Pedestrian Bridge Vibration Serviceability: A Case Study in Testing and Simulation

Pedestrian bridges are increasingly becoming landmark structures designed to promote a modern vibrant image of their surrounding landscape. Designs are becoming more daring; spans are increasing and becoming more slender and the use of lightweight materials is more prevalent. The net result is that it is often the serviceability limit state, rather than the ultimate limit state, that controls the bridge design. Sean O'Casey Bridge, Dublin, is the most recently constructed pedestrian bridge over the River Liffey. This articulated steel bridge, designed by O'Connor Sutton Cronin Consulting Engineers following an international design competition, is located in Dublin's docklands and spans approximately 88m across the river. This paper describes the pedestrian crossing tests, experimental modal analyses, and associated numerical modelling undertaken to assess vibration serviceability. The results of these analyses and their implications for the serviceability limit state assessment of pedestrian bridges are discussed in this paper.