ANALYTICAL STUDY ON EFFECTS OF EARTHQUAKE AND TSUNAMI TO A CABLE-STAYED BRIDGE WITH LARGE CAISSON FOUNDATION

Abstract

 This study is aiming at clarifying influences of the earthquake and tsunami to a cable-stayed bridge which has caisson foundation. For this purpose, a series of numeric simulations were carried out. First, flow speed, direction and tsunami height were determined by conducting a two-dimensional tsunami analysis of the large area, and they were then applied in a detailed three-dimensional tsunami analysis to obtain tsunami forces. Next, a structural analysis in which the acquired tsunami forces were input into a whole bridge system was performed. As a result, the foundation slide was not observed although the caisson foundation came floating slightly, and damage by the earthquake did not expand in the tsunami. It is concluded that the influence of tsunami force is small. Furthermore, a numerical procedure is proposed for estimating quantitatively the earthquake and tsunami induced compound damage in the whole bridge system which has large-scale caisson foundation.