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.