Transverse Bursting Stresses due to Horizontally Curved Tendons in the Top Slab of Box Girders

Abstract

In cantilever-erected concrete box-girder bridges, a great number of longitudinal posttensioning tendons curve twice in the top flange to fit their anchor position. The radial force attributable to the curved tendons produces transverse bursting stresses, resulting in tension in the concrete of the top flange. In practice, longitudinal cracking is sometimes observed in the convex side of the horizontally curved tendons. Thus, it can be inferred that the transverse bursting stresses induced by horizontally curved tendons are partially responsible for the cracking. To seek an analytical solution to such scenarios, this study used a semi-infinite slab model with proper boundary conditions. By introducing the Airy stress function and its derivative on the boundary, an analytical formula for transverse tensile stresses was developed, and this formula was verified to have good accuracy as compared with finite-element analysis. Analysis revealed that the transverse bursting stresses were predominately affected by the curved angle and the distance of the two inflection points. Finally, this paper proposes countermeasures to control this unfavorable effect.