The Analysis Of The Cable Shape, Modeling Of The Suspension Bridge And Its Rationality Study

The form-finding of the main cable is very important to the design of the suspension bridge. There are a lot of studies on the shape finding for the inextensible cable and extensible cable. This paper presents a method of the form-finding for the main cable of suspension bridge. The method is based on the design parameter (the ratio of dip to span), and elastic deformation of the cable is taken into account.For the purpose of static and modal analysis on the suspension bridge, in the paper, a simple, reasonable and valid finite element model is set up. Meanwhile, the simplification of the complicated steel-box deck is achieved. According to the equivalency principle of the bending stiffness and shear stiffness, a simple equivalent deck is put forward.Suitable type of finite element is necessary to building the bridge model. In order to consider the bend and the torsion of the cable, main tower and hanger, the three-dimensional beam element is employed. For the deck, the thin shell element is utilized. In addition, the connection between all parts of bridge model is treated as more closed to the situation of the real structure.As an example, the finite element model of Humen suspension bridge is set up. After the static analysis, we can check the finite element model and know the distribution of displacements and stress under vehicle load and wind pressure. By modal analysis, we get the natural frequency and mode shape. Comparing the calculation results with the measured results practically, the difference of the modal parameter is very small.Observing the change of the dynamic characteristics of bridge with different structure parameters (such as the deck width, support position, etc), the structure rationality of large span suspension bridge is discussed.Last, by the modal test of the bridge model, the correctness of the modeling method is proved, and we clearly know the mode characteristic of the bridge.