Local and distortional buckling of cold-formed steel beams with both edge and intermediate stiffeners in their compression flanges (original) (raw)
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Local and distortional buckling of cold-formed steel beams with edge-stiffened flanges
Journal of Constructional Steel Research, 2012
The true buckling behaviour of cold-formed steel beams with both edge and intermediate stiffeners in their compression flanges has been predicted with the aid of advanced numerical modelling. A series of nonlinear finite element analyses has been carried out to investigate the flexural behaviour of coldformed Z sections with both edge and intermediate stiffeners in their flanges, when the failure is controlled by local and/or distortional buckling. The effect of the size and position of intermediate stiffeners as well as the effect of the edge stiffener/intermediate stiffener interaction on the buckling behaviour and ultimate strength of these sections has been studied. The knowledge gained from FE analyses was used to check the accuracy of the Eurocode design rules in predicting the ultimate strengths for these sections.
Local and distortional buckling behaviour of cold-formed steel Z section beams
2011
The economic use of cold-formed steel members means that buckling and the possible loss of effectiveness it produces are important features of design. Cross-sectional instabilities in laterally-restrained cold-formed steel beams include local and distortional buckling. The prediction of the true buckling behaviour of cold-formed steel beams accounting for all governing features such as geometrical imperfections, spread of yielding, postbuckling etc. has been possible with the development of advanced numerical modelling. In this thesis, the finite element (FE) method (ABAQUS) has been used to develop numerical analyses to study the buckling behaviour of laterally-restrained cold-formed steel lipped Z-section beams. The FE models were verified against a series of four-point bending tests available from previous research, with special references to material and geometrical nonlinearities. Two sets of analyses have been conducted: FE analyses allowing for both local and distortional buc...
Thin-Walled Structures, 2011
The finite element (FE) method is capable of solving the complex interactive buckling of cold-formed steel beams allowing for all important governing features such as geometrical imperfections, material nonlinearity, postbuckling, etc.; this is unlikely to be achieved by analytical methods. In this paper, two series of finite element models for buckling behaviour of laterally-restrained cold-formed steel Z-section beams have been developed with special reference to material and geometrical nonlinearities: one to allow for the possibility of combined local/distortional buckling and the other to allow for local buckling only. Four-point bending tests carried out by previous researchers have been used to verify the FE models. A simplified configuration of the test setup has been modelled in ABAQUS. In the local buckling FE models, distortional buckling has been restricted in the member using translational springs applied to the lip/flange corner of the beam. Predictions of load carrying capacity and deformed shapes exhibit excellent agreement with both the results from the more extensive models and laboratory tests. Further papers will exploit the developed FE models to investigate the different forms of buckling that occur in laterally-restrained cold-formed steel beams i.e. local, distortional and combined local/distortional.
The aim of this paper is to be to explore the post-buckling behavior and ultimate strength of cold-formed steel (CFS) stiffened members in bending. The Finite Element (FE) models provide a supplementary tool to verify the design methods as well as to explore the buckling mechanism of cold formed steel members with various configurations. In this paper, the numbers of finite element models areestablished using ANSYS software for both stiffened and unstiffened elements. A particular emphasis has been given to the study of strength and behaviour of different cold formed steel zed sections with flange or web intermediate stiffeners. Cold formed steel members can be plain in simple applications, but if provided with flange or web stiffeners, their performance and resistance to local, distortional and lateral torsional buckling improves. The idea behind this paper is to use cold-formed steel members with modifying the shape rather than thickness to support load. Due to the relatively easy method of manufacturing, a large number of different configurations can be produced to fit the demands of optimized design for both structural and economical purposes.
Analytical and Experimental Investigation of Cold Formed Steel Sections under Bending
The primary interest of this project is to study the possible buckling occurrence on various cold formed steel closed sections like Box section, front to front Sigma and front to front Z-sections used as beams. Since the flexural load carrying capacity of the above mentioned sections under bending varies greatly with respect to its shape. In order to study different load capacity initially, a reliable finite element model was generated using the ANSYS software package to predict the flexural load above mentioned cold formed structural sections and to obtain a better understanding of the buckling failure behavior. For this purpose, a finite element model was developed using ANSYS. Theoretical study is done by using Euro code (EN1993 Part1-3) to determine the buckling behavior. Experimental study is performed by testing the specimen under bending. The Experimental investigation, theoretical investigation by Euro code (EN1993 Part1-3) and numerical investigation has been compared and concluded.
Distortional Buckling of Stiffened Cold-Formed Steel Channel Sections
This paper is concerned with distortional buckling of cold-formed steel channel sections by the semi-analytical complex finite strip method. The main purpose of this paper is to study the buckling behavior of cold-formed channel sections with extra longitudinal stiffeners at the end of flanges and also on the web. One of the most important purposes of this study is to investigate the optimum width of extra longitudinal flange stiffeners in cold-formed channel sections. Furthermore, the optimum position of longitudinal web stiffeners is calculated to maximize the distortional as well as local buckling strength of cold-formed channel sections. For validation purposes, complex finite strip method results are compared with those obtained by Generalized Beam Theory (GBT) analysis. Using the semi-analytical complex finite strip method, a comparison on the buckling behavior of unstiffened and stiffened cold-formed channel sections in local, distortional and global modes will be done.
FLEXURAL BEHAVIOUR OF STIFFENED MODIFIED COLD-FORMED STEEL SECTIONS–EXPERIMENTAL STUDY
The present study deals with the enhancement of the flexural capacity of cold formed steel beams using stiffeners. Beams with two back-to-back lipped channel sections were tested with and without stiffeners. Four such beams were considered with depth 150 mm and thickness of sheets 1mm and 2mm. ISMB 150 was also tested and was used as a yardstick for comparison with equivalent cold-formed sections. All the sections were subjected to “Four point flexural test” to study their behaviour in pure bending. From this study it was found that strength and stiffness of sections made out of 2mm sheets can be substantially enhanced using stiffeners whereas for 1mm sheets the enhancement was not so profound, primarily due to very high propensity for local buckling. Moreover, beams of 2mm sheets exhibited stiffness comparable to ISMB 150 in the initial loading stage.
BUCKLING ANALYSIS OF COLD FORMED STEEL CHANNEL SECTIONS WITH AND WITHOUT STIFFENERS
IJTIMES, 2019
The Light gauge cold-formed steel sections being used extensively in residential, industrial and commercial building as secondary load bearing members since last three decadez. In this context a study is being made to analyses C Sections with and without stiffeners to arrive at design strength criterion in compression. The direct strength method of design for cold formed steel sections has been validated over the years through research and the same has been incorporated in the standard codes of practice in the countries like USA and Australia. ABAQUS and CUFSM has been extensively used to perform Finite Element analysis and Finite Strip method of thin walled cold formed steel sections and the results are compared to each other. The analysis is being done on CUFSM and ABAQUS. The design strength curves will be arrived at using direct strength method. This is because cold-formed steel sections have a very high strength to weight ratio compared with thicker hot-rolled steel sections, and their manufacturing process is simple and cost-effective. In this context, a study is being made to analyze C sections with and without stiffeners to arrive at design strength criterion in compression members. In this study, the behavior of C sections with and without stiffeners under the action of axial loads has been carried out with various thickness and depths. In ABAQUS, the loads are applied on both ends. The clamped end conditions are considered.
A finite element analysis model for the behaviour of cold-formed steel members
Thin-Walled Structures, 1998
A finite element analysis model for the post-local buckling behaviour of cold-formed steel (CFS) members subjected to axial compression has been developed. The finite element model consists of a Total Lagrangian nonlinear 9-node "assumed strain" shell finite element, and experimental-based material properties models to represent the body of the CFS sections. Experimentally derived residual stress variations, and initial geometric imperfections have also been incorporated. A special loading technique and a displacement solution algorithm were employed to obtain a uniform displacement condition at the loading edges. Details of a test program involving 20 non-perforated, and perforated cold-formed stub-column steel sections have been presented in the second part of the paper. The comparison between the test results, and the finite element results was performed for axial and lateral displacement behaviour, buckling loads, ultimate loads, and axial stress distribution. The comparison forms the basis for the evaluation of the efficiency, and the accuracy of the finite element model, and it indicated that the finite element analysis model constructed herein gives accurate and consistent results for the behaviour of the cold-formed steel members subjected to axial compression.
IJERT-Flexural Behavior of Cold Formed Steel Beams with end Stiffeners and Encased Web
International Journal of Engineering Research and Technology (IJERT), 2014
https://www.ijert.org/flexural-behavior-of-cold-formed-steel-beams-with-end-stiffeners-and-encased-web https://www.ijert.org/research/flexural-behavior-of-cold-formed-steel-beams-with-end-stiffeners-and-encased-web-IJERTV3IS111330.pdf Cold-formed steel members are extensively used in the building construction industry, especially in residential, commercial and industrial buildings. In recent times, the use of cold-formed high strength steel members has rapidly increased.. This paper presents the results of the experimental study on the behaviour of cold-formed steel section with plain web, with end stiffened web and with encased web. The moment carrying capacity of cold-formed steel beam with plain web was studied and compared with the moment carrying capacity of beam with end stiffened web and encased .The specimens were tested under two point loading for its pure flexural behaviour. From the study, it is found that the cold-formed steel beam with end stiffened and encased web have higher load carrying capacity when compared to that of section with plain web.