Assessment of Cyclic Behavior of Hybrid FRP Concrete Columns

Previous experimental studies have shown superior performance of concrete-filled fiber-reinforced polymer (FRP) tubes (CFFTs) under static or pseudostatic loading. This study has focused on the effects of fiber type and architecture and the combined shear and flexure on the cyclic behavior of CFFT columns. One control RC and five CFFTs with different fiber types and architecture and shear span-to-depth ratios were tested under a constant axial load and reverse cyclic lateral loads. One of the tubes was off-the-shelf filament-wound product, whereas the other four were made using hand layup in the laboratory. The flexural strength and initial stiffness of the CFFT columns were shown to be dominated by the longitudinal tensile strength and stiffness of the FRP tube, respectively. On the other hand, the modulus of elasticity of the FRP tube in both the longitudinal and hoop directions was shown to be a dominant factor in the ductility of CFFT columns. The CFFT column with the combination of carbon fibers in the longitudinal direction and glass fibers in the hoop direction showed the highest energy dissipation, and all nonslender and slender CFFT columns showed a similar mode of flexural failure. An analytical study was carried out to comprehensively investigate the effects of fiber architecture and shear span-to-depth ratio on the cyclic behavior of CFFT columns.