Buckling strength of compression members considering mechanical performance variations by heat exposure

Buckling, a primary concern of structural design, is influenced strongly by material characteristics. Despite extensive research in this field, the effects of heat exposure, such as that from fire events or nuclear accidents, on the buckling capacity of steel has not been addressed adequately. This study explores microstructural changes occurring in various steel grades subjected to different heating protocols. The results are then compared with those of cyclic material tests using specific loading protocols. The findings confirm that deterioration in mechanical performance persists under cyclic stress conditions. Then combined hardening parameters are computed to establish a comprehensive database. For buckling strength evaluation, an elastic buckling strength equation is derived, incorporating end restraint stiffness. Finally, the elasto-plastic buckling strength is assessed using buckling curves from prevailing design codes, calibrated with the proposed elastic buckling strength equation and mechanical performance data considering heat exposure. In conclusion, the proposed evaluation scheme enables precise assessment of the elasto-plastic buckling strength, specifically accounting for the effects of temperature history. •Heat-exposed specimens are subjected to cyclic material tests.•Microstructural changes caused by heat exposure are investigated.•Combined hardening parameters are derived from material test results.•A theoretical equation of buckling strength is derived, reflecting end restraints.•Buckling strength is evaluated with buckling curves in existing design codes.