The Stability Of Cable-hoisting System Research Of Reinforced Concrete Arch Bridge Under Extreme Weather Conditions

According to the geographic features of our country—many mountains and rivers,the bridge construction also grew rapidly,the arch bridge is popular for the advantages of long span,high load capacity relative to other bridges,the construction of arch bridge in our country mostly adopts cable hoisting construction method.During the construction,the stability of the bridge structure is a top priority,especially in the extreme weather conditions,it must be strictly calculated and verified.Therefore,the research of the stability in the bridge construction is essential and indispensable.The engineering background of this thesis is based on A bridge and Xigonggou bridge in Ganzi state of sichuan province.In order to ensure the safe construction of the bridge structure,the static analysis,the dynamic analysis and stability calculation of the cable tower structure under extreme climatic conditions and non-extreme weather conditions are carried out by using SAP2000 and Midas/ Civil.In addition,the rib-hoisting model of the arch rib is established by using Midas/Civil,which combines with the factors that influence the internal force and stability for security analysis of the bridge structure in the hoisting process.The main contents of the thesis include:(1)Firstly,the structure and force characteristics of the cable tower in the cable hoisting structure are introduced;Analyze the factors affecting the stability of the cable tower and the reason of the instability;Make static analysis of the cable tower structure under the practical engineering background;Make a detailed analysis of these reasons and check the stability in the collapse of cable tower during the process of bridge construction.The analysis contrasts the stability of the universal pole tower and 321 beret beam tower model under extreme climatic conditions and extreme climatic conditions.The measures to increase the stability of the tower are proposed.This paper also analyzes the The dynamic response of cable tower under extreme wind load.(2)Make a detailed force analysis on the arch rib during hoisting the cable of Xigonggou bridge;Discuss how the different cable angle influence the arch rib in each construction stage under extreme climatic conditions and extreme climatic conditions.Make comparative analysis and find the angle under the best stress state.(3)Make static analysis and stability calculation of the arch rib under the snow force to judge whether it meets the standard request or not;Make comparative analysis of the changes of the arch costal line under different temperature load and use the finite element to simulate it,then obtain the best temperature range for the arch rib.The results show that the universal pole tower is superior to the 321 beret tower which with the identical structural system in the same engineering background;The first twenty steps of the tower structure are dominated by horizontal displacement,The second is the torsional type,the lateral force stiffness and torsional stiffness of the structural design should be improved;Meanwhile,the design standard value of snow load should be improved properly during structural design;At the same wind speed,the line should be as large as possible within the guy angle from the construction plan to improve the stability during the construction of the cable.