STUDY ON STRUCTURAL CHARACTERISTICS AND FEASIBILITY OF MULTI-SPAN LONG BRIDGES

<p> This study aims to clarify the static and dynamic structural characteristics of a multi-span cable-stayed bridge and a multi-span suspension bridge with three main span lengths of 650m and to confirm its structural feasibility. In terms of static structural responses, the influence of live load on the member design of both the multi-span cable-stayed bridge and the multi-span suspension bridge was larger than that of the conventional cable-stayed bridge, but it was confirmed to be feasible. In terms of dynamic structural properties, it was confirmed that there was no significant difference between the conventional cable-stayed bridge and the multi-span cable-stayed bridge regarding seismic vibration characteristics. Although the effects of Level 2 earthquake motion on some of the girders and the main towers of the multi-span cable-stayed bridge and the multi-span suspension bridge are significant, it was confirmed that there are no critical issues. It was also confirmed that the wind resistance of the multi-span continuous cable-stayed bridge was not much different from that of the conventional suspension bridges, because the deflection frequency of the multi-span cable-stayed bridge was small, and that it was sufficiently feasible by the Selberg equation. On the other hand, the deflection frequency of the multi-span suspension bridge was even smaller than that of the multi-span cable-stayed bridge, and it was suggested that careful consideration of wind resistance was necessary.</p>