Determination Of Tensile Forces Of The Inclined Cable Of Cable-Stayed Bridge During The Construction Processes Reckoning In The Geometrical Nonlinear Factors

In recent decades, with the high-speed development of bridges, the appearance of cable-stayed bridges and the improvement of construction technique, the span of the cable-stayed bridge becomes longer and longer. The difficulty of the cable-stayed bridge design, structure analysis and construction becomes higher and higher accordingly. Though in the aspects of the tensile inclined cable forces solution during the construction states have been studied a lot in foreign country and home, there are also many actual problems and lack of an integrated method to solve.This paper presents a method that the reasonable inclined cable forces during the construction process are determined by the target configuration of girder. The thought of this method is that beginning with the existing finished bridge state, the backward analysis is used to get the tensile cable forces of the construction process. Then the forward calculation is also used to get the tensile cable forces of the construction process to gain a finished bridge state under the control of the former forces. After modulating these two finished bridge state, another new backward analysis and forward analysis are carriedon again and again. The target configuration of girder attains to the designed configuration at last. Using the least squares method to modulate the inclined cable forces both in forward analysis stage and backward analysis stage, the tensile inclined cable forces during construction will be get finally.The usual finite software is used in this paper. The three-dimension cable element, three-dimension girder element, rigid element and special support element are used to build the finite element model of the whole cablestayed bridge. These geometric nonlinear behaviors such as the sag of inclined cables caused by their own dead weight, the interaction of large bending moment and axial forces in girders and towers, and the large displacement effects are considered during calculation. Newton-Raphson method and the displacementconvergence norm are used to approach the solution iteratively.The conclusions are got from the theory analysis and project example calculation in this paper as following: that the three-dimension finite clement model used in calculating the cable forces during the construction will get good results corresponding to the actual solution smoothly. The influence caused by geometric nonlinear behaviors should be considered in forward analysis and backward analysis during construction processes. Only the reasonable finished bridge state should be got by approach iteratively of forward analysis and backward analysis, the non-circled problems of the results between forward analysis and backward analysis will reach to the minimum degree.