Two-step method for bridge modal mass identification using synchronously measured bridge and vehicle dynamic responses

Abstract

For the identification of bridge parameters such as modal mass, both the excitation on a bridge and its corresponding bridge responses must be measured simultaneously. Vehicle-induced load can be used for bridge parameter identification if vehicle-bridge contact force is well estimated. Herein, a two-step algorithm is proposed to identify bridge modal mass. The first step is to estimate the vehicle tyre forces from measured vehicle responses. In the second step, the estimated tyre forces and the simultaneously measured vehicle-induced bridge acceleration responses are used as the input and output of the bridge system, respectively, to identify the bridge modal mass. Numerical examples clarify the modal mass identification performance considering observation noises and differences in the left and right path profiles. Field measurement was conducted, and the results indicate that the proposed algorithm can identify the first modal mass with satisfactory accuracy.