External confinement of low-strength brittle reinforced concrete short columns

In this study, FRP jacketed short reinforced concrete columns with low concrete strength and inadequate transverse reinforcement were tested under uniaxial compression. The diameter of the longitudinal bars and spacing of the transverse bars were designed to allow buckling of longitudinal bars. The effects of the jacket thickness, pre-damage, cross-section shape and the usage of FRP jackets either continuous or as straps like hoops or spirals were investigated. The test results showed that external confinement of this type of columns was very effective in terms of deformability and strength enhancement. The buckling of the longitudinal bars was delayed significantly by the FRP jackets. The pre-damage did not have an adverse effect on the performance of the jacketed members. It was also observed that for equivalent amount of FRP, continuous jackets and straps provided similar performances. The compressive strengths and the corresponding axial deformations of the columns were also predicted by the empirical equations proposed by the authors before. It was seen that these predictions were in reasonable agreement with experimental results.