Title: Prediction of axial capacity of octagonal concrete-filled steel tube columns considering confinement effect

Authors: Nazar J. Abbas; Ammar A. Ali

Addresses: Department of Construction and Projects, Civil Engineering Department, University of Technology, Baghdad, Iraq ' Department of Construction and Projects, Civil Engineering Department, University of Technology, Baghdad, Iraq

Abstract: The present research presents both detailed and simplified formulae on the octagonal concrete-filled steel tube (CFST) columns to define the ultimate strength of this type of column. These formulae have been validated and proved to be accurate through comparisons with experimental tests and with other available methods proposed by other researchers. On the other hand, employing the new formula in the constitutive model of core concrete in the finite element analysis (FEA) has shown to be of adequate accuracy to predict the behaviour of octagonal CFST columns. The effects of variation in both concrete-steel strength ratio (fc/fy) and depth-to-thickness of the tube (D/t) were studied. It is found that by decreasing the depth-to-thickness ratio of steel tube (D/t) the confining pressure will be increased. Also, decreasing the ratio of compressive strength of concrete to yield strength of steel (fc/fy) the confining pressure will be decreased.

Keywords: axial capacity; octagonal CFST; concrete-filled tube; confinement effect; composite columns; steel tube; concrete core; finite element; constitutive model; concrete-steel strength; FE modelling; column behaviour; nonlinear FEA.

DOI: 10.1504/IJSTRUCTE.2022.121891

International Journal of Structural Engineering, 2022 Vol.12 No.2, pp.170 - 188

Received: 05 Dec 2020
Accepted: 05 Apr 2021

Published online: 07 Apr 2022 *

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