الملخص الإنجليزي
Extensive researches are conducted on using Fiber Reinforced Polymers (FRP) as a construction material in severe environmental conditions to overcome the corrosion of steel. However, using FRP as a reinforcement for concrete columns is not acknowledged by many structural codes. The limited research work and experimental data in this field resulted in this conclusion. It is crucial to investigate the performance of FRP in compression member in order to update the current building design cod this field. This research focuses on understanding the behaviour of concrete columns reinforced with glass FRP (GFRP) bars and spiral stirrups under axial load. Nine full scale concrete columns were casted to study the effect of reinforcement material, longitudinal reinforcement ratio and transverse reinforcement spacing. The results showed that GFRP reinforced columns reached an ultimate load less than similar steel reinforced columns by only 0.43%. GFRP-RC columns showed brittle failure mode while the steel-RC columns showed ductile failure mode. Increasing GFRP longitudinal reinforcement ratio from 1.63% to 2.17% resulted in higher ultimate capacity by 28% whereas increasing the ratio to 3.87% enhanced the maximum capacity by only 21.7%. Furthermore, reducing the stirrups spacing from 75mm to 50mm enhanced the ultimate capacity of the column by 33% and produced gradual failure mode while increasing the stirrups spacing to 100 mm reduced the maximum capacity by 11%. The influence of increasing the lateral confinement on the ultimate capacity of GFRP-RC column is more than the influence of increasing the longitudinal reinforcement ratio. Design equations proposed by previous studies to predict the nominal capacity of FRP-reinforced concrete column was verified with the experimental results. The ratio between the experimental to predicted values revealed good accuracy of the suggested equation. In addition, the results showed that neglecting the contribution of FRP underestimate the nominal capacity of FRP reinforced column.
