Seismic behaviour of a caisson supporting a bridge pier

This paper shows the results of 3D FE coupled dynamic analyses carried out in the time domain to study the seismic performance of a rigid and massive caisson foundation supporting a slender bridge pier. The system is subjected to a real acceleration time history. To evaluate the permanent displacements induced by seismic loading soil behav-iour was described using an elastic-plastic hysteretic model capable to provide a fair estimate of non linear soil behaviour and hysteretic damping under cyclic loading conditions. The analyses were carried out in terms of effective stresses in undrained conditions, thus evaluat-ing excess pore water pressure induced by earthquake loading. Dis-placement and rotation time histories obtained with and without the bridge pier are presented. These results are compared with those com-puted from linear equivalent free-field analyses.