Seismic Safety of Gravity Dams: From Shake Table Experiments to Numerical Analyses

Abstract

The purpose of this paper is to present shake table experiments conducted on four 3.4-m-high plain concrete gravity dam models to study their dynamic cracking and sliding responses. The experimental results are then compared with a smeared cracked finite-element simulation using a nonlinear concrete constitutive model based on fracture mechanics. For the sliding mechanism, the numerical simulations use rigid body dynamics with frictional strength derived from the Mohr-Coulomb criterion. From the cracking tests, it is shown that a single triangular acceleration pulse could initiate and propagate a crack. The numerical correlation with the observed response is good. However, viscous damping varies experimentally from 1% in an uncracked situation to over 20% in a partially cracked case. For the sliding mechanism when the critical acceleration is exceeded, it is shown experimentally that sliding could occur due to a single triangular acceleration pulse. For actual seismic records, the cumulative sliding displacement for a given peak ground acceleration due to low frequency western North American records can be 3–4 times larger than the corresponding sliding displacements due to high frequency eastern records. For simplified pseudostatic or pseudodynamic sliding analyses, the concept of an effective acceleration is developed.