Preliminary analysis of the seismic response of bridges during the Chilean 27 February 2010 earthquake

Abstract

A preliminary analysis of the seismic behaviour of bridges during the February 27th Chilean earthquake is presented in this paper. The traditional characteristics of reinforced concrete Chilean bridges have been changing in the last two decades, especially in concessions roads. Therefore, three different superstructure configurations are indentified. In newer bridges designs, the diaphragm has been eliminated and in some bridges, the reinforced concrete shear key, or stoppers, has been replaced by weaker steel shear keys. Because of the earthquake, 10 relevant public bridges collapsed and 91 concession bridges, which include 52 pedestrian bridges, suffered damage or collapse. The observed damage in selected bridges around Santiago and Concepción are described here. The seismic behaviour of bridges was affected not only by the structural configuration but also by the foundation soil. Findings from this analysis reveal that the strength and stiffness provided by the steel shear keys was inadequate, and that the absence of diaphragms was found to be detrimental to the integrity of the superstructure. It is also concluded that skewed bridges are more susceptible to unseating of the superstructure and that the foundation soil played an important role in the seismic behaviour of some bridges, especially for soft and saturated soils responding in an undrained condition.