Investigation of the effect of reservoir bottom absorption on seismic performance of concrete gravity dams using sensitivity analysis

Abstract

In this research, probabilistic analysis of the seismic performance of gravity dams is presented considering interaction effects to quantify the sensitivity of seismic response to reservoir bottom absorption. The maximum value of horizontal displacement of dam crest, hydrodynamic pressure, 1st principle stress at heel and 3rd principle stress at toe of dam, during earthquake excitations, are considered random variables in the probabilistic analysis of base-case model. In order to propagate the parametric sensitivity to the seismic performance of the system, Monte Carlo simulation with Latin hypercube sampling is used as a probabilistic simulation method. Sensitivity of responses under seismic loading is reliably examined utilizing different values of bottom absorption as random inputs. Computational procedure for two-dimensional finite-element analysis of the base-case model is carried out in time domain considering the dynamic excitation and dam-reservoir interaction. Considering the obtained results, that the manner through which the bottom absorption can affect the seismic behavior of concrete gravity dams due to earthquake is determined. To estimate the structural performance under seismic loads, a suite of ground motions is selected and applied to the base-case model and the model sensitivity to reservoir bottom absorption is investigated. Finally, to show the effectiveness of the sensitivity and probabilistic analysis procedure presented in this paper the response of Koyna and Pine Flat dams with respect to the horizontal component of El Centro earthquake is investigated as real models. The obtained results show that the sensitivity curves of output parameters are linear or bilinear relative to the models and ground motion records.