Analytical study of the coupled motions of decks in skew bridges with the deck–abutment collision

Abstract

It has been observed from failures of highway bridges during major earthquakes that skew bridges are among the most vulnerable to seismic loading. It has been shown that the coupling between the translational motions of the deck and the collision of the deck with the abutments are two major factors influencing the vulnerability of skew bridges. This paper studies the influence of deck–abutment collision (seismic pounding) on the coupled motions of decks of skew bridges during strong earthquakes using an analytical approach. A three-degree-of-freedom model is presented to study key dynamic features of skew bridges. It is assumed that the deck of the model is rigid and the columns remain elastic during the ground motion. Contact planes between the deck and the abutments are idealized by several contact points pairwise arrayed at the end-span expansion joints. The mechanism of energy absorption and dissipation during the contact duration is simulated through the implementation of a nonlinear contact element between the contact points. A parametric study has been carried out by varying different parameters, including the skew angle (β), the size of the gap between the deck and the abutments at the end-span expansion joints (gap), and the normalized stiffness eccentricity along the x-axis (ex/r). The results of this study show that the transverse displacements of acute corners of the deck and the rotation of the deck about the mass center noticeably increase with the increases of β and ex/r, and with the decrease of the gap.