Seismic Analysis Of Arch Dams With Contraction Joints And Dam-water-foundation Interaction

For construction facilitation and in order to control tensile forces due to concrete shrinkage, temperature variations, concrete arch dams are typically built in cantilever monoliths separated by vertical contraction joints. Opening and closing or sliding of the contraction joints will happen during earthquakes in reality, which will release arch stresses at the joints and redistribute forces from the arches to the cantilevers. The contraction joint plays an important role in the nonlinear response of high arch dams during strong earthquakes. Other two key factors for the seismic analysis of arch dams are the dam-water-interaction and the effects of radiation damping of infinite foundation. The purpose of this thesis is to provide a numerical method to simulate the nonlinear seismic response of the arch dams with the consideration of the above three important factors. The main research contents are as following:1, A new algorithm—Mixed Finite Element Method, was proposed for nonlinear static and dynamic fictional contact problems of high arch dams with contraction joints. Based on this method, the system of forces acting on the contactor was divided into two parts: external forces and contact forces. The displacement of contactor was chosen as the basic variable and the nodal contact force in possible contact region was chosen as the iterate variable, so that the nonlinear iteration process was only limited in the possible contact surface. In this way, the sophisticated contact nonlinearity was shown by the variety of the contact forces. Thus the iterative procedure became easily to be carried out and much more economical.2, The numerical method for the analysis of dynamic dam-water-interaction was discussed to establish a method which is fairly simplified but without loss of accuracy for the simulation of the dynamic pressure of the water. First, an introduction of the iterative algorithm for fluid-structure-interaction problems based on the improved Wilson-θ method was given. And then, two algorithms proposed in this thesis for fluid-structure-interaction problems based on the generalized Newmark-β method were given: stagger iterative algorithm and integrated solution base on the direct integral. At last, several factors, which will affect the dynamic pressure on the surface of the dam, were discussed.3, The artificial multi-transmitting boundary condition was combined with implicit finite element formulation and applied to the nonlinear seismic analysis of high arch dams together with the mixed finite element method for fictional contact problems and the algorithm for dam-water-interaction. In this way, a fairly perfect and high efficiency analysis method for seismic analysis of arch dams with contraction joints and dam-water-foundation interaction. A new...