Earthquake damage estimation of the Koyna concrete gravity dam using explicit GFVM model considering fluid–structure interaction

In this paper, an Explicit Galerkin Finite Volume Method (E-GFVM) is employed to estimate damage paths in concrete structures through the definition of nonlinear behavior of concrete. Furthermore, to verify the accuracy and efficiency of the present method, the E-GFVM outcomes are compared with the Explicit Finite Element Method (E-FEM) which is a well-known numerical method for investigating numerous solid mechanics problems. Due to the essence of explicit methods, the method in question uses a few matrix operations in nonlinear analysis, so it diminishes computation workloads for time-dependent cases with small time-step. The reason for using E-GFVM was its simplicity and high accuracy in estimating stresses and displacements for the analysis of Computational Solid Mechanics (CSM) problems. Furthermore, one important feature of FVM is its local conservation properties which guarantee the global conservation of variables that provides more stability, particularly in dealing with complex problems. To model the nonlinear behavior of concrete, the two equivalent uniaxial stress–strain relations, taking into consideration the softening and hardening behavior in both compression and tension, are implemented in the proposed numerical method. In other words, the bi-axial concrete behavior is defined by applying the idea of current strength in principal stress space. Therefore, this study aims to introduce a new numerical method that in addition to reducing time consumption, can maintain the accuracy of the results. For reaching this purpose, first, the nonlinear behavior of concrete is modeled and two different specimens are placed under pure pressure and tension loads. The results calculated by the E-GFVM are compared with other literature. After verification of the nonlinear behavior of concrete using E-GFVM, the ability of the proposed method for analysis of a real-world case under time-dependent conditions, namely Koyna concrete gravity dam which experienced a destructive earthquake in 1967, is tested, considering the impacts of dam–reservoir interaction. Then, this problem with the same conditions is modeled and analyzed using the E-FEM. The results show that, in spite of good harmony between two utilized methods for estimating the damage on the body of Koyna dam, the CPU time of the E-GFVM became about 3 times less than the E-FEM.