Behaviors of segmental concrete box beams with internal tendons and external tendons under bending

Precast segmental prestressed concrete box beam bridges have become the preferred construction method for many elevated highway projects in recent years. These beams, which have internal and external tendons, are increasingly popular because the internal tendons can improve the ductility of the beam, and the external tendons are convenient for maintenance. This study experimentally investigates the behaviors of segmental concrete box beams with hybrid tendons. Three scaled specimens with different ratios of the number of internal tendons to the number of external tendons were tested in detail. The experimental results showed that the ratio had a significant effect on the load-carrying capacity, ductility and failure mode of the beams. The opening of gaps between the segments could not be avoided, and the joint nearest to the applied load was determined to be the critical joint. The assumption that a plane section remained planar under bending was suitable for a crack joint produced by the load. The stress increment rule of the external tendons and internal tendons, as well as the variation of the plain bar strain, were determined.