Seismic behavior of reinforced concrete bridges with skew-angled seat-type abutments

This study focuses on identifying trends in seismic behavior of reinforced concrete bridges with seat-type abutments under earthquake loading, especially with respect to abutment skew angle. To that end, a detailed approach for modeling skew-angled seat-type abutments is proposed; and a comprehensive variety of bridge configurations are considered. Specifically, three short bridges located in California are selected as seed bridges, from which different models are spawned by varying key bridge structural parameters such as column-bent height, symmetry of span arrangement, and abutment skew angle. Through extensive nonlinear time-history analyses conducted using three suites of ground motions, it is demonstrated that demand parameters for skew-abutment bridges, such as deck rotation and column drift ratio, are higher than those for straight bridges. By investigating the sensitivity of various response parameters to variations in bridge geometry and ground motion characteristics, it is shown that bridges with larger abutment skew angles bear a higher probability of collapse due to excessive rotations, and that the shear keys can play a major role in reducing deck rotations and thus the probability of collapse.