AN APPLICATION OF DAMAGE MECHANICS FOR SEISMIC ANALYSIS OF CONCRETE GRAVITY DAMS

This paper discusses the local approach of fracture using damage mecha nics concepts to evaluate the seismic response of concrete gravity dar ns. A constitutive model for plain concrete, subjected to tensile stre sses, is presented. The mesh-dependent hardening technique is adopted such that the fracture energy dissipated is not affected by the finite element mesh size. The model is implemented in conjunction with the H ilber, Hughes Taylor alpha algorithm for time marching. Koyna dam is u tilized to validate the proposed formulation. The importance of initia l damage prior to the advent of an earthquake is also investigated. A 60 m concrete gravity dam is therefore selected and subjected to groun d motion typical of eastern North America. Five scenarios of initial d amage are presented and the results confirm the importance of accounti ng for the initial state for the seismic safety evaluation of an exist ing dam.