Performance Assessment of High Strength Self - Compacting Concrete Beams with Web Reinforcement

Abstract

Self-Compacting Concrete (SCC) is a highly flowable material that achieves full compaction without external vibration, making it particularly suitable for heavily reinforced structural members where conventional compaction is difficult. Since shear failure is typically sudden and brittle, understanding the shear response of SCC members is essential for ensuring structural safety. Although extensive research has been conducted on SCC, the shear behaviour of high-strength SCC produced with manufactured sand remains insufficiently explored. The novelty of this study lies in the experimental investigation of the shear performance of M70-grade SCC incorporating manufactured sand and the evaluation of its behaviour against multiple design models and analytical approaches. Six reinforced concrete beams are cast with a constant longitudinal reinforcement ratio (ρt) and varying shear reinforcement ratios (ρs). Experimental observations include cracking load, ultimate load, crack width, midspan deflection, and one-third span deflection. The obtained results are analysed using codal provisions, established shear strength equations, and numerical predictions from Response 2000 software. The experimental results show that flexural cracks develop initially, followed by shear cracks within the shear span as loading increases. Beams failing in flexure exhibit widening tension cracks and compression-zone spalling, whereas beams failing in shear display rapid propagation of diagonal cracks toward the supports and loading points, resulting in brittle failure. Comparisons between experimental and predicted shear strengths indicate that most analytical models underestimate the measured capacity. Among the evaluated approaches, AS 3600 provides the closest agreement with experimental results, yielding a mean prediction ratio of 0.783 and a coefficient of variation of 23.72%.