Research On Structure Performance Of Prestressed Concrete Cable-stayed Bridge With Single-cable And Multi-tower

The PC cable-stayed bridge composed of single-cable, multi-low-tower and rigidgirder is studied in the thesis. This kind of bridge has a graceful figure, advancedmechanical performance and it is convenient for construction, so it is competitive inthe medium span city bridges and has a bright future. Based on the first cable-stayed bridge with single-cable and multi-tower beenbuilding in our country, two models used the finite element method are builtrespectively to analyze the bridge's static behavior, dynamic behavior and seismicresponse. And the structure behavior is confirmed further in the plexiglass modelexperiment. The conclusions about the structure behavior drawn from the analysis areas follows: (1) The bridge's features of deflection and the longitudinal stress distribution aresimilar to the continuous rigid frame bridge's at the case of the dead load. The samefeatures are presented at the case of the dead load and prestress or at the case of thedead load, prestress and the live load. (2) There is large longitudinal tensile in the box-girder at the case of the deadload. And the compressive stress is generated when prestressing. But in the case ofreplacing cable, the longitudinal stress increases large, and it should be noticed indesign. (3) The girder's vertical stiffness is large, so the maximum deflection is only1/4200 of the span and the maximum longitudinal tensile and compressive stressgenerated by the live load is 1/4 and 1/9 of the stress generated by the dead loadrespectively. (4) The cable stress is just variable in a narrow range when the live load is acted.And the cable's maximum variable value is only 6% of the cable stress in the stage ofcompletion. (5) It is illustrated in the dynamic behavior analysis that the bridge is a structureof long period and its fundamental period is between the partially cable-stayed IIbridge's and the continuous rigid frame bridge's. (6) When the earthquake motion is input in horizontal direction, the internalforce response is large in the tower-pier, in which the tower, the pier and the girder arefixed. When the earthquake motion is input in vertical direction, the variable value ofstress is little in the girder and the cable. (7) The conclusions drawn from the finite element analysis are validated in theplexiglass model experiment further, and the same rules are found between theirresults.