Failure Envelope of Circular Concrete Columns Reinforced with Glass Fiber-Reinforced Polymer Bars and Spirals: Fid-Bau Portal

Failure Envelope of Circular Concrete Columns Reinforced with Glass Fiber-Reinforced Polymer Bars and Spirals

Abdeldayem Hadhood

This paper presents the results of an experimental investigation on the eccentric behavior of 10 circular concrete columns reinforced with glass fiber-reinforced polymer (GFRP) bars and spirals. The columns measured 1500 mm (60 in.) in length and 305 mm (12 in.) in diameter. The test variables were the eccentricity-to-diameter ratio and the longitudinal reinforcement ratio. The columns were subjected to predesigned different levels of eccentricities to develop the failure envelope (axial load-moment interaction diagram). Compression failure due to concrete crushing controlled the ultimate capacity of specimens tested under low eccentric loading. Flexural-tension failure initiated in specimens tested under high eccentric loading, however, resulted from large axial and lateral deformations and cracks on the tension side until a secondary compression failure occurred due to the strain limitations in concrete and degradation of the concrete compressive block. The axial force-moment interaction diagrams were predicted based on the principles of strain compatibility and internal force equilibrium, and following the recommendations of the available design standards/guidelines and recent research work on GFRP-reinforced concrete (RC) columns. The analysis results revealed that ignoring the contribution of GFRP bars in compression conservatively underestimated the axial flexural capacity of test specimens.