Studies On Dynamic Damage Analysis And Aseismic Design Of Arch Dam

With the development of economy, a batch of arch dams with heights of more than 300 m is to be constructed in western regions of China. The arch dams are located in high seismic intensity regions with high mountains, deep valleys and steep slopes surrounded, which poses new challenges to the aseismic design of arch dam in these regions. Not only should the arch dam meet the aseismic safety requirements subject to common and occasional earthquake, but that the evaluation of its safety after rare earthquake should be given enough attention because it is of paramount importance to ensure the safety of lives and properties in the downriver region. Based on the two-stage aseismic design, the arch dam will behave nonlinearly and accumulate damage under rare earthquake. However, nonlinear analysis and damage evolution analysis of arch dam is still an unresolved problem. It therefore is of practical and theoretical significance to study the nonlinear behavior of arch dam subject to rare earthquake. It has been widely recognized that the nonlinear characteristic of monolith joint and material nonlinearity of concrete are two significant factors affecting the response of arch dam under strong earthquake. In this paper, these two types of nonlinearity in arch dam are studied.After an extensive review of the aseismic analysis of arch dam, the paper first studied the contact nonlinearity in arch dam. The basic principle of Fenves' 3-D joint element model and dynamic contact force model was introduced. Improvements were made in the dynamic contact force model to enable it to control the width of monolith joint with tension reinforcement. The simulation of the contact nonlinearity in monolith joint in ABAQUS was also discussed. Then, the concrete material nonlinearity in arch dam was studied. The method for simulation of material nonlinearity of concrete using damage theory is briefed. With the uniaxial stress-strain relationship provided in Design Code for Concrete Structures (GB 50010-2002), the damage evolution equations were formulated using the concept of continuum damage mechanics. Comparisons were made between the proposed evolution equations and other kinds of damage evolution models, including their advantages, disadvantages and application scopes. The damage evolution model was also validated in ABAQUS. Finally, aseismic design of Jinping Arch Dam was conducted. Both nonlinear characteristics of monolith joint and material nonlinearity of concrete were considered. The responses under various seismic input cases were analyzed. The joints' open/close process under earthquake action was tracked. The effects of joint open/close process and the type of joint model on dynamic responses of arch dam were discussed. Performance-based design was also introduced in the design of the Jinping Arch Dam, considering both the social and economic objectives. The conclusions obtained in this paper could provide some suggestions for the aseismic safety evaluation of arch dam.