Title: Effects of Axial Load on Seismic Behavior of Glass Fiber- Reinforced Polymer-Reinforced Concrete Columns: A Numerical Study
Author(s): Ahmed Arafa, Omar Chaallal, and Brahim Benmokrane
Publication: Structural Journal
Appears on pages(s): 81-98
Keywords: axial load; columns; finite element analysis; glass fiber-reinforced polymer (GFRP) bars; moment-axial load interaction; performance levels; reinforced concrete; residual damage; seismic behavior
In the last three decades, glass fiber-reinforced polymer (GFRP) has gained wide acceptance as an alternative reinforcement to avoid the potential of corrosion and related deterioration of reinforced concrete infrastructure. Recent experimental results for concrete columns reinforced entirely with GFRP bars have demonstrated their effectiveness in resisting lateral loads induced by wind or earthquakes. However, in most of the research studies carried out so far, the columns were tested under reversed cyclic loading, while subjected to low to moderate levels of axial load that would be rather representative of columns located in the top stories of multi-story buildings. This has been the main impetus to investigate FRP-reinforced columns under high levels of axial load with different ratios of longitudinal reinforcement. To that end, a finite element model (FEM) that considers the material and geometric nonlinearity and the bond behavior of GFRP bars was developed and validated against the available experimental results. Twenty-one specimens encompassing wide levels of axial load and longitudinal reinforcement ratios were studied. Results are presented in terms of strength, stiffness, and deformation capacity as affected by axial load. The moment-axial load interaction diagrams for the simulated specimens are also discussed. The paper concludes by proposing the most appropriate performance design levels for GFRP-reinforced columns. Quantification of the seismic response parameters within this study is aimed at facilitating the adoption of GFRP bars in North American codes as internal reinforcement for earthquake-resisting systems.