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Structural behavior of square double skin self-compacting concrete columns incorporating recycled aggregate | ||
| Al-Qadisiyah Journal for Engineering Sciences | ||
| Articles in Press, Accepted Manuscript, Available Online from 11 April 2026 PDF (7.33 M) | ||
| Document Type: Research Paper | ||
| DOI: 10.30772/qjes.2026.163718.1685 | ||
| Authors | ||
| Hamid Naji Jasim* 1; Munaf A. AL-Ramahee2 | ||
| 1General Directorate of Education Qadisiyah, Ministry of Education, Al-Qadisiyah, Iraq. | ||
| 2Department of Civil Engineering, College of Engineering, University of Al-Qadisiyah, Al-Qadisiyah, Iraq. | ||
| Abstract | ||
| Construction and demolition waste is recognized as a major waste stream made by humans around the world. The use of crushed old concrete in a type of recycled aggregate concrete (RAC) has been a promising technique to promote construction sustainability. However, the mechanical behaviors and the durability of RAC are inferior to those of concrete incorporating natural aggregate. Therefore, the creation of effective methods to lessen these harmful consequences is crucial. It stands to reason that the dilatation of concrete can be restricted by placing it in a confinement state. Due to the confinement provided by the steel casing, a steel tube filled with concrete can be considered suitable for improving the working mechanism of the RAC. In this paper, a series of comparison tests were conducted to investigate the behavior of square double skin steel tubes filled with self-compacting concrete (SCFDST) columns under different loading conditions. Ten specimens consisting of five normal SCFDST and five recycled aggregate self-compacting concrete filled double skin steel tube (RSCFDST) columns were tested under (axial, uniaxial, and biaxial) compression loads. Loading eccentricity and full replacement of coarse aggregate were adopted as the main parameters in the experiments. Overall, the failure mode, ultimate capacities, and general deformational behavior have been presented in this paper. According to the results, comparable structural behavior and failure shapes were observed between the RSCFDST columns and their normal SCFDST counterparts with an acceptable reduction in ultimate bearing capacity. The ultimate bearing capacity of both RSCFDST and conventional SCFDST are significantly harmed by eccentricity, while the ductility of the columns was improved by the RAC replacement. The failure mode of normal SCFDST and RSCFDST columns was overall buckling under a uniaxial and biaxial compression load, whereas compression failure was the failure mode of the axially loaded columns. As expected, due to the confinement effect of the steel tubes, the strength of the sandwich concrete was enhanced, and all tested columns exhibited ductile failure. | ||
| Keywords | ||
| CFDST; Eccentric compression; RA concrete; SCC | ||
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