Investigation Into Cable Force For Concrete Cable-Stayed Bridge

Cable-stayed bridge is highly redundant complex structure, stay cables makes the main beam similar to the continuous beam which has more elastic supports and could optimize the structure stress state through adjusting cable force. With the design concept and construction technology are innovating, the span of cable-stayed bridge is increasing, cable forces has more important influence on the distribution of the structure internal force, it is reasonable or not has become the key point in the design and construction of the cable-stayed bridge.This paper is based on a highway cable-stayed bridge and the finite element analysis as a platform, focuses on cable force optimization, has done the work as following:1. Summarized the development of domestic and foreign cable-stayed bridges and described the structural analysis theory;2. Summarized the theory and calculating methods of reasonable cable forces which are frequently used, compared and analyzed advantages and disadvantages;3. Proposed making the least sum of bending, tension and compressive strain energy as a goal function, used the unknown load factor method which is provided by Midas/Civil to calculate the initial tensile cable forces, used the optimization toolbox which is provided by MATLB to calculate the initial tensile cable forces that is based on binding influence matrix method, then according to the rational moment region of main beam, adjusted local cable forces and got the rational hanger cable forces;4. Calculated the cable force of cable-stayed bridge which is constructed by hanging basket of front fulcrum. According to the construction stage of hanging basket force requirements, determined the regional of cable forces during the construction stage, then chose the average of the lower limit and up limit to the model and do forward calculate, considering the force of main beam to adjust cable forces, in order to get the rational construction cable forces.The calculation results show that the structure force during the construction and finished phase is reasonable, the stress of beam meets the specification, so it could ensure security and stability of the construction and finished phase. So that, adopting the method of this paper to calculate the cable force is reasonable and possible.