Geometric Nonlinear Static Analysis Of Cable Stayed Bridge With Single Tower

By expatiating on the concept of nonlinearity and the method of analysis for geometric nonlinearity and three main factors as large displacement, cable sagging and Girder-column effect of cable-stayed bridge, this paper systemically introduces basic theory for geometric nonlinear analysis and Newton-Raphson method for value solution, studies and discusses the disposal of some problems in modeling of finite element of cable-stayed bridge in ABAQUS. The paper works at geometric nonlinear static analysis for the cable-stayed bridge which is Harbin Songpu Bridge, and depends on ABAQUS to calculate and analyze 28 construction stages and service stage. Based on a group of initial stress of cable in construction stage calculated by "Two-steps Method", linear and nonlinear calculation is carried out for every construction situation, and the results of 7 typical construction stages and service stage are analyzed. By compare analysis, the conclusions are made as follows:In construction stage, internal stress of a cable varies continually with construction process, in other words, cables' stress are redistributed, however, geometric nonlinear effects and their combination effects on cable stress are not obvious at all. So the ultimate stress of cable rests with its initial stress and structure shape. Girder-column effect is tender in construction except in several steps of double cantilever constructing. Large displacement effect is small during double cantilever constructing, but it will increase in single cantilever constructing, special for vertical displacement of girder, level displacement of tower and moment of girder. Cable sagging effect is most obvious in whole construction stage, so it is considered as the chief factor of geometric nonlinearity. Generally, the combination effect of three factors is more than a single factor of its effect, and mostly is more than sum of three factors effect, so there will be a biggish tolerance if one of three factors was ignored.In service stage under dead load, generally speaking, cable sagging effect is most obvious, large displacement effect following, girder-column effect least. The same as construction stage, the combination effect of three factors is more than a single factor of its effect and sum of them. The length of cable is the decisive parameter of the sagging, and initial stress is following.Every nonlinear effect's degree is not only different in different situation, also in different part in same situation. For unsymmetrical cable-stayed bridge, no all nonlinear factors' effect is disadvantage for structure in construction and service stage.