Structural building element
The invention provides a structural building element formed from cold-rolled lightweight sheet steel. The building element may be used as a structural upright or as a beam, and is based generally on building elements with a known C-shaped profile. The profile of the building element of the invention is however based on a continuous curve. Each of a pair of front wall portions extends in a wholly or substantially smooth arc from a central slot opening onto the corresponding lateral side. The rear portion is sinusoidal, comprising a pair of convex wall portions each extending in a wholly or substantially smooth arc from a concave arcuate or substantially arcuate rear central wall portion onto a respective one of the lateral sides.
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The invention relates to structural building elements formed from cold-rolled lightweight sheet steel. Such building elements, made to a constant profile, are known lightweight alternatives to hot-rolled steel girders and may be built up into structures with a high strength-to-weight ratio.
Lightweight sheet steel can be cold-rolled into a variety of different useful profiles. C-shaped profiles are very useful, as they can be joined together in a variety of ways to make up structures that have a good resistance to bending and excellent strength-to-weight ratios. A typical C-section profile would comprise two front wall portions extending outwardly from a central slot opening; a pair of lateral sides; and a rear portion joining together the lateral sides. If desired, a swage may be provided in the rear portion and optionally in the lateral sides, which increases the strength appreciably without increasing the weight. If desired, the front wall portions may be inturned along the line of the central slot opening, which further increases the strength and rigidity of the profile. Such profiles are made by cold-rolling, which creates a radiussed fold or bend between the generally flat front walls and the flat lateral sides and between the lateral sides and the flat rear portion, but as a generality the practice has been to keep the radii of those bends as small as possible, to create building elements that are generally rectangular in overall section.
It is an object of the invention to increase further the strength of such structural building elements, without adding to the overall weight.
The Invention
The invention provides a structural building element as defined in claim 1 herein. The building element of the invention uses curves wherever possible in place of the flat faces of known C-shaped profile building elements. The overall profile of the building elements according to the invention is preferably a continuous arcuate curve, without any creases or sharp bends, from the inner edge of one of the front wall portions, out in an arcuate path embracing the whole of the associated lateral side and joining the concave arcuate or substantially arcuate rear central wall portion, before continuing symmetrically around to the inner edge of the other wall portion on the opposite side of the central slot opening. In such a building element the depth of the element from front to back is equal to the diameter of the arc shared between the front wall portions, the lateral sides and the mutually outer extremities of the rear portion. As an alternative, however, each of the lateral sides may have a flat portion centrally thereon, the front portions joining the flat portions tangentially. That gives the building element a greater depth than the diameter of the arcs of the opposite sides. If desired, the concave arcuate or substantially arcuate rear central wall section may be formed with a central flat portion, merging tangentially with arcuate concave portions on either side of that flat portion. That gives the building element a potentially greater width than one with a totally arcuate formation throughout.
The building elements according to the invention may be made from sheet steel of thickness 2 mm or less down even to 0.05 mm. Preferably they are made from sheet steel of thickness about 0.8 mm.
It will be appreciated that because the structural building elements of the invention have not flat faces, or alternatively if their only flat faces are the flat portions centrally on the lateral or back sides, then conventional joining techniques for securing together such building elements to a grid-like framework become very difficult. The invention therefore further provides a range of connectors for connecting together the structural building elements according to the invention. Two such building elements can be connected together in a T- or L-configuration using a connector as specified in claim 6 herein. Alternatively three such elements can be connected together in a cross or a K-configuration, using a connector as specified in claim 8 herein. Any of the connectors can be made from lightweight sheet steel, preferably by press-forming. Preferably the leg portions join the jaw elements along an arcuate edge of the material from which the connector is made. That is to say, if the connector is first stamped out from sheet steel as a flat blank, that blank will be generally T-shaped or L-shaped, X-shaped or K-shaped but whatever the shape the internal angles would be cut not as abrupt angular changes in direction of the edge of the material from which the connector is made, but would be rounded to create a smooth transition in the line of the edges of the portion of the blank to be pressed into the jaw elements, and the portions to be pressed into the leg portions. During pressing, this arcuate gusset of sheet metal is cold-stretched to form the junction between two curved sections extending in mutually perpendicular directions (namely the jaw element and the associated leg portion) each of which has been press-shaped to its own profile. In some cases this cold-stretching may be sufficient to bring the material of the two side portions into contact with one another, in which case they may be spot-welded at their zone of contact. This adds very considerably to the overall strength and rigidity of the joint formed by a connector according to the invention between two or more structural building elements according to the invention.
The structural building elements of the invention can be used, together with the connectors of the invention which join them together, in the construction of modular buildings, mobile homes, commercial racking, building joists, lattice beams, partition walls, floors, ceilings, roofs, mezzanine floors, staircases, steel framed furniture, workbenches, masts, pylons, gantries, stage lighting frameworks and scaffolding. Many other uses will become apparent from the true potential is explored of the ability to join together linear struts at angles other than 90°.
DRAWINGS
Referring first to
The same section is shown in greater detail in
The curves of the structural building elements according to the invention provide a very much stronger and more versatile building element than the conventional flat-faced C-section profiles. The building elements may be used as structural uprights or as joists or beams, and their advantages are numerous. They may be joined together in lattice frameworks using pressed steel connectors according to the invention, with a far greater potential strength and a vastly greater flexibility of design than conventional C-section cold rolled lightweight steel structural building elements which have a generally rectangular box-like section with a central slot opening along one side.
To create T- or L- or X- or K-connections between structural building elements according to the invention, individual connectors are provided.
The structural building elements according to the invention can be made up into lattice beams such as that shown in
Claims
1. A structural building element formed from cold-rolled lightweight sheet steel, with a generally C-shaped profile having a front comprising a pair of front wall portions extending outwardly from a central slot opening to a pair of lateral sides of the building element, and a rear wall portion joining together the lateral sides, wherein each of the pair of front wall portions extends in a substantially smooth arc from the central slot opening onto the corresponding lateral side, and the rear wall portion comprises a central concave portion bounded by a pair of convex wall portions each extending from a concave arcuate portion of the central concave portion in a smooth arc to a respective one of the lateral sides.
2. A structural building element according to claim 1, wherein the cold-rolled sheet steel has a thickness of 0.5 mm to 2 mm.
3. A structural building element according to claim 1, wherein the cold-rolled sheet steel has a thickness of about 0.8 mm.
4. A structural building element according to claim 1, wherein the lateral sides each have a flat portion centrally thereon, and the front portions join the flat portions tangentially.
5. A structural building element according to claim 1, wherein the concave portion of the rear central wall portion comprises a flat portion bounded by two concave substantially arcuate wall portions from which the pair of convex wall portions of the rear wall portion extend.
6. A connector for connecting together two structural building elements of claim 1 in a T- or L-configuration, comprising a pair of side portions each formed as a substantially arcuate jaw element shaped to conform to a lateral side or a front portion or a convex arcuate portion of a rear of one of the structural building elements to be connected together, and a leg portion extending from the jaw element, whereby when the jaw elements are secured to opposite faces of the said one of the structural elements with the leg portions mutually aligned, the leg portions cooperate to form a profiled spur extending laterally from the said one of the structural elements, with a profile corresponding to that of the other of the structural elements to be connected together, for sleeving the said other of the structural elements onto or into the profile of the spur.
7. A connector according to claim 6, wherein each of the jaw elements of the side portions is pre-punched with a hole located to correspond to a respective one of a pair of pre-punched holes in the said one of the structural building elements to be connected together, for receiving a fixing element to define the angle made by the spur to the profile of the said one of the structural elements.
8. A connector for connecting together three structural building elements of claim 1 in a cross configuration, comprising a pair of side portions each formed as a generally convex jaw element shaped to conform to a front or rear portion of one of the structural building elements to be connected together, and two co-linear leg portions extending one from each side from the jaw element, whereby when the jaw elements are secured to opposite front and rear faces of the said one of the structural elements with the pairs of leg portions of the jaw elements mutually aligned, each pair of mutually aligned leg portions cooperates to form a profiled spur extending laterally from the said one of the structural elements, each spur having a profile corresponding to that of one of the others of the structural elements to be connected together, for sleeving the said others of the structural elements onto or into the profiles of the spurs.
9. A connector for connecting together three structural elements of claim 1 in a K-configuration, comprising two mating halves each press-formed from sheet steel, which together define three tubular cavities in a K-configuration for receiving a central portion and two end portions respectively of the three structural building elements of claim 1.
10. A connector according to claim 9, wherein the sheet steel of the two connector halves is deep-drawn to an extent such that the mating halves have zones of mutual contact, and the connector halves are welded together in the zones.
11. A connector according to claim 6, wherein the leg portion joins the jaw elements along an arcuate edge of the material from which the connector is made.
12. A connector according to claim 11, wherein the material from which the connector is made is lightweight sheet steel.
13. A connector according to claim 12, which is press-formed.
Type: Application
Filed: Dec 3, 2003
Publication Date: Jun 29, 2006
Applicant: Henley Consultants Limited (Douglas, Isle of Man)
Inventor: John Window (Market Harborough)
Application Number: 10/537,932
International Classification: E04C 2/38 (20060101);