IE45780B1 - Beam for use in construction - Google Patents

Abstract

Beam including of the sheet steel soles higher and lower and at least a plate of matter forming a heart which connects the soles, the plate having a great shear strength out of span and being made of a material other than sheet steel. [FR2367166A1]

Description

Tiiis invention relates to a beam for use in construction. When a beam supports a load it is subject to bending, and bending moments are set up in the beam. It is the capacity of the materials that make up the beam.to resist the forces caused by the bending moments that give the beam its inherent strength.

In a normally loaded beam the flanges, i.e. the material at the top and bottom of the beam, are subjected to tensile and compressive forces and the webs, i.e. the material connecting the material at the top and bottom of the beam are subjected ‘ to shear forces.

For normal circumstances, there are two requirements for an engineering structure, l'he first is that the structure should be of sufficient strength to avoid failure or collapse when subjected to any form of loading that it is reasonable to expect the structure to withstand when in service during its expected service life. The second is that the structure (or various elements within a structure) should not deflect to such an extent as to appear to be unsafe or visually unacceptable or damage materials that are fixed to them. The amount of deflection of any structure when subjected to a load bears no set relationship to its strength hut depends on the stiffness of the materials used in the structure. For teams which normally have finishing materials fixed to them (such as plasterboard. ceilings) the deflection criterion is critical. For structures such as large sheds (Portal Frame) used for storage of materials deflection is not normally so important and the strength of the frame is critical.

According to the present invention there is provided a beam comprising upper and lower flanges of sheet steel, each flange being formed with at least erne U-shaped portion the open end of each U-shaped portion facing the other; at least one sheet of material forming a web interconnecting the flanges, the sheet having an edge at each end, the edge at each end of each sheet being engaged within the U-shaped portion; and nails extending through and between both $rms^ of each U-shaped portion and through the sheet, such that the material from the arms impinge into the material of the sheet, forming a double-shear connection, the said sheet being strong in panel shear and of a material other than sheet steel.

A preferred material for the flanges is galvanised mild sheet steel. There is no advantage in using high tensile steel as although it is stronger it is not stiffer. The surface material of mild steel is stiffer than the interior material thereof because of the annealing process used. It is therefore advantageous if very thin steel, e.g. from 26 gauge to 6 gauge, is used, as the surface area is large in comparison with the volume of metal.

A preferred material for the web is oil tempered hardboard manufactured by the masonite process, although any other panel material which has a high resistance to panel shear and is comparitively inexpensive may be used. Although the structural use of hardboard is relatively new its use is now allowed in a large variety of permanent structures.

To secure the webs to the flanges nailing is used, preferably employing galvanised nails. This is a cheap method and the operation can he easily mechanised.

It is proposed not to pre-drill the metal sheet, hut to punch the nails through. This causes the metal sheet to impinge into the material of the web and thus the slip that normally takes place with mechanical fasteners is virtually eliminated.

The accompanying drawings show embodiments of the invention by way of example. In the drawings: Figure 1 is an elevation of a first embodiment of the invention; Figure 2 is a cross-section on a larger scale through the beam of Figure 1; Figure 3 is a section through a second embodiment; Figure 4 is an elevation showing beams according to the invention joined to form a portal frame; and Figure 5 is a cross-section taken on lino V-V in Figure 4.

The beam shown in Figures 1 and 2 comprises' a metal 20 top flange 1 and a metal bottom flange 2. These can conveniently be made of galvanised steel sheet for example 14,16, 18,20 or 22 gauge. The edges of the flange aro in the form of U-shaped portions and two webs 3 and 4 are each received in respective upper und lower U-shaped portions. The webs may be made, for example, oi 6.5 mm thick oil-tempered hardboard.

The flanges 1 and 2 each receive a respective timber batten 5 and 6. The webs may be in a number of'sections, and Figure 1 shows joints 7 between adjacent sections. Stiffeners 8 may be provided at intervals along the beam, and end stiffeners 9 may also be provided. The stiffeners may be, for example, in the form of timber battens.

The beam shown in Figure 3 differs from that shown 10 in Figure 2 in that it has only a single web 3' and upper and lower flanges (of which only the upper flange 1* is shown), which are each so formed as to receive the web 3' and a pair of timber battens 5'.

One use of the beam according to the invention is 15 in the construction of Portal frames, as shown in Figures 4 and 5. A roof beam 12 is shown which is of the type illustrated in Figures 1 and 2 except that the stiffeners do not run at right angles to the length thereof. Two sheet metal plates 10, for 3 example —inch thick, secure an upright beam 11 to the 20 roof beam 12 by means of nuts and bolts 13. The upright beam may he of similar construction to the roof beam or it may be different, for example it may he of solid timber.

It will he observed that in all the illustrated embodiments the webs are received at their upper and lower ends between two layers of the material forming the flanges.

The webs can thus he secured to the flanges by nailing completely through both layers of flange material and the 4S780 intervening layer of web material. The web is thus held; to the flange in what is known as a double-shear connection. This provides a firmer and more secure joint than a singleshear connection (i.e. securing together a single layer of flange material and a layer of web material side by side).

The illustrated timber battens 5 and 5r generally have little effect on the strength and stiffness of the beam and serve only to assist in forming the steel sheet flanges and in connecting of the steel flanges to the webs. The timber flanges can be formed out of random lengths of timber, with joints in any location along the beam. However, by arranging that the timber flanges are full length or that at least the joints in the timber are as far as possible from the centre of the beam additional strength and stiffness may be obtained.

Claims (9)

1. CLAIMSs1. A beam comprising upper and lower flanges of sheet steel, each flange being formed with a least one U-shaped portion the open end of each U-shaped portion facing the other; at least one sheet of material forming a web interconnecting the flanges, the sheet having an edpe at each end, the edge at each end of each sheet being engaged within the U-shaped portion: and nails extending through and between both arms of each U-shaped portion and through the sheet, such that the material from the arms impinge into the material of the sheet, forming a double-shear connection, the said sheet being strong in panel shear and of a material other than sheet steel 5

2. A beam as claimed in Claim 1, wherein each flange is provided with two of the said U-shaped portions, a respective said sheet being engaged in each of the said U-shaped portions.

3. A beam as claimed in Claim 2, wherein the two U-shaped portions are on opposite sides of the flange and a timber batten 10 is received between the said two U-shaped portions.

4. A beam as claimed in Claim 1, wherein each flange is provided with a single said U-shaped portion.

5. A beam as claimed in Claim 4, wherein a timber batten is received by the flange on either side of U-shaped portion. 15

6. A beam as claimed in any preceding claim, wherein stiffeners extending between the upper and lower flanges are provided at intervals along the beam.

7. A beam as claimed in any preceding claim, wherein the flanges are of mild steel.

8. A beam as claimed in *any .preceding claim, 'wherein, theor each s.heet is of oil-tempered hardboard formed by. the masonite' process. ,

9. A beam substantially as herein, described with reference to 5 Figures 1 and 2 qr Figure 3 of the accompanying drawings.