Advanced Steel Construction

Vol. 14, No. 3, pp. 496-513 (2018)


AXIAL RESIDUAL CAPACITY OF CIRCULAR

CONCRETE-FILLED STEEL TUBE STUB COLUMNS

CONSIDERING LOCAL BUCKLING

 

C. Yang 1, Z.X. Yu 1,2,3,*, Y.P. Sun 1,3,4, L. Zhao 5 and H. Zhao 6

1School of Civil Engineering, Southwest Jiaotong University, Chengdu, China

2National Engineering Laboratory for prevention and control of geological disasters in land transportation, Chengdu, China

3China-Japan Resilient and Sustainable Concrete Structure Research Center, Chengdu, China

4Department of Architecture, Graduate School of Engineering, Kobe University, Kobe, Japan

5Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, China

6State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu, China

*(Corresponding author: E-mail:This email address is being protected from spambots. You need JavaScript enabled to view it.)

Received: 19 June 2017; Revised: 2 September 2017; Accepted: 17 November 2017

  

DOI:10.18057/IJASC.2018.14.3.11

 

ABSTRACT:

This paper proposes a superposition method considering local buckling to estimate the residual capacity of circular concrete-filled steel tube stub columns (CFSTs) under axial compression based on substantial experimental data, consisting of 3 recently conducted tests as well as 150 test results from available literature. The proposed approach accounts for the influence of local buckling of the steel tube on confining effect, by introducing a coefficient to reduce the compressive strength of concrete in the post-buckling stage. Three specimens, including a bare steel stub column with circular hollow section (CHS), a CHS with concrete restraint and a CFSTs, were tested to investigate the contribution of concrete on the local buckling. Further, the mechanical model of steel tube was established and the design equations for residual bearing capacity of the tube were derived. The nominal load-shortening curves of the concrete core are extracted from 150 collected experimental curves of the CFSTs, with different parameters such as diameter-to-thickness (D/t) ratio, yield strength fsy and concrete strength fcp. The variation of the stiffness degradation in the curves indicates that the effect of local buckling on both ductility and residual compressive strength of the concrete core are correlated with the section type of the steel tube. The residual compressive strength decreases exponentially with the increase of the generalized outer diameter-to-thickness ratio.

 

Keywords:

CFST, stub column, circular section, axial residual capacity, superposition method, local buckling

 

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