ABSTRACT
The action of fire on steel building columns with restrained thermal elongation it is translated in a decrease of their mechanical properties associated to an increase of the restraining forces. The increase of the restraining forces with the temperature is higher as higher is the stiffness of the surrounding building structure and it is the responsible for the buckling of the columns. Besides the stiffness of the surrounding structure to the columns there are also other parameters that influence their behaviour when subjected to fire.
This paper presents the results of fire resistance tests on H and circular hollow structural sections (CHS) with restrained thermal elongation. Two types of cross-sections, four values of slenderness, and two values of load level were tested, in order to evaluate the influence of each parameter in the fire resistance.
The behaviour in fire of these two types of cross-sections is compared in this paper. It is concluded that the higher the load level the lower the critical temperature of the columns is. The type of cross-section, for similar slenderness values, has a minor effect on the critical temperature of the columns.
Keywords: Fire, Resistance, Steel, Columns, Restraining.
