Seismic damage of submerged intake tower under the sequence of mainshocks and aftershocks

Reinforced concrete intake towers are considered as main hydraulic structures constructed in dams' reservoirs, connected to the dam or as a separate structure. If an intake tower is damaged, the powerhouse or downstream of the dam may experience serious problems. In this research, the influence of mainshock-aftershock seismic sequences is studied on real intake tower. The intake tower of Encino dam is modeled by using the finite element method. The dynamic time history analyses are conducted with the real as-recorded earthquakes and the nonlinear behavior of concrete and steel bars is considered. The tower is modeled with reservoir and foundation, and their interactions are considered. The earthquake records are applied to the tower in three cases: (i) one horizontal component, (ii) two horizontal com ponents, and (iii) two horizontal components with vertical component. The main dynamic responses of the tower including relative deflections and nonlinear material responses are presented. The obtained results are discussed, and the influence of the main shock-aftershock sequences are thoroughly examined.