Improving the Direct Strength Method prediction of column flexural-torsional failure loads

Dinis, Pedro Borges; Camotim, Dinar; Landesmann, Alexandre; Martins, André Dias

doi:10.1016/j.tws.2019.106461

Cited by 15 publications

(37 citation statements)

References 10 publications

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“…As just mentioned, recent investigations [22,23] showed that the codified global strength curve underestimates, often by large amounts, the failure loads of columns with…”

Section: Articlementioning

confidence: 93%

“…Indeed, it exhibits very small scatter (0.04 standard deviation) and all the predictions are very accurate and either safe (mostly and never excessively) or a bit unsafe (1.11 ≥ P U /P nLG ≥ 0.91). This excellent performance stems from the fact that the currently codified DSM G strength curve performs quite differently for columns buckling in FT and F modes: always yields accurate failure load estimates in the latter case and may provide very significant failure load underestimations in the former case (particularly for slender C and H columns) [22,23]. iv) The LRFD resistance factors associated with the P U /P nLG ratios read [12] f = 0.99 (C columns -experimental and numerical), f = 0.94 (H columns), f = 0.99 (R columns) and f = 0.94 (Z columns) -they are all much larger than the value prescribed in [24] for compression members (f c = 0.85).…”

Section: Articlementioning

confidence: 99%

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Mode interaction in cold‐formed steel members: state‐of‐art report

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Extended keynote paper of Eurosteel 2021 This is Part 2 of a two‐part paper providing a state‐of‐art report of the most recent findings concerning the behaviour, strength and Direct Strength Method (DSM) design of cold‐formed steel (CFS) columns and beams affected by mode coupling phenomena not adequately covered by the current specifications for CFS members. This second paper covers interactions involving global buckling modes, namely local‐distortional‐global (L‐D‐G), distortional‐global (D‐G) and global‐global (flexural‐torsional/flexural – FT‐F) interaction – note that local‐global (L‐G) interaction, already well mastered by the technical/scientific community, is not dealt with. Like Part 1 [1], this paper also addresses experimental tests, numerical simulations and DSM‐based design approaches, intended to i) acquire in‐depth knowledge on the non‐linear behaviour (elastic and elastic‐plastic), load‐carrying capacity and failure mode nature of the members under consideration, and ii) make use of the above knowledge to develop, propose and assess the merits of efficient DSM‐based design approaches to estimate their failure loads/moments. Taking into account the fundamental concepts and DSM design curves presented in Part 1 [1], the paper addresses separately each mode coupling phenomenon dealt with, for columns, and only D‐G interaction for beams – recall that L‐D interaction (columns and beams) was covered in Part 1 [1]. For columns undergoing L‐D‐G interaction and angle columns susceptible to FT‐F interaction, the work reported includes experimental studies, numerical simulations and DSM‐based design considerations and/or guidelines. For columns and beams experiencing D‐G interaction and channel columns prone to FT‐F coupling, only numerical results are reported – they reveal surprising behavioural features that will be very useful in planning future test campaigns and achieving efficient design approaches. Finally, the two‐part paper closes with a few concluding remarks and a perspective about future developments in this field.

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“…As just mentioned, recent investigations [22,23] showed that the codified global strength curve underestimates, often by large amounts, the failure loads of columns with…”

Section: Articlementioning

confidence: 93%

Section: Articlementioning

confidence: 99%

Mode interaction in cold‐formed steel members: state‐of‐art report

et al. 2020

Self Cite

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“…This section briefly addresses the recent development and proposal of new DSM-based design curves to estimate the ultimate strength of i) uniformly bent simply supported beams failing in distortional modes, and ii) fixed-ended columns failing in FT modes. More details about the research work behind those proposals can be found in [10] and [26], respectively. Concerning beams failing in D modes, it was proposed to replace Eq.…”

Section: Recent Developmentsmentioning

confidence: 99%

“…where Figs. 7a-b plot the P u /P nG and P u /P nFT values reported in [26] against λ FT (= λ G ). It is clear that the set of proposed strength curves substantially outperforms Eq.…”

Section: Recent Developmentsmentioning

confidence: 99%

“…by a set of design curves dependent on the cross-section geometric parameter I I , I II and I w are the cross-section area, major and minor moments of inertia and warping constant, respectively. This DSM-based b FT -dependent strength curve set is expressed by U /M y vs. λ D plots for a) SCA, and b) SCB C, H, and Z beams, together with the current and proposed DSM distortional design curves Plots of a) P u /P nG vs. λ G , and b) P u /P nFT vs. λ FT for the numerical FT failure loads considered in[26] …”

mentioning

confidence: 99%

See 1 more Smart Citation

Mode interaction in cold‐formed steel members: state‐of‐art report

et al. 2020

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Extended keynote paper of Eurosteel 2021 This two‐part paper provides a state‐of‐art report on the most recent findings concerning the behaviour, strength and Direct Strength Method (DSM) design of cold‐formed steel (CFS) columns and beams affected by mode coupling phenomena not adequately covered by the current specifications for CFS members, namely local‐distortional (L‐D), local‐distortional‐global (L‐D‐G), distortional‐global (D‐G) and global‐global (flexural‐torsional/flexural – FT‐F) interaction. The paper addresses experimental tests, numerical simulations and DSM‐based design approaches that are intended to i) acquire in‐depth knowledge on the non‐linear behaviour (elastic and elastic‐plastic), load‐carrying capacity and failure mode nature of the members under consideration, and ii) make use of that knowledge to develop, propose and assess the merit of efficient DSM‐based design approaches to estimate their failure loads/moments. Initially, illustrative column results are briefly presented to help grasp some fundamental concepts, namely the characterisation of i) the aforementioned mode coupling phenomena, ii) different sources of mode interaction that may lead to failure load/moment erosion, and iii) the most detrimental initial geometrical imperfections. The DSM design curves currently codified and two strength curves recently developed for column flexural‐torsional and beam distortional failures are presented next. The two‐part paper then addresses separately each mode coupling phenomenon dealt with, for columns, but only L‐D and D‐G interaction for beams – while L‐D interaction (in columns and beams) appears in Part 1, the remaining column and beam coupling phenomena (all involving global buckling) are dealt with in Part 2 [1]. For columns undergoing L‐D and L‐D‐G interaction, beams experiencing L‐D interaction and angle columns susceptible to FT‐F interaction, the work reported includes experimental studies, numerical simulations and DSM‐based design considerations and/or guidelines. For the remaining coupling phenomena, only numerical results are reported, but they unveil interesting (and unexpected) behavioural features that will help plan future test campaigns and achieve efficient design approaches. Finally, the two‐part paper closes with a few concluding remarks and an outlook regarding future developments in this field.

show abstract

Mode Interaction in Cold‐Formed Steel Members: State‐of‐Art Report

et al. 2021

Self Cite

View full text Add to dashboard Cite

This work provides a state‐of‐art report on the most recent findings concerning the behaviour, strength and Direct Strength Method (DSM) design of cold‐formed steel (CFS) columns and beams affected by mode coupling phenomena not adequately covered by the current specifications for CFS members, namely local‐distortional (L‐D), local‐distortional‐global (L‐D‐G), distortional‐global (D‐G) and global‐global (flexural‐torsional/flexural ‐ FT‐F) interaction. The paper addresses experimental tests, numerical simulations and DSM‐based design approaches, intended to (i) acquire in‐depth knowledge on the non‐linear behaviour (elastic and elastic‐plastic), load‐carrying capacity and failure mode nature of the members under consideration, and (ii) make use of the above knowledge to develop, propose and assess the merit of efficient DSM‐based design approaches to estimate their failure loads or moments. Initially, illustrative column results are briefly presented to help grasp some fundamental concepts, namely the characterisation of the (i) above mode coupling phenomena, (ii) different sources of mode interaction that may lead to failure load/moment erosion and (iii) the most detrimental initial geometrical imperfections ‐ also presented are the currently codified DSM design curves, as well as two recently developed strength curves for column flexural‐torsional and beam distortional failures. Then, the paper addresses separately each mode coupling phenomenon dealt with, for columns, and only L‐D and D‐G interaction for beams. For columns undergoing L‐D and L‐D‐G interaction, beams experiencing L‐D interaction and angle columns susceptible to FT‐F interaction, the work reported includes experimental studies, numerical simulations and DSM‐based design considerations and/or guidelines. For the remaining coupling phenomena only numerical results are reported, but they unveil interesting (and unexpected) behavioural features that will help plan future test campaigns and achieve efficient design approaches. Finally, the paper closes with a few concluding remarks and a perspective about future developments in this field.

show abstract

Improving the Direct Strength Method prediction of column flexural-torsional failure loads

Cited by 15 publications

References 10 publications

Mode interaction in cold‐formed steel members: state‐of‐art report

Mode interaction in cold‐formed steel members: state‐of‐art report

Mode interaction in cold‐formed steel members: state‐of‐art report

Mode Interaction in Cold‐Formed Steel Members: State‐of‐Art Report

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