Behaviour of circular concrete-filled lean duplex stainless steel–carbon steel tubular short columns

• Published in: Engineering structures 2013-11, Vol.56, p.83-94
• Main Authors: Hassanein, M.F., Kharoob, O.F., Liang, Q.Q.
• Format: Article
• Language: English
• Subjects: Applied sciences; Building structure; Buildings. Public works; Carbon steels; Composite columns; Concrete-filled steel tubes; Concretes; Construction (buildings and works); Duplex stainless steels; Exact sciences and technology; Finite element method; Mathematical analysis; Mathematical models; Nonlinear analysis; Stainless steel; Stainless steels; Steel-concrete composite structure; Stresses. Safety; Structural analysis. Stresses; Tubes
• ISSN: 0141-0296; 1873-7323
• DOI: 10.1016/j.engstruct.2013.04.016

•A finite element model for CFSCT short columns under axial loading is presented.•A new accurate constitutive model for concrete confined by two tubes is proposed.•The verified finite element model is used to study the behaviour of CFSCT columns.•The proposed design model is shown to predict well the strengths of CFSCT columns. Recently, a concrete-filled austenitic stainless steel–carbon steel tubular column has been introduced as a new form of composite members. This column is composed of an external stainless steel tube and an internal concentrically placed carbon steel tube with concrete filling in the whole tubular section. However, the excellent performance of such composite columns can additionally be achieved by utilising the low-cost lean duplex stainless steel material. In this paper, the behaviour of circular concrete-filled lean duplex stainless steel–carbon steel tubular (CFSCT) short columns under axial loading is investigated by using the general purpose finite element analysis program ABAQUS. A new constitutive model for the concrete core confined by both the external stainless steel tube and the internal carbon steel tube is proposed and incorporated in the finite element model developed. The accurate two-stage stress–strain relationships are employed to model cold-formed lean duplex stainless steels. The finite element results obtained by the proposed concrete model are shown to be in good agreement with test results. Parametric studies are then conducted to investigate the effects of concrete compressive strength, carbon steel yield stress and cross-section geometry on the behaviour of CFSCT columns. The ACI code is found to significantly underestimate the ultimate axial strengths of CFSST columns. Therefore, a new design model is proposed for CFSCT short columns. It is shown that the proposed design model provides excellent predictions of the ultimate axial strengths of circular CFSCT columns over a wide range of diameter-to-thickness ratios of the stainless steel tubes.