State-of-the-art assessment models to extend the lifetime of bridges
To prolong the safe working lives of bridges, the EU-funded LONG LIFE BRIDGES (Long life bridges) project focused on railway bridge dynamics and life-cycle and fatigue evaluation. To achieve its aims, it carried out secondments between two leading European engineering SMEs and two academic institutes from Denmark and Sweden. Project partners investigated railway bridges subjected to high-speed trains. They developed a damping system to minimise the effect of harmful vibrations. Testing followed on a bridge in Sweden with hangers that were susceptible to fatigue damage. Simulations showed that the existing passive damping system in place on the test bridge was partly inefficient due to changes in the dynamic response during train passages. The prototype attenuated the fatigue-related stresses by about 20 % compared to the existing one. The LONG LIFE BRIDGES team developed more accurate load models for long-span bridges that take into account both traffic and wind loading. Devising a global method to assess the reliability of steel cables on cable-stayed bridges will be key to new bridge design, detailed fatigue analyses and bridge assessments. Researchers created a global methodology that considers cables as a parallel system of wires, corrosion effects and cable length. They also developed a probabilistic fatigue model for welded plate details using fracture mechanics. The developed models consider both crack width and depth, and allow for the effect of bending stresses arising from misalignments. LONG LIFE BRIDGES efforts will contribute to identifying old bridges that are safe to remain in service and those that need maintenance. This ensures maximum returns from existing bridge infrastructure, as opposed to undertaking expensive and carbon-intensive new projects.
Keywords
Bridges, safety, LONG LIFE BRIDGES, railway bridge, fatigue evaluation, bridge assessments
