Minimum Transverse Reinforcement in 65 Mpa Concrete Beams

This paper reports the experimental results from a study of the shear behavior of 65 MPa (9500 psi) concrete beams, reinforced in the transverse and longitudinal directions. A total of 11 test results are presented. The amount of the transverse steel was selected to evaluate the different requirements for minimum transverse reinforcement in the ACI Code, the CSA A23.3 Standard, and the AiTO LRFD Specifications. The performance of the specimens is evaluated based on the cracking pattern, crack widths at estimated service load, and on the postcracking reserve strength. The concrete specimens had different levels of longitudinal reinforcement to evaluate its effect on the performance of the beams. It is observed that the available amount of longitudinal steel influences the decision on what can be considered an adequate level of minimum transverse reinforcement, and that the shear capacity equations in the current ACI Code, CSA Standard, and AASHTO LRFD Specifications are conservative.