Case Studies
 
Bridge
Engineering
Magazine
 
UK and
Ireland
 
Australia
and
New Zealand
 
Back Home Forward

Devon County Council Miller's Crossing
A New Route for Pedestrians and Cyclists

A new route between Exwick and Exeter City Centre has been created exclusively for pedestrians and cyclists. The main feature of the route is the Miller's Crossing Bridge spanning the River Exe, adjacent to the Mill on the Exe Inn and Blackaller Weir.

The new Bridge crosses the River Exe in a single cable stayed span anchored to a mill wheel feature via 24m high steel pylons. The slender 54m span structure was chosen to provide an unobstructed crossing of the Exe without the need for significant foundations on the Bonhay Road bank. A 3m wide footway allows combined use by pedestrians and cyclists. The deck consist of 2 parallel steel box beams with a steel deck supported at each end by concrete abutments with intermediate supports provided by the cable stays, actually rods.

Devon County Council engineers used LEAP5 Classic for the preliminary dynamic analysis of the structure to obtain the fundamental natural frequencies. After the footbridge was completed, physical dynamic tests were carried out and actual natural frequencies were recorded. These compared well to those predicted by the analysis.

The global static analysis of the footbridge was also carried out using LEAP5 Classic using both plane frame and space frame models. Special attention was given to the connection between the deck and the vertical pylon (node connection) as was the connection between vertical and inclined pylons. Detailed finite element plate models of the connections were used to determine the stresses at the nodes.

Steel cased, drilled in situ concrete piles, installed through 6m to 8m of landfill socketed into the underlying mudstone bedrock, support a reinforced concrete combined abutment and pile cap. Piles on the East Bank also support a 3m wide combined abutment and pile cap in the river against the existing Bonhay Road retaining wall. The pile cap was formed just above summer water levels. The Abutment has a reinforced concrete cantilever deck to support the bridge and walkway. LEAP5 Classic was used to model the abutments as folded plates from which reinforcement could be designed.













 


Contact Us
Copyright © 2008 Bestech Systems Limited. All Rights Reserved.