GB2285078A

GB2285078A - Bridge

Info

Publication number: GB2285078A
Application number: GB9316414A
Authority: GB
Inventors: William J Haley; Geoffrey Freedman
Original assignee: FORESTRY COMMISSIONERS; Francis and Lewis International Ltd
Current assignee: FORESTRY COMMISSIONERS; Francis and Lewis International Ltd
Priority date: 1993-08-06
Filing date: 1993-08-06
Publication date: 1995-06-28
Anticipated expiration: 2013-08-06
Also published as: GB9316414D0; GB2285078B

Abstract

A bridge 15 comprises a pair of sections 10 laid side-by-side, so that their base longitudinal elements 11 lie a common plane and so that their top longitudinal elements 12 lie in a separate elevated common plane. The sections 10 are interconnected by plates 17 and cross members 18, 19. A walkway 26 is mounted or the top longitudinal elements 12. <IMAGE>

Description

BRIDGES This invention relates to bridges and in particular, but not exclusively, to pedestrian bridges for use in remote locations.

As the pressures to open up the countryside increase, and as their increase in usage creates erosion and other pressures on the countryside, there is a need for the provision of easily erectable bridges which do not require significant maintenance. Current bridges tend to be made up on site from timber and the transportation involved for bridges of significant span can be extremely difficult and may, for example, require helicopter operations.

From one aspect the invention consists in a bridge comprising a pair of open-framework supports positioned side by side and each having a longitudinal member located above a base, means for rigidly attaching the supports one to the other and a walkway or the like supported on the longitudinal members.

It is preferred that the supports are of triangular section and are arranged with an apex located above a base.

They may, for example, have longitudinal members at each corner of the triangle and zigzag linking members engaging the longitudinal members for forming a rigid structure. As structures, these are already known and are sold as sections of masts, for example the Unimast Series sold by Francis & BR< Lewis International Limited. The ends of such supports can be formed with flanges allowing a series of supports to be interconnected longitudinally to create bridges of different spans.

The means for rigidly attaching the supports may be in the form of end plates bolted, for example, to the flanges at the free ends of the supports. Additionally or alternatively cross members may be fixed to the longitudinal members at the base apices by means of U-bolts or the like and indeed further such cross members may interconnect the longitudinal members at the projecting apices. These cross members would extend at spaced locations along the length of the bridge.

In this arrangement uprights for a handrail may be connected to a base cross member and/or a projecting apices cross member. For example, the base member may have a socket for receiving the handrail upright.

A walkway may be mounted on the projecting apices by means of ties or straps or other fastening member. Thus the walkway may consist of its own longitudinal supports and suitable cross planking.

The triangular section supports and all other elements can be readily assembled and dismantled and, hence, the bridge is easily transportable and light. The triangular supports produce considerable rigidity and so spans of, for example, up to 10 or more metres may readily be achieved without central piers.

Although the invention has been defined above, it is to be understood it includes any inventive combination of the features set out above or in the following description.

The invention may be performed in various ways and a specific embodiment will now be described with reference to the accompanying drawings, in which Figure 1 is a side view of a bridge; Figure 2 is an end view on the arrow W; Figure 3 is a section along the line X-X in Figure 1= Figure 4 is a scrap view from above of the walkway of the bridge; Figure 5 is a section along the line Y-Y in Figure 4; Figure 6 is a section along the line Z-Z in Figure 2; Figure 7 is a side view of Figure 6, and Figure 8 is a view from above of Figure 6.

As has been explained above, triangular section lengths are currently available in the form of sections of lightweight aerial masts, one of these is generally indicated at 10, and at best can be seen from Figures 6 to 8, each section 10 comprises a pair of base longitudinal members 11 and an upper longitudinal member 12. Each of the members 11 and 12 have been located at the approximate apices of a triangle. The elements 11,12 are rigidly interconnected by zigzag members 13 which are welded to them at points along their lengths. Each free end of the longitudinal members 11,12 carries a flange 14 so that the longitudinal members can be bolted together.

Whilst such structures have been known for use in masts, they have never formed the basis for structural supports.

Turning to Figures 1 and 2, a bridge 15 comprises a pair of sections 10 laid side-by-side, so that their base longitudinal elements 11 lie in a common plane and so that their top longitudinal elements 12 lie in a separate elevated common plane. Preferably the sections 10 are interconnected by their flanges 14 to form a total support span 16. Connecting plates 17 are provided at the free ends of the span 16 to interconnect each set of sections 10 so that they together form a rigid structure. This rigidity is enhanced and increased by the provision of base cross members 18 and top cross members 19 which are affixed to the respective longitudinal members 11,12 at spaced locations along the length of the span 16. Preferably the cross members 18,19 are arranged in aligned pairs and are located at the position at which handrail uprights 20 are required.

Thus conveniently the cross members 18 carry sockets 21 into which the uprights 29 can be located and bolted. The uprights 20 can further be affixed by U-bolts 22 attaching them to cross members 19. Once the uprights are in position a handrail 23 can be located, as can a railing 24. Each of these may be made from interconnectable lengths.

As can be seen, particularly in Figure 6, the cross members 18,19 are conveniently connected to the longitudinal members 11,12 by further U-bolts 25. Other fixing arrangements can, of course, be used where appropriate.

The bridge 15 further includes a walkway generally indicated at 26. The walkway includes a pair of spaced longitudinal cross planking 28. The walkway 26 can be located on the longitudinal members 12 so that the planking 28 rests on those members and the longitudinal supports 27 can then be attached to the longitudinal members 12 by ties or other binding mechanisms 29. The spacing of the planking 28 should be such as to accommodate the U bolts 25 on the longitudinal members 12.

It will be appreciated that a further triangular section could be inserted into the inverted gap between the existing sections 10 to provide an even stronger structure and that wider bridges could be made up by having a greater number of sections laid side-by-side. Longer bridges could also be achieved by providing central piers.

Although the invention has been described in terms of triangular sections, because these have a particularly good combination of lightness and strength, it will be appreciated that many of the advantages could still be achieved with other geometric cross sections having longitudinal members at each corner and being interconnected by lightweight strengthening members.

Claims

1. A bridge comprising a pair of open-framework supports positioned side-by-side and each having a longitudinal member located above a base, means for rigidly attaching the supports one to the other and a walkway or the like supported on the longitudinal members.

2. A bridge as claimed in Claim 1, wherein the supports are of triangular section and are arranged with an apex located above a base.

3. A bridge as claimed in Claim 2, wherein the supports have longitudinal members extending through each apex or corner of the triangle.

4. A bridge as claimed in Claim 3, wherein the supports further comprise zigzag linking members engaging the longitudinal members for forming a rigid structure.

5. A bridge as claimed in an one of the preceding Claims, wherein the ends of the supports are formed with flanges allowing a series of supports to be interconnected longitudinally.

6. A bridge as claimed in any one of the preceding Claims, wherein the means for rigidly attaching the supports are or include end plates attached to the free ends of the supports.

7. A bridge as claimed in any one of the preceding Claims, wherein the means for rigidly attaching the supports are or include cross member fixed to the longitudinal members.

8. A bridge as claimed in Claim 7, further including uprights for a handrail connected to cross member.

9. A bridge as claimed in any one of the preceding Claims, wherein the walkway is mounted on the longitudinal members by ties, straps or other fastening member.

10. A bridge as claimed in Claim 9, wherein the walkway comprises a pair of laterally spaced longitudinal members spanned by cross-planking.

11. A bridge as hereinbefore described, with reference to the accompanying drawings.