Broad Chalke bridge , Wiltshire
The arch is one of the most basic structural forms. Since it was first used by the Romans, the masonry arch, vault and dome have been the key components in many of our greatest buildings and structures. However since the beginning of the 20th century the advent of steel and reinforced concrete has meant that much of the knowledge of how to design and build real arches has been lost.
Stand Consulting Engineers have continued the tradition of building masonry arches together with stone mason Sarah Pennal and constructed a small masonry and stone bridge over a chalk stream in Wiltshire.
A small bridge has to address the same issues as most larger span bridges. These include how to support the vertical and horizontal forces generated, how to provide the centering needed to build the bridge, and completing the arch in a way that ensures the load paths are close to what was found during the design. More modern considerations included how to build the foundations without running the risk of concrete entering into the stream.
Analysis of the main part of the bridge was by the use of force diagrams rather than numerical calculations, with the calculator only coming out for the design of the Grundomat piled foundation.
We were delighted that the bridge has won Commendations for the New Building Awards Scheme 2011 by the Salisbury Civic Society.