GB2145054A

GB2145054A - A method of lifting a bridge end, and a jacking frame therefor

Info

Publication number: GB2145054A
Application number: GB08321741A
Authority: GB
Inventors: Richard Charles Edward Forsyth
Original assignee: MABEY BRIDGE Co Ltd
Current assignee: MABEY BRIDGE Co Ltd
Priority date: 1983-08-12
Filing date: 1983-08-12
Publication date: 1985-03-20
Also published as: GB8321741D0; AU563284B2; GB2145054B; AU1962983A

Abstract

A method of temporarily raising and subsequently lowering an end of a lattice girder bridge onto its foundation(s) by the use of jacks (8, 8') comprises, at each side of the bridge, connecting to upper and lower parts of an end post (6, 6') of the bridge the respective ends of a two-armed (1, 2) jacking frame (J). This frame is provided, adjacent the apex of the angle between the arms (1, 2) with at least one thrust pad (4, 4') engaged by a jack (8 or 8') to enable the jacking frame, and thereby the bridge end, to be successively raised and lowered. The invention also resides in a jacking frame for use as aforesaid. <IMAGE>

Description

SPECIFICATION Improvements relating to lattice panel bridges This invention relates to Lattice Panel Bridges of the so-called Bailey type (British Patent 553374).

Bridges of the type referred to are com monly built on rollers on one of the banks of the gap to be bridged and are equipped with a skeleton structure or "nose" projecting from the leading end of the bridge. The entire construction is then rolled or "launched" across the gap between the banks. The skeleton nose is then removed, the bridge is jacked up to remove the rollers and then jacked down onto its previously prepared foundations.

The present invention has been devised with the object of enabling the jacks to work more effectively and with a greater degree of safety.

Thus in accordance with the invention a method of temporarily raising and subsequently lowering an end of a lattice girder bridge onto its foundation(s) by the use of jacks comprises, at each side of the bridge, connecting to upper and lower parts of an end post of the bridge the respective ends of a two-armed jacking frame which is provided, adjacent the apex of the angle between the arms, with at least one thrust pad engaged by a jack to enable the jacking frame and thereby the bridge end to be successively raised and lowered.

The invention also comprises an angled two-armed jacking frame for the performance of this method.

The invention is hereinafter described in more detail by reference to the accompanying drawings in which: Figure 1 is a side elevation of the two ends only of a lattice girder bridge showing alternative positions of bridge end jacking frames; Figure 2 is an end elevation of a double truss lattice bridge girder with jacking frames attached thereto; and Figure 3 is a perspective view of a jacking frame.

Referring firstly to Fig. 3 the jacking frame J comprises a long arm 1 and a short arm 2 fixed at one end to a bracket plate 3 so as to form an acute angle to one another. Each arm comprises two spaced parallel bars and an end terminal with aligned attachment apertures. The bracket plate 3 has a thrust pad 4, 4' at its respective ends.

Fig. 1 shows two different modes of use of a jacking frame. At one end of the bridge structure--shown to the right in Fig. 1-a jacking frame J is shown with its longer arm 1 uppermost and connected at its free end by a pin 5 to the upper part of a male end post 6 supported on a bearing 11 whereas the free end of the shorter arm 2 is connected by a pin 7 to the lower end of the same post 6.

The thrust pads 4, 4' are horizontal and the thrust member of a ground based jack 8 is in position to raise or lower the jacking frame J, and thereby the bridge end, by engagement, with the lower pad 4.

As shown in Fig. 2 the bridge girders are, or may be, of double truss configuration with jacking frames J connected to both trusses and stabilised by an x-shaped bracing frame 9 attached across them. The bracing frame and its bolts are standard lattice bridge parts, as are the pins which secure the jacking frame J to the end posts 6.

To the left in Fig. 1 that end of the bridge structure is shown with a jacking frame J in a reversed position, that is to say with its shorter arm 2 uppermost and connected by a pin 5' to the upper part of a female end post 6' whilst its longer arm 1 has its lower free end connected by a pin 7' to the lower end of the female end post 6'. At this same end a jack 8' mounted on a buttress wall 10 has its thrust member positioned to engage the lowermost pad 4.

It should be apparent from the foregoing that by using the jacking frames J, the operating jacks 8, 8', even at different levels, can be kept far enough away from the bridge end posts 6, 6' to enable safety timber packs to be inserted during jacking operations and to enable final adjustments to be made to the positions of the bridge bearings 11.

1. A method of temporarily raising and subsequently lowering an end of a lattice girder bridge onto its foundations by the use of jacks in which at each side of the bridge there is connected to upper and lower parts of an end post of the bridge the respective ends of a two-armed jacking frame which has, adjacent the apex of the angle formed between the arms, at least one thrust pad which is engaged by a base-supported jack to enable the jacking frame and thereby the bridge end to be successively raised and lowered.

2. A method as claimed in claim 1 when applied to a bridge with double truss girders wherein a said jacking frame is connected to each truss and a bracing frame is attached across them.

3. A method as claimed in claim 2 wherein the bracing frame is of x-shaped configuration.

4. A jacking frame for use in a method as claimed in claim 1, 2 or 3 and comprising two arms connected together at an angle at one end by a bracket and at least one thrust pad fixed to the bracket.

5. A jacking frame as claimed in claim 4 in which the two arms are of unequal length and there are two pads, whereby the frame can be utilised in either of two alternative

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements relating to lattice panel bridges This invention relates to Lattice Panel Bridges of the so-called Bailey type (British Patent 553374). Bridges of the type referred to are com monly built on rollers on one of the banks of the gap to be bridged and are equipped with a skeleton structure or "nose" projecting from the leading end of the bridge. The entire construction is then rolled or "launched" across the gap between the banks. The skeleton nose is then removed, the bridge is jacked up to remove the rollers and then jacked down onto its previously prepared foundations. The present invention has been devised with the object of enabling the jacks to work more effectively and with a greater degree of safety. Thus in accordance with the invention a method of temporarily raising and subsequently lowering an end of a lattice girder bridge onto its foundation(s) by the use of jacks comprises, at each side of the bridge, connecting to upper and lower parts of an end post of the bridge the respective ends of a two-armed jacking frame which is provided, adjacent the apex of the angle between the arms, with at least one thrust pad engaged by a jack to enable the jacking frame and thereby the bridge end to be successively raised and lowered. The invention also comprises an angled two-armed jacking frame for the performance of this method. The invention is hereinafter described in more detail by reference to the accompanying drawings in which: Figure 1 is a side elevation of the two ends only of a lattice girder bridge showing alternative positions of bridge end jacking frames; Figure 2 is an end elevation of a double truss lattice bridge girder with jacking frames attached thereto; and Figure 3 is a perspective view of a jacking frame. Referring firstly to Fig. 3 the jacking frame J comprises a long arm 1 and a short arm 2 fixed at one end to a bracket plate 3 so as to form an acute angle to one another. Each arm comprises two spaced parallel bars and an end terminal with aligned attachment apertures. The bracket plate 3 has a thrust pad 4, 4' at its respective ends. Fig. 1 shows two different modes of use of a jacking frame. At one end of the bridge structure--shown to the right in Fig. 1-a jacking frame J is shown with its longer arm 1 uppermost and connected at its free end by a pin 5 to the upper part of a male end post 6 supported on a bearing 11 whereas the free end of the shorter arm 2 is connected by a pin 7 to the lower end of the same post 6. The thrust pads 4, 4' are horizontal and the thrust member of a ground based jack 8 is in position to raise or lower the jacking frame J, and thereby the bridge end, by engagement, with the lower pad 4. As shown in Fig. 2 the bridge girders are, or may be, of double truss configuration with jacking frames J connected to both trusses and stabilised by an x-shaped bracing frame 9 attached across them. The bracing frame and its bolts are standard lattice bridge parts, as are the pins which secure the jacking frame J to the end posts 6. To the left in Fig. 1 that end of the bridge structure is shown with a jacking frame J in a reversed position, that is to say with its shorter arm 2 uppermost and connected by a pin 5' to the upper part of a female end post 6' whilst its longer arm 1 has its lower free end connected by a pin 7' to the lower end of the female end post 6'. At this same end a jack 8' mounted on a buttress wall 10 has its thrust member positioned to engage the lowermost pad 4. It should be apparent from the foregoing that by using the jacking frames J, the operating jacks 8, 8', even at different levels, can be kept far enough away from the bridge end posts 6, 6' to enable safety timber packs to be inserted during jacking operations and to enable final adjustments to be made to the positions of the bridge bearings 11. CLAIMS

5. A jacking frame as claimed in claim 4 in which the two arms are of unequal length and there are two pads, whereby the frame can be utilised in either of two alternative positions.

6. A method of temporarily raising and subsequently lowering an end of a lattice girder bridge substantially as hereinbefore described with reference to the accompanying drawings.

7. A bridge end jacking frame substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.