Muthanna Journal of Engineering and Technology
Volume (13), Issue (1), Year (30 June 2025), Pages (51-65)
DOI:10.52113/3/eng/mjet/2025-13-01-/51-65
Research Article By:
Zain AL-abdeen Injers Tomma and Samoel Mahdi Saleh
Corresponding author E-mail: zainalmaliky451@gmail.com
ABSTRACT
A series of experimental tests were carried out to investigate the behavior of sustainable self-compacting concrete-filled double skin steel tubular (HSCFDST) columns. Nine column specimens were tested in the present study, taking into account the effects of the inner shape of the column cross section (circular or square), the hollowness ratio, and the recycled aggregate replacement ratio. For comparison, three of the tested specimens were filled with normal recycled aggregate concrete. It was observed that the maximum axial strength of CFDST columns increases with the increase in void fraction for round inner tubes and decreases with the increase in void fraction for square inner tubes. Also, it was found that for square column specimens, the ultimate axial strength of HSCFDST columns was inversely proportional to their hollowness and slenderness ratios. CFDST column specimens filled with recycled aggregate concrete compared with those filled with normal aggregate concrete decreased stiffness and ultimate axial strength but gave unexpected results for the ultimate axial strength; therefore, the suitable choice for the section properties of the inner steel tube is required. The bearing capacity of CFDST square columns with concrete aggregate (30% and 60%) decreases by 5% and 10%, respectively. Increasing the volume of recycled concrete led to a decrease in maximum load capacity, with a 30% volume resulting in a 5%-10% reduction and 60% volume further reducing capacity by 10%-14.6%. The experimental results and analytical approach that were developed by other researchers showed good agreement.
Keywords: CFDST, Sustainable concrete, self-compacting concrete, Composite column, Hollowness ratio, recycled aggregate.