Research On The Parameter For Geometric Control Of Main Cable Of Suspension Bridge Based On Reliability Theory

Main cable is one of the important components of suspension bridge, its shape has a critical influence on the bridge. It is impossible to achieve the design ideal shape by track and adjustment in the construction stage. So it relies on precise computational method, strict manufacture and construction quality control, to make sure the real shape tallies with the ideal one.Analysis and discussion are launched by regarding the main cable shape computational method as well as the real construction. First of all, the variables such as span error, wire diameter measurement error etc, which may affect the main cable shape precision are presented and analyzed. Then, the theoretical calculation is combined with the experimental data and calculated the distribution of each variable.Considering that the reliability of cable shape of suspension bridge is issued of small failure probability of implicit limit state equation, the reliability sensitivity analysis method based on adaptive importance sampling is proposed and the reliability calculation software based on the parabola theory and catenary theory is established.Four suspension bridges, named Jiaolongba Bridge, Haicang Bridge, Balinghe Bridge and Xihoumen Bridge, which differ from each other in span, are taken as examples in the thesis. By the use of the importance sampling method, the reliability of datum strand shape absolute control and relative control and the reliability of unloaded cable shape as well as the reliability of final bridge cable shape at the time of dead load P-control or P-no-control are calculated. After that the datum strand stage absolute control and relative control as well as final bridge cable shape stage dead load P-control and P-no-control are analyzed and compared and then reaches conclusions. In order to analyse the influences of the variables on the shape reliability, the sensitivity of each parameter is analyzed. According to the calculation results, the control standard for the parametric errors are proposed.Base on the reliability analysis of series connection system, which is constituted by datum strand shape, unloaded cable shape and final bridge cable shape, the final bridge cable shape system reliability of the four bridges is concluded. At the same time, the control standard of each stage for reaching the final bridge cable shape system reliability is also presented in the thesis, what provides references to the real constructions.