Cold-formed steel battened built-up columns: Experimental behaviour and verification of different design rules developed

Abstract

Some of the past studies on cold-formed steel (CFS) battened built-up columns have resulted in the development of new design rules for predicting their axial strengths. However, the main drawbacks of such studies are that they are purely numerical and the numerical models developed for such parametric studies were validated using the test results on similar built-up column configurations, but not the exact ones. Therefore, experimental studies on CFS battened columns comprising of lipped channels are needed for verifying the accuracy of the proposed design rules for CFS battened columns. This paper reports an experimental study performed on CFS built-up battened columns under axial compression. Adequately spaced identical lipped channels in the back-to-back arrangement were used as chords and were connected by batten plates laterally with self-driving screws to form the built-up members. The dimensions of chords were fixed as per the geometric limits given out in the North American Specifications (NAS) for the design of CFS structural members. The sectional compactness of the chords and the overall slenderness of the built-up columns were varied by altering the thickness of the channels and height of the built-up columns, respectively. A total of 20 built-up sections were tested under uniform compression to investigate the behavioural changes in the built-up columns due to these variations. The behaviour assessment was made in terms of peak strengths, load–displacement response and failure modes of the test specimens. The current design standards on CFS structures were used to determine the design strengths and were compared against the test strengths for assessing their adequacy. Furthermore, as discussed in the beginning, the test strengths were used to verify the accuracy of the different relevant proposed design rules in the literature.

Normal stress distribution in built-up cold-formed column in relation to interconnecting bolt spacing

“…Authors inform that codes accurately predicted local buckling modes but procedures are less precise in the field of global buckling behaviour. Similar tests described in 12 indicate Eurocode as a more precise code in the case of built-up column behaviour. Authors of 13 presented a parametric study and improved design guidelines for CFS battened built-up columns.…”

Normal stress distribution in built-up cold-formed column in relation to interconnecting bolt spacing

“…Authors inform that codes accurately predicted local buckling modes but procedures are less precise in the eld of global buckling behaviour. Similar tests described in [12] indicate Eurocode as a more precise code in the case of built-up column behaviour. Authors of [13] presented a parametric study and improved design guidelines for CFS battened built-up columns.…”

Structural behaviour of built‐up battened cold‐formed steel columns

“…Previous research studies [18] recommend L/1000 for global imperfections and t (thickness of the profile) for local imperfections; however, EN 1993-1-1 [3] recommends L/500 for battened columns (clause 6.4.3). In Figure 6, the experimental results and the obtained numerical results are compared for CFS battened columns comprising both C [16] and ∑-shaped individual profiles. A very good agreement was observed between experimental and numerical results enabling additional parametric studies.…”

“…Based on the available experimental results and other research studies available in the literature [16], advanced finite element models were developed to accurately reproduce the observed structural behaviour of battened CFS columns comprising both C [16] and ∑-shaped individual profiles.…”