Elasto-plastic analysis of circular concrete-filled steel tube stub columns

This paper presents a full-range elasto-plastic analysis using continuum mechanics on circular concrete-filled steel tube (CFT) stub columns under concentric loading condition, covering concrete strengths from 30 to 120 MPa and diameter-to-wall thickness ratio (D/t) greater than 20. Firstly, a constitutive model was employed for laterally-confined concrete under axial compression. A continuum mechanics model was then established and the corresponding elasto-plastic analysis was performed through a FORTRAN program. This model is able to present full-range stress-strain developments in axial, radial and perimeter directions and further clarify the load sharing pattern between the steel tube and the concrete core. Based on the proposed model, parametric analysis was conducted to investigate the effects of material strengths and sectional steel ratio on the triaxial stress-strain developments and the load sharing pattern. In addition, the model was simplified to predict the ultimate capacity and the load-axial strain relationship of CFT composite sections and the results are in good agreement with experiments. Further comparisons were made of the approach developed by Han et al. 2004 and the existing international standards. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.