a b s t r a c tCross-section classification is an important concept in the design of metallic structures, as it addresses the susceptibility of a cross-section to local buckling and defines its appropriate design resistance. For structural stainless steel, test data on cross-section capacity have previously been relatively scarce. Existing design guidance has been developed based on the limited experimental results and conservative assumptions, generally leading to unduly strict slenderness limits. In recent years, available test data for stainless steel cross-sections have increased significantly, enabling these slenderness limits to be re-assessed. In this paper all available stainless steel test data have been collected and additional moment-rotation curves have been presented. The study covers both cold-formed and welded plated elements as well as CHS. Following analysis of the test results, new slenderness limits for all loading conditions have been proposed and statistically validated. In addition to re-assessment of the current slenderness limits, a new approach to the treatment of local buckling in structural elements -the Continuous Strength Method -has been outlined. The Continuous Strength Method (CSM) is based on a continuous relationship between cross-section slenderness and deformation capacity and is applied in conjunction with accurate material modelling. The method enables more rational and precise prediction of local buckling than can be achieved with the traditional cross-section classification approach, thus allowing better utilization of material and more economic design.

High strength steels, considered in the context of the structural Eurocodes, as steels with a yield strength over 460 MPa, are gaining increasing attention from structural engineers and researchers owing to their potential to enable lighter and more economic structures. This paper focuses on the bending strength of hot-finished high strength steel (HSS) square and rectangular hollow sections; the results of detailed experimental and numerical studies are presented and structural design rules for HSS cross-sections are proposed. A total of 22 in-plane bending tests, in three-point bending and four-point bending configurations, on HSS sections in grades S460 and S690 were conducted.The experimental results were replicated by means of non-linear finite element modelling. Upon validation of the finite element models, parametric studies were performed to assess the structural response of HSS sections over a wider range of cross-section slenderness, cross-section aspect ratio and moment gradient. The experimental results combined with the obtained numerical results were used to assess the suitability of the current European (EN 1993-1-1 and EN 1993-1-12) cross-section classification limits for HSS structural components. The reliability of the proposed cross-section classification limits was verified by means of the EN 1990 -Annex D method.

Stainless steels are employed in a wide range of structural applications. The austenitic grades, particularly EN 1.4301 and EN 1.4401 and their low-carbon variants EN 1.4307 and EN 1.4404 are the most commonly used within construction and these typically contain around 8-11% nickel. The nickel represents a large portion of the total material cost and thus high nickel prices and price volatility have a strong bearing on both the cost and price stability of stainless steel. While austenitic stainless steel remains the most favourable material choice in many applications, greater emphasis is now being placed on the development of alternative grades with lower nickel content. In this study, the material behaviour and compressive structural response of a lean duplex stainless steel (EN 1.4162), which contains approximately 1.5% nickel are examined. A total of eight stub column tests and twelve long column tests on lean duplex stainless steel square (SHS) and rectangular hollow sections (RHS) are reported.Precise measurements of material and geometric properties of the test specimens were also made, including the assessment of local and global geometric imperfections. The experimental studies were supplemented by finite element analysis and parametric studies were performed to generate results over a wider range of cross-sectional and member slenderness. Both the experimental and numerical results were used to assess the applicability of the Eurocode 3: Part 1-4 provisions regarding the Class 3 slenderness limit and effective width formula for internal elements in compression and the column buckling curve for hollow sections to lean duplex structural components. Comparisons between the structural performance of lean duplex stainless steel and that of other more commonly used stainless steel grades are also presented, showing lean duplex to be an attractive choice for structural applications.

a b s t r a c tCold-formed stainless steel oval hollow sections (OHS) offer the combined aesthetic appeal of circular hollow sections and stainless steel, together with the structural efficiency associated with cross-sections of differing geometric properties about their two principal axes. To date, no structural design guidance exists for these cross-sections, principally due to their relatively recent introduction and a lack of fundamental structural test data. This paper examines the structural response of stainless steel OHS compression members and presents design recommendations. A series of laboratory tests was carried out to generate fundamental structural performance data. Tensile coupon tests were initially performed to establish the basic material stress-strain characteristics of the sections. These were followed by stub column tests to determine the average compressive response of the cross-sections and flexural buckling tests to obtain ultimate load carrying capacity data for use in the determination of a suitable buckling curve for stainless steel OHS. Measurements of the geometric properties of the test specimens including initial imperfections were carried out. The full load-displacement responses of the specimens were recorded and have been presented herein. A finite element (FE) modelling programme was performed in parallel with the experimental study. Once the FE models had been validated against the test results, parametric studies were carried out to further investigate the influence of individual key parameters, including the aspect ratio and local slenderness of the cross-sections as well as the member slenderness. Based on the obtained experimental and numerical results, a class 3 limit for stainless steel OHS in compression and a suitable buckling curve for OHS columns have been proposed.

Laser-welding is a high precision fabrication process suitable for joining a wide range of steels and stainless steels. Laser-welded structural stainless steel members, for which there are currently little experimental data owing to their recent introduction to the construction industry, are the focus of the present study. To address the lack of test data and to investigate their structural response, a total of 9 stub column tests and 22 flexural buckling tests (14 buckling about the minor axis and 8 about the major axis) have been performed on laserwelded austenitic stainless steel I-section members. Complementary tensile coupon tests, initial geometric imperfection measurements, and residual stress measurements have also been carried out and are reported herein. Based on the results obtained, a representative residual stress pattern is proposed, the design provisions of Eurocode 3 Part 1.4 and the continuous strength method are assessed, and column buckling curves for laser-welded stainless steel I-section members are recommended. Gardner, L., Bu, Y. and Theofanous, M. (2016). Laser-welded stainless steel I-sections: residual stress measurements and column buckling tests. Engineering Structures. 127, 536-548. 2