Study On Construction Monitoring Technology Of Long-span Continuous Rigid Frame Bridge With High Pier

With the rapid development of transportation industry in China,high pier and long-span continuous rigid frame bridge is widely used because of its application to the complex landform of mountain canyon.And the stability problem is prominent in the high pier long-span continuous rigid frame bridge.In this paper,taking the actual project(65 + 120 + 65)m long-span continuous rigid frame bridge with high piers as the research object,MIDAS / civil,the finite element software,is used to study the stability of high piers in the construction and completion state of the bridge,and to guide the site construction,linear monitoring and stress monitoring.The main research contents and conclusions are as follows:(1)This paper briefly introduces the research status of bridge monitoring and high pier stability at home and abroad,and briefly introduces two kinds of stability problems,namely,fulcrum instability and extreme point instability.The criteria and evaluation criteria of stability are described.The finite element analysis method of stability problem and the solution method of nonlinear equation are introduced.(2)The finite element software MIDAS / civil is used to build the simulation model of the bridge.With the help of the simulation model,the stability of the open pier state,the maximum cantilever state and the completed state of the bridge are analyzed.The most unfavorable state is the maximum cantilever state.At the same time,geometric non-linear analysis of the model is carried out,and the stability eigenvalues of geometric non-linear are less than the linear stability eigenvalues,which is closer to the actual situation of the project.The influences of the main pier and main girder concrete strength,concrete bulk density,pier wall thickness,pier height and initial defects on the stability of the bridge are discussed,which provides a reference for the design of this type of bridge.(3)This paper summarizes the basic theoretical content and method of construction monitoring,uses MIDAS / civil finite element model to calculate and analyze the stress distribution results of several key construction stages,and obtainsthe pre camber results.At the same time,it analyzes and compares the sensitivity of the construction control design parameters.The calculated stress and deflection are compared with the measured data.The results show that the theoretical values agree well with the measured values,which verifies the correctness of the model.The project can be closed smoothly,and the alignment and stress also meet the design requirements.