WO2008140521A1

WO2008140521A1 - Composite construction beam

Info

Publication number: WO2008140521A1
Application number: PCT/US2007/068734
Authority: WO
Inventors: William D. Liddell; Guenter W. Sengel
Original assignee: International Contractors Services Llc
Priority date: 2007-05-11
Filing date: 2007-05-11
Publication date: 2008-11-20
Also published as: US20090249742A1

Abstract

A composite construction beam comprising a first chord and a second chord connected by a web, wherein the first and second chords are made of wood or a wood product and the web is made of a material other than wood or a wood product such as polymer or aluminum. A method of constructing a composite beam includes forming a web from a material other than wood or a wood product and securing it to a first and second chords, which are made of wood or a wood product.

Description

Composite Construction Beam

BACKGROUND OF THE INVENTION

Construction beams or girders, elongated beams frequently with an I-shape, are widely used in the construction industry. These construction components may be used for temporary or permanent support of horizontal structures. For example, these beams may be used to support horizontal concrete slab constructions. These beams may furthermore be used as either a primary support, or stringer, or as secondary supports or joists, which run perpendicular to and are supported by, a stringer.

A wide variety of materials have been used in the past for construction beams. Among these are steel, aluminum, and wood. Steel girders or I-beams have long been used in construction. Aluminum beams have also found usage. Lumber has also been used for joists and stringers in construction for many years. More recently, I-beams have been engineered from engineered wood products such as particle board or fiberboard. Another wood beam that has found use in recent years is an engineered wood I-beam containing a wood or wood fiber web or vertical element, inserted into a pair of wood horizontal flanges.

These construction beams each have drawbacks to their usage. While steel is certainly durable and resistant to damage from environmental conditions, its cost and weight make it unsuitable for some applications. Aluminum is lighter than steel, but it is also subject to more physical damage due to its greater ductility. Wood and wood products are light weight and relatively inexpensive, but are also subject to physical damage from abuse and weather conditions. Wood can also vary in its properties, since it is a natural product.

There is, therefore, a need for an alternative construction beam.

SUMMARY OF THE INVENTION

A composite construction beam comprises wood chords connected by a metal or plastic web. In one example, the web is aluminum. In another example, the web comprises four walls enclosing a cavity, hi another example, the four walls of the web extend beyond the cavity enclosed by the four walls. Stated another way, the walls of the web extend perpendicularly from the area enclosed by the walls on all four sides. The web has a height, a width and a length. The dimensions of the web, and therefore the length of the beam itself, may vary according to the demands of a particular application. The walls that extend upward and downward from the web may protrude into the chord or flange. The chord may be wood or a wood product, which extends along the length of the web. It is also envisioned that the web may be made of a polymer.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is cross sectional view of an example of a composite construction beam; and Fig. 2 is a side perspective view of an example of a composite construction beam.

DETAILED DESCRIPTION OF THE INVENTION

The following examples should not be viewed as limiting the scope of the invention. The claims will serve to define the inventions. In the following description, the composite construction beam will be described relative to a standard orientation of an "I-beam" in use, with a first flange or chord referred to as a "top" chord and a second flange or chord referred to as a "bottom" chord.

A composite construction beam comprises a pair of wood chords or flanges, connected by a metal or plastic web. In one example, shown in Figs. 1 and 2, a composite construction beam 10 comprises top chord 20 and bottom chord 22 connected by a web 15. Web 15 comprises four walls enclosing a cavity 11, namely first 12 and second 14 side walls, a top wall 16 and a bottom wall 18. The first and second side walls 12, 14 may extend beyond cavity 11 so that they extend into top 20 and bottom 22 chords, located above and below the web respectively. First and second side walls 12, 14 may extend at least about 30, 40, 50, 60, 70, or 80 percent or more into top and bottom chords 20, 22. In one particular example, first and second side walls extend about 50 percent into top and bottom chords 20, 22. Side walls 12, 14 may be secured in place by glue (not shown), or by pins 28 inserted through the chords and side walls 12, 14, or similar methods or combinations thereof. In one particular example, pins 28 are spaced apart about 19 inches (48 cm) on center. Other spacings may also be used, such as any spacing between 12 inches (30.5 cm) and 24 inches (61 cm).

Top wall 16 may extend beyond the side walls 12,14 and adjoin the top chord 20 along a majority of the bottom surface 24 of top chord 20 and the bottom wall 18 may extend beyond the side walls 12,14 and adjoin the top surface 26 of the bottom chord 22. Top and bottom walls 16, 18 may extend along at least about 60, 65, 70, 75, 80, 85, 90, 95, or even about 100 percent of the adjoining surface of top and bottom chords 20, 22, respectively. In one particular example, top and bottom walls 16, 18 may extend along about 91 percent of the adjoining surface of top and bottom chords 20, 22, respectively.

The thickness of first and second side walls, top wall and bottom wall 12, 14, 16, 18 may also vary according to the requirements of a particular application. In some examples, first and second side walls, top wall and bottom wall 12, 14, 16, 18 are between about 0.05 inches (1.3 mm) and about .5 inches (1.3 cm) thick, hi one particular example, one or more of walls 12, 14, 16, 18, are about 0.094 inches (2.4 mm) thick + 0.015 inches (0.4 mm). In some examples, the widths of walls 12, 14, 16, 18, are at least approximately identical. In other examples, it is envisioned that the widths of side walls 12, 14 may differ from the widths of top wall 16 and bottom wall 18.

In one particular example, when web 15 is viewed in cross section, side walls 12, 14 define an overall height of about 6 inches (15.2 cm) and top and bottom walls 16, 18 define an overall width of about 2.9 inches (7.4 cm). Side walls 12, 14 and top and bottom walls 16, 18 enclose a cavity about 1 inch (2.5 cm) wide and about 4.7 inches (11.9 cm) high. Top and bottom walls 16, 18 extend about 0.84 inches (2.1 cm) past side walls 12, 14. Similarly, side walls 12, 14 extend about 0.65 inches (1.6 cm) past top and bottom walls 16, 18. Each of walls 12, 14, 16, 18 is about 0.1 inches (.25 cm) thick. Chords 20, 22, in cross section, are about 1.5 inches (3.8 cm) in height and about 3.15 inches (8.0 cm) in width. Side walls 12, 14 are inserted into chords 20, 22 and top and bottom chords 20, 22 adjoin top and bottom walls 16, 18, respectively. Web 15 maybe secured in top and bottom chords 20, 22 with the use of glue (not shown), pins 28 inserted into chords 20, 22 and through side walls 12 and 14 , or both glue and pins 28. Other methods of securing web 15 to chords 20, 22 may also be used. In another example, when web 15 is viewed in cross section, side walls 12, 14 define an overall height of about 6.52 inches (16.6 cm) and top and bottom walls 16, 18 define an overall width of about 2.86 inches (7.3 cm). Side walls 12. 14 and top and bottom walls 16, 18 enclose a cavity about 0.98 inch (2.5 cm) wide and about 4.65 inches (11.8 cm) high. Top and bottom walls 16, 18 extend about 0.84 inches (2.1 cm) away from side walls 12, 14. Likewise, side walls 12, 14 extend about 0.84 inches (2.1 cm) past top and bottom walls (16, 18). Each of walls 12, 14, 16, 18 is about 0.1 inches (.25 cm) thick. Chords 20, 22, in cross section, are about 1.675 inches (4.3 cm) in height and about 3.15 inches (8.0 cm) in width.

Gussets or reinforcing beads 19 may be present at one, two, three or all four inside joints, that is, the joints facing cavity 11, where side walls 12, 14 meet top and bottom walls 16, 18. Alternatively or in addition, reinforcing beads or gussets 19 may be present on one or more of the outside joints where side walls 12, 14 meet top and bottom walls 16, 18. In one particular example, the reinforcing beads or gussets form an arc having a radius of about 0.19 inches (0.5 cm). Reinforcing beads or gussets with other radii may also be used, such as, for example, 0.03 inches (0.8 mm), 0.05 inches (1.3 mm), 0.3 inches (0.8 cm) or 0.5 inches (1.3 cm). Other dimensions of the reinforcement may also be used. As with the previous example, side walls 12. 14 are inserted into chords 20, 22 and top and bottom chords 20, 22 adjoin top and bottom walls 16, 18, respectively.

In still another example, web 15 comprises side walls 12, 14 defining an overall web height of about 6.03 inches (15.3 cm) and an overall width of 2.875 inches (7.3 cm) inserted into the longest sides of a pair of chords having dimensions of 3.15 inches (8.0 cm) by 1.675 inches (4.3 cm). Side walls 12, 14 and top and bottom walls 16, 18 enclose a cavity about 1.0 inch (2.5 cm) wide and about 4.5 inches (11.4 cm) high. Top and bottom walls 16, 18 extend about 0.84 inches (2.1 cm) away from side walls 12, 14. Side walls 12, 14 extend about 0.66 inches (1.7 cm) past top and bottom walls (16, 18). Each of walls 12, 14, 16, 18 is about 0.1 inches (2.5 mm) thick. Chords 20, 22, are about 1.675 inches (4.3 cm) in height and about 3.15 inches (8.0 cm) in width. Reinforcing beads 19 are present at all four inside joints where side walls 12, 14 meet top and bottom walls 16, 18, providing a radius of 0.05 inches (1.3 mm). Additionally, reinforcing beads 19 are also present on all 12 of the remaining outer joints where side walls 12, 14 meet top and bottom walls 16. 18. Each of the reinforcing beads on the outer joints of web 15 provides a radius of approximately 0.03 inches (0.8 mm).

A set of several composite construction beams was made with an aluminum web having an overall height of 6.03 inches (15.3 cm) and an overall width of 2.875 inches (7.3 cm) inserted into a pair of chords 3.15 inches (8.0 cm) by 1.675 inches (4.3 cm) in dimension, as described above. The beams were tested for deflection under defined loads by placing the beam between supports placed 7 feet, 10.5 inches (240 cm) apart with the load applied to a 28 inch (71 cm) section in the center of the beam. A control beam of a commercially available engineered wood girder (Klenk HoIz AG, Oberrot, Germany) of similar dimensions was also tested. The amount of deflection for the load applied in the test is provided in Table I.

TABLE I

Deflection for Load Applied

Sample 1 was assembled with glue and pins securing the web in the chords. Samples 2-4 utilized only pins to do the same. In samples 1-4, the pins were spaced from each other 19 inches (48.3 cm) on center. While not wishing to condition patentability on any particular theory, the variations between samples in deflection are believed to be due primarily to variations in the wood chords used. As a natural product, the wood used in the chords can vary in strength and other properties according to species and grade as well as simply varying from piece to piece. This indicates that the composite construction beam is an improvement on prior construction beams, since the composite construction beam eliminates one source of natural variation in wood quality by utilizing an aluminum web.

The maximum load bearable by a composite girder was also determined. The average maximum load for the above samples was 11862.5 lbs (5381 kg), which compares favorably to the capacity of an all lumber construction beam. Furthermore, the composite girder shows improved performance in other parameters. The composite girders show about 50 percent greater shear strength than wood girders and greater than 100 percent greater tension strength as determined as follows.

The shear strength of a 12 inch section of a composite girder was tested by placing the girder section on a solid, unyielding base surface and applying a load to the top surface of the girder until the girder failed, i.e. until the web portion of the composite girder buckled. The load was applied to a 4 inch (10.2 cm) square plate placed on top of the girder and the load was applied through a round bar to distribute the load equally across the girder. The ultimate load that caused failure of the web was 14,900 pounds (6759 kg). This represents an approximately 50 percent increase in shear strength over prior all wood girders of similar design.

The tension strength of the composite girder was tested in two different ways. In the first tension test, a series of three 18 inch (45.7 cm) sections of composite girder were assembled by stacking the sections, with the second (middle) composite girder section in the series oriented approximately perpendicular to both the first composite girder section and the third composite girder section (i.e., the first and third girder sections were approximately parallel). The bottom composite girder section was secured in the testing machine by clamping the entire length of the bottom chord and bottom wall ( 18 in Fig 1 ) of the aluminum web in the testing machine. The top composite girder section was similarly secured in the testing machine, by clamping the entire length of the top chord and the top wall (16 in Fig. 1) of the aluminum web in the testing machine. The middle composite girder section was clamped at approximately right angles to each of the top and bottom composite girder sections by a pair of clamps. One pair of clamps encompassed the top chord and top wall of the web of the bottom girder section and the bottom chord and bottom wall of the web of the middle girder section; each clamp flanking the girders on opposite sides. Similarly, the second pair of clamps attached the middle girder section to the top girder section, encompassing the top chord and top wall of the web of the middle girder section and the bottom chord and bottom wall of the web of the top girder section, with the two clamps within the pair being located on opposite sides of the girder sections. The test involved applying force to attempt to pull the assembled girder sections apart. In this test, an ultimate tension of 2,950 pounds (1338 kg) was applied when the clamps failed, rather than any of the girder sections.

A second tension test was then performed as described above, but with two composite girder sections (18 inches (45.7 cm) long) arranged one on top of another, approximately perpendicular to each other. As with the previous tension test, the bottom composite girder section was secured in the testing machine by clamping the entire length of the bottom chord and bottom wall of the aluminum web in the testing machine and the top composite girder section was secured in the testing machine by clamping the entire length of the top chord and the top wall of the aluminum web in the testing machine. The top and bottom girder sections were then clamped together with a series of four clamps. Again the testing machine attempted to pull the top and bottom beam apart and again, the clamps failed prior to the composite beam failing. In this particular test, the ultimate tension was 4,950 pounds (2245 kg) when the clamps failed. This represents greater than 100 percent improvement over prior wood girders.

A composite beam of the type described herein may be constructed by forming a web of a material other than wood or wood products and securing the web to a first and a second chord made of wood or wood-product. In one example the web is aluminum and may be formed as a single piece by extrusion or other similar methods . It is also envisioned that a polymer web may also be used. The web may be secured to the first and second chords with glue, pins or a combination thereof. The web may comprise first and second side walls that project into and are attached to the first and second chords. The web may also include an aluminum top wall and an aluminum bottom wall. The top wall and the bottom wall may intersect the first and second side walls, enclosing a cavity. The web may also include one or more reinforcing beads or gussets located at the intersection of the side walls with the top and bottom walls.

A composite beam as described herein may be used in a method of construction to support a structure. As provided above, the composite beam used in such a method comprises a first chord and a second chord connected by a web. The first chord and second chord are made of wood or wood products and the web is made of a material other than wood or wood products such as polymer or metal as described above.

Based upon the foregoing disclosure, it should now be apparent that the composite construction beam will carry out the objects set forth hereinabove. It is, therefore, to be understood that any variations evident fall within the scope of the claimed invention and thus, the selection of specific component elements can be determined without departing from the spirit of the invention herein disclosed and described.

Claims

CLAIMS We claim:

1. A composite construction beam comprising a first chord and a second chord connected by a web, wherein the first and second chords are made of wood or a wood product and the web is made of a material other than wood or a wood product.

2. The composite construction beam of claim 1, wherein the web comprises at least one aluminum wall that projects into and is attached to the first and second chords.

3. The composite construction beam of claim 1, wherein the web comprises first and second aluminum side walls that project into and are attached to the first and second chords.

4. The composite construction beam of claim 3, wherein the web additionally comprises an aluminum top wall and an aluminum bottom wall, wherein the top wall and bottom wall intersect the first and second side walls, enclosing a cavity.

5. The composite construction beam of claim 4, wherein the top and bottom walls project from the first and second side walls and adjoin the first and second chords.

6. The composite construction beam of claim 3, wherein the web additionally comprises one or more gussets or reinforcing beads located at the intersection of the side walls with the top wall, the bottom wall or both.

7. The composite construction beam of claim 4, wherein the web is a unitary, extruded structure.

8. A method of construction comprising utilizing a composite construction beam to support a structure, wherein the composite construction beam comprises a first chord and a second chord connected by a web, wherein the first and second chords are made of wood or a wood product and the web is made of a material other than wood or a wood product.

9. The method of claim 8, wherein the web comprises at least one aluminum wall that projects into and is attached to the first and second chords.

10. The method of claim 8, wherein the web comprises first and second aluminum side walls that project into and are attached to the first and second chords.

11. The method of claim 10, wherein the web additionally comprises an aluminum top wall and an aluminum bottom wall, wherein the top wall and bottom wall intersect the first and second side walls, enclosing a cavity.

12. The method of claim 11 , wherein the top and bottom walls project from the first and second side walls and adjoin the first and second chords.

13. The method of claim 11, wherein the web additionally comprises one or more gussets or reinforcing beads located at the intersection of the side walls with the top wall, the bottom wall or both.

14. The method of claim 11, wherein the web is a unitary, extruded structure.

15. A method of making a composite construction beam, the method comprising: forming a web of a material other than wood or wood products; and securing the web to a first chord and a second chord made of wood or a wood product.

16. The method of claim 15, wherein the web is aluminum.

17. The method of claim 15, wherein the web is formed by extrusion.

18. The method of claim 16 wherein the web is secured to the first and the second wood chords by pins, glue or a combination thereof.

19. The method of claim 18 , wherein the web comprises first and second aluminum side walls

m that project into and are attached to the first and second chords.

20. The method of claim 19, wherein the web additionally comprises an aluminum top wall and an aluminum bottom wall, wherein the top wall and bottom wall intersect the first and second side walls, enclosing a cavity.

21. The method of claim 20, wherein the web additionally comprises one or more gussets or reinforcing beads located at the intersection of the side walls with the top wall, the bottom wall or both.