Low-Cost Solutions for Concrete Enhancement: Assessing Steel Clamp Efficacy

Abstract

This study evaluates the effectiveness of steel clamps as a low-cost passive confinement system for reinforced concrete (RC) under axial compression. Cylindrical RC specimens with different unconfined strengths, reinforcement types, and numbers of steel clamps (3, 5, and 11) were experimentally tested to investigate their influence on failure modes, compressive strength, strain capacity, and energy dissipation. The results show that steel clamp confinement significantly delayed cracking, improved ductility, and enhanced compressive performance. Peak compressive strength increased by up to 77%, while strain at peak strength and ultimate strain improved by up to 268% and 900%, respectively. Energy dissipation increased by nearly 2000% in highly confined specimens. Based on the experimental data, nonlinear regression-based expressions were developed to predict peak strength, peak strain, and post-peak degradation behavior, enabling accurate simulation of the full stress–strain response. The proposed analytical model follows the ACI 440 formulation style and provides a practical design-oriented tool for applying steel clamp confinement in RC elements.