Behavior of stiffened concrete-filled steel tube columns infilled with nanomaterial-based concrete subjected to axial compression.

Abstract

The use of nanotechnology in the field of construction emerged as the utilization of nanomaterials to improve the mechanical properties of concrete. In this study, a novel form of stiffening scheme was suggested, named a catty-cornered propped concrete-filled steel tube (CFST) column. The performance of the suggested stiffened CFST column was analyzed under axial compression. The steel tube of CFST specimens was filled with normal and nanomaterial-based concrete. The three kinds of nanomaterials were utilized viz., nano-silica (NS), carbon nanotubes (CNT), and nano-titanium dioxide (NT). The results of the investigation were collected in terms of ultimate capacity, load vs strain behavior, and load vs deformation response. The ductility index (DI), secant stiffness, composite interaction, and confining effect variation were also discussed further. It was observed that the suggested stiffening scheme was able to increase the ultimate capacity of unstiffened CFST by approximately 14%. The use of nanomaterials in CFST infill concrete also resulted in an approximately 7% increase in load capacity. Further increasing the number of stiffening bars improved the ductility and stiffness of the column section. On the other hand, the inclusion of nanomaterials resulted in a decrease in the ductility index and improved the stiffness of the section. The proposed stiffening scheme resulted in better composite interaction and increased confinement. It was also concluded that the utilization of nanomaterial-based concrete as an infill in the stiffened CFST column could enhance its performance under axial compression loading.