Nonlinear Seismic Assessment of Concrete Dams Using a Novel Elastoplastic Damage Numerical Framework

Abstract

Numerical simulations were conducted to investigate the damage modes of concrete dams under seismic loading. The employed numerical model is based on an elastoplastic damage numerical framework for concrete, which innovatively unifies the stress–strain curves and the damage variables for both tension and compression. A scalar equivalent strain, with few parameters and concise form, is used to transform the complex multiaxial stress state of concrete into a simple uniaxial stress state. A net equivalent strain and a nominal damage variable are creatively defined to overcome the tensile-stress conversion problem due to the nonnegativity of the equivalent strain during the numerical realization. The numerical implementation process is independent of the mathematical models, which can be flexibly adapted according to the practical situation to better describe the stress state of concrete structures. By comparison with multiple classical experiments, it is demonstrated that the framework, with high accuracy and generality, can reflect a range of nonlinear behaviors for concrete under cyclic loading. Finally, a three-dimensional finite-element model of the Baihetan arch dam in China is established, and the effects of transverse joint contact nonlinearity and foundation radiation damping are considered. Based on the proposed framework, the dynamic response of the dam under different peak ground accelerations is calculated. The ultimate seismic capacity of the dam is comprehensively evaluated by examining the damage distribution and acceleration. The results showed that the damage at the bottom of the dam is relatively obvious under seismic loading. Under the influence of water pressure and gravity, the peak acceleration at the dam crest in the downriver direction is the largest, and the nonlinear effect of the dam in the downriver and vertical directions is also more obvious.