Computational modeling of cold-formed steel: characterizing geometric imperfections and residual stresses
TL;DR: In this paper, a preliminary set of guidelines for computational modeling of imperfections and residual stresses of cold-formed steel members is presented, based on simple rules of thumb and probabilistic concepts for characterization of both quantities.
About: This article is published in Journal of Constructional Steel Research.The article was published on 1998-09-01. It has received 672 citations till now. The article focuses on the topics: Computational model.
Citations
More filters
TL;DR: In this paper, the authors classify different residual stresses measurement methods and provide an overview of some of the recent advances in this area to help researchers on selecting their techniques depending on their application and the availabilities of those techniques.
633 citations
TL;DR: A review of the development and current progress in the Direct Strength Method for cold-formed steel member design is provided in this paper, where a brief comparison of the direct strength method with the Effective Width Method is provided.
525 citations
Cites background from "Computational modeling of cold-form..."
...More attempts to understand the inputs to thin-walled member strength such as geometric imperfections and residual stresses [11] as well as modelling assumptions (elements, material modelling) related to the underlying mechanics are needed [12]....
[...]
TL;DR: In this paper, the structural response of stainless steel hollow sections is modeled using the Ramberg-Osgood model and a simple but accurate model is proposed for the prediction of enhanced strength corner properties.
Abstract: This article describes numerical modeling of the structural response of stainless steel hollow sections. The aim of the investigation was to develop a consistent approach to the modeling of stainless steel structures. The developed finite element models are more sophisticated than any other reported attempts to model stainless steel structural behavior, with general expressions defined for material stress-strain behavior, enhanced strength corner properties, initial geometric imperfection modes, and amplitudes (local and global), and residual stresses. The general expressions define a consistent means of describing the key input parameters. A compound (two-stage) Ramberg-Osgood model is developed to describe stainless steel material stress-strain behavior in tension and compression. For the prediction of enhanced strength corner properties, a simple, though accurate model is proposed. Characterization of local plate imperfection amplitudes is described whereby a model originally devised for hot-rolled carbon steel cross sections was recalibrated and applied to stainless steel cross sections. Numerical prediction of the key performance measures from tests is achieved with a high degree of accuracy: On average, ultimate load was predicted to within 3 percent and with a low standard deviation; deformation at ultimate load was within 6 percent, but exhibited a higher standard deviation; and the general form of the load-deformation response and the failure modes were similar.
346 citations
Cites background from "Computational modeling of cold-form..."
...Schafer and Peköz (1998) presented some rules of thumb for the prediction of the maximum local imperfection in a stiffened element that apply for a width-to-thickness ratio less than 200, and a material thickness of less than 3mm....
[...]
...…9, where 0 is the amplitude of the initial imperfection, w is the width of the plate, and t is the thickness of the plate in mm. 0 0.006w (8) 0 6te-2t (9) Based on observations, Schafer and Peköz (1998) also applied a probabilistic approach to the characterization of imperfection amplitudes....
[...]
...Deformationally induced residual stresses Deformationally induced residual stresses in carbon steel cross-sections have been investigated experimentally and analytically by Ingvarsson (1975, 1979), Weng and Peköz (1988), Abdel-Rahman and Sivakumaran (1997) and Schafer and Peköz (1998)....
[...]
TL;DR: In this paper, a closed-form prediction of the buckling stress in the local mode, including interaction of the connected elements, and the distortional mode including consideration of the elastic and geometric stiffness at the web/flange juncture, is provided and shown to agree well with numerical methods.
Abstract: Open cross-section, thin-walled, cold-formed steel columns have at least three competing buckling modes: local, distortional, and Euler ~i.e., flexural or flexural-torsional ! buckling. Closed-form prediction of the buckling stress in the local mode, including interaction of the connected elements, and the distortional mode, including consideration of the elastic and geometric stiffness at the web/flange juncture, are provided and shown to agree well with numerical methods. Numerical analyses and experiments indicate postbuckling capacity in the distortional mode is lower than in the local mode. Current North American design specifications for cold-formed steel columns ignore local buckling interaction and do not provide an explicit check for distortional buckling. Existing experiments on cold-formed channel, zed, and rack columns indicate inconsistency and systematic error in current design methods and provide validation for alternative methods. A new method is proposed for design that explicitly incorporates local, distortional and Euler buckling, does not require calculations of effective width and/or effective properties, gives reliable predictions devoid of systematic error, and provides a means to introduce rational analysis for elastic buckling prediction into the design of thin-walled columns.
326 citations
Cites background from "Computational modeling of cold-form..."
...Based on existing work f beams~Schafer and Peko¨z 1998b!, the following form is suggested for local buckling of columns: Pnl P 5F120....
[...]
TL;DR: In this paper, the authors provide an overview of computational modeling, both elastic buckling and nonlinear collapse analysis, for cold-formed steel members, and the importance of imperfections, residual stresses, material modeling, boundary conditions, element choice, element discretization, and solution controls in collapse modeling of cold-form steel.
Abstract: The objective of this paper is to provide an overview of computational modeling, both elastic buckling and nonlinear collapse analysis, for cold-formed steel members. Recent research and experiences with computational modeling of cold-formed steel members conducted within the first author's research group at Johns Hopkins University are the focus of the presented work. This admittedly biased view of computational modeling focuses primarily on the use of the semi-analytical finite strip method and collapse modeling using shell finite elements. Issues addressed include how to fully compare finite strip and finite element solutions, and the importance of imperfections, residual stresses, material modeling, boundary conditions, element choice, element discretization, and solution controls in collapse modeling of cold-formed steel. Examples are provided to demonstrate the expected range of sensitivity in cold-formed steel collapse modeling. The paper concludes with a discussion of areas worthy of future study that are within the domain of cold-formed steel modeling.
236 citations
References
More filters
Book•
01 Jul 1976
1,174 citations
"Computational modeling of cold-form..." refers background in this paper
...General discussion of this type of generation can be found in the literature on random vibrations [14,15]....
[...]
Book•
01 Aug 1992
TL;DR: In this paper, the authors address random vibration of mechanical and structural systems commonly encountered in aerospace, mechanical and civil engineering and propose techniques for determining probabilistic characteristics of the response of dynamic systems subjected to random loads or inputs and for calculating probabilities related to system performance or reliability.
Abstract: This book addresses random vibration of mechanical and structural systems commonly encountered in aerospace, mechanical and civil engineering. It offers techniques for determining probabilistic characteristics of the response of dynamic systems subjected to random loads or inputs and for calculating probabilities related to system performance or reliability.
605 citations
"Computational modeling of cold-form..." refers background in this paper
...General discussion of this type of generation can be found in the literature on random vibrations [14,15]....
[...]
TL;DR: In this paper, a large deflection elastic-plastic finite strip analysis including the measured distributions of yield stress and residual stress is used to investigate the behaviour of the stub and pin-ended columns.
Abstract: An experimental programme investigating the column behaviour of four sizes of square hollow section was undertaken at the University of Sydney using Australian produced cold-formed square hollow sections. Stub and pinended column tests were performed and detailed measurements of the yield stress and residual stress taken around the sections. A large deflection elastic—plastic finite strip analysis including the measured distributions of yield stress and residual stress is used to investigate the behaviour of the stub and pin-ended columns. In particular, the influence of the measured through thickness residual stress components on the ultimate load and behaviour of the square hollow section columns is demonstrated. The analysis accounts for plate geometric imperfections, the variation of yield stress around a section, the stress—strain characteristics of the material forming the section and the highly complex patterns of residual stress produced by the cold-forming process. Comparison of the analytical results with the test results is provided.
117 citations
TL;DR: In this paper, the tensile and compressive properties of light-gage steel members were investigated using tensile coupon tests. But the results of the tests were not distributed uniformly in the cross sections, being considerably larger in the corners than in the flats.
Abstract: Cold-forming causes significant changes in the mechanical properties of certain light-gage steel members The average yield strength in a cold-formed section may be as much as 70% larger than that of the original, as-rolled sheet steel These changes in properties are not distributed uniformly in the cross sections, being considerably larger in the corners than in the flats of light-gage members However, the quantitative information obtained in this investigation permits more rational and economical design of many such members Both the tensile and compressive properties of corners, flats, and full sections were determined in an extensive experimental investigation A method is devised for determining the stress-strain characteristics of full sections from simple tensile coupon tests These stress-strain properties are related analytically to the inelastic buckling of compact cold-formed columns, using a generalized form of Shanley's tangent modulus equation
44 citations
TL;DR: In this paper, the authors investigated the use of transverse web plate stiffeners to improve the lateral buckling capacity of hollow flange beam (HFB) by using finite-element analyses and large-scale experiments.
Abstract: A new cold-formed and resistance-welded section known as the hollow flange beam (HFB) has been developed recently in Australia. In contrast to the common lateral-torsional buckling mode of I-beams, this unique section comprising two stiff triangular flanges and a slender web is susceptible to a lateral-distortional buckling mode of failure involving lateral deflection, twist, and cross-section change due to web distortion. This lateral-distortional buckling behavior has been shown to cause significant reduction of the available flexural capacity of HFBs. An investigation using finite-element analyses and large-scale experiments was carried out into the use of transverse web plate stiffeners to improve the lateral buckling capacity of HFBs. This paper presents the details of the finite-element model and analytical results. The experimental procedure and results are outlined in a companion paper.
42 citations