FORTH ROAD SUSPENSION BRIDGE - WHERE ARE WE TODAY?

摘要

The Forth Road Bridge was officially opened in 1964 and was estimated to have cost, with surrounding infrastructure, around ￡19.5 million (￡322 million in the current climate). Initially, a design life of 120 years was predicted for the structure, with replacement of the main cable suspender ropes set at 35 year intervals. However, an inspection performed on the main cables in 2004 identified corroded wire strands, which reduced the expected life estimation. The conclusion was that load restrictions would be required as early as 2017. Since the first inspection, two subsequent cable investigations were carried out in 2008 and 2012. Although bridge inspections are common place in the US and now becoming more widespread in the UK, some elements of wire failure are still considered a complex phenomenon. The process of fracture initiation and final failure are understood but arguments still exist concerning the exact mechanism of propagation. This study communicates some of the findings from the 2012 metallurgical cable inspection performed by ESR Technology and provides a brief discussion on failure mechanisms.