Abstract

This study explores the structural behaviour of reinforced recycled aggregate concrete (RAC) columns confined with post-tensioned metal straps (PTMS) through experimental testing and numerical analysis. Twelve specimens with varying slenderness values (λ = 6.9, 13.9, 41.6) and confinement ratios (ρ<inf>v</inf> = 0, 0.20, 0.27, 0.53) were tested in compression, including eight confined columns. The experimental results demonstrate that at the highest confinement ratio (ρ<inf>v</inf> = 0.53) and the largest slenderness value (λ = 41.6), PTMS confinement significantly increased axial deformation by up to 19% and load capacity by 18%, enhancing column performance. These experimental results were used to calibrate numerical models in ABAQUS^® software. Finite Element Analysis (FEA) proved highly accurate, with nearly all errors staying under 8% for load capacity and 9% for deformability. FEA results revealed that confinement reduces P-Δ effects and improves stability, with critical buckling loads (P<inf>cr</inf>) increasing by 174% in slender columns at high confinement (ρ<inf>v</inf> = 0.53). The results confirmed experimental observations and offered additional insights into the effects of slenderness, extending beyond the limitations of the experiments. While light and moderate PTMS confinement enhances the strength of short columns, more slender columns require dense confinement to reduce lateral instability and bending. The study contributes the better understanding of RAC column behaviour with active confinement, encourages to use RAC in structural applications.