Assessment on required separation length between adjacent bridge segments to avoid pounding

This paper presents a probability-based method, based on the design required separation length, to evaluate the likelihood beyond the required separation length of pounding of bridge structures under seismic excitations. Firstly, based on the stochastic vibration theory, the probabilistic pounding model was developed to model the influence of different seismic intensity levels and local soil condition on determination of the required separation gap between bridge segments. Then, the varying relationship between exceedance probability of pounding and seismic intensity measure (PGA) was derived. The proposed probability-based pounding evaluation approach was applied to a real bridge for predicting the pounding occurrence under various seismic intensity levels, along with the finite element model of the bridge pounding system built in ANSYS. Finally the pounding risk assessment beyond the required separation length of the bridge structure was conducted and presented based on the required separation distance. The results of this study delivered explicit and direct specifications and guidelines for seismic pounding design of bridges with different separation gap.