Study On Construction Control Of The Long-span And Variable Cross-section Prestressed Concrete Continuous Rigid Bridge

It is easier for large-span curved continuous rigid-frame bridge to overcome the restrictions on terrain and surface features that by shortening the length of the road or avoiding unfavorable geologic areas such as karst cave, landslip and debris flow as possible, people could reduce engineering cost efficiently. Curved bridges have got more and more widely used in traffic engineering projects at present。In this paper, based on Changxi bridge, we consider the main factors of curved beam force such as sectorial moment of inertia, central angle φ0as well as ridge width and curvature radius ratio and so on.To apply the modern control theory to the analysis of it by advancing analysis backward analysis and grey theory forecast.Meanwhile, its simulation analysis was done by dint of Midas/Civil software. Here we got some conclusions after monitoring the deformation, stress and temperature of the working condition in the cantilever casting construction.①In the process of the cantilever pouring, the rotational displacements of z-axis and ρ axis in the cylindrical coordinate and the linear displacement of the axis of beam will be compensated in part or even full with pouring the next segmental girder concrete. In addition, the bridge’s horizontal alignment can be guaranteed by setting aside the linear displacement of γ on radial Axis ρ, and the vertical alignment can be obtained through reserving the linear displacement of δ in vertical face.So putting the point of the linear control on δ,γ,φ, is not only feasible but also can meet the engineering requirements.②On the principle of linear control first and stress control second in the construction process. We compare the real deformation with theory value in the cantilever casting period of side span closing, middle span closing and bridge deck pavement and they dovetail very well.③The cross-section of box girder under load will emerge Longitudinal normal stress and shear stress under the combination of moment and torsion; and bending stress and shear stress also emerge at the combination of moment and torsion in transverse.The result of the stress test we monitored on-site fit the calculated value very well.