Seismic analysis of highway skew bridges with nonlinear soil–pile interaction

Abstract

Performance of highway bridges during an intense seismic event is an issue of utmost importance. Of particular interest is the response of skewed highway bridges, where the skew angle and other related factors make the problem more complex. Although a number of studies had been carried out to address these issues in the past, most of them have neglected or over-simplified the soil–structure interaction effects, primarily relying upon the assumption that soil–structure interaction generally leads to a conservative estimation of seismic demands. The present study focuses on investigating the effect of skew angle on seismic response of a bridge-foundation system including nonlinear soil–pile interaction subjected to bi-directional ground motions. It has been observed that the rotational demand of the bridge deck is greatly affected by the skewness, indicating an increased vulnerability of skewed bridges due to rotational movement of the deck leading to deck unseating. It is also observed that the shear and moment demands of the piers increase significantly with increasing skew angle, as much as 54% and 37%, respectively. The maximum bending moment of the pile shaft is also found to increase upto 55%, indicating higher design requirements for the foundation components of the skew bridges compared to a similar normal bridge.