Typological study of the elastic seismic behavior of cable-stayed bridges

摘要

The elastic seismic response of cable-stayed bridges with different types of towers, cable arrangement, main span length and type of foundation soil is studied and compared in order to obtain useful conclusions for the design of such outstanding structures in seismic areas. A previous research on the size of a large number of cable-stayed bridges constructed worldwide has been performed to obtain 35 finite element models, which have been studied using rigorous time domain modal analysis, considering twelve synthetic accelerograms obtained from the design spectrum proposed by Eurocode 8 and validated with predicted results of empirical models. Both extreme seismic forces and stresses have been collected, besides conducting specific studies about the seismic transverse interaction between the deck and the towers, the influence of each component of the accelerogram record in the global response and the effect of the smooth transition between sections along the tower. Cracking or plastification problems would appear in all studied models, especially those founded in soft soil (type D). In light of the results bridges with two planes of cables are more recommended in seismic areas and towers for which the lower segments are connected to a single vertical element may dangerously concentrate the seismic demand. The transverse component of the accelerogram record is the most demanding one which enforces the idea of the incorporation of seismic devices substituting the traditional rigid transverse connection between deck and towers.