Cable Replacement Plan And Structural Force Analysis Of Hybrid-girder Cable-stayed Bridge

With the vigorous development of infrastructure construction,more and more cable-stayed bridges are built.After several years of operation,the cable-stayed bridge has exposed more and more problems due to the comprehensive influence of various factors,the most important of which is the corrosion of the stayed cables.As one of the main components of the load transfer,the cable stayed cable,if its disease is not treated in time,it will bring huge hidden dangers to the safe operation of the cable stayed bridge.At present,the most common measure to solve the corrosion problem of stay cables is to replace them.This thesis takes a mixed-beam cable-stayed bridge in the northwest region as a background,and conducts research from two aspects: cable replacement scheme design and structural stress analysis,and provides a certain reference and basis for future cable replacement construction of similar bridge types.The main work content is as follows:(1)Analyze the cable-stayed bridge’s cable-changing optimization theory.On this basis,combined with the characteristics of the mixed-girder cable-stayed bridge,using the principle of minimum residual energy,it is proposed to improve the internal force and line shape of the main girder and the line shape of the bridge tower through cable change Theory and method.(2)Use the finite element analysis software Midas civil to establish an overall finite element model of a mixed-beam cable-stayed bridge,and obtain the bridge status before calculation and analysis through cable adjustment.Three cable-changing schemes are proposed,and the influences of the three cable-changing schemes on cable force,main beam line shape and stress are calculated and analyzed,and the optimal cable-changing scheme is obtained.On the basis of the optimal cable-changing plan,the influence of the lane load on the structural stress state when the cable is changed without interrupting the traffic is analyzed,and the traffic organization plan is obtained.The cable-changing plan and the traffic organization plan,the cable force,the vertical displacement of the main girder and the stress of the main girder all meet the requirements of the structural force control conditions.The construction period is short,the efficiency is high,and there is certain feasibility.(3)The finite element analysis software ANSYS was used to establish the plate and shell element model of the steel box girder of the main span of the cable-stayed bridge.According to the cable replacement plan and the traffic organization plan determined in Chapter 3,the cable removal and the impact of the vehicle load on the main girder were analyzed.Part of the plate is affected by the force.The analysis results show that under the action of vehicle load,the anchorage area at the unloading cable,the plate connection and other places belong to the areas where the stress changes are more concentrated.Among them,the main beam bottom plate and the web connection at the cable unloading have the greatest impact.Therefore,in the actual cable replacement construction,the connection between the main girder bottom plate and the web is a place that needs to be paid attention to.