Mechanical Properties Of Self-anchored Suspension

As a novel bridge type, self-anchored suspension bridge develops quickly in China for its advantages in asesthetics, economics and adaptability of geology and topography. It has been a competitive plan for bridge with span from 100m to 400m. Taking Sanchaji Bridge as background, the thesis carried out research on self-anchored suspension bridge.Firstly, it studied computation methods of cable system of self-anchored suspension bridge. The methods can be divided by two categories. One is without considering the girder's effects on cable system, including parabolic method and segmental cateneries method, and another is finite element method which could consider the girder's effect. The thesis expounded those methods, deduced a series of formulae and compared them. According to the feature of self-anchored suspension bridge, it is recommended to apply finite element methos to obtain exact results.Next, it calculated the cable system of Sanchaji Bridge through finite element method by compiling SASB program using APDL, parametric language of finite element program ANSYS. Through iteration computing of orderly-erecting analysis, it calculated cable in bridge completion stage, cable finished stage, excursion of saddles and the installing position of hangers considering the influence of girder and construction process. The result showed that there were about 0.53% and 1.96% deviations in zero-stress length and horizontal force of cable between method without considering girder's stiffness and finite element method.Finally, it carried out static and dynamic computation and parametric analysis to research mechanical behavior of self-anchored suspension bridge. The results showed that the stiffness of self-anchored suspension bridge would decrease with the decreasement of rise-span ratio while earth-anchored suspension bridge has the opposite behavior. And the distance between hangers had nonlinear effect on bridge's stiffness as being too long or too short would reduce structure's rigidity, so it need comparation to determine the optimal distance between hangers. In addition, the set of girder camber could increase structure's rigidity. Besides, the longitudinal damping has great influence on self-anchored suspension bridge's fundamental frequency. With the increasement of damping, the fundamental frequence would increase.