Effect Of Oblique Incidence Of Seismic Wave On Seismic Response Of Arch Dam

Number and height of arch dams in China have been the first in the world. Near ten high arch dams whose heights are about 300m are being and will be constructed. Most of these arch dams lie in the southwest where the earthquake intensity is high. The earthquake resistance of arch dam is therefore important. In the world the seismic analysis of 300m arch dams is seldom. This provides change and challenge to us. At present, the vertical incidence of seismic wave is considered in the seismic response analysis of arch dam. However, this assumption is not consistent with the fact. The effect of oblique incidence of seismic wave on the responses of arch dam should be considered. In this paper, based on the time-domain wave motion analysis method coupling the finite element method with the viscous-spring boundary, the input method of obliquely incident seismic wave is proposed in three dimensions. The effect of oblique incidence on the seismic response of Xiaowan arch dam is studied. The concrete works include:The two-dimensional in-plane normal and tangential viscous-spring boundary conditions, and the three-dimensional normal and tangential viscous-spring boundary conditions are introduced. The methods modifying artificial boundary parameters are summarized.The equivalent boundary force input methods are proposed for the two-dimensional and three-dimensional seismic waves of oblique incidence. The program for computing equivalent boundary force is given. The effectiveness of the input method and program is verified by numerical examples.The responses of Xiaowan arch dam are analyzed under seismic wave of oblique incidence. Comparing with the result under seismic wave of vertical incidence, the responses at some key points are considerably increased. Therefore, the effect of oblique incidence of seismic wave should be considered in the seismic response analysis of high arch dam.