Hollow and SCC-filled high-strength GFRP tubes under concentric and eccentric compression

This paper presents the results of an experimental investigation that was carried out with the aim of obtaining the load–displacement behaviour, ultimate strengths and failure modes of hollow and concrete-filled, high-strength, glass fibre-reinforced polymer (GFRP) tubes under axial and eccentric compression. The tubes that were used contained reinforcements at ±45° to the tube axis while self-compacting concrete (SCC) was used for the infill. The main parameters considered were column length, cross-section and load-eccentricity. A total 36 GFRP tubes, with cross-sections of 100 mm × 100 mm and 75 mm × 100 mm, were tested at lengths of 0·7 m and 1·3 m. Out of these, four were hollow GFRP tubes that were loaded concentrically. Eccentricities of 0, 5, 10 and 15 mm were considered for the concrete-filled tubes tested under axial load. It was observed that filling the tubes with SCC improved their stiffness, strength and ductility although the failure mode was still brittle akin to the behaviour of hollow tubes. The ends of the column specimens were found to be preferential locations for failure under both concentric and eccentric loading. It was also found that the in-filled concrete was able to utilise an enhanced compressive strength due to the confinement provided by the tube, although this effect decreased with eccentricity.