Experimental Investigation on Axially and Rotationally Restrained Circular and Elliptical Concrete-Filled Hollow Columns Subjected to Fire

Abstract

This paper presents the outcomes of an experimental investigation on the performance of axially and rotationally restrained concrete-filled hollow columns subjected to fire. The specimens were uniformly exposed to a standard fire curve and the critical time (fire resistance), the failure temperature and the respective failure modes were assessed. The paper also includes a comparison of the behavior of these columns under both axial and rotational restraint with identical columns under axial restraint only. The primary test parameters take into account in this research work were the column slenderness, the type of cross-section (circular and elliptical) and the restraint level imposed by a surrounding steel frame to the column in test. Finally, the results of this research study showed mainly that the fire resistance of identical columns under low load levels may be not significantly affected by the stiffness of the surrounding structure, except for low rotational restraint levels and high slenderness values.