Structural Performance of Columns with Glass Fiber-Reinforced Polymer Bars Under Axial Compression

Document Type

Article

Publication Title

Fibers

Abstract

Highlights: What are the main findings? The study experimentally, numerically and analytically investigates GFRP-reinforced concrete columns under axial compression, comparing them with steel-RC columns. Load capacity of GFRP-RC columns achieved 85–90% of the load carrying capacity of the steel-reinforced column, with the contribution of GFRP bars of 10–12% of total axial load capacity. Reducing stirrup spacing from 75 mm to 50 mm increased load capacity by 15% and ductility by 12%, improving structural behavior. Numerical models (ABAQUS) matched experimental results within 7–10% and analytical predictions within 10–15%, confirming the reliability of modified design equations. What are the implications of these findings? The proposed design factor (1.15) investigated based on tested specimens enhances predictive accuracy in the Indian context, supporting safer adoption of GFRP-RC columns. GFRP reinforcement is a viable alternative to conventional steel in corrosive or marine environments, extending service life. Corrosion continues to be a major challenge affecting the service life, safety and durability of steel-reinforced concrete (RC) structures. The deterioration of steel not only reduces structural capacity but also increases long-term maintenance costs. To address this limitation, glass fiber-reinforced polymer (GFRP) is being investigated as an alternative to conventional steel reinforcement, particularly in aggressive environments. This work examines the behavior of composite columns reinforced with GFRP bars with steel stirrups. Sixteen square columns of 150 × 150 × 850 mm dimensions, cast with M30 grade concrete, were reinforced using either GFRP or steel, while varying stirrup spacing and bar diameters. Experimental observations showed that GFRP reinforcement contributed about 10–12% of the ultimate capacity of the columns. A marked enhancement in load carrying capacity of GFRP-RC columns was obtained with closer stirrup spacing. The axial strength of GFRP-reinforced columns was comparable to steel-reinforced ones with the same main reinforcement ratio. Ductility increased by 12% when stirrup spacing was reduced. The difference between analytical and experimental values ranged between 12% and 15%, whereas experimental and numerical results differed by 10–12%. Based on these results, a modification factor derived from IS 456:2000 is proposed for predicting the capacity of ‘GFRP-reinforced’ columns. The outcomes clearly highlight the potential of GFRP reinforcement as a durable, sustainable and practical substitute for conventional steel reinforcement.

DOI

10.3390/fib13110156

Publication Date

11-1-2025

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