Reliable design and optimization of SRP-, CFRP-, and GFRP-confined concrete: experimental validation and cost-effectiveness analysis

The external confinement of concrete columns using Fiber Reinforced Polymer (FRP) and Steel Reinforced Polymer (SRP) systems has emerged as a highly effective retrofitting technique for improving structural performance. This paper introduces newly developed predictive and design models for the compressive strength and ultimate strain of concrete confined with SRP, Carbon FRP (CFRP), and Glass FRP (GFRP). Making use of extensive experimental datasets, robust predictive equations are derived, and design equations are formulated using the “design assisted by testing” methodology outlined in Annex D of Eurocode 0 (EN 1990:2023), ensuring reliability and accuracy. The study highlights key differences in confinement mechanisms and failure modes across materials, with newly calibrated design equations offering practical applicability for a wide range of structural retrofitting scenarios. A comparative optimization analysis is also presented, evaluating the cost-effectiveness of SRP, CFRP, and GFRP systems for both strength enhancement and strain increment. This analysis provides engineers with actionable insights for selecting the most suitable material based on performance requirements and budget constraints. The findings represent a significant advancement toward unified, reliable, and economically viable design equations for enhancing the strength and ductility of reinforced concrete elements. This work promotes the broader adoption of SRP, CFRP, and GFRP systems by providing economically viable and reliable tools for practice.