Cold-formed Stainless Steel Columns Research Articles

Buckling Curves for Cold-Formed Stainless-Steel Columns and Beams

AbstractThis paper summarizes the background information and methodology used to derive a set of buckling curves proposed for cold-formed stainless steel columns and beams incorporated in the recen...

Design procedures for cold-formed stainless steel equal-leg angle columns

Currently, there is still no explicit design approach for cold-formed stainless steel columns with equal-leg angle sections in Europe. A comprehensive numerical investigation, validated by the available experiments collected in the literature, has therefore been undertaken to provide benchmark data for the assessment of design procedures for cold-formed stainless steel angle columns currently adopted in European and Australian codes. Minor-axis flexural buckling, as well as flexural-torsional buckling have been considered. In total, 27 different cross-section sizes covering both slender and non-slender sections, and a wide range of column slenderness values have been examined including austenitic, duplex and ferritic grades. On the basis of the experimental and numerical results, new design recommendations for cold-formed stainless steel equal-leg angle columns have been made per family of stainless steel. The suitability of the proposals was confirmed by means of a reliability analysis.

Flexural buckling behaviour and design of duplex and ferritic stainless steel I-section columns

In this paper, the flexural buckling behaviour and design of duplex and ferritic stainless steel I-section columns fabricated through the welding of individual hot-rolled stainless steel plates are investigated. Finite element models able to mimic the structural response of stainless steel I-section columns are developed and validated against experimental results from the literature. Employing the validated finite element models, extensive numerical parametric studies are performed for the purpose of comprehensively assessing the behaviour of duplex and ferritic stainless steel I-section columns, considering various member slendernesses and cross-section proportions. The accuracy, safety and applicability of the existing column design provisions provided in the European, North American and Australian & New Zellandian structural stainless steel design standards and guides, some of which are only recommended for the design of cold-formed stainless steel columns, are assessed for the design of welded duplex and ferritic stainless steel I-section columns. Modifications to the column design method given in the current European structural stainless steel design standard EN 1993-1-4 are proposed. The higher accuracy of the modified column design method of EN 1993-1-4 relative to the column design methods in the existing structural stainless steel design standards and guides is illustrated in addition to its safety and high level of reliability.

Design of cold-rolled stainless steel rectangular hollow section columns

Considering the effects of cold-forming and strain hardening in the design of cold-formed stainless steel columns is an effective way to reduce construction costs. This approach has become a common trend in the revision of relevant design codes. A few studies were conducted in the past on two key aspects: (i) predicting the enhanced material properties in cold-formed stainless steel cross-sections and (ii) modifying the design methods to adapt to stainless steel material characteristics. However, in the existing literature, they had been separately studied, and integration of these two aspects to form a complete design method was rarely reported. In this study, a series of column tests were conducted on 19 stub and 32 long columns in rectangular hollow sections. The measured imperfections, material properties, load-displacement curves, and failure modes were reported. A new design method for columns was developed, which could clearly and accurately determine the column capacity over the space encompassed by member slenderness and cross-sectional slenderness values. The proposed design method and the method laid out in the Design Manual for Structural Stainless Steel were evaluated against the test data. It was demonstrated that the two design methods were both very conservative in predicting the column capacity when material properties in the annealed condition were used. However, their performances improved when the predicted enhanced material properties were used. Generally, the predictions of the proposed design method matched the test data better. Furthermore, a reliability analysis was conducted, and resistance factors were recommended for the corresponding design methods.

Simplified design approach for cold-formed stainless steel compression members subjected to flexural buckling

The design criteria of stainless steel compression member are more complicated than those of carbon steels due to the nonlinear stress strain behavior of the material. In general, the tangent modulus theory is used for the design of cold-formed stainless steel columns. The modified Ramberg–Osgood equation given in the ASCE Standard can be used to determine the tangent modulus at specified level of stresses. However, it is often tedious and time-consuming to determine the column buckling stress because several iterations are usually needed in the calculation. This paper presents new formulations to simplify the determination of flexural buckling stress without iterative process. Taylor series expansion theory is utilized in the study for numerical approximations. The proposed design formulas are presented herein and can be alternatively used to calculate the flexural buckling stress for austenitic type of cold-formed stainless steel columns. It is shown that the column strengths determined by using the proposed design formulas have good agreement with those calculated by using the ASCE Standard Specification. A design example is also included in the paper for cold-formed stainless steel column designed by using the ASCE Standard equations and the proposed design formulas.

Column curves for stainless steel alloys

The paper describes a column curve formulation capable of producing accurate strength curves for cold-formed stainless steel columns. The formulation uses a non-linear expression for the imperfection parameter but is otherwise identical to the Perry–Robertson equation used in Eurocode3, Parts 1.1, 1.3 and 1.4. It is shown that several column curves are necessary for accurately describing the strength of austenitic and austenitic–ferritic stainless steel alloy columns and two curves are proposed. One of these is close to the curve for cold-formed sections currently used in the draft Eurocode3, Part 1.4. A new column curve is also proposed for ferritic alloys and 12% chromium weldable structural steels.