Experimental Investigation of Prestressed Concrete Beams Strengthened with Fiber-Reinforced Polymer Laminates

Abstract

This study evaluates the effectiveness of externally bonded glass fibre-reinforced polymer (GFRP) laminates in improving the static performance of pre-stressed concrete beams. Fourteen post-tensioned concrete beams were fabricated and tested under progressively applied static loading, with two unstrengthened beams serving as control specimens and the remaining beams strengthened using various GFRP laminate configurations. The experimental program included beams cast with M35 and M60 concrete grades and reinforced using Chopped Strand Mat (CSM), Woven Roving (WR), and Uni-directional Cloth (UDC) laminates with different thicknesses. The influence of concrete strength, laminate type, and laminate thickness on structural performance was assessed by examining yield load, deflection, ductility, energy absorption, and failure characteristics. The findings demonstrated that the application of GFRP laminates substantially enhanced the load-carrying capacity, flexural stiffness, and ductility of the strengthened beams compared with the control specimens. In addition, Finite Element Method (FEM) simulations closely replicated the experimental results, confirming the reliability of the numerical model. Regression-based predictive equations were also developed to estimate the key structural performance parameters, providing a practical tool for the analysis and design of GFRP-strengthened pre-stressed concrete beams.