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Steel and Composite Structures
  Volume 38, Number 6, March25 2021 , pages 617-635
DOI: https://doi.org/10.12989/scs.2021.38.6.617
 


Analytical behavior of built-up square concrete-filled steel tubular columns under combined preload and axial compression
Jian-Tao Wang and Fa-Cheng Wang

 
Abstract
    This paper numerically investigated the behavior of built-up square concrete-filled steel tubular (CFST) columns under combined preload and axial compression. The finite element (FE) models of target columns were verified in terms of failure mode, axial load-deformation curve and ultimate strength. A full-range analysis on the axial load-deformation response as well as the interaction behavior was conducted to reveal the composite mechanism. The parametric study was performed to investigate the influences of material strengths and geometric sizes. Subsequently, influence of construction preload on the full-range behavior and confinement effect was investigated. Numerical results indicate that the axial load-deformation curve can be divided into four working stages where the contact pressure of curling rib arc gradually disappears as the steel tube buckles; increasing width-to-thickness (B/t) ratio can enhance the strength enhancement index (e.g., an increment of 1.88% from B/t=40 to B/t=100), though ultimate strength and ductility are decreased; stiffener length and lip inclination angle display a slight influence on strength enhancement index and ductility; construction preload can degrade the plastic deformation capacity and postpone the origin appearance of contact pressure, thus making a decrease of 14.81%~27.23% in ductility. Finally, a revised equation for determining strain e corresponding to ultimate strength was proposed to evaluate the plastic deformation capacity of built-up square CFST columns.
 
Key Words
    built-up square CFST columns; compressive behavior; FE modelling; full-range analysis; construction preload
 
Address
Jian-Tao Wang and Fa-Cheng Wang: Department of Civil Engineering, Tsinghua University, Beijing 100084, P. R. China
 

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