Research On Construction Simulation And Elevation Control Of Prestressed Concrete Continuous Bridge

With the rapid development of transport, prestressed concrete continuous bridge due to its characteristics of riding comfort and long-span, has grown up to a primary bridge of long-span bridges in our country, and cantilever construction of continuous bridge due to its characteristics, in recent years, has been gaining more and more favor in the construction of bridge. As its state from cantilever construction to operation, the girder nodes' elevation is in constantly changing. In order to ensure the bridge linearity and force can accord with design, the main beams' deflection and force should be monitored in construction. So the simulation analysis of full-bridge in every construction stage should be conducted, then can gain ideal state of the structure's force and deformation, and the results can be used in elevation control.First, according to the characteristics of cantilever construction, choose a suitable structural analysis method and use Midas/Civil software to establish full-bridge's construction simulation analysis model. Through analysis and calculate, get the continuous bridge's change results of the girder nodes' elevation and the calculated results of the key sections' stress in various stages of construction, sum up the deformations of the girder nodes' elevation change and changing trend of the key sections' stress. In the construction simulation analysis, consider gravity of beam, prestress load, pavement load, creep and shrinkage of concrete, structural system conversion and support conditions change etc.Secondly, the key to the success or failure of elevation control is the set of elevation of formwork erection reasonably and accurate. In order to control the girder nodes' elevation change and make bridge's line consistent with ideal line at the end of the construction, should propose formula of elevation of formwork erection and use the girder nodes' displacement results from construction simulation analysis, mount construction camper when erect every formworks to offset adverse effects from various loads of the main beams' deformation.Again, because there are many factors which can make the construction state different to the design state, sensitivity analysis of parameters which will affect the elevation of the main beam has been investigated. Choose the largest cantilever stage and the final stage, change the parameters which can influence the main beams' elevation control, analysis the girder nodes' elevation subsequent change when these parameters changed certain level so that to identify which are the main impact parameters, then use the least square theory and the experimental method to gain the parameters' true value, and make the calculation model consistent with fact through amend the calculation model.Finally, when the girder nodes' elevation error appears which belong to the completed beam of the cantilever construction of the continuous bridge, the error almost impossible to adjust, so adjust the elevation of formwork erection of next girder seemed very important. The grey theory could be applied to the continuous bridge elevation control in this paper, use GM(1,1) to forecast regulative information of elevation for the next girder. According to the measured result and design result of bridge's line can prove GM(1,1) is feasible to used in continuous bridge elevation control.