Simple models for simulating shear key arrangement in nonlinear seismic analysis of arch dams

Abstract

Shear keys are commonly designed on contraction joints to limit joint slipping and improve the overall seismic behavior of arch dams. However, shear keys are usually over-simplified in the current nonlinear seismic analysis. This paper proposes a geometric simplification method for simulating shear key arrangement. Actual shear keys on a contraction joint are simplified into the combination of large oblique-type shear keys along the cantilever direction and horizontal direction. Key geometric features and progressive failure of shear keys can be naturally considered using the contact boundary model and the plastic-damage model. Nonlinear seismic analysis of the Xulong arch dam is implemented with different shear key models for verification and comparison. The proposed method is firstly verified by analyzing seismic responses of the dam with geometrically-simplified shear keys and fine shear keys, respectively. Furthermore, seismic responses of the dam with geometrically-simplified shear keys, free-slipping plane joints (ignoring shear keys but considering surface friction), and non-slipping plane joints (modeling perfect shear keys) are compared to investigate the effects of shear key modeling methods. Ignoring shear keys and modeling perfect shear keys underestimate and overestimate the seismic capacity of the dam, respectively. The nonlinear dynamic behavior of shear keys can be more reasonably represented with the proposed method without much increasing modeling efforts.