Circular concrete-filled double skin steel tubes under concentric compression: Tests and FEA parametric study

Berika C. Cihan Yilmaz*, Ergun Binbir, Cem Guzelbulut, Hasan Yildirim, Oguz C. Celik

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Both experimental and numerical investigations are performed to determine complete inelastic behavior of circular concrete filled double skin steel tubes (CFDSTs) with different compositions. In the experimental part, 8 circular tubes including 2 DSTs (double skin steel tubes without infill) and 6 CFDSTs are tested under concentric axial compression to failure. Presence/absence of infill concrete, hollow ratio (χ = 0.47 ∼ 0.70), and concrete type (plain, polypropylene and steel fibers added) are the parameters. To cover more parameters such as further hollow ratios, inner and outer tube thicknesses, a numerical work is added. AISC 360–16 and Eurocode 4 (EC4) are employed to evaluate their applicability for CFDSTs. Results show that the hollow ratio and outer/inner tube slendernesses (D/t) have a significant impact on the behavior. Experimental and numerical results reveal that, independent of the concrete composition (i.e. with or without any fibers) and hollow section ratio, concrete infill has significantly improved axial strength (up to 86 %) and ductility (up to 314 %) by delaying local buckling. Polypropylene and steel fibers improve the overall behavior with an enhanced displacement ductility and energy absorbtion. CFDSTs with smaller hollow ratios (say 0.47 or smaller) present much better inelastic behavior mainly from the enhanced confinement effect.

Original languageEnglish
Article number116765
JournalComposite Structures
Publication statusPublished - 1 Apr 2023

Bibliographical note

Publisher Copyright:
© 2023 Elsevier Ltd


This experimental research was partially supported by Istanbul Technical University (ITU) BAP Unit under Project ID of MYL-2019-42065. Tested specimens were donated from Borusan Mannesmann. Technical assistance of staff in Construction Materials Laboratory of ITU is sincerely appreciated. However, any opinions, findings, conclusions, and recommendations presented in this paper are those of the authors and do not necessarily reflect the views of the sponsor and the people.

FundersFunder number
Istanbul Teknik ÜniversitesiMYL-2019-42065


    • Compression Behavior
    • Concrete-filled Double Skin Steel Tubes
    • Ductility
    • Polypropylene and Steel Fiber-Reinforced Concrete
    • Ultimate Strength


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