Research On Cable-stayed Bridge Tension Optimization Considering Geometric Nonlinearity And Cable Force Adjustment After Construction

As a kind of flexible structure with great ability of span, cable-stayed bridge has quiet great progress in recent years. The cable is one of the key parts of cable-stayed bridge. It takes on most part of the Load in constructing and constructed of cable-stayed bridge. Rational cable force can guarantee the structure safety in construction and make the structure’s internal force reasonable after construction.Therefore; the cable force optimization of the cable-stayed bridge has important effect on internal force after construction whether reasonable.For long-span cable-stayed bridge, the geometric nonlinear effects can not be ignored. Therefore, the optimization of the cable force is necessary to consider its impact. However, the existing cable tension optimization program based on linear conditions obtain the initial cable tension. Although many scholars have done a lot of the nonlinear cable forces of cable-stayed bridge research, and achieved certain results, but its optimization method derived from the internal forces of cable-stayed Cable Stayed Bridge, and does not describe how you reached the initial tension of the cable.This paper based on the existing researches on cable-stayed bridge, centers around the calculate methods for rational cable force. Which can be summarized as follows:(1) Geometric nonlinear behaviors in large span cable-stayed bridges have been analyzed, which include the sag of inclined cable stays caused by their own dead weight; the interaction of large bending and axial deformation in bending members; and the large displacements effects. Then analyzing theories and researching levels of geometric nonlinear problems of modern cable-stayed bridges have summarized. And methods of modeling cable-stayed bridges for nonlinear finite element analysis have been discussed, which are the equivalent modulus of elasticity, introducing stability functions and continuously modifying geometry of structure. Then in this thesis some basic methods for geometric nonlinear analysis of cable-stayed bridges have also been discussed and algorithm of co-moving coordinate iteration combined incremental and iterative approach is established. (2) Cable-stayed bridge is to realize the correct cable force to determine reasonable bridge state priority, and through the adjustment to the stress of the structure change of cable force distribution, to optimize the force is especially important. At first the research results about cable force optimization both at home and abroad are reviewed, and then the present situation of cable force optimization is preliminarily analyzed, and the optimization principle of cable-stayed bridge is concluded in the paper.(3) Analysis of the cable-stayed bridge three geometric nonlinear factors on cable-stayed Bridges of reasonable initial tension influence. In the three factors of geometric nonlinearity, cable sag effect has the most obvious effect on the moment of main girder and nonlinear of large displacement has greater effect, while the combined effect of moment and axial force has the least influence. As Yuyang Hanjiang Highway Bridge for example, using the Midas/Civil existing linear optimization function iteration calculate the nonlinear of the cable-stayed under initial tension.