Post-Fire Exposure Behavior of Circular Concrete-filled Steel Tube Column under Axial Loading
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Online ISSN 2093-6311 Print ISSN 1598-2351
Post-Fire Exposure Behavior of Circular Concrete-filled Steel Tube Column under Axial Loading Aditya Kumar Tiwary1 · Ashok Kumar Gupta1 Received: 26 July 2019 / Accepted: 21 September 2020 © Korean Society of Steel Construction 2020
Abstract Concrete-filled steel tube (CFST) columns are a composite member which mainly consists of steel tube infilled with concrete that are increasingly being used as load-carrying members these days. In construction industry, CFST columns are being preferred for the development of tall buildings and long-span bridges. This paper presents an experimental investigation on concrete-filled steel tube (CFST) columns which were post heated and were subjected to axial loading. The thickness of the casing steel was 4 mm and 5 mm and diameter was 100 mm, 125 mm and 150 mm and were infilled with concrete of grade M30 which were used in the present study. This study also represents the behavior of CFST columns for two cooling regimes (annealing and quenching) after exposure to elevated temperatures of 600 °C and 800 °C. The results obtained from experimental analysis were compared to each other in terms of load-deformation pattern, ultimate load capacity, residual strength index, secant stiffness and ductility index. The test results showed that as compared with water quenching, annealing is slightly better for post fire cooling of CFST columns. Also, the results obtained by the experimental investigation were compared with each other on the basis of two cooling regimes. Keywords Concrete-filled steel tube (CFST) columns · Ultimate strength · Secant stiffness · Ductility index · Residual strength index · Cooling regimes Abbreviations CFST Concrete-filled steel tube. C1T4 First column with steel thickness 4 mm and diameter 100 mm. C1T5 First column with steel thickness 5 mm and diameter 100 mm. C2T4 Second column with steel thickness 4 mm and diameter 100 mm. C2T5 Second column with steel thickness 5 mm and diameter 100 mm. C3T4 Third column with steel thickness 4 mm and diameter 100 mm. C3T5 Third column with steel thickness 5 mm and diameter 100 mm. AB Ambient. * Aditya Kumar Tiwary [email protected] Ashok Kumar Gupta [email protected] 1
Department of Civil Engineering, Jaypee University of Information Technology, Waknaghat, Himachal Pradesh 173234, India
AN Annealing. QN Quenching. D Steel tube outer diameter. H Height of the column. As Steel area. Ac Concrete area. DI Ductility index. t Steel tube thickness. fcu Cube compressive strength. fy Steel yield stress. fck Characteristic compressive strength of concrete. τ Shear stress. τcrit Critical shear stress. εt Strain hardening. εu Ultimate strain. fult Ultimate stress. fcc Confined compressive strength of concrete. fc Unconfined compressive strength of concrete. εcc Unconfined concrete strain. ε’c Unconfined concrete strain. fcp-max Maximum confining pressure. Ne Experimental axial load capacity.
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Nc Eurocode 4 axial design
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