Numerical analysis on circular concrete-filled tubular columns subjected to fire
Journal of Structural Fire Engineering
ISSN: 2040-2317
Article publication date: 28 February 2019
Issue publication date: 28 February 2019
Abstract
Purpose
Nowadays, circular concrete-filled tubular (CFT) columns are largely used in construction because of structural and architectural advantages such as high load bearing capacity and aesthetic appearance. The behavior of CFT columns at ambient and high temperatures is good; however, there are problems related to their behavior in fire when inserted in a real building structure, as for example, the influence of the restraining to thermal elongation that have to be addressed in order to improve their design. This study aims to present the results of a numerical study on the behavior of CFT columns with restrained thermal elongation in case of fire.
Design/methodology/approach
The parameters tested in the numerical simulations included column slenderness, load level, surrounding structure stiffness and steel reinforcement ratio. A sequentially coupled thermal stress analysis was carried out. The numerical model was validated with results from a large series of fire resistance tests carried out at Coimbra University, in Portugal. From these, simple equations to evaluate CFT column critical times were derived.
Findings
The results were also compared with the ones obtained from the current EN 1994-1-2:2005 simplified calculation and tabulated data methods. For the analyzed cases, it was verified that, while the simplified calculation method led to safe results on the evaluation of the fire resistance of CFT columns with restrained thermal elongation, the tabulated data method led, in certain cases, to unsafe results. This research showed also lower critical times than those from literature on similar type of columns.
Originality/value
The influence of the stiffness of the surrounding structure on the behavior of CFT columns subjected to fire was not yet clear in the major part of the studies already carried out. So, this paper has the originality to consider this parameter in the numerical simulations of this type of columns.
Keywords
Acknowledgements
The authors would like to thank the PhD scholarship awarded to the first author by Erasmus Mundus in the framework of the “Improving Skills Across Continents (ISAC)” program, the Portuguese Foundation for Science and Technology (FCT) for the financial support under the framework of PTDC 65696/2006 research project and the Portuguese companies A. Costa Cabral S. A., a steel retailer, and Metalocardoso S. A., a steel structures builder, for their contribution with steel tubes for specimens.
Citation
Pires, T.A.d.C., Rodrigues, J.P.C. and Silva, J.J.R. (2019), "Numerical analysis on circular concrete-filled tubular columns subjected to fire", Journal of Structural Fire Engineering, Vol. 10 No. 1, pp. 2-23. https://doi.org/10.1108/JSFE-06-2017-0036
Publisher
:Emerald Publishing Limited
Copyright © 2018, Emerald Publishing Limited