Resistance of cold-formed built-up stainless steel columns – Part II: Numerical simulation Jelena Dobrić a, ⁎, Marko Pavlović b , Zlatko Marković a , Dragan Buđevac a , Milan Spremić a a University of Belgrade, Faculty of Civil Engineering, B. k. Aleksandra 73, 11000 Belgrade, Serbia b Delft University of Technology, Faculty of Civil Engineering and Geosciences, Stevinweg 1, 2628, CD, Delft, The Netherlands abstract article info Article history: Received 21 May 2017 Received in revised form 21 October 2017 Accepted 23 October 2017 Available online xxxx In parallel with an experimental investigation of the flexural buckling behaviour of built-up stainless steel columns presented in the accompanying paper (Dobrić et al., submitted for publication), a detailed Finite Element Analysis (FEA) has been performed to simulate the experiment and identify the key factors affecting the buckling response. The FEA entailed realistic geometry, measured geometric imperfections and material properties of the specimens. Very good agreement was obtained between the experiment and FEA, which proved the capability of the computational approach to replicate experimental results and predict ultimate buckling loads. In the absence of explicit design rules for flexural buckling resistance of stainless steel closely spaced built-up members, the experimental results were compared with design predictions according to the existing European Standard and American Specification for carbon steel structures. The findings indicate that the mentioned design standards may be very conservative regarding the buckling resistance of stainless steel built-up members; this under-prediction may be associated with the impact assessment of chord slenderness and interconnection stiffness on the buckling response. The main purpose of this research is to establish a qualitative data base reliable for the further quantitative numerical parameter analysis and for the development of new design rules for compressed stainless steel cold-formed built-up members. © 2017 Elsevier Ltd. All rights reserved. Keywords: Stainless steel Built-up member Flexural buckling Finite element analysis Design resistance 1. Introduction The cost of structural stainless steel elements is increasingly impor- tant in a competitive construction market. Closely spaced built-up members may provide relatively light structures which have very good overall performance under compression loads. This type of struc- tural element is often made from two parallel individual chord mem- bers discontinuously interconnected by bolts or welds. The chord members are usually channels or angles which may be in direct contact or closely spaced and interconnected through packing plates. The most popular structural configuration is to arrange the chords back-to-back, essentially forming an open section. The proper position of individual chords within the built-up section is strongly associated with the mag- nitude of the cross-section's second moment of area and consequently with the beneficial structural effectiveness of various compressed elements. The main goal of the research presented in this and an accom- panying paper [1] is to improve the competitiveness of stainless steel members in civil structural applications. The research is intended to cover an experimental and numerical work with the aim of acquiring further knowledge that will facilitate the development of design rules for closely spaced built-up stainless steel columns. The investigation was concentrated on the most commonly used austenitic stainless steel grade EN 1.4301 (X5CrNi18-10). The research activities focused on pin-ended centrically compressed built-up members formed from two press-braked channel chords, directly interconnected and oriented back-to-back. The sizes of the built-up sections were selected so that the tested columns had a semi-compact ultimate response, in order to avoid the reduction of compressive member capacity by elastic local buckling. Discontinuous welds between the individual chord members were investigated in order to reduce the cost and minimize the sections' distortions usually caused by continuous welding in the production process. In addition, the behaviour of the welded built-up columns is compared with the columns having individual chords discontinuously connected by means of bolts at the webs. The series of flexural buckling tests of closely spaced built-up stainless steel columns about their minor structural axis were performed and presented in [1]. This paper focuses on the numerical procedures employed for the simulation of the structural responses of the built-up specimens used in the experiment [1]. A quasi-static analysis was made with the Abaqus software package [2] employing its explicit dynamic solver, which is suitable for simulating the quasi-static buckling response by properly using the mass-scaling technique. The devel- oped Finite Element (FE) models were calibrated and validated by Journal of Constructional Steel Research 140 (2018) 247–260 ⁎ Corresponding author. E-mail addresses: jelena@imk.grf.bg.ac.rs (J. Dobrić), m.pavlovic@tudelft.nl (M. Pavlović), zlatko@imk.grf.bg.ac.rs (Z. Marković), budjevac@grf.bg.ac.rs (D. Buđevac), spremic@imk.grf.bg.ac.rs (M. Spremić). https://doi.org/10.1016/j.jcsr.2017.10.032 0143-974X/© 2017 Elsevier Ltd. All rights reserved. Contents lists available at ScienceDirect Journal of Constructional Steel Research