Experimental study on compressive behavior of concrete-filled double-skin circular tubes with active confinement

A convenient family member of composite columns is concrete filled double skin tube (CFDST); it contains two tubes of concentric steel and also shell concrete that there is between them. The superior or equal potential offering characteristics of CFDST columns are more than counterparts of filled steel tubes of classical concrete (CFST). The purposes of the present study are to provide experimental investigation results into the prestressed load-carrying capacity of CFDST columns. Here, an innovative and novel technique is used to confined concrete prestressing, in which the fresh concrete is compressed for a short-run duration. Sixty-four total specimens were tested with various outer thickness (to) and diameter (Do), inner thickness (ti) and diameter (Di), and also CFDST columns of concrete strength that resist axial compression. The experimental results support that the present technique prestressed confined concrete, and it demonstrates that CFDST specimens' load-carrying capacity enhanced significantly. The development of an accurate and simple formula for the short circular of CFDST columns' ultimate axial strength prediction in terms of active/passive confinement, concrete compressive strength, Di/ti, and Do/to is the other purpose of the present study.