SEISMIC STRENGTHENING OF LOW TOWER CABLE-STAYED BRIDGE USING METAL ALLOY BRACE

A low tower cable-stayed bridge with a span of 30m+60m+120m+60m+ 30m had been built before Guidelines for Seismic Design of Highway Bridge was promulgated. Because of its importance and specificity, it is necessary to do research on seismic performance of the bridge. Based on three-dimensional finite element model, it is found that the bearing deformation across the bridge is very big, and it might be destroyed if earthquake happened. In this article, a new damper (Metal Alloy Brace) is used to achieve seismic strengthening. Under frequently occurred earthquake excitation, MAB will supply a small stiffness, but its hysteretic curve is plump, so the structural deformation is re- duced. Under rare earthquake excitation, MAB can supply so big stiffness that the structural deformation is limited, and the damper will also dissipate much energy. Through comparing, it is found that MAB is better that caging device. And the dam- per has no problem with leakage and metamorphism. So, MAB has a good prospect in seismic strengthening.