Seismic Behavior of RC Columns Retrofitted with FRCM Jackets

Many existing concrete structures are vulnerable to earthquake events, which could result in catastrophic consequences. Fabric-reinforced cementitious matrix (FRCM) systems offer unique advantages and are a viable alternative to other conventional materials for strengthening concrete structures. However, a comprehensive understanding of FRCM’s impact on retrofitted reinforced concrete (RC) columns has yet to be explored. This study experimentally investigated the seismic behavior of RC columns retrofitted with carbon FRCM jackets. The 300-mm- diameter circular RC columns were 1,720 mm long and had a deficiency in their seismic reinforcement detailing in the plastic hinge region. The columns were retrofitted with either one or two FRCM layers installed in the plastic hinge region. The columns were subjected to quasi-static lateral cyclic loading, and the seismic performance was evaluated in terms of failure mode, load capacity, ductility, stiffness degradation, and energy dissipation. The test results revealed that the FRCM jacket with one layer delayed the buckling of the longitudinal rebars and enhanced the overall seismic response. The addition of a second FRCM layer allowed further improvement in the response as it prevented the buckling and resulted in a slower degradation rate. The comparison between the control unretrofitted column and the retrofitted columns showed that the FRCM jackets resulted in an average increase of 34% in lateral load capacity, 65% in ductility, and 30% in energy dissipation. This study highlighted the progressive failure of the FRCM system and how this is associated with the structural performance of the retrofitted columns.