Behavior of R.C. Columns Strengthened by CFRP Sheets Reinforced Partially by GFRP Bars

This paper presents results obtained from the tests to investigate the behavior of column specimens’ reinforcement by partially and fully GFRP bars and strengthened by CFRP sheets subjected to concentric and eccentrically applied loading. 12 half-scale column specimens reinforced with varied ratios of GFRP (36%, 64%, 100%) in addition to the control specimen, which was reinforced by traditional steel bars strengthened with CFRP sheets and investigated under load with different eccentric’s ratio e/h (0, 0.66, and 1). The failure mode, the axial load, the average axial displacement relation, and a comparison between the experimental results and theoretical interaction diagram for strengthened and un-strengthened columns were conducted. The results show that the experimental results for the strengthening specimens by CFRP sheets are higher than the theoretical results. That indicates that the theoretical design is conservative according to the ACI code. CFRP sheets improved the specimens' performance and increased the moments' value. the average axial bearing capacity of the columns strengthened by CFRP sheet in the groups that the GFRP bars were used as a partial or complete replacement in the main reinforcement was reduced with increasing the number of GFRP bars. Furthermore, the percentage of dropping the average axial bearing capacity for columns with GFRP bars tested under eccentric load reduced with increasing the number of GFRP bars.