GB2224297A - Hinge assembly for connecting parallel girders in a panel bridge - Google Patents

Abstract

A bridge comprises at least two pivotally connected bridge units, each unit comprising two parallel girders each of which comprises a plurality of pre-fabricated panels connected end-to-end, the girders being spaced apart by a plurality of spaced parallel transoms (2) which extend between the girders to form a support for a plurality of deck panels (4). At least one pair of plates (18, 20) are pivotally connected along one edge and are each pivotally connected to a bridge unit along their opposite edge. <IMAGE>

Description

IMPROVEMENTS IN AND RELATING TO PANEL BRIDGES This invention relates to bridges and in particular to bridges constructed from pre-fabricated panels.

Bridges of this type comprise, in their simplest form, two parallel spaced girders each formed from a single row (or truss) of panels joined end-to-end, I-section joints known as transoms which span between the girders and carry the roadway and the roadway itself, which comprises a number of deck panels. The deck panels comprise a series of parallel spaced I-section beams known as stringers, to which is secured a deck plate of timber or steel. This arrangement may be modified as required either by adding one or more rows of panels to each girder and cross bracing and/or by bolting one or more further rows of panels on top of the row or rows in each girder. Additionally, reinforcing chords may be added to the top and bottom of each row.

The panels themselves comprise two chord members interconnected by vertical and diagonal bracing. Three vertical bracing members are provided, one at either end of the chords and one in the middle. At one end of the panels both chords have male eyes in the form of lugs while at the other end both chords have female jaws.

The lugs and jaws have pin holes to allow the panels to be connected.

In multi-span bridges, that is bridges with three or more points of support, the panels forming the main girders may be pinned together end-to-end throughout the whole length of the bridge or hinges may be introduced into the girders at each support so that the girders supporting each individual span react individually as loads move over them. The latter is known as a broken-span or discontinuous bridge. When there is a change of gradient at each support or where some settlement of the supports can be expected it is essential to provide hinges between the panels.

Moreover, if the supports are in the form of, for example, floating piers the two spans must be able to rotate relative to each other.

One known device for providing a hinge comprises two posts known as span junction posts. The posts are provided on one side at top and bottom with either a male lug or a female jaw by which they can be connected to the main panels. On the other side they have either male lugs, a 'male' post, or female jaws, a 'female' post, at top, bottom and at deck level by which they are pinned together. During launching of a bridge, a male post and a female post can be pinned together at the top and bottom by means of lugs and jaws, but in use these parts are disconnected so that the deck level jaws act as the hinge point. The bottom of the posts includes means for securing a member which transfers loads from the posts to the bridge support.

Another solution to the problem of providing a hinge between the girders of a bridge at each support is described in our co-terminously filed Application No. 8823791. This describes a panel which has a horizontal bracing member connected between the middle vertical bracing member and one of the end vertical bracing members, the horizontal member and the vertical member to which it is secured being formed from stronger section beams than the other bracing members. The panel therefore has a reinforced end and the reinforced ends of two such panels can be hinged together at their lower chords and are sufficiently strong to connect two spans which are at different gradients, or which in use will rotate vertically.

Whatever type of span junction equipment is employed to allow adjacent spans to be set at different gradients or to allow adjacent spans to rotate vertically, the connection can provide inadequate resistance to horizontal transverse shear forces due, for example, to wind or other lateral forces. The connection will provide resistance to vertical forces and forces in the direction of the panel chords but not to forces transverse to the plane of the panels.

A bridge in accordance with the invention comprises at least two pivotally connected bridge units, each bridge unit having at least two parallel girders, each girder comprising a plurality of pre-fabricated panels connected end-to-end, and a plurality of parallel transoms which extend between the girders to space the girders apart and to form a support for a number of deck panels, at least one pair of plates being provided which are pivotally connected together along one edge, the plates each being pivotally connected respectively along their opposite edge to one of a pair of adjacent bridge units.

The advantage of this is that the hinged plates provide resistance against shearing forces across the gap between the two bridge units.

The plates are suitably connected to the outermost transoms of adjacent bridge units.

Preferably the plates extend for substantially the whole width of the bridge. Alternatively, a pair of plates may be provided on either side of the bridge, adjacent each girder.

Suitably the cross girders are I-section beams and those cross girders to which the hinge member is to be attached have U-shaped members secured to their webs. These members may be provided integral with the hinged plates or alternatively as modified cross girders. The U-shaped members are dimensioned so as to receive a member for mounting the edges of the hinged plates. The edges of the hinged plates are hinged to the mounting member to allow the two spans freely to rotate The invention will now be further described by way of example with reference to the accompanying drawings in which: Figure 1 is an exploded view of part of a bridge in accordance with the invention; Figure 2 is a view of part of a bridge in accordance with the invention with the spans in one relative position and Figure 3 is a similar view to Figure 2 with the spans in a second relative position.

The bridge, only part of one side of which is shown, comprises at least two pivotally connected spans or bridge units. Each span or unit comprises a girder 2 on either side of the bridge and, as shown in Figure 1, each girder 2 is constructed from two rows of prefabricated panels 4 connected end-to-end. Each panel consists of two horizontal chord members 6,8 which are interconnected by vertical and diagonal bracing members 10,12 respectively. Hinge members 14,15 are connected to the end vertical members 10 of each bridge unit and are hinged together at a point by means of a pin inserted through holes 16.

Cross girders in the form of I-section beams known as transoms 18 extend between the girders of the units. The Figures show the transoms 18 on either side of the pivot connection 16 between the units. These support deck panels 20 which comprise a series of spaced parallel I-section beams known as stringers 22, to the upper flanges of which is secured a deck plate 24 of timber or steel.

The pivot connection 16 between the bridge units allows adjacent units to be set at different gradients or allows adjacent units to rotate vertically. However this connection does not provide resistance against horizontal shear wind forces; that is forces in a direction out of the plane of the drawings.

A pair of shear plates 26,28, pivotally connected together along one edge, are therefore pivotally connected to the two transoms 18 on either side of the hinge 16. U-shaped channels 30, which are secured to the webs 32 of the transoms 18, support mountings 34 which include a shaft 36 which cooperates with one end of a shear plate 26,28 to form a hinge.

As shown in Figure 1, a pair of plates 26,28 are positioned adjacent each girder 2, the plates being positioned below the hinge members 14,15.

When the two spans rotate relative to each other from one extreme (Figure 2) to another (Figure 3) around a centre of rotation indicated at 40, the two shear plates 26,28 also rotate relative to each other to accommodate the movement of the spans. Thus they are always in a position to resist any shear forces on the spans which would weaken the connections between them.

Claims (8)

CLAIMS:

1. A bridge comprising at least two pivotally connected bridge units, each bridge unit having at least two parallel girders, each girder comprising a plurality of pre-fabricated panels connected end-toend, and a plurality of parallel transoms which extend between the girders to space the girders apart and to form a support for a number of deck panels, at least one pair of plates being provided which are pivotally connected together along one edge, the plates each being pivotally connected respectively along their opposite edge to one of a pair of adjacent bridge units.

2. A bridge as claimed in claim 1 wherein the plates extend for substantially the whole width of the bridge unit.

3. A bridge as claimed in claim 1 wherein a pair of pivotally connected plates is positioned adjacent each girder.

4. A bridge as claimed in any preceding claim wherein each plate respectively is pivotally connected to the outermost transom of the adjacent bridge units.

5. A bridge as claimed in claim 4 wherein those transoms to which the plates are to be connected have means for pivotally mounting the plates thereto.

6. A bridge as claimed in claim 4 or 5 wherein the transoms are I-section beams.

7. A bridge as claimed in claim 6 wherein the mounting means comprises a U-shaped member which extends for the length of the plates, having its base attached to the web of the transoms and being dimensioned so as to pivotally receive the free edge of plate.

8. A bridge substantially as described herein with reference to the accompanying drawings.