Elimination of stochastic traffic flow effects on modal identification of beam type bridge under ambient excitation

Bridge modal parameters identified under ambient excitation are normally used for damage detection and condition assessment. However, stochastic traffic flow is often assumed as part of the ambient excitation without considering its additional mass attribution. This paper investigates the influence of stochastic traffic flow on the modal identification results of beam type bridge under ambient excitation and proposes an elimination method accordingly. Firstly, specific location of stochastic traffic flow acting on bridge is simulated by using cellular automata model. Then, finite element model is established to analyze the effects of stochastic traffic flow on the identified modal parameters of beam type bridge under ambient excitation. Finally, the empirical formula is proposed to eliminate the effects of stochastic traffic flow and verified by field monitoring data of a five-span continuous bridge with variable cross-section.