Seismic Fragility Assessment of Skewed MSSS-I Girder Concrete Bridges with Unequal Height Columns

Abstract

Multi Span Simply Supported Bridges (MSSS) are categorized among the most vulnerable bridge classes and their vulnerability increases when different sources of irregularities such as skewness as well as columns height differences are included. Different sources of irregularities make the irregular bridge more complicated in case of dynamic response than regular bridges, and therefore a comprehensive study should be implemented to explore the effect of different irregularities on seismic performance of bridges individually and jointly. This paper explores the effect of skewness and unequal height columns on the seismic response of MSSS-I girder concrete bridges commonly constructed in Central and Southeastern United States (CSUS). The scope of the study is limited to tree spans which are the most prevalent spans in this class of bridges. The results show that the component fragilities become more sensitive to column height ratio with increase in the bridge skew angle particularly in longitudinal direction. The study of the combined effects of skewness and column height ratio on the bridge system fragility also reveals that the column height ratio has negative effect on the fragility of bridge system in all damage states and different skew angles but this effect increases by increasing the skewness as well as damage state of interest.