On the gradient of the yield plateau in structural carbon steels

Title: On the gradient of the yield plateau in structural carbon steels
Authors: Sadowski, AJ
Rotter, JM
Stafford, PJ
Reinke, T
Ummenhofer, T
Item Type: Journal Article
Abstract: New design methodologies are being developed to allow stocky steel members to attain and exceed the full plastic condition. For theoretical validation, such methods require a characterisation of the uniaxial stress-strain behaviour of structural steel beyond an idealised elastic-plastic representation. However, the strain hardening properties of carbon steels are not currently guaranteed by the standards or by any steel manufacturer. Assumptions must thus be made on what values of these properties are appropriate, often based on limited information in the form of individual stress-strain curves. There is very little consistency in the choices made. This paper first illustrates, using an example elastic-plastic finite element calculation, that a stocky tubular structure can attain the full plastic condition at slendernesses comparable with those defined in current standards and supported by experiment when using only a very modest level of strain hardening, initiated at first yield. It is then hypothesised that the yield plateau in the stress-strain curve for structural carbon steels, classically treated as flat and with zero tangent modulus, actually has a small but statistically significant positive finite gradient. Finally, a robust set of linear regression analyses of yield plateau gradients extracted from 225 tensile tests appears to support this hypothesis, finding that the plateau gradient is of the order of 0.3% of the initial elastic modulus, consistent with what the finite element example suggests is sufficient to reproduce the full plastic condition at experimentally-supported slendernesses.
Issue Date: 18-Dec-2016
Date of Acceptance: 26-Nov-2016
URI: http://hdl.handle.net/10044/1/42737
DOI: https://dx.doi.org/10.1016/j.jcsr.2016.11.024
ISSN: 0143-974X
Publisher: Elsevier
Start Page: 120
End Page: 130
Journal / Book Title: Journal of Constructional Steel Research
Volume: 130
Copyright Statement: /©2016The Authors. Published by Elsevier Ltd.Thisisan open access article under theCC BYlicense (http://creativecommons.org/licenses/by/4.0/).
Sponsor/Funder: Engineering and Physical Sciences Research Council
Funder's Grant Number: EP/N024060/1
Keywords: Civil Engineering
0905 Civil Engineering
Publication Status: Published
Appears in Collections:Faculty of Engineering
Civil and Environmental Engineering



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