Analysis On Torsional Property Of Curved Prestressed Concrete Box Girder

Due to the influence of plan curvature, under load the torsion will appear inevitably in curved girder bridge, which will also cause bending deformation. Aimed at the flexure-torsion coupling mechanical property of curved prestressed concrete girder bridge, under bending and asymmetrical torsional load, the properties correlation with torsion were researched in this article.The formula of equipollent load of spatial pre-stress was deduced based on the equilibrium equation of curved prestressed concrete girder bridge. The formula of twist moment caused by spatial pre-stress was also deduced. Stress distribution of the boxing section caused by pre-stress was analyzed by spatial finite element method.Under bending and asymmetrical torsional load, the formulas, which were fit to analyze the warp stress and warp bimoment of curved prestressed concrete girder, were established. The equations of warp bimoment could be solved by the initial parameter method. Based on case study, under unit positive and eccentric loads the variable rules of warp bimoment and torsion of the boxing section were studied. Warp ratio was presented to describe the distortion degree of boxing section.On the basis of variable-angle spatial truss model theory, considering softening of concrete, the equation which was appropriate for calculating the ultimate torsional strength of curved prestressed concrete girder was deduced.A two spans continuous curved prestressed concrete girder bridge was analyzed by the spatial finite element method. The stress and deflection distributions under different loads were showed in the article. According to the calculated result, primary stress contour charts of inward and outward web which was under composite load were given out.The design method of curved prestressed concrete box girder was proposed. And a relevant design example was presented.