Design Of Stainless Steel Rhs Beams Columns And Beam Columns

Author : Itsaso Arrayago Luquin
Publisher :
ISBN 13 :
Total Pages : 225 pages
Book Rating : 4.:/5 (112 download)

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Download or read book New Approach for Efficient Design of Stainless Steel RHS and SHS Elements written by Itsaso Arrayago Luquin and published by . This book was released on 2016 with total page 225 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis investigates the cross-section and member behaviour of cold-formed stainless steel RHS and SHS elements and proposes an alternative and more efficient design approach. Combined with aesthetic appeal, exceptional mechanical properties and excellent corrosion and fire resistances, efficient design methods present stainless steel as an attractive alternative to the usual carbon steel for structural applications. Exhaustive studies of the nonlinear stress-strain behaviour and the analytical modelling of the response are presented for different stainless steel alloys. The study was based on 600 experimental stress-strain curves obtained from the literature and complemented with 42 tensile coupon tests. Although the material model currently included in Annex C of EN1993-1-4 (2006) was found to accurately represent the measured stress-strain curves for the different stainless steel grades and material types, revised equations were proposed for the strain hardening parameters n and m and for the ultimate tensile stress and strain for ferritics. A comprehensive experimental programme on five cross-sections of ferritic stainless steel grade 1.4003 tubular elements is also described. The actual geometry and initial geometric imperfections were carefully measured and the material response of flat and corner regions of each section were characterized by conducting 20 tensile tests on coupons extracted from the cross-sections. The cross-sectional behaviour was investigated through 10 stub column tests under pure compression and 16 subjected to combined loading conditions, while 8 beams were tested under four-point bending configuration and 4 subjected to three-point bending loading conditions. At member level, the bending moment redistribution capacity of ferritic continuous beams was investigated by conducting 9 five-point bending tests. Finally, 12 tests were conducted on ferritic stainless steel columns to determine the behaviour of members subjected to concentric and eccentric compression loads. Additional data on austenitic, ferritic and duplex stainless steel elements was generated from parametric studies based on finite element models validated from the conducted experiments. The assessment of the codified design expressions was derived by comparing experimental and numerical strengths with the calculated resistance predictions for stainless steel cross-sections and members subjected to different loading conditions. Results demonstrated that predictions are noticeably conservative for stocky and slender cross-sections since enhanced material properties are not considered and the susceptibility of cross-sections to local buckling is underestimated. Thus, a full slenderness range Direct Strength Method (DSM) approach was proposed for stainless steel RHS and SHS cross-sections and members based on the same strength curve for all loading conditions. The proposed approach was found to be more accurate for cross-sections, columns and beam-columns since strain hardening effects are incorporated and due to the fact that the actual stress distribution of the cross-section is considered when determining the slenderness. The reliability of the approach was demonstrated by statistical analyses, enabling its use in structural design standards. Finally, the applicability of design approaches based on plastic analysis to stainless steel continuous beams was assessed. The analysis of continuous beam strengths demonstrated that capacity predictions based on the first hinge formation result in a considerable overconservatism and that traditional plastic design can be safely applied with the Class 1 cross-section limit provided in EN1993-1-4 (2006). However, it was also statistically demonstrated that the best capacity predictions are obtained for design methods including both bending moment redistribution and strain hardening effects, such as the Continuous Strength Method for indeterminate structures or the proposed DSM-based approach.