Durability evaluation of retrofitted corroded reinforced concrete columns with FRP sheets in marine environmental conditions

Abstract

The purpose of this paper is to investigate the effect of marine environmental condition on durability of RC-corroded columns strengthened with FRP sheets. In this study, three retrofit methods based on substrate repairs were evaluated. There are two common retrofit methods for the corroded RC columns, which are directly wrapping FRP (method 1) and wrapping FRP after replacing damaged concrete with repair mortar (method 2), respectively. Also, a durable retrofit method was developed in this study (method 3). In this method, after removing damaged concrete, wrapping was carried out, and then repair mortar was applied around GFRP sheet. After strengthening, specimens were stored in a marine simulator for 3000 and 9000h. In retrofit method 1, ultimate strength of retrofitted columns by one layer of GFRP and CFRP sheet decreased by 27.4% and 19.7%, respectively, after 9000h marine exposure. The decrease in ultimate strength of columns wrapped by one layer of GFRP and CFRP in retrofit method 2 was 25% and 18.3%, respectively. In retrofit method 3, 9000h marine exposure caused 8.8% and 2.2% increase in ultimate strength of strengthened columns with one and two layers of GFRP, respectively. The failure mode of strengthened columns by methods 2 and 3 was brittle. Finally, Distance Based Approach (DBA) was used in order to compare different retrofit methods. It was found that the performance of retrofitted columns in method 3 would be ideal in marine environmental conditions.