Cold-formed steel columns made with open cross-sections subjected to fire

•Behaviour of cold formed steel (CFS) columns at high temperature studied.•Lipped channel (C) and built-up I (2C) slender cross-sections considered.•Cross-section and end-supports type, thermal restraint and load levels, tested.•Critical temperature of columns affected by the thermal restraint and load level.•Global flexural about minor axis and distortional buckling as predominant failure.

An experimental study on the fire behaviour of cold-formed steel lipped channel (C) and built-up I (2C) slender columns with restrained thermal elongation is presented. The studied parameters were the stiffness of the surrounding structure, type of cross-section, end support conditions and initial applied load level on the columns. The results showed that increasing the stiffness of the surrounding structure and initial applied load level for the semi-rigid support conditions and both cross-sections, lead to a significant reduction of the critical temperature whereas for the pin-ended support conditions the reduction is supposed to be smaller.