Axial compressive behaviour of corroded steel reinforced concrete columns retrofitted with a basalt fibre reinforced polymer-ultrahigh performance concrete jacket

Abstract

• An accelerated retrofit approach is developed. • The axial compressive behaviour of retrofitted columns are analyzed in detail. • A simple model was proposed with relatively conservative predictions. Steel-reinforced concrete (SRC) members suffer from severe corrosion in some scenarios. Therefore, new techniques and materials are required for the timely rehabilitation of the deficient structures. To address this challenge, the authors have developed an accelerated retrofit approach using a basalt fibre-reinforced polymer (BFRP) sheet combined with an ultrahigh-performance concrete (UHPC) jacket. The BFRP sheet was internally embedded within the UHPC matrix to enhance its durability under marine environmental conditions. The treatment of corroded steel stirrups in SRC columns replaced with fiber-reinforced polymer (FRP) composites is also considered in the retrofit approach. The authors then investigated the axial compressive behaviour of a series of corroded RC columns retrofitted with a BFRP–UHPC jacket or with a UHPC jacket. Specifically, 16 RC columns (six control specimens and 10 retrofitted specimens) were prepared and tested under monotonic axial compression. The test variables were the sectional geometry (i.e. circular or square cross -section), transverse steel reinforcement ratio (i.e. two different stirrup spacings), and retrofitting method (i.e. BFRP–UHPC jacket or UHPC jacket). The test results showed that the maximum increase in the peak load after retrofitting was as large as 145.89%. The authors also developed a simple model for retrofitted RC columns that can provide reasonably accurate but relatively conservative predictions.