This paper aims to investigate the stability and ductility characteristics of concrete filled columns using high performance steel (HPS). Previous research in HPS and current applications of HPS are discussed at length. Eight columns were tested under compression as two hollow high strength steel and two hollow stainless steel box sections were compared to two concrete filled high strength and stainless steel box sections.
Experimental Study, Results, and Discussion
The high strength steel columns considered were constructed with a box section of 4.3 x 4.3 in. with a 0.197 in. nominal plate thickness. A nominal yield stress of 65 ksi was chosen. The hollow sections exhibited quite ductile behavior. The concrete filled sections reached a peak load and gradually experienced a load reduction; the author attributes this to internal concrete crushing. The paper suggests that confinement is less likely to take place for high strength steel sections because the strains at which yields are often achieved are often in the vicinity of the crushing strains of most normal strength concrete.
The stainless steel columns had a nominal dimension of 3.94 x 3.94 in. cross section with 0.197 in. nominal wall thickness. The tensile coupon tests revealed a mean 0.2% proof stress of this material to be about 32 ksi and the mean ultimate stress to be about 61 ksi. The hollow section columns achieved a maximum load just larger than 180000 lbs., at which point loads began to stabilize. Results for the concrete filled steel sections revealed that the presence of the concrete infill allowed local buckling to be considerably delayed and a gradual increase in the steel allowed. Furthermore, the steel section appeared to significantly confine the concrete in these sections.
The paper concludes with the statement that further research on HPS is necessary.
Uy, B. (2008). "Stability and ductility of high performance steel sections with concrete infill," Journal of Constructional Steel Research, 64 (7-8) , pp. 748-754. doi:10.1016/j.jcsr.2008.01.036