A two-dimensional formulation based on the boundary element method is presented to investigate earthquake induced fracture in concrete gravity dams. The cracking is represented by the discrete approach wherein each crack surface is modelled in a separate dam domain employing the concept of multi-domain discretization. The principles of linear elastic fracture mechanics are used to define the stress field in front of the crack tip and the stress singularity occurring at the tip is captured utilizing traction singular quarter-point boundary elements placed on each side. Stability of cracks under dynamic loads is monitored employing a propagation criterion based on the maximum tensile strain theory. The dynamic analysis is carried out by direct integration of the equations of motion. The ability of the formulation to predict correctly the stress singularity at the crack tip is demonstrated. Also verified is the ability of the formulation to simulate and monitor a changing crack profile under dynamic loading through comparison with available experimental data.;Seismic cracking of the prototype Koyna dam is investigated in detail employing both single and multiple fracture models. For the single fracture model, a parametric investigation is conducted to determine the influence of various analytical and material parameters on the fracture response of a gravity dam subjected to an earthquake. Refinement of the numerical modelling of the dam by means of internal collocation is studied and the adopted dual-reciprocity approach is shown to be adequate for seismic fracture analysis of dams. In order to obtain an enhanced database, the seismic cracking response of a monolith of the Pine Flat dam, which represents a more standard gravity-type dam, is also studied. It is demonstrated that the final pattern of cracking, as well as the fracture process itself, is largely unaffected by the geometrical properties of the cross-section. Furthermore, an attempt is made to examine the likelihood of hydrodynamic pressure build-up in cracks on the water retaining face of a dam. To this end, the corresponding opening/closing data during various phases of the dam response is analyzed. It is found that the dynamic water pressure is more likely to influence response during the post-rupture phase, rather that affect the behavior prior to rupture.;Finally, noting that the fracture investigations undertaken herein assume fixed conditions for the dam base, a time-domain boundary element procedure is proposed to allow future dam/foundation coupling in the dynamic crack propagation analysis of concrete dams.
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