The objective of this paper is to provide an overview of computational modeling, both elastic buckling and nonlinear collapse analysis, for cold-formed steel members. Recent research and experiences with computational modeling of cold-formed steel members conducted within the first author's research group at Johns Hopkins University are the focus of the presented work. This admittedly biased view of computational modeling focuses primarily on the use of the semi-analytical finite strip method and collapse modeling using shell finite elements. Issues addressed include how to fully compare finite strip and finite element solutions, and the importance of imperfections, residual stresses, material modeling, boundary conditions, element choice, element discretization, and solution controls in collapse modeling of cold-formed steel. Examples are provided to demonstrate the expected range of sensitivity in cold-formed steel collapse modeling. The paper concludes with a discussion of areas worthy of future study that are within the domain of cold-formed steel modeling.

Computational modeling of cold-formed steel

The objective of this paper is to provide a brief review of recent (over approximately the last five years) advances in the application, analysis and design of cold-formed steel structures. Attention here is focused on load-bearing cold-formed steel structures; as opposed to secondary systems, curtain walls, etc. Cold-formed steel applications continue to advance in three primary categories: framing, metal buildings, and racks. Examples largely derived from the author’s experiences in North America are used to illustrate the applications. The behaviour of cold-formed steel structures can be complicated due to the thin-walled nature of the sections; thus, analysis advances are required. Recent work in Generalized Beam Theory and the constrained Finite Strip Method demonstrate that, at least when it comes to thin-walled members, significant advances in structural analysis are still possible and desirable. Design of cold-formed steel structures continues to see significant improvements and refinements. Recent efforts related to the Direct Strength Method of design are highlighted, including novel extensions from the member to the system level. Finally, similar to many other areas of structural engineering, seismic engineering has motivated notable advances in applications, analysis, and design. For cold-formed steel structures these advances are reviewed to demonstrate current progress and future directions in this important area.

Cold‐formed steel structures around the world

A research study on the structural behaviour of cold formed steel beams with C-, I-, R- and 2R-shaped cross-sections at ambient temperature is presented, based on the results of a large programme of experimental tests and numerical simulations. Firstly, several four-point bending tests were carried out in order to assess mainly the failure loads and failure modes of the beams. Secondly, a suitable finite element model was developed to compare with the experimental results, and finally, a parametric study was undertaken in order to investigate the influence of the thickness, height and length of the beams on its structural behaviour.

Experimental and numerical analysis on the structural behaviour of cold-formed steel beams

Non-linear behaviour and load-carrying capacity of CFRP-strengthened lipped channel steel columns

Post-buckling behaviour and direct strength design of lipped channel columns experiencing local/distortional interaction

FEM-based analysis of the local-plate/distortional mode interaction in cold-formed steel lipped channel columns

https://estudogeral.sib.uc.pt/bitstream/10316/3956/1/filec270a2dcb98f4865b37c82ddf88a27ca.pdf

Lateral-torsional buckling of singly symmetric web-tapered thin-walled I-beams: 1D model vs. shell FEA

This paper reports a numerical investigation concerning the post-buckling behaviour of cold-formed steel lipped channel beams, subjected to uniform major axis bending, affected by local/distortional mode interaction – the results presented and discussed were obtained through shell finite element analyses performed using the code Abaqus . One analyses simply supported beams (locally/globally pinned and free to warp end sections) (i) with cross-section dimensions ensuring coincident local and distortional critical buckling moments and (ii) having critical-mode initial geometrical imperfections with different shapes and the same overall amplitude – local buckling is triggered either by the compressed flange (most common case) or by the web. The results reported consist of (i) elastic and elastic–plastic post-buckling equilibrium paths, (ii) curves and figures showing how the beam deformed configuration evolves along those paths and, for the elastic–plastic beams, (iii) figures making it possible to visualise (iii1) the location and growth of plastic strains and (iii2) the nature of the failure mechanisms detected.

P. Borges Dinis

Papers

FEM-based analysis of the local-plate/distortional mode interaction in cold-formed steel lipped channel columns

Lateral-torsional buckling of singly symmetric web-tapered thin-walled I-beams: 1D model vs. shell FEA

Local/distortional mode interaction in cold-formed steel lipped channel beams