Abstract:To determine the influence of pile-soil interaction on the seismic fragility curves and post-earthquake traffic capacity of a 110 m-long, three-span continuous girder bridge, two diffe-rent finite element models that consider fixed pier bottoms and the pile-soil interaction were constructed. Then, 50 seismic waves with different intensities were selected as excitation. The ducti-lity ratio of the rotation angle and the shear strain of the bearing were calculated with the maximum displacements of the pier top and bearing as the target responses. Subsequently, the seismic fragility curves of the entire bridge were established through the wide-bound method, and a new formula for the calculation of average damage level was developed to estimate the post-earthquake traffic capacity of the girder bridge. Analytical results demonstrate that under the same seismic intensity, the peak displacement of the pier under pile-soil interaction is larger than that estimated by the consolidation model, which better agrees with the practical situation. With respect to the fragility curves of bridge components, the maximum damage exceedance probability of the bearing occurs when the pile-soil interaction is considered, but is not large different from the situation of fixed pier bottoms. Changes in traffic flow can be reasonably evaluated by using the seismic fragility curves of the entire bridge system. However, the traffic capacity assessment given by the consolidation model is unsafe. This result implies that the influence of pile-soil interaction on the seismic fragility of bridges cannot be ignored in class-Ⅲ sites.
