EFFECTS OF NEAR-FAULT GROUND MOTIONS IN SEISMIC PERFORMANCE EVALUATION OF A SYMMETRY ARCH DAM ON RIGID AND MASS-LESS FOUNDATIONS

In this paper near-fault ground motions effects in comparison with far-fault ground motions on seismic performance of a symmetry concrete arch dam are investigated. Various sets of nearfault and far-fault ground motions with approximate identical peak ground acceleration were used for analyses of coupled system. For this purpose Karaj arch dam was selected as case study and two different options were considered for dam-foundation interaction. In the first case foundation rock was supposed as rigid and in second one foundation rock was simulated as mass-less medium. The behavior of dam and foundation were expressed in term of displacement and reservoir was modelled based on fluid elements. The seismic performance evaluation of arch dam was performed by using demand-capacity ratios obtained from linear analyses. In addition displacements, principal stresses, total cumulative inelastic duration and the percentage of overstressed areas in upstream and downstream faces of dam body were calculated and compared in near-fault and far-fault ground motions. It was concluded that generally near-fault ground motions are more effective than far-fault ground-motions in non-cumulative damage indices; however it is vice-versa in cumulative damage indices.

کلیدواژه ها:

Symmetry Arch Dam ، Near-Fault ، Far-Fault ، Seismic Performance Evaluation