The influence of the soil-foundation frequency-dependent behavior on the seismic performance of bridges

Bridge structure performance estimation under a seismic hazard can be significantly influenced by the level of modelling detail within the simulation of the soil structure interaction phenomenon. As the computational burden of the stochastic processes essential to the performance based analysis greatly restricts the implementation of a detailed truncated finite element simulation of the semi-infinite soil domain, the Kelvin-Voigt Model within the framework of the substructure method along with other frequency independent simplified methods are frequently selected in the literature as a computationally viable alternative. As a result of their limited dynamic properties, the aforementioned simplified methods are prone to an inefficient approximation on the loading scenario of earthquake excitations with rich frequency content. To this end the limitations of the frequency independent simulation approach and subsequently the necessity of the frequency dependent simulation approach are thoroughly investigated in this paper using a comparison of the bridge structure performance assessed using the conventional Kelvin-Voigt Models and the lumped parameter modelling method. Analyses demonstrate the phenomenon of redistribution of the damage among the bridge's structural components with the significance of error being highly correlated with the predominant frequency of the excitation.