Earthquake response of concrete arch dams: a plastic-damage approach

摘要

There are several alternatives to evaluate seismic damage-cracking behavior of concrete arch dams, among which damage theory is the most popular. A more recent option introduced for this purpose is plastic-damage (PD) approach. In this study, a special finite element program coded in 3-D space is developed on the basis of a well-established PD model successfully applied to gravity dams in 2-D plane stress state. The model originally proposed by Lee and Fenves in 1998 relies on isotropic damaged elasticity in combination with isotropic tensile and compressive plasticity to capture inelastic behaviors of concrete in cyclic or dynamic loadings. The present implementation is based on the rate-dependent version of the model, including large crack opening/closing possibilities. Moreover, with utilizing the Hilber-Hughes-Taylor time integration scheme, an incremental-iterative solution strategy is detailed for the coupled dam-reservoir equations while the damage-dependent damping stress is included. The program is initially validated, and then, it is employed for the main analyses of the Koyna gravity dam in a 3-D modeling as well as a typical concrete arch dam. The former is a major verification for the further examination on the arch dam. The application of the PD model to an arch dam is more challenging because the governing stress condition is multiaxial, causing shear damage to become more important than uniaxial states dominated in gravity dams. In fact, the softening and strength loss in compression for the damaged regions under multiaxial cyclic loadings affect its seismic safety.