Long-span Prestressed Concrete Box Girder Cracks Study

Prestressed concrete box girder bridges are widely used in long span bridges, and will be more widely used. But their calculation theory isn抰 very perfect in the present. Taking advantage of hear forces current theory? this paper deduces the formula of bending shear stresses, in which the influences of axial force, bending moment, variable section depth and the variable thickness of top slab, bottom slab and webs are taken into account. In this paper, the practical model for calculation torsion is set up in ALGOR FEAS, which is 3-D girder element model with rigid arms. The model is better used to calculate the effect of deviation load. In order to coordinate internal force calculation in ALGOR FEAS, the preceding processing program and post processing program are worked out. The calculation method above being used, the internal forces and stresses of all sections of Yellow River Bridge at Sanmenxia are calculated, moreover, the calculation results are checked by the special bridge software. According to the analysis result, the reason of the inclined cracks in the box girder webs of the bridge is found.