GB2380210A

GB2380210A - Stiffening member for masonry panels

Info

Publication number: GB2380210A
Application number: GB0222540A
Authority: GB
Inventors: Aidan Mark Thomas Chippendale
Original assignee: Ancon CCL Ltd
Current assignee: Ancon CCL Ltd
Priority date: 2001-09-28
Filing date: 2002-09-30
Publication date: 2003-04-02
Also published as: IE20020787A1; GB0222540D0; GB0123307D0

Abstract

A stiffening member for a masonry panel comprises a sheet of material defined by a number of regions including a neutral axis region 3 and one or more extreme regions 4 which are disposed at an extreme distance from the neutral axis region 3. A leading edge 5 of the sheet of material in the or each extreme region 4 is folded back on itself to produce an overlapping double layer 8 of material in the extreme region 4. Suitably the stiffening member is a windpost. The sheets of the overlapping double layer are generally separated by a gap 8 having a thickness less than a thickness of the sheet of material. Stiffening members formed in accordance with the invention can result in a material saving of about 20%. The invention also relates to a process for producing a stiffening member for a masonry panel.

Description

STIFFENING MEMBER FOR MASONRY PANELS Introduction The invention relates to a stiffening member for a masonry panel, and particularly windposts, and methods of production thereof.

Windposts are structural members which are used to span vertically between members of the main structure of buildings and help to resist and distribute wind loading on masonry panels. They are known to be manufactured from stainless and carbon steels, in the form of angle sections, plain channel sections, lipped channel sections, tee sections and rectangular hollow sections. These sections can be standard rolled sections or, more commonly, be coldformed from plate or sheet metal. The method of tying the masonry panel to the post can be by means of lugs or ties permanently attached (e. g. welded) to the post, ties which attach moveably onto the

edges of the flanges of the post, ties which attach moveably between the lips of lipped channel sections or ties which attach moveably within slots formed in the flanges (s) and/or web of a section or any combination of the above.

It is a known principle of mechanics that, in a beam of any given section, certain regions of the section are subjected to higher bending stress than other regions. Every section has a"neutral axis"where there is no bending stress. The highest stresses occur in regions which are at the extreme distance from the neutral axis. Savings in cost and, therefore, improvements in efficiency can be made if there is more material in the section at the extreme regions and less near the neutral axis-hence the sectional shape of a normal universal beam (Isection).

Traditionally, in cold-formed windposts, made from plate or sheet metal in the form of angle or channel sections, the metal is distributed uniformly throughout the section, since they are made from material of uniform thickness.

Statements of Invention According to the invention there is provided a stiffening member for a masonry panel comprising a sheet of material defined by a number of regions including a neutral axis region and one or more extreme regions which are disposed at an extreme

distance from the neutral axis region, wherein a leading edge of the sheet of material in the or each extreme region is folded back on itself to produce an overlapping double layer of material in the extreme region.

Stiffening members formed according to the invention have an effective thickness increase at the or each extreme location, while the region near the neutral axis remains the original thickness. By manipulation of dimensions, it is found that with a small increase in overall size of the section, material of half the original thickness can be used, folded at the extremes, to produce a section with structural properties at least equal to those of the original section of uniform.

Preferably, the stiffening member is a windpost.

Suitably, the stiffening member has a uniform crosssection.

Tradition teaches that, in order to avoid cracking of the metal at the outside of a bend when cold forming sheet or plate material, the internal radius of any bend should not be less than the thickness of the material and, preferably, should be at least one-and-a-half to two times material thickness.

From this, it is obvious that, when bent back on itself, there would be, at best, a gap between the folded sections equal to twice the thickness of the material and, possibly, four times the thickness of the material. This presents problems in forming

slots for the attachment of ties since they are very difficult to punch after the material has been folded and very difficult to align if punched before folding. Further, when there is a sizeable gap between the folded metal, the significant"spring" in the thinner material can result in greater movement of the tie than is suitable for its effective application.

Accordingly, the sheets of the overlapping double layer are generally separated by a gap having a thickness less than a thickness of the sheet of material. In one particularly preferred embodiment of the invention, the overlapping sheets in the double layer substantially abut, ideally leaving no significant gap therebetween. Stiffening members formed in accordance with the invention can result in a material saving of about 20%.

Preferably, the sheets of the double layer are fixed in a folded arrangement. This can be achieved by any suitable fixing means such as, for example, gluing, arc welding, resistance welding, mechanical fixings such as bolts, screws, rivets etc, or deforming localised areas of the metal to form a mechanically interlocking connection means. Such a mechanically interlocking connection means can be formed as a discrete unit or be incorporated into the punching of slots in the panel.

Typically, the stiffening members are formed from stainless and carbon steels, and may be in the form

of angle sections, plain channel sections, lipped channel sections, tee sections, or rectangular hollow sections. These sections may be standard rolled sections or cold-formed from plate or sheet metal. Typically, the sheet of material will have a thickness of less than 4mm, preferably greater than or equel to lmm, more preferably about 2 to 3mm.

Ideally, the gap between overlapping sheets in the extreme region is less than 75%, preferably less than 50%, more preferably less than 25%, of the thickness of the sheet of material. In one embodiment of the invention, the gap between overlapping sheets in the extreme region is between about 0.5 and 1. 0 mm.

The invention also relates to a process for producing a stiffening member for a masonry panel, which process comprises the steps of providing a sheet of material defined by a number of regions including a neutral axis region and one or more extreme regions which are disposed at an extreme distance from the neutral axis region, and folding a leading edge of the sheet material in the or each extreme region back on itself to produce a double layer of material in the or each extreme region. In forming the double layer in the extreme region, the leading edge of the sheet of material is preferably bent beyond about 90 degrees before being pressed substantially flat against the overlapping part of the sheet of material. Typically, a radius in a curve of the bend is also pressed into a substantially flat configuration. The process

typically also includes a further step of forming slots in the stiffening member, and particularly in the extreme regions of the member. Generally, the slots are formed by punching. Ideally, the stiffening member is a windpost.

Description of the Drawings The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings in which: Fig. 1A is an illustration of a section of a conventional windpost; - Fig. 1B is an illustration of a section of a windpost according to the invention; - Fig. 2A is an illustration of a section of a further conventional windpost; - Fig. 2B is an illustration of a section of a windpost according to a further embodiment of the invention; - Fig. 3 is a plan view of a slot formed in an extreme region of the windpost of Fig. 2; Fig. 4 is a sectional view taken along the line A-A of Fig. 3; and - Fig. 5 is a detail of the section of Fig. 4.

Detailed Description

Referring to the drawings, and initially to Fig lA, there is illustrated a section of a conventional windpost A comprising a central region B and extreme regions C, the material forming the windpost having a thickness of 4mm. Referring to Fig. 1B there is illustrated a windpost according to the invention and indicated generally be the reference numeral 1.

The windpost 1 (which again is shown in section) comprises a sheet of stainless steel 2 which is formed into a neutral axis region 3 and extreme regions 4 which are disposed at an extreme distance from the neutral axis region 3. A leading edge 5 of the sheet of stainless steel 2 in each extreme region 4 is folded back on itself to produce a double layer of material 8 in the extreme region, wherein each sheet of the double layer 8 are separated by a gap 9 having a thickness less than a thickness of the sheet of material. In this embodiment, the sheet of stainless steel has a thickness of 2mm and the gap between the sheets of the double layer 8 is about 1mm.

The windpost according to the invention uses 19% less steel than the conventional windpost illustrated, without sacrificing any structural properties.

Referring to Figs 2A and 2B, there is illustrated a conventional windpost, and a windpost according to a further embodiment of the invention, respectively, in which parts similar to those identified with reference to the previous embodiments are given the

same reference numerals. The windpost of Fig. 2B has a sheet thickness of 2mm, a gap of about 0.5mm, and has structural properties which are the equivalent of the conventional windpost of Fig. 2A while using 17% less steel in its manufacture.

Referring to Figs. 3 to 5, there is illustrated part of a extreme region of the windpost 1 of Fig. 2B showing a slot 10 punched through the double layer of material 8.

The invention is not limited to the embodiments hereinbefore described which may be varied in both construction and detail without departing from the spirit of the invention. Thus, although the stiffening members illustrated above are both windposts, it should be understood that the invention may be applied to other types of stiffening members.

Claims

Claims 1. A stiffening member for a masonry panel comprising a sheet of material defined by a number of regions including a neutral axis region and one or more extreme regions which are disposed at an extreme distance from the neutral axis region, wherein a leading edge of the sheet of material in the or each extreme region is folded back on itself to produce an overlapping double layer of material in the extreme region.
2. A stiffening member as claimed in Claim 1 which is a windpost.
3. A stiffening member as Claimed in Claim 1 or Claim 2 in which the sheet of material has a uniform cross-section.
4. A stiffening member as claimed in any preceding Claim in which the sheets of the overlapping double layer are generally separated by a gap having a thickness less than a thickness of the sheet of material.
5. A stiffening member as claimed in any preceding Claim in which the overlapping sheets in the double layer substantially abut, leaving no significant gap therebetween.
6. A stiffening member as claimed in any preceding Claim in which the sheets of the double layer are fixed in a folded arrangement.

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7. A stiffening member as claimed in Claim 6 in which the sheets of the double layer are fixed by fixing means, which fixing means are selected from the group comprising: gluing, arc welding, resistance welding, mechanical fixings such as bolts, screws, rivets, and mechanically interlocking connecting means formed by deforming localised areas of the sheet of material.
8. A stiffening member as claimed in Claim 7 in which the mechanically interlocking connecting means can be formed as a discrete unit or be incorporated into the punching of slots in the panel.
9. A stiffening member as claimed in any preceding Claim formed from stainless or carbon steel.
10. A stiffening member as claimed in any preceding Claim in the form of an angle section, a plain channel section, a lipped channel section, a tee section, or a rectangular hollow section.
11. A stiffening member as claimed in any preceding Claim which is a standard rolled section or cold-formed from plate or sheet metal.
12. A stiffening member as claimed in any preceding Claim in which the sheet of material has a thickness of between 1 mm and 4mm.
13. A stiffening member as claimed in Claim 12 in which the sheet of material has a thickness of about 2 to 3mm.

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14. A stiffening member as claimed in any preceding Claim in which the gap between overlapping sheets in the extreme region is less than 75% of the thickness of the sheet of material.
15. A stiffening member as claimed in any preceding Claim in which the gap between overlapping sheets in the extreme region is less than 50% of the thickness of the sheet of material.
16. A stiffening member as claimed in any preceding Claim in which the gap between overlapping sheets in the extreme region is less than 25% of the thickness of the sheet of material.
17. A stiffening member as claimed in any preceding Claim in which the gap between overlapping sheets in the extreme region is between about 0.5 and 1. 0 mm.
18. A stiffening member substantially as hereinbefore described with reference to the accompanying drawings.
19. A process for producing a stiffening member for a masonry panel such as a windpost, which process comprises the steps of providing a sheet of material defined by a number of regions including a neutral axis region and one or more extreme regions which are disposed at an extreme distance from the neutral axis region, and folding a leading edge of the sheet material in the or each extreme region back on itself to produce a double layer of material in the or each extreme region.

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20. A process as claimed in Claim 20 in which the leading edge of the sheet of material is preferably bent beyond about 90 degrees before being pressed substantially flat against the overlapping part of the sheet of material.
21. A process as claimed in Claim 20 in which a curve of the bend is pressed into a substantially flat configuration.
22. A process as claimed in any of Claims 19 to 21 which includes a further step of forming at least one slot in the panel.
23. A process as claimed in Claim 22 in which the at least one slot is formed in an extreme region of the panel.
24. A process as claimed in Claim 22 or 23 in which at least one slot is formed by punching.
25. A process substantially as hereinbefore described with reference to the accompanying description.