Ambient vibration-based seismic evaluation of a continuous girder bridge

An ambient vibration-based seismic evaluation procedure of a three span continuous girder bridge is presented. The procedure includes field ambient vibration testing, finite element (FE) modeling, selection of earthquake ground motion, time history analysis and seismic safety evaluation of the bridge. Ambient vibration tests were carried out to determine the dynamic characteristics of the bridge, i.e. eigenfrequencies, mode shapes and damping ratios. A three-dimensional FE model was calibrated based on the ambient vibration test results. The results of the seismic analysis show that a few steel members have to be strengthened and anchor bolts of bearings may fail.