FIRE TESTING OF HIGH-STRENGTH STEEL CIRCULAR COLUMNS

This paper presents an experimental-numerical study on the behaviour of High Strength Steel (HSS) columns at elevated temperature, both on Circular Hollow Sections (CHS) and on a Concrete Filled Tube (CFT). The measured yield strength of the circular sections was in the order of 820 MPa. In detail, three HSS CHS and a HSS CFT were tested under the standard ISO fire with constant eccentric compression load. The evolution of temperature and defor-mation patterns were measured by means of a comprehensive instrumentation made of ther-mocouples and displacement transducers. Numerical analyses were performed and compared with experimental data by employing stress-strain relationships of carbon steel at elevated temperatures provided by EN1993-1-2 associated with two different sets of reduction factors: i) those provided by EN1993-1-2 valid up to S460 steel grades; and ii) those proposed in the literature and based on tests on HSS.