Construction Monitoring Research On Wuhan Railway Beam-Arch Composite Bridge Across The River Bank Yard

Whether the bridge has the ideal geometric linear and reasonable internal forces state in the finished bridge state,depends not only on design,but also on scientific and rational construction method. Although possible conditions in construction are considered in design, the disagreement still exists between actual structure and original design, which is caused by many factors difficult to estimate accurately in the construction, and by the construction error. Therefore it apperas very important to real-time monitor the bridge and make corresponding adjustment to control parameters in constructon according to the monitoring results. The purpose of monitoring the bridge is to ensure the safety of the construction firstly,to guarantee the force and the elevation to meet the design requirements in a maximum state when the bridge is finished by controlling the internal forces and linear of the structure when constructing the bridge.The article introduces the developments,construction method and the overview of the construction monitoring; also especially described is the basic principle,basic method,main contents of the construction monitoring,factros affecting the monitoring and the error criterion of the beam-arch composite bridge,which is built by the "arch after beam"method,which means cantilever casting in the main girder first and then assembling the arch rib through building the scaffold.Based on the construction supervision of the Wuhan beam-arch composite bridge across the river bank yard,this paper mainly study the determination of the reasonable constrution state of the structure and the implementation of the construction monitoring.The determination of the reasonable constrution state of the structure should be achieved by establishing a rational finite element method model,and taking appropriate structural analysis method to simulate and analyse the construction process and the completion state of the bridge.The plane model,established by Doctor Bridge,and the space model, established by Midas,are both presented in this article,and the deformation and the stress are compared respectively.The contents of the implementation of construction monitoring is various,and this article mainly describes the temperature monitoring,deformation monitoring stress monitoring and suspender tensile force monitoring.In deformation monitoring,the method of determinating the formwok placing elevation of the main girder is elaborated;in stress monitoring,the article introduces the impact analysis of the concrete shrinkage and creep,and by prorerly seperating the measured field stress,the paper obtains the effective stress of the structure. And the feasibility is confirmed when comparing the effective stress of the structure with the theoretical value.Construction monitoring not only ensures the safety of bridge in constructon process,but also makes the actual internal forces and linear in the finished bridge state in good agreement with the design.