Variability evaluation of dynamic characteristics of highway steel bridge based on daily traffic-induced vibrations

Abstract The paper presents a study on the variability in the dynamic characteristics of the highway cable-stayed Maxau Rhine Bridge based on its multi-mode vibrations recorded under daily traffic conditions. A two-day field test was performed to measure accelerations of the bridge deck, pylon and cables. A total of 11 natural frequencies ranging up to 4.5 Hz, corresponding mode shapes and damping ratios of the bridge deck were identified. To improve the accuracy of damping evaluation, a stability ratio and second-order Chebyshev band-pass digital filter were introduced in a specific algorithm of the Random Decrement Method. It was found that the natural frequencies of the bridge modes can exhibit variation between 1.7% and 5.5%, while the damping ratios between 30.1% and 92.1%. The serviceability of the bridge in the vertical direction was considered. The obtained results provided relevant data for structural health monitoring of other bridges with a similar structural system.