Retrofit of Damaged RC Columns Using CFRP Jackets

Abstract

This paper presents results of an experimental program undertaken to investigate the possibility of application of carbon fiber reinforced polymer (CFRP) jackets to reduce the risk of rebar buckling of axially loaded RC columns with circular or rectangular cross-section. Ten RC columns with height of 300 mm and three different cross-sections, i.e. circular of 150 mm diameter, and square of 100 mm and 150 mm side, with two ratios of stirrup spacing to longitudinal bar diameter, i.e. 7.6 and 11.7, are tested. Scaling of 1/3 was followed in general, also in the rebar diameter and the concrete mix. The specimens, after being tested under axial compression up to failure, were strengthened with CFRP jackets using wet lay-up process. The number of CFRP layers used in the jacket was determined in relation to the degree of damage the columns had suffered according to a damage scale that is introduced. The results of this work are encouraging towards the potential of using CFRP jackets in RC columns with sparsely spaced stirrups, both for strengthening of intact RC columns and also as a retrofit technique for RC columns with buckled longitudinal bars, e.g. after the event of an earthquake. This application may be extremely helpful for the retrofit of RC columns in earthquake prone areas in buildings that were not designed according to the modern code principles and therefore their stirrups are sparsely spaced. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.