Experiments on cold-formed ferritic stainless steel slender sections

Abstract

The usage of stainless steel in construction has been increasing owing to its corrosion resistance, aesthetic appearance and favourable mechanical properties. The most common stainless steel grades used for structural applications are austenitic steels. The main drawback of these grades relies on their nickel content (around 8-10%), resulting in a relatively high initial material cost. Other stainless steel grades with lower nickel content such as the ferritic steels offer the benefits of stainless steels in terms of functional qualities and design but within a limited cost frame. Hence, ferritic stainless steels may be a viable alternative for structural applications. Given the fact that little experimental information on ferritic stainless steels is currently available, the purpose of this investigation is to report a series of material and cross-section tests on ferritic grade EN 1.4003 (similar to 3Cr12) stainless steel square and rectangular hollow sections to enable a better understanding of their material response and structural performance. Four different cross-section geometries have been tested under pure compression and in-plane bending. Measurements of geometric imperfections and material properties are also presented. The obtained test results are used to assess the adequacy of the slenderness limits and effective width formula given in EN 1993-1-4 to ferritic stainless steels, those proposed by Gardner and Theofanous and Zhou et al. design approach.Highlights  Experimental study of ferritic stainless steel stub columns and beams  Local buckling of cross-sections with different aspect ratios  Applicability of various design methods for cross-section design to ferritic stainless steel  Design recommendations Keywords Effective width, element interaction, experiments, ferritic stainless steel, slenderness limits, local buckling IntroductionThe chromium present within the internal crystalline structure of stainless steels forms a selfhealing passivation layer of chromium oxide (Cr 2 O 3 ) when exposed to oxygen preventing surface corrosion. Other alloying elements are added to meet specific needs in terms of strength, corrosion resistance and ease of fabrication. Depending on their chemical composition, stainless steels can be classified into main five categories: ferritic, austenitic, martensitic, duplex and precipitation hardening. The most commonly used materials in construction are the austenitic grades which have reasonable mechanical strength with 0.2% proof stress of 210-240 N/mm 2 and display high ductility with ultimate strains ε u laying between 50 and 60%. These positive features, however, may be inhibited by the high initial material cost and considerable price fluctuations associated with the amount of nickel involved in austenitic stainless steels (8-11%). Ferritic stainless steels, on the other hand, contain little nickel leaving chromium as the main alloying element (min. 10.5%); hence, they are price stable and cheaper alloys. In comparison with the austenitic grades, the i...

Experimental Study on Ferritic Stainless Steel RHS and SHS Cross-sectional Resistance Under Combined Loading

“…Since slenderness values obtained for the tested specimens are far from the Class 3 limit c/t<37, the trend line of the experimental results has also been presented. Figure 9 confirms that both considered classifications provide safe Class 3 predictions, although the revised limit presented by [18] seems to be more accurate for ferritic stainless steel RHS and SHS, as highlighted before by [12,13,19]. …”

“…S5-F S1-F S1-C S5-C In order to correctly analyse the experimental results, several authors [11,12,13] define some weighted average material properties which consider the effect of the cold-forming processes and include both flat and corner mechanical properties. The calculation of these weighted average properties is simple, and consists of assigning the corresponding value of the material parameter to be calculated to the part of the cross-section considered, weighting it according to its area referred to the total area of the cross-section.…”

Experimental study on ferritic stainless steel simply supported and continuous beams

“…All the tests were conducted in the Laboratori de Tecnologia d'Estructures Luis Agulló, in the Department of Construction Engineering at Universitat Politècnica de Catalunya. This experimental programme was developed together with additional compression tests and simply supported bending tests on slender ferritic stainless steel RHS and SHS, reported in Bock et al [6] and complements this study on the flexural behavior of ferritic elements with stockier cross-sections. The specimens were made from grade EN1.4003 ferritic stainless steel and were cold-rolled and seam welded.…”

“…The specimens were made from grade EN1.4003 ferritic stainless steel and were cold-rolled and seam welded. The chemical composition and tensile properties of the original coil material provided by the manufacturer in the mill certificates have already been reported in [6].…”

Effective width equations accounting for element interaction for cold-formed stainless steel square and rectangular hollow sections

“…The structural applications of this latter type of stainless steel have been recently investigated within a European Project framework and comprehensive design guidance for construction applications has been developed [11]. For the local buckling proposed design provisions, which were firstly based on numerical analyses [12,13], experimental research [14] was undertaken to provide further verification and is presented hereafter.…”