Seismic analysis of damaged concrete gravity dams subjected to mainshock-aftershock sequences

The current study aims at seismic analysis of damaged concrete gravity dams subjected to aftershocks loading of earthquake. Dams' sliding behaviour is also discussed to shed light on the issue. For the purpose of the study, a cracked concrete gravity dam was modelled, and zero thickness contact elements were used to model the contact between the main body and the separated damaged parts of the dam. The augmented Lagrangian method, considering frictional sliding and opening of contact joints, was used in non-linear analyses. Fluid-structure-interaction, considering fluid compressibility and absorptive boundary of reservoir, was also taken into account. The damage model of 'Konya' and 'Manjil' dams comprised our case study. Non-linear dynamic analyses were done based on both models. Stiffness and damping coefficients effect on the seismic response of dam were examined. Dam, foundation and reservoir interaction effects were also included. The results were compared to the results obtained from other methods, which showed adequate similarities. The differences between damages caused by aftershocks are discussed, and it is pinpointed that the stability of dam during aftershocks is not compromised. It is demonstrated that top block slides during each aftershock and finally incurs some permanent sliding which may destroy the dam.