BUCKLING BEHAVIORS OF METALLIC COLUMNS UNDER COMPRESSIVE LOAD AT EXTREMELY HIGH TEMPERATURES

This study aims to investigate buckling behaviors of a slender stainless steel column under compressive loads in severe accident conditions, which addresses the accidents in Fukushima Daiichi nuclear power plants. Firstly, buckling load, defined a load which generates a failure of the column (plastic collapse) was experimentally measured in a wide range of temperatures from 25 ºC up to 1200 ºC. The buckling load values measured were compared to numerical estimations for both an ideal column and for a column initially bent. Secondly, creep buckling tests were also performed for extremely high temperatures (800 ºC, 900 ºC, and 1000 ºC). Creep buckling was found to occur very quickly compared to general creep times under tensile stresses. Time to creep buckling was exponentially increased with decrease of loads applied. Lateral deflection of a test column was estimated using captured images by a high speed camera. It was suggested to represent creep buckling behaviors as a time-lateral deflection curve. Moreover, an empirical correlation was developed to predict creep buckling time, based on the Larson-Miller model with experimental results obtained in present study. NOMENCLATURE Q Activation energy rc Minimum creep rate R Universal gas constant tr Rupture time T Absolute temperature Initial creep strai