Experimental and numerical investigation on the effect of concrete infill in pultruded GFRP CHS intermediate and long columns under axial and eccentric compression

The paper presents an experimental investigation of concrete-filled (CFFT) pultruded glass fibre-reinforced (GFRP) circular tubular columns under concentric and eccentric loading. The effective slenderness ratios of the CFFTs were 33, 44 and 55 and were tested under two different eccentricities of 28.5 mm and 57 mm. The failure modes observed for the CFFTs include localised hoop rupture and longitudinal splitting of the GFRP tube with concrete crushing. The axial load-carrying capacities of the CFFTs decreased with increasing eccentricity and slenderness. The strength and the ductility of the CFFTs were compared with their circular hollow section (CHS) counterparts tested in a previous study. A P-M interaction curve was developed, and its applicability was assessed against the experimental results for different slenderness ratios. The ultimate axial load and the locus and nature of the failure modes of CFFTs predicted from the developed finite element models were in good agreement with the experimental observations. The extent of damage of the GFRP tube in the CFFTs was compared to the damage of the GFRP CHS columns using FE analysis employing the Hashin damage material model for GFRP tube.