Title: Proposed Flexural Stiffness of Slender Concrete Columns Reinforced with Glass Fiber-Reinforced Polymer Bars
Author(s): Waseem Abdelazim, Hamdy M. Mohamed, and Brahim Benmokrane
Publication: Structural Journal
Appears on pages(s): 227-240
Keywords: design codes; flexural stiffness; glass fiber-reinforced polymer (GFRP) reinforcing bars; reinforced concrete; second-order analysis; slender columns; stability; statistical analysis
The well-established moment magnification procedure in ACI 318 for the structural analysis of slender steel-reinforced concrete (steel-RC) columns was reexamined to accommodate concrete columns reinforced with glass fiber-reinforced polymer (GFRP) bars. This could encourage North American codes and guidelines (ACI 440.1R; CSA S806) to include detailed sections dealing with the design and analysis of RC columns entirely reinforced with GFRP bars. Consequently, a second-order analytical model was derived to assess the structural performance of more than 9500 slender GFRP-RC columns with a wide range of design parameters. The developed analytical model correlated well with the experimental data of 72 large-scale FRP-RC columns assembled from this study and the literature. The investigated parameters were the applied eccentricity ratio, slenderness ratio, longitudinal GFRP-reinforcement ratio, elastic modulus of GFRP bars, concrete compressive strength, column cross section geometry, and GFRP bar arrangement. Then, a multiple linear regression analysis of the simulated theoretical data was conducted to propose a simple and practical design equation for the effective flexural stiffness of slender GFRP-RC columns. Lastly, the stiffness reduction factor used to reduce the critical buckling load of a single isolated slender GFRP-RC column was recommended as 0.6 based on the performed one-percentile statistical analysis.