US20110036052A1

US20110036052A1 - Reinforced girder

Info

Publication number: US20110036052A1
Application number: US12/461,522
Authority: US
Inventors: Robert M. Callahan
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-08-14
Filing date: 2009-08-14
Publication date: 2011-02-17

Abstract

A reinforced girder including a first C-shaped member formed of sheet metal. A second C-shaped member, formed of sheet metal, is welded to the first C-shaped member to form a rectangular box. A first pair of metallic stringers is welded in a spaced-apart relationship within the first C-shaped member. The first pair of metallic stringers extends the length of the first C-shaped member. A second pair of metallic stringers is welded in a spaced-apart relationship within the second C-shaped member and extends the length of the second C-shaped member. A pair of first, metallic, transverse connectors is welded within the first C-shaped member between the first pair of metallic stringers. The first, metallic, transverse connectors radiate outwardly from a common point of contact at an angle. A pair of second, metallic, transverse connectors is welded within the second C-shaped member between the second pair of metallic stringers. The second, metallic transverse connectors radiate outwardly from a common point of contact at an angle.

Description

FIELD OF THE INVENTION

The present invention relates generally to static structures and, more particularly, to elongated, rigid structures such as girders, columns, etc., having a composite construction.

BACKGROUND OF THE INVENTION

Homebuilders are confronted with significant challenges in offering high-quality products at competitive prices. Design trends, fluctuations in lumber costs, and economic fluctuations often prevent builders from obtaining a reasonable profit for their work. In response to marketplace uncertainties, steel-framed home construction is becoming increasingly popular.
Homebuilders are attracted to the strength, termite resistance, and dimensional stability of steel. Steel materials being used in modern residential construction are also relatively lightweight and easy to handle. Therefore, homes with larger, open spaces; longer ceiling spans; and higher walls are possible.
Homes constructed with steel frames have proven to be more durable than those framed with wood. In areas vulnerable to hurricanes or earthquakes, steel is better able to withstand forces generated by winds and shifting earth. Further, because steel is non-combustible, homes constructed from steel easily comply with local building codes and fire regulations. Because it is termite proof, pesticide treatments are unnecessary. Health experts recommend steel framing for chemically sensitive homebuyers seeking the best possible interior air quality.
Most residential steel framing is assembled using the “stick-built” construction method. Stick-built construction, utilizing steel components, is similar to that involving wood. Layout and assembly are the same except for one crucial difference, steel components are joined together with screws rather than nails. Powered screwdrivers make it a snap to turn screws into steel framing members.

SUMMARY OF THE INVENTION

It is my principal object to provide a girder that is stronger and lighter than known structural members, whether made of metal or wood, of similar dimensions. My new, reinforced girder can, therefore, carry greater loads and extend across longer spans than conventional girders, joists, posts, and beams. My girder, therefore, can be used in buildings with few, if any, additional supports.
It is a further object of mine to provide a girder of the type described that is made of galvanized steel. Such a material is inherently resistant to corrosion and insect pests. It is also not combustible, making buildings constructed with my girders especially safe.
It is another object of mine to provide a girder that is easily trimmed in the field and installed in a building without resort to special tools or the need for prolonged training in their use. The girder is cut to a desired length with common tools, like reciprocating or circular saws, having metal-cutting blades. Threaded fasteners, like self-tapping screws, are employed to join the girder to another structural member. No welding is required.
It is still a further object of mine to provide a girder that is “green,” environmentally friendly, and can be made from recycled materials. There are few uses for recycled wood in new building projects. Recycled steel can be used in every component of my girder.
I wish to provide improved features and arrangements thereof in a reinforced girder for the purposes described which is lightweight in construction, inexpensive to manufacture, and fully dependable in use.
Briefly, my reinforced girder achieves the intended objects by featuring a pair of C-shaped channel members welded together to form a rectangular box. A pair of stringers is welded in a spaced-apart relationship into each of the C-shaped channel members. The stringers extend the lengths of the C-shaped channel members. A number of transverse connectors are welded between the stringers within each of the C-shaped channel members. The transverse connectors are arranged in pairs and oriented at acute angles to one another to form a strong, load-bearing truss.
The foregoing and other objects, features, and advantages of my reinforced girder will become readily apparent upon further review of the following detailed description of the girder as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

My invention can be more readily described with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a reinforced girder having portions broken away.

FIG. 2 is a longitudinal, cross-sectional view of the girder of FIG. 1 with portions broken away.

FIG. 3 is a lateral, cross-sectional view of the girder.

Similar reference characters denote corresponding features consistently throughout the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the FIGS., a reinforced girder is shown at 10. Girder 10 includes a pair of C-shaped, channel members 12 affixed to one another so as to form an elongated, open-ended, rectangular box. Stringers 14, affixed within the corners of the channel members 12, internally reinforce the box. Transverse connectors 16 are affixed within the channel members 12 and join the stringers 14 together, effectively locking stringers 14 in place.
Channel members 12 are cold-formed by bending a thin strip of galvanized steel sheeting into a C-shape. Channel members 12 include a pair of opposed end walls 18 affixed to, and extending at right angles from, an intermediate wall 20. Each channel member 12 also includes a pair of flanges 22 affixed to, and extending inwardly toward one another from, the free ends of end walls 18 in a common plane parallel to intermediate wall 20.
Channel members 12 are reinforced to better support expected loads without excessive bending and twisting. In this regard, a pair of steel rods or stringers 14 is affixed, as by welding or brazing, within each of the corners where intermediate wall 20 and end walls 18 meet. Stringers 14 extend the length of members 12 which may be any desired length. At set distances from one another, short pairs of steel rods or transverse connectors 16 are affixed, as by welding or brazing, at their ends to stringers 14 and between their ends to intermediate wall 20.
The paired connectors 16 have a single point of contact from which they radiate outwardly at an acute angle. The contact point is adjacent one of the stringers 14 and defines the apex of an inverted “V” clearly seen in FIG. 2. The inverted “V” pattern is repeated along the length of each channel member 12. If desired, the paired connectors 16 can be so tightly spaced that they zigzag from one end of each channel member 12 to the other end, forming a particularly strong, box truss. As shown, the connectors 16 affixed to one channel member 18 are positioned directly opposite the connectors 16 affixed to the other channel member 18, but this is a matter of design choice.
Connectors 16 are formed from the same material as stringers 14. One suitable type of material is rebar commonly used in reinforced concrete structures. Rebar is usually formed from carbon steel and is given ridges along its length for better mechanical anchoring. Since rebar has an expansion coefficient that is similar to that of channel members 12, no additional, longitudinal and perpendicular stresses develop within girder 10 at varying temperatures during use.
Most rebar is suitable for welding and is available in different grades that permit a builder to pick rebar with the right strength and chemical composition for a given job. Common rebar is made of unfinished, tempered steel making it susceptible to rusting. Common rebar is available at low cost and is usable where dry conditions are expected throughout the life of girder 10. Galvanized or stainless steel rebars are, thus, employed as stringers 14 and connectors 16 in damp situations where corrosion of girder 10 is more likely to occur. Although galvanized and stainless steel has a greater initial expense, it can greatly increase the service life of girder 10.
After affixing stringers 14 and transverse connectors 16 within channel members 12, channel members 12 are affixed to one another. To do this, channel members 12 are positioned side by side with flanges 22 of one channel member 12 in contact with the flanges 22 of the other channel member 12. Then, channel members 12 are welded or brazed together along the area of contact. The step of affixing the channel members 12 together requires only a few minutes to complete and leaves girder 10 ready to use. Since the steps of affixing the stringers 14 and connectors 16 in the channel members 12 similarly require only a few minutes time, it will be appreciated that girder 10 is rapidly constructed.
The use of girder 10 is straightforward as it withstands loads primarily by resisting bending forces imparted by gravity. The bending force is usually the result of the external loads and the weight of girder 10. Girder 10 can also carry horizontal loads, i.e., loads due to an earthquake or wind. The loads carried by girder 10 are transferred to other girders, walls, columns, or beams, which then transfer the loads to adjacent, structural, compression members. In light frame construction, one girder 10 can rest on another girder 10 and can serve as a joist, beam, or column.
Internally, girder 10 experiences compressive, tensile, and shear stresses as a result of applied loads. Typically, under the influence of gravity, the original length of girder 10 is slightly reduced to enclose a smaller radius arc at the top of girder 10, resulting in compression, while the same original length at the bottom of girder 10 is slightly stretched to enclose a larger radius arc, and so is under tension. The original length of the middle of girder 10, halfway between the top and bottom, is the same as the radial arc of bending, and so it is under neither compression nor tension.
The compressive, tensile and shear stresses generated within girder 10 are shared by channel members 12, stringers 14, and connectors 16. Without stringers 14 and connectors 16, channel members 12, joined along abutting flanges 22 to form a box, do not offer great resistance to bending under load. With the addition of stringers 14 and connectors 16, channel members 12 carry great loads and can be employed to span long distances without support between their ends.
Girder 10, being hollow, is lighter in weight than its conventional, wood counterparts of similar load-bearing capability. Thus, building structures, incorporating airy architectural designs, can be constructed with relative ease and minimal cost. Transporting girder 10 to a construction site is relatively easy because of its lightweight. If girder 10 is too long for a particular application, it can be cut to length with conventional saws. Sheet metal screws (not shown) are employed to secure girders 10 to other building members, such as headers and footers when used in a wall. If the sheet metal used to form channel members 12 is thick, it may be necessary to drill pilot holes in channel members 12 before the screws will penetrate.
While girder 10 has been described with a high degree of particularity, it will be appreciated by those skilled in the art that modifications can be made to it. For example, the dimensions of channel members 12, stringers 14 and connectors 16 can be varied to accommodate expected loads with larger features generally being more appropriate for higher loads. Furthermore, the number of connectors 16 employed between stringers 14 can be increased to boost the stiffness of girder 10. A lightweight and strong girder 10 can be made by locating a single pair of connectors 16 in an inverted “V” between the stringers 14 at the midpoint of each channel member 12. Finally, the diameter of rebar used in stringers 14 can be different from the diameter of rebar employed in connectors 16. The respective diameters can be selected to provide a balance of compressive, tensile, and shear stresses for a particular installation of girder 10. Therefore, it is to be understood that the present invention is not limited to girder 10, but encompasses any and all girders within the scope of the following claims.

Claims

1. A reinforced girder, comprising:

a first C-shaped member being formed of sheet metal;

a second C-shaped member being formed of sheet metal and being welded to said first C-shaped member so as to form a rectangular box;

a first pair of metallic stringers being welded in a spaced-apart relationship within said first C-shaped member, said first pair of metallic stringers extending the length of said first C-shaped member;

a second pair of metallic stringers being welded in a spaced-apart relationship within said second C-shaped member, said second pair of stringers extending the length of said second C-shaped member;

a pair of first, metallic, transverse connectors being welded within said first C-shaped member between said first pair of metallic stringers, said first, metallic, transverse connectors radiating outwardly from a common point of contact at an angle; and,

a pair of second, metallic, transverse connectors being welded within said second C-shaped member between said second pair of metallic stringers, said second, metallic, transverse connectors radiating outwardly from a common point of contact at an angle.

2. A reinforced girder, comprising:

a first C-shaped member including:

a first intermediate wall;

a first pair of end walls being affixed to said first intermediate wall and extending at right angles therefrom; and,

a first pair of flanges being affixed to said first pair of end walls and extending at right angles therefrom in a common plane parallel to said first intermediate wall;

a first pair of metallic stringers being respectively welded within said first C-shaped member at the junctions of said first pair of end walls with said first intermediate wall;

a pair of first, metallic, transverse connectors being welded to said first intermediate wall between said first pair of metallic stringers, said first, metallic, transverse connectors radiating outwardly from a common point of contact at an acute angle;

a second C-shaped member being welded to said first C-shaped member so as to form a box, said second C-shaped member including:

a second intermediate wall;

a second pair of end walls being affixed to said second intermediate wall and extending at right angles therefrom; and,

a second pair of flanges being affixed to said second pair of end walls and extending at right angles therefrom in a common plane parallel to said second intermediate wall, said second pair of flanges being in abutment with said first pair of flanges;

a second pair of metallic stringers being respectively welded within said second C-shaped member at the junctions of said second pair of end walls with said second intermediate wall; and,

a pair of second, metallic, transverse connectors being welded in a spaced-apart relationship to said second intermediate wall between said second pair of metallic stringers, said second, metallic, transverse connectors radiating outwardly from a common point of contact at an acute angle.

3. A reinforced girder, comprising:

a first C-shaped member being formed of sheet metal;

a pair of first, metallic, transverse connectors being welded within said first C-shaped member between said first pair of metallic stringers, said first, metallic, transverse connectors radiating outwardly from a first, common point of contact at an angle, and said first, common point of contact being located at the midpoint of said first C-shaped member; and,

a pair of second, metallic, transverse connectors being welded within said second C-shaped member between said second pair of metallic stringers, said second, metallic, transverse connectors radiating outwardly from a second, common point of contact at an angle, and said second, common point of contact being located at the midpoint of said second C-shaped member.