Session 04: Flexural MembersCopyright (c) 2017 Missouri University of Science and Technology All rights reserved.
http://scholarsmine.mst.edu/isccss/21iccfss/21iccfss-session4
Recent Events in Session 04: Flexural Membersen-usThu, 07 Dec 2017 01:21:44 PST3600Load Distribution in Floor to Wall Connections
http://scholarsmine.mst.edu/isccss/21iccfss/21iccfss-session4/8
http://scholarsmine.mst.edu/isccss/21iccfss/21iccfss-session4/8Fri, 24 Aug 2012 00:00:00 PDT
Presented in this paper is a cold formed steel load distribution system developed by iSPAN Systems LP that enables the installation of floor joists without the need to align them with the supporting wall studs. The floor joists are supported by a shear connection attached to a cold formed steel perimeter distribution member. In addition to the load distribution aspect, the system results in a simplified lateral design approach. An experimental verification study was carried out to establish the load distribution capability of the system, resulting in a simplified procedure to determine the connection requirements and load transfer characteristics to the wall studs.
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D. M. Fox et al.The Effects of Web Holes on Web Crippling Strength of Cold-formed Steel Channels under End-two-flange Loading Condition
http://scholarsmine.mst.edu/isccss/21iccfss/21iccfss-session4/7
http://scholarsmine.mst.edu/isccss/21iccfss/21iccfss-session4/7Fri, 24 Aug 2012 00:00:00 PDT
Cold-formed steel sections are often used as wall studs or floor joists; such sections often include web holes for ease of installation of the services. Web crippling at points of concentrated, or localised, load or reaction in thin-walled beams is well known to be a significant problem, particularly in the case of beams with slender webs, and is of high importance in the field of cold-formed steel members, as such members are generally not stiffened against this type of loading. In this paper, a combination of experimental tests and non-linear elastoplastic finite element analyses are used to investigate the effect of such holes on web crippling under end-two-flange (ETF) loading condition. In the case of the tests with web openings, the web holes located at the mid-depth of the webs. A non-linear elasto-plastic finite element model is developed in this study, and the results compared against the laboratory test results; a good agreement was obtained in terms of both strength and failure modes.
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Asraf Uzzaman et al.Shear Buckling of Thin-walled Channel Sections with Complex Stiffened Webs
http://scholarsmine.mst.edu/isccss/21iccfss/21iccfss-session4/6
http://scholarsmine.mst.edu/isccss/21iccfss/21iccfss-session4/6Fri, 24 Aug 2012 00:00:00 PDT
For cold-formed channel section design in shear, the traditional approach has been to investigate shear plate buckling in the web alone. Recently, an improvement in the elastic buckling stress of the whole thin-walled channel section including flanges and lips in pure shear has been demonstrated. For webs with relatively large depth to thickness ratios, the local buckling mode in shear occurs mainly in web. The structural efficiency of such a web can be improved by adding intermediate stiffeners cold-formed longitudinally in the middle of the webs. This paper presents numerical buckling analyses implemented by means of the Semi-Analytical Finite Strip Method (SAFSM). The shear signature curve from the SAFSM is used in a design proposal for a newly developed Direct Strength Method (DSM) for shear. The DSM was formally adopted in the North American Design Specification in 2004 and in the Australian/New Zealand Standard for Cold-Formed Steel Structures (AS/NZS 4600:2005) in 2005 as an alternative to the traditional Effective Width Method (EWM). The theory and development of the shear signature curve has been clearly presented and discussed in a separate paper in this conference. The objective of this paper is to apply this methodology to investigate the effect of web stiffeners on the elastic shear buckling stress by varying the number, shape, location and size of the longitudinal web stiffeners. A series of shear signature curves and corresponding buckling mode shapes are studied for three different cases of web stiffener geometry where the variables are stiffener position and dimensions. The results from the analysis are included to identify local and distortional buckling caused by shear stresses. The explanation of the occurrence or disappearance of the minima of the shear signature curves where local or distortional buckling occur is also discussed.
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Song Hong Pham et al.Behaviour of LiteSteel Beams Subject to Combined Shear and Bending Actions
http://scholarsmine.mst.edu/isccss/21iccfss/21iccfss-session4/5
http://scholarsmine.mst.edu/isccss/21iccfss/21iccfss-session4/5Fri, 24 Aug 2012 00:00:00 PDT
This paper presents the details of a numerical study of a cold-formed steel beam known as LiteSteel Beam (LSB) subject to combined shear and bending actions. The LSB sections are produced by a patented manufacturing process involving simultaneous cold-forming and electric resistance welding. They have a unique shape of a channel beam with two rectangular hollow flanges. To date, however, no investigation has been conducted into the strength of LSB sections under combined shear and bending actions. Hence a numerical study was undertaken to investigate the behaviour and strength of LSBs subject to combined shear and bending actions. In this research, finite element models of LSBs were developed to simulate the combined shear and bending behaviour and strength of LSBs. They were then validated by comparing their results with test results and used in a parametric study. Both experimental and finite element analysis results showed that the current design equations are not suitable for combined shear and bending capacities of LSBs. Hence improved design equations are proposed for the capacities of LSBs subject to combined shear and bending actions.
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P. Keerthan et al.Finite Element Analyses of Lipped Chanel Beams with Web Openings in Shear
http://scholarsmine.mst.edu/isccss/21iccfss/21iccfss-session4/4
http://scholarsmine.mst.edu/isccss/21iccfss/21iccfss-session4/4Fri, 24 Aug 2012 00:00:00 PDT
Cold-formed steel members are increasingly used as primary structural elements in buildings due to the availability of thin and high strength steels and advanced cold-forming technologies. Cold-formed lipped channel beams (LCB) are commonly used as flexural members such as floor joists and bearers. Shear behaviour of LCBs with web openings is more complicated and their shear capacities are considerably reduced by the presence of web openings. However, limited research has been undertaken on the shear behaviour and strength of LCBs with web openings. Hence a numerical study was undertaken to investigate the shear behaviour and strength of LCBs with web openings. Finite element models of simply supported LCBs with aspect ratios of 1.0 and 1.5 were considered under a mid-span load. They were then validated by comparing their results with test results and used in a detailed parametric study. Experimental and numerical results showed that the current design rules in cold-formed steel structures design codes are very conservative for the shear design of LCBs with web openings. Improved design equations were therefore proposed for the shear strength of LCBs with web openings. This paper presents the details of this numerical study of LCBs with web openings, and the results.
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P. Keerthan et al.Shear Strength of Hollow Flange Channel Beams with Stiffened Web Openings
http://scholarsmine.mst.edu/isccss/21iccfss/21iccfss-session4/3
http://scholarsmine.mst.edu/isccss/21iccfss/21iccfss-session4/3Fri, 24 Aug 2012 00:00:00 PDT
This LiteSteel beam (LSB) is a new cold-formed steel hollow flange channel section produced using a patented manufacturing process involving simultaneous cold-forming and dual electric resistance welding. The LSBs are commonly used as floor joists and bearers with web openings in buildings. Their shear strengths are considerably reduced when web openings are included for the purpose of locating building services. Shear tests of LSBs with web openings have shown that there is up to 60% reduction in the shear capacity. Hence there is a need to improve the shear capacity of LSBs with web openings. A cost effective way to eliminate the shear capacity reduction is to stiffen the web openings using suitable stiffeners. Hence numerical studies were undertaken to investigate the shear capacity of LSBs with stiffened web openings. In this research, finite element models of LSBs with stiffened web openings in shear were developed to simulate the shear behaviour and strength of LSBs. Various stiffening methods using plate and LSB stiffeners attached to LSBs using both welding and screw-fastening were attempted. The developed models were then validated by comparing their results with experimental results and used in further studies. Both finite element and experimental results showed that the stiffening arrangements recommended by past research for cold-formed steel channel beams are not adequate to restore the shear strengths of LSBs with web openings. Therefore new stiffener arrangements were proposed for LSBs with web openings. This paper presents the details of this research project using numerical studies and the results.
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P. Keerthan et al.Critical Elastic Shear Buckling Stress Hand Solution for C- and Z-sections Including Cross-section Connectivity
http://scholarsmine.mst.edu/isccss/21iccfss/21iccfss-session4/2
http://scholarsmine.mst.edu/isccss/21iccfss/21iccfss-session4/2Fri, 24 Aug 2012 00:00:00 PDT
This paper presents an approximate solution for the critical elastic buckling stress of cold-formed steel C- and Z-section members including cross-section connectivity. The elastic buckling solution is developed to support the extension of the Direct Strength Method to the shear ultimate limit state, where the cross sectional critical elastic shear buckling stress (load) is employed to predict shear capacity. The shear buckling stress and buckled half-wavelength are calculated with a classical energy solution for a thin plate with edges rotationally restrained. Rotational stiffness expressions in the AISI S100-07 specification, originally derived for distortional buckling of C- and Z-sections, are used with the energy solution to calculate the rotational restraint provided to the web flange juncture by the flanges. The approach is validated with thin shell finite element eigen-buckling analysis.
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Kevin Aswegan et al.Direct Strength Method of Design for Shear of Cold-formed Channels Based on a Shear Signature Curve
http://scholarsmine.mst.edu/isccss/21iccfss/21iccfss-session4/1
http://scholarsmine.mst.edu/isccss/21iccfss/21iccfss-session4/1Fri, 24 Aug 2012 00:00:00 PDT
Thin-walled sections in compression and/or bending may undergo one of the three modes of local, distortional or overall (Euler) buckling, or combinations of these. The Semi-Analytical Finite Strip Method (SAFSM) developed by YK Cheung has been widely used in computer software (THIN-WALL, CUFSM) to develop the signature curve of the buckling stress versus buckling half wavelength for a thin-walled section under compression or bending to allow identification of these modes. The minimum points on the signature curve are now used in the Direct Strength Method (DSM) of design of cold-formed sections in the American Specification and Australian/New Zealand Standard for cold-formed steel structures. Plank and Wittrick (1974) included shear in the SAFSM theory for calculating the stiffness and stability matrices by using complex mathematics. The complex mathematics is needed to allow for the phase shifts in the buckling modes (eigenvectors) for sections under shear. This paper briefly summarises the theory then applies it to the buckling of channel sections in pure shear. Signature curves for shear are developed for channel sections and compared with classical solutions, and those produced by the Spline Finite Strip Method (SFSM) previously published by the authors. A proposed Direct Strength Method (DSM) of design for shear is explained in the paper.
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Gregory J. Hancock et al.