Abstract
Concrete-encased concrete-filled steel tube (CFST) composite columns provide high bearing capacity, good seismic performance and an easier connection with arbitrary angle beams, which are widely used in high-rise buildings. Considering the high frequency of building fires, experimental research investigated the axial compressive behavior of the composite columns’ exposure to high temperature in this paper. Fourteen specimens after exposure to high temperatures with different parameters, including the heating temperature, steel tube diameter and concrete cover thickness, were fabricated to test under axial compressive loading. The failure pattern, load-displacement curve, bearing capacity, initial stiffness, deformation performance and damage rule of the specimens were discussed. The test results showed obvious differences in damage of specimens subjected to various high temperatures. The failure of the specimens began with the spalling and crushing of the concrete at the edge and ends in a lantern shape. The load-displacement curves of the specimens were significantly affected by high temperature, while the influence the of steel tube diameter and concrete cover thickness was relatively weak. A method of calculating axially loaded capacity for the composite column exposure to high temperature is proposed considering the effects of the main parameters of heating temperature and steel tube position, and the calculated results are in good agreement with the experimental results.
Highlights
With the rapid development of high-rise buildings, concrete-filled steel tube (CFST) columns have received extensive attention and investigation due to their high strength and performance
Concrete-filled steel tube (CFST) columns have higher bearing capacity and ductility than normal steel reinforced concrete (RC) columns [1,2]. Their bearing capacity degrades rapidly after fire exposure, so a series of research studies have been performed on the fire performance of CFST column structures [3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19]
It was found that the post-fire performance of circular columns was better than that of square columns, while the eccentricity of columns had a significant effect on their fire performance
Summary
With the rapid development of high-rise buildings, concrete-filled steel tube (CFST) columns have received extensive attention and investigation due to their high strength and performance. Concrete-filled steel tube (CFST) columns have higher bearing capacity and ductility than normal steel reinforced concrete (RC) columns [1,2]. Tao et al [5] analyzed the post-fire bond between the steel tube and concrete in 37 CFST columns. Hu et al [7] reported a numerical study on the temperature distribution of high-strength concrete-filled steel tube subjected to a fire. Lu et al [12] investigated the fire performance of high strength self-consolidating concrete-filled steel tubular shtiugbh cstorleunmgtnhs.seSlof-ncgonestoalild. Tcohleuimnflnusesnucbejeocftdeidffetorehnitghheatetimngppaerraatmueretesrws,esrteeedletsuibgeneddiafmoretaenrsa,xainadl ccoomncprreetsescioonvelroathdiicnkgnteessste.sTohne tihnefluaxeinaclecoomf dpirfefesrseivnet performance and damage rules were investigated, and a calculation method for the residual bearing capacity of the composite columns after fire exposure was proposed
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