Ghannam, Jawad, and Hunaiti 2004
An experimental study was conducted to investigate the failure modes of square, rectangular, and circular steel tubular sections filled with normal or lightweight concrete. Forty five specimens were tested under monotonic concentric axial loading.
Experimental Study, Results, and Discussion
Eighteen of the forty five columns were filled with normal weight concrete; another eighteen were filled with lightweight concrete, and the remaining nine were tested as hollow tubes. Six different steel sections were tested with cross-section dimensions (side length or diameter) ranging from 7.9 in. to 3.5 in. and width to thickness ratios ranging from 20 to 58. The L/D ratio ranged from 15 to 25. The normal weight concrete had a compressive cube strength of 4.8 ksi, and the lightweight concrete had a compressive cube strength of 1.4 ksi. The yield strength of the steel ranged from 35 ksi to 53 ksi.
The peak load achieved for all columns in addition to selected load deformation curves were presented. The specimens filled with lightweight concrete exhibited some local buckling when failure by flexural buckling occurred. This is in contrast to the columns filled with normal weight concrete which showed no signs of local buckling when flexural buckling occurred. The hollow tube specimens failed by local buckling. The authors suggest that, considering the experimental results, the low density, and beneficial thermal conductivity, lightweight concrete could be a viable alternative for use in CFTs.
Reference
Ghannam, S., Jawad, Y. A., and Hunaiti, Y. (2004). “Failure of Lightweight Aggregate Concrete-Filled Steel Tubular Columns,” Steel and Composite Structures, Vol. 4, No. 1, pp. 1-8.