Study On Random Seismic Responses Of Arch Dams Considering Radiation Damping Of Infinite Canyon

Seismic behavior and safety guarantee of high arch dams located in seismically active regions are very important and of great concern to the owners and designers. Much attention has been paid on research of this topic and a lot of achievements have been made. Presently, the anti-seismic design of arch dams is mostly based on deterministic analyses, without considering the random issues. But for earthquakes with the same PGA, their processes are always different. Subsequently structural dynamic responses with different wave process excitaions can be of great difference. So, in the anti-seismic design of arch dams, the random characteristics of earthquakes must be considered.Based on the random vibration analysis model of arch dam-foundation interaction developed by Wujian, which combines the finite element, boundary element and infinite boundary element models in time domain with PEM algorithm, the thesis performed calculations of the seismic responses of Dagangshan arch dam and Baihetan arch dam. Some findings are drawn from the seismic responses of two arch dams under multiple excitation and uniform excitation. The correlation of the earthquake in three directions and the spatially varying effects of ground motions were investigated in the analysis, and the pseudo-static effects on seismic responses of the arch dams were also studied. The result demonstrates that considering the spatially varying effects of the ground motion, the seismic responses can significantly vary with that of which neglected these effects. So it should be considered in seismic analysis of arch dams. The effect of pseudo-static responses under multiple excitations is more significant when considering the spatially varying effects of ground motions. Finally,by superposing the random dynamic responses with the static responses, a simple estimation was made for the safety evaluation of arch dams. For optimizing numerical solution, the precise integration oscillating function integration formula - a new integration method proposed by Wujian– is applied to the program of the random analysis model of arch dams under multiple excitations, in order to improve the efficiency of random vibration analysis. The example of the calculation of Xiluodu arch dam shows a high efficiency and accuracy of this improvement under multiple excitations.