Experimental Study of Circular High-Strength Concrete Columns Reinforced with GFRP Bars and Spirals under Concentric and Eccentric Loading

Abstract

Integrating fiber-reinforced polymer (FRP) reinforcement into high-strength concrete (HSC) would effectively contribute to enhancing the stiffness of cracked concrete sections when the FRP bars are undergoing high strain and stress levels. Nonetheless, neither the concentric nor the eccentric behavior of HSC columns reinforced with FRP reinforcement has yet been investigated. This paper presents the results of an experimental investigation on the concentric and eccentric behavior of full-scale circular HSC columns reinforced with glass FRP (GFRP) bars and spirals. A total of 10 columns were tested under monotonic loading with different eccentricities. The test variables were the eccentricity-to-diameter ratio and the longitudinal-reinforcement ratio. Compression failure in the concrete controlled the ultimate capacity of specimens tested under small eccentric loading. A flexural-tension failure initiated in specimens tested under high eccentric loading, however, resulted from excessive axial and lateral deformations and cracks on the tension side until a secondary compression and stability failure occurred owing to the strain limitations in the concrete. The axial force–moment interaction diagrams were predicted based on the principles of strain compatibility and internal force equilibrium in accordance with the recommendations in the available design standards.