Hybrid E-Glass/Basalt (H-BE) Composites Confinement for Reinforced Concrete Square Columns and Development of Stress-Strain Models

Abstract

<title>Abstract</title> This study performs an experimental and analytical framework to explore the compressive response of concrete confined with hybridized chopped glass and Basalt (H-BE) layers. The research variables comprised the strength of unconfined concrete and the quantity of H-BE layers. Results showed significant improvements in ultimate strength, ultimate strain, and ductility with H-BE confinement, up to 161% and 269% enhancement, respectively. Unconfined concrete strength inversely affected the efficiency of confinement, while the magnitude of H-BE layers had a positive influence. The maximum enhancement in ultimate strain for low, medium, and high unconfined strength types was 219%, 146%, and 111%, respectively. An analogous trend in ultimate strength was noted, demonstrating 161%, 83%, and 33% increase for low, medium, and high unconfined strength, respectively. The elastic modulus increased with the magnitude of H-BE confinement and unconfined concrete strength. The stress vs. strain response of H-BE-strengthened concrete was characterized by an initial parabolic part, which was succeeded by a linear branch with a gentler slope. Based on regression analysis, specific expressions were presented for different key points on the curve, and their efficiency was evaluated with the coefficient of determination (𝑅²) valuesexceeding 0.90. Moreover, a methodology was presented to precisely predict the complete stress vs. strain response of concrete under H-BE confinement based on the proposed expressions. The comparison between predicted and experimental curves demonstrated close agreement, validating the proposed approach.