Seismic upgrade of concrete columns with fibre reinforced polymers

A large inventory of existing structures in North America may not have the ability to resist major earthquakes that are expected in the area. Columns in these structures are very important in providing adequate safety against failure. In this paper, retrofitting of deficient columns with carbon fibre reinforced polymers (CFRP) is investigated to upgrade them for resisting major earthquakes. Results from 9 large size columns with circular and square sections tested under simulated earthquakes forces are presented. Columns were designed with non-seismic steel reinforcement details. Four columns were tested without CFRP upgrade and five columns were retrofitted with one, two or three wraps of CFRP in the lateral direction. Results show that responses of columns with both circular and square sections can be greatly improved by reinforcing them with CFRP and that the behaviour of CFRP-retrofifted columns is superior to the steel reinforced columns designed according to the seismic provisions of design codes. As expected, the effectiveness of circular CFRP confinement was superior to the confinement provided by square CFRP wraps.