Seismic plastic-damage analysis of mass concrete blocks in arch dams including contraction and peripheral joints

摘要

Seismic nonlinear analysis of concrete arch dams is a topic having been extensively studied in the last two decades. Due to the existence of different joints within the body of arch dams, the discrete crack (DC) approach utilizing interface elements for the joints is the most realistic method. In fact, it could be the first step to assess the seismic safety of an arch dam. Furthermore, since the mass concrete blocks may crack due to severe ground excitations, a plastic damage (PD) model well capturing stiffness degradation and permanent deformation due to tensile cracking and compressive crushing might be needed. In this study, a special finite element program called SNACS is developed based on the combined discrete crack and plastic damage (DC PD) technique. The dam reservoir interaction as an important factor affecting the seismic response of arch dams is also treated by the Lagrangian Eulerian formulation. The joints modeling strategy adopted herein is addressed first and then, a brief review of the plastic damage model proposed by Lee and Fenves and extended herein to 3-D space is presented. Afterwards, the nonlinear seismic analysis of a typical thin arch dam is performed based on the combined approach and the response is compared with the results of each method. It is emphasized that employing the combined DC and PD models gives more reliable and consistent response in comparison with using DC or PD approaches applied alone. Therefore, the DC PD technique could be considered as a major step toward a more accurate seismic safety evaluation of concrete arch dams.