Behavior and Design of Slender Rectangular Concrete Columns Longitudinally Reinforced with Fiber-Reinforced Polymer Bars

Fifteen slender rectangular reinforced concrete (RC) columns with longitudinal glass fiber-reinforced polymer (FRP) bars were tested under compression in this paper. Results showed that all columns with varying length-to-depth ratios and eccentricity ratios failed by concrete crushing, and no rupture of FRP bars was experienced. Moreover, validated nonlinear finite element model was used to perform a detailed parametric study of 27,000 FRP-RC columns using Opensees. Based on parametric analysis results in conjunction with the moment magnifier method, a refined design equation of the effective flexural stiffness EI was then statistically derived to determine the second-order bending moments. On this basis, a design approach was proposed for slender FRP-RC rectangular columns, in which the contribution of FRP bars in compression to the strength of sections was taken into account. The proposed approach is more consistent and accurate than existing design methods by comparing their predictions with available experimental results of 46 columns.