Fire performance of innovative steel-concrete composite columns using high strength steels

• Innovative steel-concrete composite columns with inner steel profiles are studied.
• The fire performance of these columns is analysed through a finite element model.
• The convenience of using HSS in the inner profiles is assessed.
• Parametric studies are conducted, varying the inner profiles and steel grade.
• Design strategies are proposed for enhancing the fire performance of CFST columns.

This paper presents the results of a numerical investigation on strategies for enhancing the fire behaviour of concrete-filled steel tubular (CFST) columns by using inner steel profiles such as circular hollow sections (CHS), HEB profiles or embedded steel core profiles. A three-dimensional finite element model is developed for that purpose, which is capable for representing the various types of sections studied and the nonlinear behaviour of the materials at elevated temperatures. High strength steel is considered in the numerical model, as a possible way to lengthen the fire endurance. The numerical model is validated against experimental results available in the literature for various types of steel-concrete composite sections using inner steel profiles, obtaining satisfactory results. Based on the developed numerical model, parametric studies are conducted for investigating the influence of the cross-sectional geometry and the steel grade of the inner profiles on the fire performance of these composite columns, for eventually providing some practical recommendations.