Research Of Self-anchored Suspension Bridge To Sudden Breakage Of Hangers

Self-anchored suspension bridge anchors its main cables to the two ends of the girder, and the main cables exert large horizontal component on the stiffening girder. If the hangers supporting the girders break, it maybe makes the girder damage and makes the whole bridge collapse. With the using time increasing, due to corrosion hangers’bearing capacity reducing may occur suddenly break. The sudden breakage of hangers can make the structure vibrate fiercely and the Structural internal force change greatly, even endangers bridge safety.This paper takes a concrete self-anchored suspension bridge with main span of 200m as example, uses nonlinear static and dynamic analysis methods and adopts 3D finite element model, to study the responses to sudden breakage of hangers. The results tell that the sudden breakage of a hanger has large effects on tensions of the hangers next to the broken hanger, reaction forces of the bearings, torsion moments of the girder and moments of the towers bending. The results adopt dynamic analysis methods are very different from those adopt static analysis methods. If two adjacent hangers on the same side break one by one, it would make the maximum tension of other adjacent hangers exceeds 3.0 times of its initial value. If adopt a low safety factor to design the hangers, or the hangers have been exposed to corrosion generally, the breakage of two adjacent hangers will lead the bridge to collapse. To study the influences of weight of main cable, torsion stiffness of girder, breakage time of hanger, span to sag ratio of main cable, weight of girder, distance of hangers, flexural stiffness of girder, span length and flexural stiffness of main cable on the dynamic responses. At last, discuss the influences of double hangers on the structure dynamic response caused by breakage of hanger, and give the suggestions for the improvement of structure safety.