Empirical crack estimation on the strengthened concrete members with FRPs

Abstract

The crack pattern in a strengthened concrete member differs from that in a traditional reinforced concrete member. Generally, average crack spacing and width in strengthened concrete is dependent on strengthening factors other than the rebar. Therefore, it is difficult to determine actual crack widths in a strengthened concrete member with FRPs, such as a beam or a two-way slab, using existing equations. In this study, crack propagation characteristics were identified based on test results; a semi-empirical crack equation is proposed to evaluate the serviceability of strengthened concrete members and the possibility of intermediate crack-induced interfacial debonding failure. Although the proposed equation provides more accurate results, prediction error increases with the strain in the rebar or strengthening material after the rebar yields due to fatigue loading conditions. Therefore, further research is required to improve crack-width predictions after rebar yields.