| Dynamic response and seismic safety analysis of high arch dams are in?uencedby several key factors, such as earthquake input mechanism, radiation damping e?ectsdue to infinite foundation, contraction joint opening and closing during earthquakesand concrete damage cracking, etc. The major focus of this study is on development ofa nonlinear coupled model in which all the aforementioned physical e?ects are consid-ered. The nonlinear coupled model is used in realistically simulating the response ofhigh arch dams during extremely strong earthquakes. As an engineering application,the Dagangshan arch dam with 210m in height is analyzed for damage cracking processduring designed earthquakes. The main innovation and results in this study includes:1. A 2-D and 3-D viscous-spring boundary model and the corresponding earth-quake input method are implemented for seismic analysis of concrete dams consideringradiation damping. Numerical verification of accuracy is performed for the viscous-spring boundary model. In?uence of several features, including dam height, ratio ofelastic sti?ness of rock and concrete and di?erent earthquakes, on radiation e?ects inseismic response of gravity dams is studied. Generally, seismic response of gravitydams is significantly reduced when considering radiation damping. The smaller the ra-tio of elastic sti?ness of rock and concrete, the more significant reduction of responseof dams due to radiation e?ects.2. Equivalent models for considering radiation damping e?ects in massless foun-dation model are presented and used in seismic analysis of gravity and arch dams.The equivalent models are simple and have su?cient accuracy in seismic analysis ofconcrete dams.3. The phantom node extended finite element method (XFEM) (improved XFEM)based on static function of XFEM in the commercial finite element software ABAQUSis extended to dynamic analysis. The method can be used in analysis of multi-crackextension of gravity dams during strong earthquakes. 4. A comparison study of di?erent concrete fracture models is presented. Threefracture models are discussed herein, i.e. extended finite element method with cohesivecrack model (XFEM-COH), crack band finite element method with plastic-damage re-lations (FEPD) and finite element Drucker-Prager elasto-plastic model (DP). The cor-relation of material parameters and the equivalence principle of stress-strain relationsbetween the three fracture models are proposed. Several benchmark problems includ-ing mode I and mixed-mode static and dynamic fracture in concrete are analyzed usingthe three procedures. The results are compared with the corresponding experimentaldata demonstrating that the numerical results are accurate and comparable. Overload-ing capacity of gravity dams with longitudinal cracks and dynamic fracture of Koynagravity dam are analyzed using the three models. The three procedures give reason-able and comparable results. However, the crack patterns are of significant di?erencesfrom the di?erent fracture models. Smooth curvature discrete cracks are obtained inXFEM-COH model, while hackle band cracks appear in FEPD model and ?aky yieldzones emerge in DP model.5. A nonlinear coupled model for seismic analysis of high arch dams includingradiation damping e?ects, contraction joints opening and closing and concrete damagecracking is presented. The nonlinear coupled model is used for realistically simulatingthe response of Dagangshan arch dam during strong earthquakes. It is found thatdamage cracking appears in the upper portion of the dam. The cracks are localized inthe downstream face. Contraction joints are opening during earthquakes. In addition,the in?uence of the aforementioned factors on seismic response of arch dams is alsoinvestigated.
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