Issue 72

A. J. Patel et alii, Fracture and Structural Integrity, 72 (2025) 1-14 DOI: 10.3221/IGF-ESIS.72.01

Axial behaviour of Concrete Filled Double Skinned Steel Tubular (CFDST) column with concrete imperfections

Arth J. Patel, Sharadkumar P. Purohit Civil Engineering Department, Institute of Technology, Nirma University, Gujarat, India arth.patel@nirmauni.ac.in, http://orcid.org/0000-0003-2633-399X sharad.purohit@nirmauni.ac.in, http://orcid.org/0000-0002-2678-4320

Citation: Patel, A. J., Purohit S. P., Axial behaviour of Concrete Filled Double Skinned Steel Tubular (CFDST) column with concrete imperfections, Fracture and Structural Integrity, 72 (2025) 1-14.

Received: 28.08.2024 Accepted: 13.12.2024 Published: 07.01.2025 Issue: 04.2025

Copyright: © 2025 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

K EYWORDS . Axial loading, Concrete imperfection, Confinement effect, Failure modes, Steel-concrete composite column.

I NTRODUCTION

T

he Concrete Filled Double Skinned Steel Tubular (CFDST) composite columns are being widely adopted in high rise buildings, bridges, and elevated corridors and are extensively being investigated under axial-flexural and torsional loading owing to their excellent load-carrying capacity, enhanced global stability, better strength to weight ( ⁄ ) ratio, superior ductility and convenience in construction [1–3]. Since two types of materials, Hollow Steel Tubes (HSTs) and concrete, are used to fabricate CFDST composite members, it is expected that there may be imperfections potentially originating from both the steel tube and sandwiched concrete commonly known as steel imperfection and concrete imperfection. Concrete imperfection is considered to be a serious issue as compared to steel imperfections as later being manufactured in controlled environments in industries. Concrete imperfection manifests due to improper construction practices, temperature gradient, shrinkage, creep, etc, and can be realized as gap defect as featured in Concrete Filled Steel Tube (CFST) members of arch bridges in China [4]. In the last two decades, most research studies reported in literature comprised experimental and/or numerical investigations on perfect (non-defective) CFDST composite columns under a variety of loadings [5–8]. However, gap defects may lead to very serious issues on the safety of composite columns owing to incorrect prediction of the ultimate load-carrying capacity

1