Low-grade glass fibre-reinforced polymer-confined circular RC columns under simulated seismic loads

Glass fibre-reinforced polymer (GFRP) with low tensile strength (hereafter referred to as low-grade GFRP) is a cost-effective alternative to other types of GFRPs with higher tensile strength. This paper investigates the prospect of retrofitting deficient and repairing damaged circular concrete columns with low-grade GFRP jackets. Two identical one-third scale models of a seis-mically deficient prototype bridge pier were constructed and tested under constant axial compression and quasi-static reversed cyclic loading. The first column was tested twice, first under "as-built" condition and second under repaired conditions. The second column was retrofitted prior to testing. The repaired and retrofitted columns were characterized with enhanced flexu-ral, ductility, and energy dissipation capacities when compared to the deficient column, and were stable up to the maximum applied drift. Provisions of the Seismic Retrofitting Manual for Highway Structures were found to yield conservative estimates of the required thickness of the low-grade GFRP jacket.