City Research Online

Abstract

Studies regarding partially compressed rectangular concrete-filled steel tube (CFST) slender columns are still scarce. Experimental study on 13 partially compressed and 4 fully compressed reference specimens was performed, considering key parameters: partial compression area ratio (β[jls-end-space/]), relative stiffness radius of the upper endplate (Rrs[jls-end-space/]), slenderness ratio (λ[jls-end-space/]), and depth-to-width ratio (w[jls-end-space/]). Failure patterns in partially compressed specimens are characterized by local downward deformation of the upper endplate and widespread, low-amplitude outward bulging of the steel tube near the top. This contrasts with the localized, high-amplitude outward bulging of the steel tube and overall lateral deflection observed in fully compressed specimens. Parameters β and Rrs predominantly affect failure patterns, load-deformation responses, and mechanical indicators. Compared to fully compressed specimens, partially compressed specimens show reductions in bearing capacity (6.7–69.3%) and initial stiffness (4.9–48.0%), but increased ductility coefficients (0.3–79.9%). Among parameters, β causes the most significant variation in mechanical indicators, while λ has the least. Additionally, a finite element (FE) model was developed to simulate the structural behavior of axially partially and fully compressed rectangular CFST slender columns. The accuracy of the numerical model was validated against the experimental data. Using the verified FE model, an extended parametric analysis was conducted to systematically evaluate the influence of key variables. Based on the combined experimental and numerical findings, design formulae to predict the bearing capacity of axially partially compressed rectangular CFST columns are finally proposed and assessed.

Publication Type:	Article
Additional Information:	© 2026 Elsevier Ltd. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/
Publisher Keywords:	Rectangular CFST slender columns, Axial partial compression, Experiments, Finite element (FE) model, Design formulae
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Departments:	School of Science & Technology School of Science & Technology > Department of Engineering
SWORD Depositor:	Symplectic Administrator

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