Nonlinear seismic response and damage analysis for continuous prestressed concrete rigid-frame bridge considering internal force state under near-fault ground motions

Abstract

The internal force state of continuous prestressed concrete rigid-frame (CPCR) bridges is significantly influenced by the construction process. To determine the initial internal force state, this study proposed an equivalent load calculation method that is specifically tailored for large-span high-pier CPCR bridges. This method involves calculating equivalent loads that account for the effect of the construction process. Nonlinear dynamic analysis model of a CPCR bridge was established in OpenSees, where the equivalent loads were applied to consider the initial internal force state and the Hertz-damp model was incorporated to simulate the pounding effect. Three groups of near-fault ground motions were selected as three-dimensional inputs for nonlinear time history analysis. Moreover, the paper investigated the seismic damage and the evolution of cracks in the main girder. The results show that the proposed internal equivalent load calculation method can effectively obtain the initial internal force state, which is in good agreement with the actual internal force state. The main girder of the main bridge will pound with the approach bridge and the top of the transition pier in strong earthquakes. The displacement and damage of the transition pier will be greatly underestimated if the pounding effect between the end of the main bridge and the top of the transition pier is neglected. In addition, the cracking damage of the top and bottom plates of the main girders and the distribution of the crack-prone areas were analyzed, and the cracked areas of the top plates of the main girders increased significantly with the increase of the peak ground acceleration.