Simulation of geometric imperfections in cold-formed steel members using spectral representation approach

Zeinoddini, V. M.; Schafer, B.W.

doi:10.1016/j.tws.2012.07.001

Cited by 89 publications

(37 citation statements)

References 14 publications

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“…Results reflect that, inspite of mode 1 represents the critical buckling mode, it has no remarkable effect on the ultimate moment of short beams, L/r y = 50 and 75, for the practical range of imperfections (0.1-1 t, [2,6,15]). However, the flexural strength of beams with L/r y = 75 reduces by 16% when the imperfection value is equal to 2 t. Note that, the value 2 t is considered a large value.…”

Section: Nonlinear Analysismentioning

confidence: 82%

Effect of geometric imperfections on the ultimate moment capacity of cold-formed sigma-shape sections

Gendy

Hanna

2017

HBRC Journal

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In recent years, cold formed steel sections are used more and more as primary framing components and as a secondary structural system. They are used as purlins and side rails or floor joist, and after that in the building envelops. Beams are not perfectly straight and are usually associated with geometric imperfections. Initial geometric imperfections can significantly influence the stability response of cold-formed steel members. This paper reports a numerical investigation concerning the effect of these imperfections on the behavior of the simply supported beams subjected to a uniform bending moment. The beam profile is cold formed sigma sections. Group of beams with different overall member slenderness ratios were studied. Several approaches have been utilized to model the geometric imperfections. First, the elastic buckling modes were considered as the imperfect beam shape. In this approach, the elastic buckling analysis was done first to get the elastic buckling modes. In the second approach, the imperfections were considered by assuming the beam bent in a half sine wave along its length. Finally, combination of these two approaches was considered. Results reveal that, the ultimate bending moments of beams with short and intermediate overall slenderness ratios are sensitive to the imperfect shape that comprise compression flange local buckling. ª 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of Housing and Building National Research Center. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

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Section: Nonlinear Analysismentioning

confidence: 82%

Effect of geometric imperfections on the ultimate moment capacity of cold-formed sigma-shape sections

Gendy

Hanna

2017

HBRC Journal

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“…The data may be used to provide insights on classic out-offlatness, out-of-straightness, and bow, camber, and twist -or more directly on local, distortional, and global deformation modes [23]. The data also provides critical inputs for the proposed 1D modal spectra method [24] -which provides a means to simulate artificial imperfection fields that are realistic, but not directly tied to measurements. The measurement rig has relatively high throughput and has potential for use in manufacturing QA/QC and for developing broad sets of data characterizing expected imperfection magnitudes, as would be appropriate for standards providing guidance on imperfection magnitude for simulation.…”

Section: Imperfection Measurementsmentioning

confidence: 99%

00.02: Developments in research and assessment of steel structures: Highlights from the perspective of an American researcher

Schafer

2017

ce papers

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The objective of this paper is to provide a summary of recent developments in the research and assessment of steel building structures. The task is too broad to accomplish in a general sense, as such the perspective and biases of the author as an American research professor who primarily focuses on thin-walled steel building applications is explicitly recognized. The discussed research is separated into three areas: cold-formed steel structures, hot-rolled steel structures, and earthquake engineering for steel structures. The focus of the presentation is on research conducted within each of these three areas, in the last 5 years, primarily in the United States, with particular emphasis on projects that the author was directly involved in or lead. In addition, each area concludes with a brief discussion of developments in American steel codes and standards that are related to the research. Cold-formed steel structures have enjoyed a large body of recent research, advancements in: modelling, imperfection measurement, stiffness characterization, coupled instabilities, design under multiple actions, and system reliability are all highlighted. The author has had less direct involvement in much of the recent hot-rolled steel structural research, but serves on the committees where this research is brought into the American standards. Work that has had a specific impact on the American hot-rolled steel standards in beams, slender columns, composite columns, bracing, fire, and progressive collapse are all highlighted. In addition, recent research advancing modelling for fracture in steel is summarized due to the authors belief in the large long term impact of those efforts. Earthquake engineering for steel structures spans a broad space, highlighted research includes: benchmark tests and building models for cold-formed steel framing; new tests, modelling, and design guidance on structural steel seismic force-resisting systems; and new research in steel diaphragm systems. Taken as a whole, the paper aims to demonstrate the vibrancy in American steel building research, now more than 125 years since the first steel-framed skyscraper.Activity in cold-formed steel research is broad and it is impossible to provide a complete summary, recent efforts by Hancock [1] provide a more comprehensive treatment than that provided here. In this paper, a subset of key developments that the author believes have significant potential to transform the analysis or design of cold-formed steel structures is highlighted. Without a doubt, this paper leaves out significant advances that the author was either unaware of, or did not properly contemplate when preparing this summary. Computational Advances: GBT, cFSM, cFEMCold-formed steel members primarily utilize open singly-point-or un-symmetric thin-walled sections. As a result, global buckling modes are nearly always coupled (in flexure and torsion) and must include warping torsion. Due to the thin nature of the sheet used to form the sections, local plate deformations are engaged even at service ...

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“…In this research, the geometric imperfection was not measured due to the lack of appropriate measuring equipment. Based on the research of Zeinoddini and Schafer [15], the magnitude of the imperfection was taken as 0.31 times of the plate thickness, which was in correspondence with 50% probability of exceedance.…”

Section: Finite Element Modellingmentioning

confidence: 99%

Investigation on flexural strength of cold-formed thin-walled steel beams with built-up box section

Shen

2016

Thin-Walled Structures

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Simulation of geometric imperfections in cold-formed steel members using spectral representation approach

Cited by 89 publications

References 14 publications

Effect of geometric imperfections on the ultimate moment capacity of cold-formed sigma-shape sections

Effect of geometric imperfections on the ultimate moment capacity of cold-formed sigma-shape sections

00.02: Developments in research and assessment of steel structures: Highlights from the perspective of an American researcher

Investigation on flexural strength of cold-formed thin-walled steel beams with built-up box section

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