Mechanical Properties Analysis And Evaluation Of The Cable-stayed Bridge Of Fire Damag Cables

Cable-stayed bridge is becoming the fastest growing and the most competitive type, because it is the large span capacity and novel structure advantages of bridge project.The vehicle of transporting flammable and explosive goods has gradually increased with the rapid economic development. Meanwhile the bridge fire rate also increased. The cable is usually near the carriageway, once a fire occurs, It will inevitably result in the damage of cable in different degrees, especially for large cable-stayed bridges, as the traffic throat, after the fire, it is bound to stop using it for a period of time, resulting in huge economic losses. It is especially important to assess on the cable-stayed bridge of fire damage cable accurately and rapidly,and provide accurate scientific basis for the policymakers.Taking Sifangtai bridge of fire accident as the engineering background, based on damage theory and finite element theory, through the different simulation analysis of cable damage and the static load test of bridge, this dissertation researches on the mechanical properties of the cable-stayed bridge of fire damage cable, the main contents include the followings:1、According to the cable damage mechanism and damage mechanics model, based on the material properties of cable material after high temperature, simulation method on the cable-stayed bridge of fire damage cable is determined.2、Three dimensional finite element model is established, first it analies the static and dynamic response under lossless state,as the initial state of the analysis of cable damage caused by the fire.Abundant numerical simulation is given to simulate the different cable damage locations by fire and different damage grades in the same location by fire. Based on these simulations, the variation characteristics of the static structural parameters such as the beam line and the cable forces and the dynamic structural parameters such as formation and frequency are analyzed.3、This chapter on the engineering example puts forward the load test scheme, with the deflection of beam, the change of tension of the cables, strain and tower bias as the main test elements, comparing the results of load test results and finite element calculation. Calculating the beam deflection and strain partial load increase effect coefficient through the partial load test data and comparing with similar cable-stayed bridge. It indicates that the bridge works at reasonable state after the fire under the normal applying load, satisfying the designed request.