ISO Standard Fire Tests of Concrete-Filled Steel Tube Columns with Solid Steel Core

Abstract

Concrete-filled steel tube columns with solid steel core are prefabricated innovative composite columns that are especially designed to achieve high fire resistance, even with high slenderness ratios and load levels. These features make them architecturally and economically appealing for use in high-rise buildings. Conceptually, their exceptional structural fire behavior is attributed to a process of gradual load redistribution to the solid steel core during fire that is thermally protected by the concrete infill. In this paper the results of a series of four ISO fire tests with concrete-filled steel tube columns with solid steel core of three different cross-sectional types and two different end conditions are presented. This novel experimental database for this type of composite column (1) validates the concept of their structural fire behavior; and (2) shows that, without additional fire protection, extraordinary fire resistance of almost 180 min can be achieved with common slenderness and load ratios with respect to building practice.