What is it about?
The demand for lightweight materials in construction has become very popular due to its flexibility and economical importance. Cold-formed steel beams and columns are used for provision of lightweight, durable and cost-efficient structures, and its usage also helps to optimize the construction time. Cold-formed steel section exhibits post-buckling strength, in which hot rolled section is deficient. However, more theoretical background on design and behavior of cold form section is still required, especially when it is subjected to axial loading. Thus, this paper presents numerical and theoretical behavior of pin -jointed cold-formed steel (CFS) column section (built-up battened Lip channel) under axial loading. The numerical modeling was done by using ABAQUS 6.10 software. Based on American Iron and Steel Institute (AISI) specifications, two types of sections were selected for single lipped channel, and it was ensured that the selected chord spacing permits both moment of inertia about the major axis and minor axis are equal. The numerical and theoretical study were done using a varying batten number and section slenderness ratio. The ultimate loads were obtained under the two approaches, for the lipped channel built-up columns, and were compared for the effective section proposed. From the results, the prediction of buckling mode and the failure load of the column were found to be stable and approximately relevant to the FEM results from slenderness ratio ranging from 20 to 60. Also, flexural buckling of all column sections occurred about the axis parallel to the webs, where there is an opportunity for composite action.
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Why is it important?
The need for provision of lightweight steel structural member in construction has been on the increase in recent years, owing to its versatility and cost-effectiveness. Lightweight sections are mostly produced using cold-formed steel members, which in most cases, can be produced in a wide variety of section profiles. The most common cold formed section is the “C” channels, and for minor applications is the “Z” type sections. There are also plain sections, which are used as a secondary member, for ordinary flange sections or flange section with stiffeners. Such sections with effective cross-section area, and stiffened is known to have good ability to resist local, distortion and overall buckling [1]. Depending on construction need, it is also possible to vary the aspect ratio (profile) of a cold-formed member, especially during manufacturing by changing the cross-sectional dimensions. The cold-formed steel can be framed into members subjected to loading, and this case, both the structural strength and stiffeners are fully considered during design
Perspectives
The precision of the existing design standards; (AS/NZS), North American Specification (NAS) and direct strength method (DSM) has become a main concern to researchers. However, with the application of Finite Element Analysis (FEA) in cold-formed structures, it has aided finding solutions to parametric study of cross-section geometries. Despite the difficulty involved in the investigation of the effects of geometric imperfections and residual stresses of structural members experimentally, the FEA modeling has somewhat provided solutions to the problems. Its only limitation is when model is inaccurate, which makes the obtained solution to be unreliable.
Prof Gobinath R
S R Engineering College
Read the Original
This page is a summary of: Numerical simulation and specification provisions for buckling characteristics of a built-up steel column section subjected to axial loading, Engineering Structures, March 2020, Elsevier,
DOI: 10.1016/j.engstruct.2020.110256.
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