GB2279387A

GB2279387A - Framework for a bridge or truss

Info

Publication number: GB2279387A
Application number: GB9412420A
Authority: GB
Inventors: Malcolm Martin Strong
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-06-23
Filing date: 1994-06-21
Publication date: 1995-01-04
Anticipated expiration: 2014-06-21
Also published as: GB2279387B; GB9312941D0; GB9412420D0

Abstract

A framework for a bridge or a truss having two two dimensional lattices formed of a plurality of elongate members joined at a number of vertices and a jointed brace member having selected joints connected to selected vertices of the two lattices. The two lattices are disposed substantially parallel to each other and are connected by means of the brace member which is orthogonal to the two lattices. The framework can be supplied in a pack for construction on site by applying a force to opposing ends of the framework to decompress the members of the lattice and brace member. <IMAGE>

Description

FRAMEWORK FOR A BRIDGE OR A TRUSS This invention relates to a framework for a bridge or a truss.

In this field it is already known that trusses can span between two points whilst supporting a load. These structures can be formed in various materials, for example wood, metal, plastics etc. Various arrangements of trusses are known and illustrations of these arrangements are shown in Fig la to le. As can be seen from Fig la to le, it is also known that trusses may comprise members which are pin-jointed together and are either in tension or in compression.

Most known arrangements are time consuming to fabricate on and off site and problematical in their haulage and storage due to the bulk of the structure.

According to the first aspect of the present invention there is provided a framework comprising a two dimensional lattice formed of a plurality of elongate members, the lattice having a plurality of vertices, and a jointed brace member having selected joints connected to selected vertices of the lattice.

Preferably, alternate joints of the brace member are connected to alternate vertices of the lattice.

Preferably, two lattices are disposed substantially parallel to each other and are connected by means of a base member orthogonal to the two lattices.

The two lattices share a common brace member which also acts as the base member.

Preferably, the two lattices and base member form a bridge or truss. Preferably, the lattice is of crisscross form and defines adjacent quadrilateral areas.

According to a second aspect of the present invention there is provided a method of constructing a framework comprising having a compressed two dimensional lattice formed of a plurality of elongate members having a plurality of vertices and a jointed brace member having selected joints connected to selected vertices of the lattice, and applying opposing forces to the framework to decompress the lattice and in so doing straighten the jointed brace member.

Preferably, two lattices are placed vertically in a substantially parallel arrangement and a base member is disposed orthogonally between the two lattices. The two lattices share a common brace member which also acts as a base member.

Preferably, means are provided to prevent the brace member from decompressing once it has been straightened.

Preferably, the two lattices are used to form the sides of a bridge or truss.

According to a third aspect of the present invention there is provided a pack for construction of a framework comprising a lattice formed of a plurality of elongate members having a plurality of vertices and a jointed brace member having selected joints connected to selected vertices of the lattice.

Preferably, a base member is provided in the form of a plurality of slats for construction as a flat base member.

Preferably, support struts are provided for reinforcing adjacent vertices of the lattice.

Embodiments of the present invention will now be described with reference to the accompanying drawings in which: Fig la to le shows five known frameworks of bridges or trusses; Fig 2a to 2d are diagrammatical side elevations of a framework in accordance with the present invention showing the framework in various stages of construction as it is decompressed; Fig 3a to 3d are diagrammatical side elevations of the lattice member of the framework of Fig la to ld; Fig 4a to 4c are diagrammatical side elevations of alternative lattices of a framework in accordance with the present invention; Fig 5a to 5d are diagrammatical side elevations of a brace member of the framework of Fig la to ld; Fig 6 is a perspective view of a brace member of a framework in accordance with the present invention; and Fig 7 is a side elevation of a framework in accordance with the present invention.

Referring to the drawings, a framework 1 for a bridge or a truss is formed from two lattice members 2 each formed of a number of elongate members 4 jointed at vertices 6 and a brace member 8 formed of a plurality of parallel elongate members 9 which are jointed at their ends to adjacent rows of parallel elongate members at joints 10.

The lattice members 2 may be formed in different arrangements as shown in Fig 4a to 4c. The lattice may be a straight square lattice 16 (Fig 4a) having adjacent quadrilateral areas 17 defined by the elongate members 4. A curved form of lattice 18 (Fig 4b) is suitable for providing a resultant curved framework 1.

The curved lattice 18 has adjacent quadrilateral areas 19 in which the two upper elongate members 20 of the quadrilateral area 19 are longer than the two lower elongate members 21 of the quadrilateral 19. This means that when the curved lattice 18 is fully extended it forms an arc rather than a straight line. A multiple lattice 22 (Fig 4c) is provided with a double layer of quadrilateral areas 23 such that a single elongate member 24 defines the sides of three quadrilateral areas 23. The multiple lattice arrangement 22 may provide additional stability to the lattice 2.

Two lattices 2 are disposed substantially parallel to each other and are connected by means of a brace member 8 orthogonal to the two lattices 2.

Fig 2 illustrates the interaction between each of the lattice members 2 and the brace member 8. Fig 2 is a diagrammatical side elevation showing one lattice member 2 and its interaction with the joints of the brace member 8. The lattice member 2 shown in Fig 2 has alternate base vertices B connected to alternate joints A of the brace member 8. In this arrangement the lattice 2 and the brace member 8 can be compressed at their joints 10 or vertices 6 without disconnection of the brace member 8 from the lattice members 2. The joints 10 and vertices 6 are secured by pin-joints which allow the rotation of the elongate members 4,9 about the joint 10 and vertices 6 enabling compression of the framework 1.

The brace member 8 may be formed of elongate members 9 with a square cross-section such that a flat surface is provided on which the floor of a bridge can be disposed. Such a floor may be formed of parallel slats which can be rolled up for ease of transportation.

The fully extended lattice 2 may be reinforced by the provision of struts 15 between the adjacent vertices 6 at the upper edge of the lattice 2. Such an arrangement of struts 15 is shown in Fig 7.

In use the framework can be provided in its constituent parts these being two lattice members 2, a brace member 8, struts 15 for the reinforcement of the lattice 2 and slats for the floor of the base member 8. The lattice 2 and the brace member 8 are provided in a fully compressed form wherein the elongate members 4, 9 are compressed against one another. For the construction of the bridge or truss the alternate vertices B of the two lattice members 2 are each connected to the alternate joints A of the brace member 8 such that the two lattice members 2 extend orthogonally from either side of the brace member 8. The framework 1 can then be formed by applying a force to each end of the framework 1 such that the two lattice members 2 and the brace member 8 are decompressed and the brace member 8 flattens such that all its elongate members 9 are in line.

In the case of a framework 1 using the curved lattice 18, the elongate members 9 of the brace member 8 form an arc when the framework 1 is fully assembled. The system of decompressing the framework 1 is shown in Fig 2.

The framework 1 can be reinforced when fully decompressed by the addition of struts 15 across the top of the lattice members 2 between adjacent vertices 6 at the top of the lattice members 2. The slats can be provided as the floor of the framework which is disposed upon the brace member 8. The joints C of the brace member, which are disposed in between the alternate joints A already connected to the vertices C of the lattice member 2, can be connected to the vertices D which are disposed in between the alternative vertices B of the lattice member 2. This provides extra strength to the framework 1. The framework 1 can then support a vertical load.

The framework 1 can be dismantled by reversing the procedure for constructing the framework 1. The brace member 8 can have elongate members 9 of any length or width with variable numbers of joints in the widths or lengths of the brace member 8.

The framework 1 is flat-packing and can therefore be easily transported and storage is economical. The framework 1 can be supplied ready to assemble with the pin joints already made such that the framework 1 can be assembled without the need for specialist skill.

Improvements and modifications can be made to the above without departing from the scope of the present invention.

Claims

1 A framework for a bridge or a truss comprising a two dimensional lattice formed of a plurality of elongate members, the lattice having a plurality of vertices, and a jointed brace member having selected joints connected to selected vertices of the lattice.

2 A framework as claimed in Claim 1 wherein alternate joints of the brace member are connected to alternate vertices of the lattice.

3 A framework as claimed in Claim 1 or Claim 2 wherein two lattices are disposed substantially parallel to each other and are connected by means of a base member orthogonal to the two lattices.

4 A framework as claimed in Claim 3 wherein the two lattices share a common brace member which also acts as the brace member.

5 A framework as claimed in Claim 3 or Claim 4 wherein the two lattices and the base member form a bridge or truss.

6 A framework as claimed in any one of the proceeding Claims wherein the lattice is of criss cross form and defines adjacent quadrilateral areas.

7 A method of constructing a framework comprising having a compressed two dimensional lattice formed of a plurality of elongate members having a plurality of vertices and a jointed brace member having selected joints connected to selected vertices of the lattices, and applying opposing forces to the framework to decompress the lattice and in so doing straighten the jointed brace member.

8 A method as claimed in Claim 7 wherein alternate joints of the brace member are connected to alternate vertices of the lattice.

9 A method as claimed in Claim 7 or Claim 8 wherein two lattices are placed vertically in a substantially parallel arrangement and a base member is disposed orthogonally between the two frameworks.

10 A method as claimed in Claim 7, 8 or 9 wherein the two frameworks share a common brace member which also acts as a base member.

11 A method as claimed in any one of Claim 7 to 10 wherein means are provided to prevent the brace member from decompressing once it has been straightened.

12 A method as claimed in any one of Claims 7 to 11 wherein the two lattices are used to form the sides of a bridge or truss.

13 A pack for construction of a framework comprising a lattice formed of a plurality of elongate members having a plurality of vertices and a jointed brace member having selected joints connected to selected vertices of the lattice.

14 A pack as claimed in Claim 13 wherein alternate joints of the brace member are connected to alternate vertices of the lattice.

15 A pack as claimed in Claim 13 or 14 wherein a base member is provided in the form of a plurality of slats for construction as a flat base member.

16 A pack as claimed in Claim 13, 14 or 15 wherein support struts are provided for reinforcing adjacent vertices of the lattice.

17 A frameworks substantially as hereinbefore described with reference to the accompanying drawings.

18 A method substantially as hereinbefore described with reference to the accompanying drawings.

19 A pack substantially as hereinbefore described with reference to the accompanying drawings.