Probabilistic seismic response and uncertainty analysis of continuous bridges under near-fault ground motions

This paper focuses on the pulse-like near-fault ground motion, developing a probabilistic seismic demand model to estimate the seismic response of regular continuous bridges. A three-span bridge with continuous deck is taken as the basic case to establish 25 representative samples by changing the geometrical parameters and modeled with OpenSees software. The ground motions of both near fault and far fault are selected from PEER NGA strong ground motion database. The seismic response of the bridge is evaluated using the drift ratio at the top of the pier. A series of nonlinear dynamic time history analysis is carried out to compare the damage obtained with near-fault and far-fault ground motions for three different site conditions. Subsequently, a sensitivity analysis is performed on the design parameters according to the orthogonal experimental design methodology. After selecting the Housner intensity as the most suitable intensity measure and drift ratio as the engineering demand parameter, the probabilistic seismic demand model is established for the near-fault earthquake on the site II condition which is classified by Chinese design code. The results show that the near-fault earthquake can lead to more serious damage with respect to regular bridges and that the probabilistic seismic demand model allows for a quick evaluation of the seismic behavior of regular continuous bridges under pulse-like near-fault earthquake.