Damage evaluation of fiber reinforced plastic-confined circular concrete-filled steel tubular columns under cyclic loading using the acoustic emission technique

Glass-fiber reinforced plastic (GFRP)-confined circular concrete-filled steel tubular (CCFT) columns comprise of concrete, steel, and GFRP and show complex failure mechanics under cyclic loading. This paper investigated the failure mechanism and damage evolution of GFRP–CCFT columns by performing uniaxial cyclic loading tests that were monitored using the acoustic emission (AE) technique. Characteristic AE parameters were obtained during the damage evolution of GFRP–CCFT columns. Based on the relationship between the loading curve and these parameters, the damage evolution of GFRP–CCFT columns was classified into three stages that represented different damage degrees. Damage evolution and failure mode were investigated by analyzing the b -value and the ratio of rise time to waveform amplitude and average frequency. The damage severity of GFRP–CCFT columns were quantitatively estimated according to the modified index of damage and NDIS-2421 damage assessment criteria corresponding to each loading step. The proposed method can explain the damage evolution and failure mechanism for GFRP–CCFT columns and provide critical warning information for composite structures. (paper)