Effect of incidence angle on the seismic performance of skewed bridges retrofitted with buckling-restrained braces

Abstract

This study examines the effect of ground motion (GM) incidence angles on the seismic response of skewed bridges retrofitted with buckling-restrained braces (BRBs) under far-field and near-field ground motions (FFGMs and NFGMs). Bridge models for a three-span reinforced concrete bridge with skew angles of 0°, 18°, 36°, and 54° are used as a case study. Three-dimensional nonlinear dynamic analyses are performed with scaled GMs under 11 incidence angles (from 0° to 180°) to obtain the maximum bridge response parameters on the maximum considered earthquake hazard level. This study demonstrates the effectiveness of a BRB retrofit to reduce the influence of GM incidence angle. The results indicate that skewed bridges are less sensitive to the GM incidence angle and BRBs further decrease the incidence effect. Also, the seismic response under different GM incidence angles is more predictable when the bridge is subjected to FFGMs. In general, the maximum response of skewed bridges could be estimated by applying the scaled principal GMs along the bridge’s longitudinal axis and its orthogonal direction (i.e., 0° and 90°), regardless of GM characteristics, skewed angle, and BRB retrofit.