Improved Method for Shape Finding of Long-Span Suspension Bridges

In recent years, many long-span suspension bridges have been constructed and the shape finding is a key issue in the design stage. This paper presents an improved shape-finding method which can overcome the shortcomings of the previous shape-finding method. The improved method is based on the common finite element analysis and convenient to be widely used in normal engineering practice. The main step can be summarized as follows. First, the vertical force components of the hangers are determined according to the construction method. Second, in the midspan, the initial equilibrium state of the main cable is calculated iteratively based on the Newton–Raphson method. Third, in the side span, the shape finding for the main cable is executed according to the horizontal force equilibrium of the pylon. Finally, the full-bridge model is obtained and examined carefully. The improved method is demonstrated through one suspension bridge with a planar cable system and one with a spatial cable system. The results show that the improved method is more efficient and accurate compared with the previous shape-finding method.