Direct finite element method for nonlinear earthquake analysis of concrete dams: Simplification, modeling, and practical application

Abstract

Summary A direct finite element (FE) method for nonlinear response history analysis of semi‐unbounded dam‐water‐foundation systems has recently been presented. The analysis procedure employs standard viscous‐damper absorbing boundaries to model the semi‐unbounded foundation and fluid domains and specifies the seismic input as effective earthquake forces—determined from a control motion defined at the foundation surface—at these boundaries. Presented in this paper are several simplifications to this direct FE method that greatly facilitates its implementation in commercial FE software. Also addressed is the modeling of the principal nonlinear mechanisms for concrete dams, calibration of damping in the numerical model to ensure consistency with values measured at actual dams, and practical procedures for implementation of the direct FE method with a commercial FE program.

State-of-the Art-Powerhouse, Dam Structure, and Turbine Operation and Vibrations

“…The results showed that characterizing the variability of the sliding safety factor is possible. Others applied the direct FE method to the non-linear response of the semi-unbounded dam-water-foundation system using seismic input as an effective earthquake to model the non-linear mechanisms of concrete dams [128]. Similar studies were conducted using foundation mass and earthquake input for a concrete dam in one case, and in another, radiation damping and foundation mass were used as input to design two models (free-field boundary condition and domain reduction method) based on the FE method.…”

“…The results showed that the cavitation rate, the magnitude of pressure pulsation, and performance loss increase with increasing suction head. Hydraulic turbines and types of cavitation have been described [128,129]; numerical and analytical research with theoretical studies on cavitation phenomena in hydraulic turbines have been extensively reported. Sufficient predictions for cavitation have been provided via numerical methods.…”

Characterization of the dynamic behavior of a concrete arch dam by means of forced vibration tests and numerical models

“…Further improvements were made with better representation of the dam‐water‐foundation interaction, dam joints, viscoelastic and absorbing boundaries conditions, non‐linear behavior of the joints and concrete, and others . A discussion of current key issues in dam analysis models is presented by Løkke and Chopra, who show the advantages of the direct finite element approach, based on foundations with mass and absorbing boundaries, for nonlinear analysis. Similar conclusions are drawn by Penner et al based on a 2D LS‐DYNA model, and by Robbe .…”

Numerical and Physical Analysis on the Response of a Dam’s Radial Gate to Extreme Loading Performance

“…In this research, a contribution of sloshing effects on the gates was also investigated and it was determined that such dynamic loads can be neglected. Advanced finite element method (FEA) techniques are now typically applied to determine the hydrodynamic loads on dams and spillway gates, reflecting current reclamation practice [9][10][11][12][13][14][15]. In this approach, the reservoir is modeled using solid elements with a fluid equation of state and the dam, foundation, and gates as an elastic structure.…”