Effect of Longitudinal Bars on Shear Strength Prediction of High-Strength No-Coarse Aggregate Concrete

High-Strength Concrete (HSC) offers a higher strength-to-volume ratio than that of normal-strength concrete, which has become increasingly popular in recent decades. However, its design provision is not explicitly served in most building codes. This study focuses on the shear strength of HSC and the longitudinal reinforcement ratio, which influences the shear strength. The ratio has been analyzed and compared with 12 reinforced HSC beams without coarse aggregate. Concretes with cylinder compressive strengths from 58 to 110 MPa have been used. The concrete mixes have been made without coarse aggregate and a maximum fine aggregate size of #30 sieve. The specimens have been reinforced with various longitudinal reinforcement ratios and tested until failure by using a four-point bending test setup. The tests have shown that the degree of influence of longitudinal reinforcement has been in agreement with the ACI 318 formula, but it has overestimated the concrete’s shear strength. Based on the results, a modification has been proposed to the existing formula to improve its accuracy for HSC. The proposed formula shows significant improvement in terms of accuracy in predicting concrete shear strength compared to those from the ACI 318M-19 as well as the formulas proposed by other researchers for the range of specimens used in this research.