Experimental and numerical study of axial behaviour of slender-waist shaped concrete-filled steel tubular stub columns

This paper presents an experimental and numerical study on large dimension concrete-filled square low steel ratio steel tubular (CFST) stub columns under axial loading. Four specimens were designed to investigate the effects of steel ratio on the confinement effect of square CFST stub columns with a low steel ratio. ABAQUS was used to establish 3D finite element (FE) models for simulation of square CFST stub columns with a low steel ratio under axial loading. Furthermore, based on the experimental verification, the definition of the confinement index (ϕ = fsAs/(fcAc)) was discussed and the effect of the grade of concrete and steel tube was also investigated. With the same cross-sectional dimensions, the confinement effect of the square CFST stub columns with a low steel ratio (less than 0.05) was better than the others. The stub columns with the yield strength of steel tube fs = 235 MPa (345, 420 MPa) and compressive cubic strength of concrete fcu = 40 MPa (60, 80 MPa) can give fully demonstrate the material performance and reflect the better confinement effect. Based on the experimental results and FE modeling, a practical calculation formula for the ultimate load-carrying capacity of square CFST stub columns with a low steel ratio was proposed. The formula calculation results presented in this paper show good agreement with the experimental results. Compared with the existing formulas, the proposed formula has better precision.

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Numerical study of concrete-filled austenitic stainless steel CHS stub columns with high-strength steel inner tubes

Proceedings 12th international conference on Advances in Steel-Concrete Composite Structures - ASCCS 2018 ◽

10.4995/asccs2018.2018.8273 ◽

2018 ◽

Author(s):

Fangying Wang ◽

Ben Young ◽

Leroy Gardner

Keyword(s):

Stainless Steel ◽

High Strength Steel ◽

Failure Modes ◽

Numerical Study ◽

High Strength ◽

Reduction Factor ◽

Fe Model ◽

Structural Behaviour ◽

Concrete Filled Tubes ◽

Stub Columns

A numerical modelling programme simulating the structural behaviour of concrete-filled double skin tubular (CFDST) stub columns with stainless steel outer tubes and high strength steel inner tubes is presented in this paper. The numerical model, which was developed using the finite element package ABAQUS, was initially validated against existing experimental results considering ultimate load, load-deflection histories and failure modes, with good agreement observed. Upon validation of the FE model, an extensive parametric study was undertaken whereby the cross-section slendernesses of the outer and inner tubes, the strength of the inner tube and the concrete grades were varied. These generated results together with the experimental data were then employed to assess the suitability of the design provisions of the European Standard EN 1994-1-1 and American Specification for concrete-filled tubes. Modifications to these design rules are also proposed, and a reduction factor (η) is suggested to account for the effective compressive strength in high strength concrete.

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