Non-linear seismic behaviour of concrete gravity dams using coupled finiteelement-boundary element technique

In this paper, the seismic response of concrete gravity dams is presented u sing the concept of Continuum Damage Mechanics (CDM) and adopting the hybri d Finite Element-Boundary Element technique (FE-BE). The finite element met hod is used for discretization of the near field and the boundary element m ethod is employed to model the semi-infinite far field. Because of the non- linear nature of the discretizied equations of motion modified Newton-Raphs on approach has been used at each time step to linearize them. Damage evolu tion based on tensile principal strain using mesh-dependent hardening modul us technique is adopted to ensure the mesh objectivity and to calculate the accumulated damage. The methodology employed is shown to be computationall y efficient and consistent in its treatment of both damage growth and damag e propagation in gravity dams. Other important features considered in the a nalysis are: (1) realistic damage modelling for concrete that allows isotro pic as well as anisotropic damage state and exhibits stiffness recovery upo n load reversals. (2) softening initiation and strain softening criteria fo r concrete, and (3) proper modelling of semi-infinite foundation using FE-B E method that allows to consider dam-foundation interaction analysis. As an application of the proposed formulation a gravity dam has been analysed an d the results are compared with different foundation stiffnesses. The resul ts of the analysis indicate the importance of including rock foundation in the seismic analysis of dams. Copyright (C) 1999 John Wiley & Sons, Ltd.