Fire performance of stiffened concrete filled double skin steel tubular columns |
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| Affiliation: | 1. Civil Engineering Department, Urmia University of Technology, Urmia, Iran;2. Civil Engineering Department, Sahand University of Technology, Tabriz, Iran;1. School of Mechanics, Civil Engineering and Architecture, Northwestern Polytechnical University, ShaanXi 710072, China;2. School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore;1. Department of Structural Engineering, Faculty of Engineering, Tanta University, Tanta, Egypt;2. School of Civil, Environmental and Mining Engineering, Faculty of Engineering, Computing and Mathematics, The University of Western Australia, Australia;3. School of Engineering and Mathematical Sciences, Collage of Science, Health and Engineering, La Trobe University, PO Box 199, Bendigo, VIC 3552, Australia;1. Dept. of Civil, Structural and Environmental Engineering, Univ. at Buffalo, Buffalo, NY 14260, United States;2. Dept. of Structural Engineering, University of California at San Diego, La Jolla, CA 92093, United States;1. Department of Structural Engineering, Faculty of Engineering, Tanta University, Tanta, Egypt;2. Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, United Kingdom;1. Civil Engineering Department, University of Gaziantep, 27310 Gaziantep, Turkey;2. Civil Engineering Department, University of Mosul, 41001 Mosul, Iraq |
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| Abstract: | A major deficiency of the concrete-filled double skin steel tube (CFDST) columns in fire exposure is the inadequate steel-concrete interface bonding leading to separating concrete and steel surfaces at elevated temperatures and triggering buckling failure of the columns. To improve interface interaction as well as postpone overall buckling, it is proposed in this study to use longitudinal steel stiffeners in CFDST columns. Different patterns of stiffeners including six, four and two number of stiffeners embedded in the interior or exterior surfaces of the inner or outer tubes are considered in the analysis. A sequentially-coupled thermal-stress analysis procedure is conducted to evaluate the effects of different patterns of stiffeners on the fire performance of these columns. One of the novelties of the current study is the incorporation of the confinement effects of both inner and outer tubes on the compressive strength of concrete at elevated temperatures which gives a realistic prediction of the fire resistance behavior of the CFDST columns. From the results, it is found that among the different patterns studied, stiffeners embedded in the exterior surface of the inner tubes or interior surface of the outer tubes enhancing steel-concrete interface interaction have a determinant role in much-improving fire endurance of the columns. With increase in the load ratio fire resistance of the specimens decreases drastically. The stiffeners strength and concrete strength have minimal effect on the fire performance of the stiffened CFDST columns. The conclusions, drawn from this study, can in turn, lead to the suggestion of some guidelines for the design of CFDST columns. |
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| Keywords: | CFDST columns Longitudinal steel stiffeners Coupled thermal-stress analysis Fire resistance |
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