Concrete-filled steel tubular (CFST) members are commonly used as composite columns in modern buildings. However, the current guidelines for member design in the fire situation (EN1994-1-2) have been proved to be unsafe under certain slenderness conditions. In addition, the simplified design methods in Eurocode 4 are limited to circular and square CFST columns, while in practice columns with rectangular and elliptical hollow sections are being increasingly used due to their architectural aesthetics. In the framework of this European Project, carried out with a financial grant of the Research Programme of the Research Fund for Coal and Steel, new design tools based on numerical and experimental investigations will be developed and proposed for their incorporation to the codes.
The main objectives of this research project are:
- To evaluate the existing design methods, to review the existing usage and to analyze the results of previous tests, in order to define properly the tests parameters.
- To provide full range of experimental evidence about the fire behavior of CFST columns by carrying out a number of fire tests, a necessary basis for the development of both numerical models and simple calculation rules. Some experimental tests at room temperature in case of elliptical CFST columns should be provided, due to the lack of tests.
- To modify the actual simple calculation methods in the fire part of Eurocode 4 related to CFST columns with circular and square hollow sections, based not only on the previous tests but also on an extended parametric study based on a validated numerical model.
- To extend the previous methods to columns with rectangular, elliptical and innovative sections such as concrete-filled hollow sections with embedded steel core profile.
- To develop a user-friendly design tool in order to increase significantly the application efficiency of the developed simple design rules above.
- To disseminate the results to the practitioners and steel work associations, including actions to incorporate the proposed design rules within the Eurocode 4 .