Modified EC2's Shear Strength Equation for No Coarse Aggregate RC Beams

High-strength concrete is one of the various special concretes that have become increasingly popular in recent decades. High-strength concrete offers a higher strength-to-volume ratio than normal-strength concrete. However, the design provision is not explicitly served in most building codes. This study focuses on the shear strength of high-strength concrete and one of many factors that influence the shear strength, i.e., the longitudinal reinforcement ratio. The influence of the longitudinal reinforcement ratio was analyzed and compared with twelve high-strength reinforced concrete beams without coarse aggregate. Concretes with cylinder compressive strengths ranging from 58 to 110 MPa were used. The concrete mixes were made without coarse aggregate, with the maximum aggregate size of #30 sieve. The beam specimens were reinforced with various longitudinal reinforcement ratios and were tested until failure using a four-point bending test setup. The tests showed that the degree of influence of longitudinal reinforcement was in agreement with the Eurocode 2 (EC2) formula, but the formula overestimated the concrete's shear strength. Based on the results, a modification was then proposed to the existing formula to improve its accuracy for high-strength concrete. The modified formula significantly improves shear strength prediction accuracy compared to the existing EC2-2004 and the formulas by other researchers for specimens used in this research. Due to the limited number of specimens used in this research, future research could be done to verify the resulting modified equation and generalize it for a wider range of concrete strength and section shape