Experimental and Analytical Studies on Compressive Behaviour of Concrete Filled Circular GFRP Tubes

Background/Objectives: An extensive experimental and analytical investigation was carried out to explore the behaviour of circular concrete filled GFRP tubes (CFFTs) using NSC (Normal Strength Concrete), HSC (High Strength Concrete) and UHSC (Ultra High Strength Concrete). Methods/Statistical Analysis: The experimental study explored the compressive behaviour of 27 CFFTs having three different diameters 75, 100 and 150mm of constant thickness 3mm. Un confined concrete strength up to 98 MPa was achieved under normal curing conditions. Findings: The research findings prove that adequately confined high strength CFFTs can exhibit highly ductile behaviour and they are highly sensitive to the level of confinement. The GFRP tubes with UHSC infill could not maintain the load carrying capacity after attaining initial peak strengths. A newer methodology using shell elements was adapted for simulation of CFFTs in ANSYS and the results agreed with that of the experimental investigation. Applications/Improvements: The investigation explored that specimen size does not have major influence on strain reduction factor. New values of strength and strain enhancement ratios K1 and K2 has been arrived.