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Steel and Composite Structures
  Volume 35, Number 1, April10 2020 , pages 93-109
DOI: https://doi.org/10.12989/scs.2020.35.1.093
 


Numerical study of concrete-encased CFST under preload followed by sustained service load
Gen Li, Chao Hou, Lin-Hai Han and Luming Shen

 
Abstract
    Developed from conventional concrete filled steel tubular (CFST) members, concrete-encased CFST has attracted growing attention in building and bridge practices. In actual construction, the inner CFST is erected prior to the casting of the outer reinforced concrete part to support the construction preload, after which the whole composite member is under sustained service load. The complex loading sequence leads to highly nonlinear material interaction and consequently complicated structural performance. This paper studies the full-range behaviour of concrete-encased CFST columns with initial preload on inner CFST followed by sustained service load over the whole composite section. Validated against the reported data obtained from specifically designed tests, a finite element analysis model is developed to investigate the detailed structural behaviour in terms of ultimate strength, load distribution, material interaction and strain development. Parametric analysis is then carried out to evaluate the impact of significant factors on the structural behaviour of the composite columns. Finally, a simplified design method for estimating the sectional capacity of concrete-encased CFST is proposed, with the combined influences of construction preload and sustained service load being taken into account. The feasibility of the developed method is validated against both the test data and the simulation results.
 
Key Words
    concrete-encased CFST; construction preload; sustained service load; numerical analysis; sectional capacity
 
Address
Gen Li and Luming Shen: 1School of Civil Engineering, The University of Sydney, Sydney, NSW 2006, Australia
Chao Hou: Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
Lin-Hai Han: Department of Civil Engineering, Tsinghua University, Beijing, 100086, P. R. China
 

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