Stability Analysis Of Construction Process Of Long Span Concrete Cable-stayed Bridge

The bridge construction stability analysis is an important part of bridge construction safety analysis.Based on the Xuancheng Shuiyangjiang river cable-stayed bridge,this thesis considers the complex boundary conditions of the long side spanning section of the bridge and calculates the buckling load coefficient and nonlinear stability safety factor of the whole process of the bridge construction.The variation law of the stability of the longspan concrete cable-stayed bridge during construction can be summarized based on the calculated safety factor.The main research contents and conclusions of the dissertation are summarized as follows:1.The basic theory of structural stability analysis and the principle of nonlinear analysis are first introduced.Then,the convergence criterion of nonlinear equations and the stability evaluation criterion of cable-stayed bridge which provides a theoretical basis for the later work of stability evaluation are discussed.2.The stability of the bridge of the whole process of the bridge construction based on the theory of linear elastic stability analysis are analyzed.The variation law of the linear elastic stability and some typical buckling model are explained reasonably in details.The instability mode indicates that when there is an ultra-long side support cast-in-place beam section,the closure of the side span cannot significantly enhance the stability of the whole structure.3.The geometric nonlinearity and double nonlinearity stability analysis of the bridge based on the nonlinear stability analysis theory are also calculated.In the analysis process,the bridge appears the instability phenomenon of the structural side-span cast-in-place beam section.It is also verified that when there is an ultra-long-side support cast-in-place beam section,the closure of the structure cannot significantly enhance the stability of the whole structure.Therefore,the nonlinear stability analysis result of the structure is closer to real engineering if the analysis take the complex boundary conditions into account.4.The influence of construction hanging basket load and static wind load on the nonlinear stability of cable-stayed bridge in typical construction stage.The analysis results show that the construction hanging basket load has great influence on the nonlinear stability of the typical construction stage of cable-stayed bridge,but the static wind load has little effect on the nonlinear stability.This thesis also studies the effects of the adjustment of the cable's pre-stress load and layout form of live vehicle load on the stability of cable-stayed bridges.The results show that reasonable adjustment of the whole bridge's cable before the deck pavement can enhance the stability of the bridge,and the full bridge eccentric load which needs to be avoided when the bridge is open to traffic can lead to lateral instability of the cable-stayed bridge.