Shear strength of prestressed concrete beams with short shear span: Full‐scale experiments and evaluation of design methods

Abstract

AbstractPrestressed concrete (PC) is increasingly used in civil engineering construction. Notably, research on shear resistance in PC beams with short shear span remains relatively limited, necessitating further comprehensive exploration. In the study, tests were conducted on bonded post‐tensioned PC T‐beams with short shear span (a/h = 1.0), subjecting them to monotonic loading destructive tests. These beams measured 24.9 m in length, 1.605 m in height, and had a top flange width of 2.0 m. They featured a uniform cross‐section with a 0.22 m web thickness. Given the size of the full‐scale test beams and space constraints for loading, an innovative loading scheme was devised to minimize the counterweight. Test results demonstrate the safety and feasibility of the loading scheme. The tests were conducted five times and the main test variables were the draped tendons and the quantity of horizontal web reinforcement. The tests revealed that horizontal web reinforcement significantly influenced crack propagation but had a minimal effect on shear strength. For the parameter values taken for the test beams, the prestressing level has less effect on the shear strength of the beam. Simultaneously, an investigation was conducted involving a total of 119 PC beams. This investigation aimed to evaluate the degree of conservatism and accuracy in shear design code provisions and shear strength equations derived from various standards, including the strut‐and‐tie model (STM) of ACI, AASHTO, and Tan, as well as the critical crack model of Yuan and the truss model of Laskar. Comparative analysis indicates that, the design method provided by Yuan exhibit relatively superior predictive capabilities.