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Humber Bridge A Frames

Eadon Consulting worked with Arup to produce the design for the support bearings as part of the A-Frame replacement work on the Humber Suspension Bridge. Structurally critical components of the bridge, the longest in the world when opened back in 1981, were in need of replacement after becoming heavily worn.

Key facts

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Location

Humber Bridge, England

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Client

Humber Bridge Board

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In Partnership with

Ove Arup

Eadon produced the detailed design of replacement arrangements to allow for longitudinal movement of the bridge and also accommodate vertical and transverse loads. A new solution was developed which saw the functions of the A-Frame split into 2 separate mechanisms. Vertical load is now transferred into the support towers by a pair of pendles located at the ends of the main span. The transverse loads generated by wind are resisted by a wind shoe. Longitudinal movement is not resisted but is accommodated by both systems. Bearings in the wind shoe are pre-loaded onto a running surface hydraulic system to ensure the bearings never come out of contact, thus ensuring debris can not enter the sensitive bearing contact interfaces.

Due to the restricted space beneath the carriageway at the support towers much of the work done as part of this project had to be carried out on scaffolding platforms which created an expanded, uncluttered working area underneath the bridge deck. This was one of several obstacles engineers had to bear in mind when working on the design of the 5 tonne A-Frames. The replacement solution has been designed to ensure the equipment can be inspected and maintained for many decades into the future.

We also supported Arup with the finite element analysis of the temporary works interfaces for the existing bridge to assess the impact of mating plate flatness and bolting tolerances.

The A-frame project as a whole has gone on to win numerous awards including recognition by the Institution of Civil Engineers Yorkshire and Humber Region.