Improving Shear Performance of Precast Concrete Segmental Beams Through Continuous Longitudinal Reinforcements Across Joints.

Despite the widespread use of precast concrete segmental bridges (PCSBs), concerns persist regarding their structural reliability, particularly due to the interruption of longitudinal reinforcement at joints. To address this, a novel approach based on the Grid Shear Reinforcement Theory is proposed, featuring precast segmental beams with continuous longitudinal reinforcements across joints. Experimental tests were conducted on one monolithic beam and two segmental beams under combined bending and shear with joint types as the primary variable. Key performance metrics included crack propagation, reinforcement strain, failure modes, stiffness, and load-bearing capacity. Results show that continuous longitudinal reinforcement effectively resists axial tension from shear forces, contributing to shear resistance comparable to stirrups. It also restrains diagonal crack propagation and limits main crack widths, significantly improving shear stiffness. Reinforced joints adhered to the plane section assumption and exhibited monolithic beam behavior throughout loading. These findings highlight the critical role of continuous longitudinal reinforcement in segmental beam joints. The study further compares shear reinforcement design approaches in European Codes, ACI, AASHTO, GB, JTC, and the Grid Shear Reinforcement Theory. Practical construction methods for implementing continuous longitudinal reinforcements are also proposed, offering valuable insights for engineering applications.