Seismic behavior of pine flat concrete gravity dam using microplane damage-plasticity model

The response of concrete gravity dams under seismic loads is a major concern of dam safety assessment in earthquake-prone areas. This study focuses on the seismic analysis of the tallest non-overflow monolith of Pine Flat Dam. The paper presents results of numerical modelling considering the effects of fluid-structure interaction for both linear and nonlinear analysis using accelerations records of the historical Taft earthquake and of an artificially designed Endurance Time Acceleration Function (ETAF). Linear analyses establish the dynamic properties of the reservoir-dam-foundation system and its behavior considering non-zero mass foundation as compared with massless foundation, for two typical reservoir water levels. Whilst the former is physically more complete, it leads to an effective horizontal displacement after the dynamic loading whereas the massless foundation model shows no residual horizontal displacement of the dam base. A damage-plasticity model based on microplane formulation is used to model the extent of damage in the dam body during nonlinear dynamic analysis. Results show the ability of the model to represent cyclic loading conditions, with recovery of the stiffness lost during cracking in the transition from tension to compression state, and subsequent failure of the dam body.