Dynamic investigation of a suspension footbridge

Abstract

This paper describes the analytical and experimental investigation of a 50 m span pedestrian suspension footbridge in Central Wales, UK. In the analytical study modelling of the three-dimensional structure determined vibration modes involving deck, towers and cables. The prototype testing employed hammer (impact) testing and excitation by pedestrians to determine the corresponding measured modes. The testing showed that adequate descriptions of the vibration characteristic of flexible structures can be obtained without artificial forcing but that appropriate instrumentation should be used. The validated analysis showed that the concrete panelling in the bridge and other structural details have a significant effect on stiffness and the testing demonstrated the susceptibility of this lightly damped structure to pedestrian-induced vibration. © 1994.