Study On The Influencing Factors Of The Reasonable Bridge Condition Of Hybrid Girder Cable Stayed Bridge

The girder of hybrid girder cable bridge is composed of prestressed concrete girder in side spans and steel girder in middle span,respectively. The combined section generally close to the bridge tower. The girder using different materials, can make full use of the weight of concrete material and the light quality and large span of steel material. Hybrid girder cable bridge has big spanning capacity and the cost of the economy. Reasonable state of cable bridge is the layout shape of girder and tower compling with the design requirements in the final state,the relatively uniforming stress of girder and tower,the the roughly same stress of cables and the less quantity of cables varieties as far as possible.In this thesis, a hybrid girder cable bridge as the background,some parameters,that may having some influence on the reasonable bridge state of a hybrid girder cable bridge,are studied. The main contents are as follows:1.Through the comprehensive analysis of cable bridge at domestic and abroad, a comprehensive practical cable force optimization method is put forward with the combination of minimum bending energy method, influence matrix method and the feasible region method, making up for the shortage of the single cable force optimization method. For example, minimum bending energy method can not consider the effect of live load and prestress, etc. The algorithm is implemented by unknown load coefficient function of Midas/Civil and optimization toolbox of Matlab. Finally, the method is proved simple and effectiveness by practical calculation;2.In view of the different section of steel and concrete girder having big difference in weight andstiffness and the integration of location determining the length ratio between the steel and concrete, so the fringe location choice for force especially the stress of the main girder of cable bridge have a large influence. Integration of location selection need to comprehensively consider the effect of various factors. This thesis selective analysis the different location of combination impacting on force especially girder bending moment distribution of cable bridge and girder flexural deformation peak structure of live load effect;3.This thesis discussed the stiffness of concrete girder and steel girder changing structure behavior influence on deformation of cable-stayed bridge, etc.