Experimental study on seismic performance of square RC columns strengthened with multi-layer prestressed CFRP fabric

In this study, a wedge tensioning anchorage device, which enables strengthening of square reinforced concrete (RC) columns with multi-layer prestressed carbon fiber reinforced polymer (CFRP) fabric, was designed and tested. Nine RC columns (three unstrengthened and six strengthened with prestressed CFRP fabric) were tested under combined constant axial loading and horizontal cyclic loading at different axial compression ratios, various prestress levels, different numbers of CFRP fabric layers, and variable area wrapped with prestressed CFRP fabric. The results showed that both the ductility and energy dissipation capacity of the strengthened columns significantly improved. The increase in the prestress level strongly affected the stiffness and horizontal load bearing capacity of the columns, and the increase in the number of CFRP layers had a larger effect on the enhancement of their energy dissipation capacity. For the RC columns fully wrapped with prestressed CFRP fabric, the energy dissipation capacity significantly increased, the ultimate drift ratio was 167% higher than that of the unstrengthened columns, and the energy dissipation capacity increased 6.5 times, respectively. •A wedge tensioning anchorage device was designed.•The device can effectively reduce the prestress loss of CFRP fabric.•The transverse restraint provided by multi-layer prestressed CFRP was more effective.•The change in the number of CFRP layers greatly affected energy dissipation.•The increase in the prestress level greatly affected the load bearing capacity.•The energy dissipation capacity of the fully wrapped column was the highest.