board. When it is sandwiched composite laminated board, the shear capacity is mostly provided by the metal sheet, and the wooden board itself provide very little shear capacity if any at all.
The metal connectors may be bolts, screws, nails and/or staples in various embodiments. The bolts and/or screws may be applied horizontally. The screws, nails and/or staples may be applied diagonally.
Advantageously, the composite I-beam member is stronger than wood I-beams, and is also lighter than conventional steel I-beams.
In the following drawings like reference numbers are used to refer to like elements. Although the following figures depict various examples of the invention, the invention is not limited to the examples depicted in the figures.
An apparatus, system, method, and method of manufacture for a composite I-beam member, are described herein. The following detailed description is intended to provide example implementations to one of ordinary skill in the art, and is not intended to limit the invention to the explicit disclosure, as one of ordinary skill in the art will understand that variations can be substituted that are within the scope of the invention as described.
The member 100 can be a conventional I-beam configuration having a web, a top flange and a bottom flange, as is discussed below with respect to
The member 100 is configured as a confined top flange and a confined bottom flange coupled to either end of a composite laminated web. In one embodiment, the metal jacket 120A is wrapped around the top core 110A, in a pre-stressed manner, to provide a two-way lateral interaction. The interaction can be normal to an interface between the metal jacket 120A and the wooden core 110A. When the top core is subjected to compression, the two-way lateral interaction generates an amount of amount of support to the top flange that surpasses a sum of an amount of support provided by the metal jacket and the wooden core when being used separately. In other words, the two-way lateral interaction makes the composite top flange stronger than the individual components.
More specifically, the wooden core 110A fails at a certain pressure at which the wood dilates. As the wood dilates, splits within the wooden core 110 open up spaces that span the length or height by opening up spaces within. However, the metal jacket 120A resists the splitting action and maintains integrity in the wooden core 110A beyond the point of individual failure. As a result, the compressive strength and ductility of the top flange is increased.
Similarly, the metal jacket 120A fails at a certain pressure at which the metal buckles. As the metal buckles, rather than opening up spaces as does the wood, the metal folds over itself. In response, the wooden core 110A resists the buckling action and maintains integrity in the metal jacket 120A beyond the point of individual failure. Further, premature local buckling is prevented.
Metal jackets are wrapped around wooden cores. For example, the metal top flange 120A is wrapped around the wooden top flange 110A, and the other parts are similarly wrapped. In more detail, the metal top flange 120A wraps around surface portions of the wooden top flange 110A, and in some embodiments, along the inner side walls of a slotted channel spanning a length of the wooden top flange 110A. In some embodiments, the two opposing inner side walls of the slotted channel are wrapped while a third end side remains unwrapped. The metal top flange 120A is wrapped to generate a pre-stress for confinement of the wooden top flange 110A. The bottom flange 120B can be substantially a mirror image of the top flange 120A.
The wooden top and bottom flanges 110A and 110B are both slotted along the length to form a channel in the center of one surface. The flanges can be square (for example, as in
A height 125A,B of the metal flanges 120A,B determines how much of a rectangular channel of the wooden cores 110A,B is covered by metal. Some embodiments cover no or less than half of a channel height, some cover about half, and others cover more than half to almost all. The metal flange height 125A,B determines how many layers metal connectors 120D pierce, as described more below.
In an embodiment, the composite laminated web 120 comprises a wooden board sandwiched between two light-gauged metal covers. The wooden web 110C provides lateral support to the metal cover 120C and prevent it from pre-mature lateral buckling, so that the metal sheet can develop the full tensile potential of the metal material, which is so-called one-way lateral interaction. The one-way interaction can also be normal to an interface between the outer metal sheets and the inner wooden board. When subjected to shear force, the shear capacity is mostly provided by the metal sheet, and the wooden board itself provide very little shear capacity if any at all.
The composite laminated web 120 only accounts for shear force support. In one embodiment, the wooden web 110C is sandwiched by the metal cover 120C, and provide a one-way lateral interaction. The interaction can be normal to an interface between the metal cover 120C and the wooden web 110C. More specifically, the wooden web 110C provides lateral support to the metal cover 120C and prevent it from pre-mature lateral buckling, so that the metal cover can develop the full tensile potential of the metal material. The shear capacity is mostly provided by the metal sheet, and the wooden web 110C primarily help to increase the shear capacity of the metal cover, but the wooden web 110C itself provides very little shear capacity if any at all. In another embodiment, the composite action of the laminated web can increase the capacity of the dowel connection 120D significantly. The presence of wooden web 110C can prevent pre-mature tear-off failure of the metal covers, and the confinement effect of metal covers that may sandwich the wooden web 110C can significantly increase local bearing capacity of wooden web 110C, so that a much higher shear force can be reliably transferred between the composite laminated web 120 and flange through the connectors 120D.
In one embodiment, localized composite action at the connection between the composite laminated web 120 and confined flange can increase the connection capacity significantly. This composite action is similar to the two-way lateral interaction of the flange, but at a localized region around each metal connector. In this case, the confinement effect is originated from the pre-compression of the metal connector, not the metal jacket. For example, tightening of a nut to a pre-compression when the connector is a bolt.
As discussed above, the metal connector 120D can be applied in various manners to cross-section A-A of
Also discussed above, the metal connector 120D can penetrate various numbers of layers of cross-section A-A of
The metal covers 120A,B over top and bottom flanges 110A,B can have various configurations (e.g., metal cover flange height 125A,B within channel) on the inner channel which affect the number of layers the connecter 120D penetrates. With respect to
With respect to the circular top and bottom flanges 120A,B of
At step 1010, a confined top flange 110A is provided. The confined top flange can comprise a metal jacket 120A wrapped around an outer perimeter of a wooden core, and along the two inner side walls of a rectangular channel slotted along the wooden core. The metal jacket can be pre-stressed to confine the wooden core. The pre-stress generates a two-way lateral interactions that, in some embodiments, is normal to an interface between the metal jacket and the wooden core. The two-way later interaction allows the member to provide an amount of support surpassing a sum of amount of support provided by the metal jacket and the wooden core when being used separately.
At step 1020, a confined bottom flange 110B is provided. In an embodiment, the confined bottom flange is substantially a mirror image of the confined top flange 110A.
At step 1030, a composite laminated web (120C+110C+120C) is provided. The composite laminated web can have a top edge portion inserted into the slotted channel within the confined top flange 110A and a bottom edge portion inserted into the slotted channel within the confined bottom flange 110B. Then, the laminated web are locked to both top and bottom flanges using metal connectors 120D. The connectors can penetrate the top and bottom flanges in the middle-depth of the slotted channel along the length of the member in various manners as described above.
In summary, the overall load carrying capacity of the composite I-beam 100 is significantly increased through a list of composite actions occurring in the individual components and their connections. Specifically, (1) the compression capacity of the flanges 110A and 110B is increased through the two-way lateral interaction; (2) the tension capacity of the flanges is increased because metal has very high tensile capacity by nature; (3) shear capacity of the web 120 is increased through the one-way lateral interaction; and (4) the shear capacity of the connection is also increased through localized composite action similar to the two-way lateral interaction. The end result is a light weight composite I-beam that has very high strength and ductility.
The disclosure herein is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.
Number | Date | Country | |
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Parent | 12804601 | Mar 2010 | US |
Child | 13225518 | US |
Number | Date | Country | |
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Parent | 13772338 | Feb 2013 | US |
Child | 14541130 | US | |
Parent | 13225518 | Sep 2011 | US |
Child | 13772338 | US |