Axial compressive behaviour of CFDST stub columns with large void ratio

This paper describes the experimental and numerical study on axial compressive behaviour of circular-in-circular concrete-filled double-skin steel tube (CFDST) stub columns with large void ratio. Nine specimens various ratio (Rv), diameter-to-thickness outer (Do/to) strength concrete (fcu) were tested under compression. The failure patterns, load versus displacement (strain) relationship, ultimate capacity elastic composite stiffness investigated. results show that all have good structural performance. typical patterns this new type include local buckling or inner tubes crushing infill at primary locations both tubes. It is observed from tests that, there are three key stages in namely: approximative elastic, elastoplastic nonlinear post-peak, augment Rv Do/to reduce fcu, decrease. Apart tests, a finite element (FE) model was developed to further CFDST ratio, validated against results. Finally, simplified analytical predict developed, accuracy verified by available can be used practising engineers future design columns.