The Analysis Of Safety And Cause Of Dislocation Of Flexible High Pier Of Continuous Beam

Because of the characteristics of the expressway in the mountain area,the pier in the continuous beam bridge on the expressway is more higher and flexible in the mountain area.The flexible pier of continuous beam bridge has been widely used in the expressway,but in the recent ten years,large-scale construction and long-term operation also have some defects,such as deformation of the girder deflection,bearing cavity,slip,deformation,dislocation and crack of bottom section of pier and so on.Especially the dislocation and slip diseases of the support are the special diseases in the flexible high pier continuous beam bridge.And this kind of disease will cause the pier top to deviate along the longitudinal bridge.It also seriously affects the mechanical performance and stability of the pier,which affects the safety of the pier.Based on the engineering background of Hongxing Reservoir Bridge with such diseases on a highway in this paper,Researching on the reasons for the dislocation of support and the safety of piers after dislocation and reinforced.(1)Analysis on the cause of dislocation of supportSet up the solid pier model of the left amplitude 19#with ABAQUS,the bearing installation uneven pier stress performance and deflection are analyzed,Firstly,considering the two cases of geometric nonlinearity and geometric nonlinearity,Then the deviation value of pier top under two cases of uneven installation and roof falling is analyzed.The results show that the main reason for the dislocation of the bearing is the comprehensive influence of the uneven installation of the bearing and the bearing void,and the constant live load of the upper structure will aggravate the dislocation of the support.(2)Influence of pier top deviation on pier's mechanical behavior,damage performance and bearing capacityEstablish the model with ABAQUS,considering the influences of geometric and material nonlinearities,analyzing and evaluating the stress performance,damage performance and bearing capacity of the deflection of the bridge pier,the results show that:the stress and strain of concrete and reinforcement of bridge pier after partial position is larger,and the damage degree is great,it has been in a very unfavorable state of stress.It should be rectified and carried out in effective reinforcement measures in time.(3)Stability analysis of pier with initial defectEstablish the model with ABAQUS,considering the influences of geometric and material nonlinearities,analyze the stability of piers with initial imperfections.the results show that the initial defect is larger,the ultimate bearing capacity and the corresponding stability and safety factor is smaller.(4)Stability analysis of reinforced PierEstablish the model with ABAQUS,considering the influence of geometric and material nonlinearities,these two states of the stability are compared and analyzed from the aspect of before reinforcement and after reinforcement in the pier,The results show that:? the stability(the vertical ultimate bearing capacity)of the pier is improved by the reinforcement of the bridge pier,and the double nonlinearity must be taken into consideration when analyzing the ultimate bearing capacity of the pier.? the ductility of single pier strengthened after a lot of improvement,and the ultimate load carrying capacity is 3.7 times than that of unreinforced.(5)Influences of support slippage on mechanical performance and stability performance of pierThe ABAQUS model is built to analyze the bearing capacity and stability of the pier after the slide disease is strengthened.The results show that the bearing slip disease has little influence on the force performance and stability of the pier,but it has a large impact on the local area of the bridge,and there is a big security risk after the support slide out of the cover beam.It is suggested that the slip support must be replaced.