Research Of Design Methods For Asymmetry Suspension Bridges

The application of the suspension bridge is very wide because of its great spanning ability and aesthetic appearance. To adapt to some special engineering situation, the asymmetry suspension bridge appears. To search the effective design methods for the asymmetry suspension bridge (no towers, the height of the two supports of the flexible cables are unequal), based on the Lifangyan village pedestrian bridge in Xinshan country of Hubei province, the differences of structural properties between the normal suspension bridge and the asymmetry suspension bridge were analyzed. The properties and the design methods of asymmetry suspension bridges were researched, and several directive results for the design of asymmetry suspension bridges were obtained.The analysis of the suspension bridge under vertical loads is the most important content during the course of the design; it is the most important foundation for the design of the main components of the bridge. First, theoretical analysis methods were used for the static analysis of the suspension bridge. The formulas for endogen force of the asymmetry suspension bridge through elastic theory were deduced and they were contrasted with those of the normal suspension bridge. The basic differential equation of deflection theory was deduced and the method of getting the roots of the equation was offered, and some simplified methods for deflection theory were presented.Second, a nonlinear static analysis via the great finite element analysis programs ANSYS was carried out. By building a series of model, the states of the asymmetry suspension bridge under vertical live loads were calculated more precisely, and the effects of the sensitive parameter "m" (ratio of height difference between the supports and the span of flexible cables) to the structure response was analyzed.Last, a modal analysis via finite element analysis programs ANSYS was carried out and the effects of sensitive parameter "m" to the structure's front six modes and corresponding frequency were analyzed.