Study of the dynamic soil-abutment-superstructure interaction for a bridge abutment

The abutment is the part of a bridge that has a more significant dynamic interaction with the soil; the behaviour of the abutment is also influenced by the interaction with the superstructure, producing a reciprocal time-dependent exchange of inertial forces between them. This note illustrates a finite element description of the coupled dynamic interaction of an abutment with the bridge structure and with the soil, occurring in the occasion of a severe seismic event. The computation procedure was entirely implemented in OpenSees with the aim to investigate the dynamic response of the specific abutment of the Pantano viaduct, which would be used as an accessing facility to the still unbuilt Messina Strait suspension bridge, in Italy. The potentiality and versatility of OpenSees were used to reach an accurate numerical modelling of both the soil and the structure. The mechanical behaviour of the soil was reproduced through the Manzari and Dafalias hardening plasticity constitutive model, that was calibrated in order to reproduce the experimental laboratory data. The abutment was regarded as an elastic structure, while the dynamic interaction of the abutment with the superstructure was studied by means of two approaches of increasing complexity and accuracy. Parallel computing, obtained with the OpenSeesSP interpreter, was needed to optimize the computation time for the non-linear time domain analyses. The strategy solution presented herein is useful in that it enhances the current capability to evaluate the dynamic behavior of bridge structures, implementing a coupled soil-structure interaction analysis that considers explicitly the propagation of seismic waves in the foundation soils ant their interaction with the structure.