Research For Construction Monitoring And Control On The Prestressed Concrete Continuous Box Grider Bridges By Cantilever And Truss Erection

It is necessary for bridge's construction monitoring and control to ensure the shape control of girder and the stress accord the design codes because of the complications of the construction for long-span continuous box girder bridges.As the force characteristics are relatively simple and the construction process is very easy to control,therefore,the cantilever casting method for construction is appled to most of long-span concrete continuous grider.However,in recent years,we must take into account the transport needs and save the cost of construction in the municipal bridge construction,the combined construction with the cantilever and truss erection is applied.This method is a type of dissymmetric construction.The construction process and the force characteristics are complex and difficult to carry out the construction control.Therefore,it is necessary to study the dissymmetric construction method.This paper gives the study of the bridge construction with the project background of the Hangzhou desheng road bridge and has conducted the research of the following aspects.1.In this papers,it is generalized on the development,construction control and the control methods of prestressed concrete girder bridge at home and abroad and expounded the characteristics of the combined construction with the cantilever and truss erection.2.The construction simulation model is established by using finite element program Dr.Bridge according to the construction example.The deformation and stress analysis of the bridge construction process is carried out.The analytical results is applied to guide the construction monitoring.3.The sensitivity analysis for the major and minor design parameters is analyzed.The key control parameters can be found from the sensitivity analysis.During the construction of the bridge,through the key parameters adjustment the errors is reduced to ensure a smooth bridge closure.4.Construction monitoring system of Hangzhou desheng road bridge are set up. stresses and deformations of concrete at the controlled girder sections are monitoring.The monitoring and effect factors are comparatively analyzed between the measured value and the theoretical value in the construction control process,adjusting parameters,summarizing changes in the law and giving notice of control information are carried out to ensure that the internal forces of the state and the bridge structure to meet the design requirements.5.The combined construction with cantilever and truss erection is applied,this method is a dissymmetric construction method and there are many factors on the impact of internal forces and the line of the bridge.According to comparing the measured values with the theoretical values,the real-time monitor,analysis and adjustment are carried out during the construction,the entire construction control is a success and the completed bridge meets the design requirements.