City Research Online

Abstract

This study presents the concept of rectangular glass fiber-reinforced polymer (GFRP) tube-concrete-double steel tube (GTCDST) composite columns. The research primarily investigates the performance of such composite stub columns under axial compression. Tests were first conducted on nine specimens, with cross-sectional hollow ratio (ϕ[jls-end-space/]) and nominal cross-sectional FRP content (ρn,f[jls-end-space/]) considered as key investigation parameters. All specimens ultimately failed at specific corner regions, manifested as GFRP tube rupture and severe cracking and crushing of sandwich concrete; however, no significant failure was observed in the inner steel tubes. Generally, ρn,f exerts a significant effect on the measured load-deformation responses, whereas the effect of ϕ is relatively minor. When ρn,f increases from 0.4% to 1.2%, the bearing capacity of the specimens improves by up to 13.9%; in contrast, variations in ϕ result in a maximum change of only 4.2% in bearing capacity. The nominal compressive strength of the confined sandwich concrete is found to be 3.1%-29.5% higher than the cylindrical compressive strength of unconfined concrete, with greater enhancement observed at higher ρn,f[jls-end-space/]. Furthermore, the hoop strain in the GFRP tube at the ruptured corners reaches only 57.7%-98.0% of its ultimate tensile strain, indicating underutilization of the FRP’s tensile capacity. A developed finite element (FE) model was used to simulate the performance of rectangular GTCDST composite stub columns, and the simulation results were validated against experimental data, showing good agreement. Finally, predictive models are proposed for the compressive stress-strain relationship of the confined sandwich concrete and the axial compressive bearing capacity of rectangular GTCDST composite stub columns, both yielding generally accurate results.

Publication Type:	Article
Additional Information:	© 2026, the authors. This is the accepted manuscript of an article published by Elsevier. Please refer to the publisher’s terms and conditions for information on re-use.
Publisher Keywords:	GFRP tube-concrete-double steel tube, (GTCDST), Rectangular section, Composite stub columns, Axial compressive performance, Tests, Finite element (FE) simulation, Predictive models
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) T Technology > TH Building construction
Departments:	School of Science & Technology School of Science & Technology > Department of Engineering
SWORD Depositor:	Symplectic Administrator

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