Ground motion selection for nonlinear response history analyses of concrete dams

Evaluating the seismic performance of a 3D concrete dam using nonlinear response history analysis (NLRHA) requires three orthogonal components of ground acceleration histories, or ground motions (GMs) for brevity. Although much progress has been made for the topic of ground motion selection and modification (GMSM) in the context of multistory buildings, NLRHA of dams requires at least two additional considerations: (i) accounting for multiple modes of vibration and (ii) including three orthogonal components of GMs. To convey the key ideas in developing an ensemble of multicomponent GMs for this context, the fundamentals of GMSM are first briefly reviewed using a case study. Then, special considerations for concrete dams are highlighted. Finally, a practical method for developing target spectra and selecting multicomponent GMs is presented.