Relevance of the incidence angle of the seismic waves on the dynamic response of arch dams

This paper aims at studying the influence of the nature and direction of incidence of impinging seismic waves on the dynamic response of arch dams. A model for the seismic excitation is proposed in which the three free-field accelerograms defining the seismic input signal at ground surface are generated by different sets of simultaneous obliquely-incident P and S planar body waves. The dynamic response of the Morrow Point dam under such seismic excitations is studied considering the situation of a full reservoir and the existence of bottom sediments. Such response is computed by means of a multidomain boundary element code that allows the direct dynamic analysis of problems. It is found that, for the cases studied herein, oblique incidence produces seismic responses significantly larger than those observed for vertical incidence, which suggests that analyses considering only vertical incidence could be underestimating the seismic response of this type of structures.