Experimental and numerical investigation of high-strength steel circular columns subjected to fire

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 applied load. The evolution of temperature and deformation patterns were measured by means of a comprehensive instrumentation made of thermocouples 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 the Eurocodes associated to two different sets of reduction factors: i) those provided by the Eurocodes valid up to S460 steel grades; and ii) those proposed in the literature and based on tests on HSS.