Experimental and analytical investigations of CFFT columns with and without FRP bars under concentric compression

This research study investigates experimentally and analytically the axial compressive behaviour of Concrete Filled

Fiber Reinforced Polymer Tube (CFFT) columns with and without Fiber Reinforced Polymer (FRP) bars. The experimental

program comprises five circular columns of 204-206 mm outer diameter and 800-812 mm height. All columns were tested under

concentric axial compressive loads. It was found that CFFT columns with and without FRP bars achieved higher peak axial

compressive loads and corresponding axial deformations than conventional steel reinforced concrete (RC) column. The

contribution of FRP bars was about 12.1% of the axial compressive loads carried by CFFT columns reinforced with FRP bars.

Axial load-axial deformation (P ‒ δ) curves of CFFT columns were analytically constructed, which mapped well with the

experimental P ‒ δ curves. Also, an equation was proposed to predict the axial compressive load capacity of CFFT columns with

and without FRP bars, which adequately considers the contributions of the circumferential confinement provided by FRP tubes

and lower ultimate strength of FRP bars in compression than in tension.