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Ben Young - One of the best experts on this subject based on the ideXlab platform.
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tests of cold formed steel built up Open Section members under eccentric compressive load
Journal of Constructional Steel Research, 2021Co-Authors: Ben YoungAbstract:Abstract An experimental study was performed on cold-formed steel built-up Open Section members under eccentric compressive load. The specimens with member lengths varied from 300 to 1500 mm were manufactured by composing two identical channels using self-tapping screws. The channels with longitudinal stiffeners were fabricated from the steel grades G500 and G550 zinc-coated sheets with nominal 0.2% proof stresses of 500 and 550 MPa, respectively. A total of thirty-three combined minor axis bending and compression tests were carried out under pin-ended supports to explore the buckling behaviour of the newly designed built-up Section members. Six test series with a relatively wide range of axial load-to-moment ratio were included in this study to examine the interaction relationship of the built-up Section Beam-columns. The test loading capacities, full-history responses and failure modes were obtained for all the test specimens. Since the novel built-up Open Sections are not covered in the current cold-formed steel design standards, the comparisons of experimental loading capacities with nominal strengths predicted by the North American Specification, Australian/New Zealand Standard, European Code and American Specification were conducted to assess the appropriateness of the existing design rules. The applicability of axial load-moment interactive formulae specified in the aforementioned design standards with the nominal pure compressive resistance and nominal pure bending resistance determined by direct strength method was evaluated for the built-up Section Beam-columns. It is found that the axial load-moment interactive formulae generally underestimate the strengths of the cold-formed steel built-up Open Section Beam-columns.
Sekwon Jung - One of the best experts on this subject based on the ideXlab platform.
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effect of web distortion on the buckling strength of noncomposite discretely braced steel i Section members
Engineering Structures, 2007Co-Authors: Donald W White, Sekwon JungAbstract:The influence of the web distortional flexibility typically is not addressed explicitly in standards for flexural design of steel I-Section members. This is due in part to the fact that there are no simple closed-form solutions that account for these effects, whereas closed-form solutions are well established for elastic lateral-torsional buckling using thin-walled Open-Section Beam theory. Thin-walled Open-Section Beam theory is of course based on the assumption that the cross-Section profile does not distort. Furthermore, accurate strength predictions are obtained for a wide range of experimental tests without explicit accounting for web distortion in the lateral-torsional buckling calculations. Nevertheless, it is clear from prior research studies that the web distortional flexibility can lead to a substantial reduction relative to the Beam theory lateral-torsional buckling resistance for I-Sections with torsionally-stiff flanges and relatively thin webs. [AASHTO. AASHTO LRFD bridge design specifications. 3rd ed. Washington (DC): American Association of State and Highway Transportation Officials; 2004; AISC. Specification for structural steel buildings. Chicago (IL): American Institute of Steel Construction; 2005 [in press]] give specific limits on cross-Section geometry and yield strengths aimed at controlling the unconservative errors due to the neglect of web distortion effects. This paper evaluates the effectiveness of these limits. Potential future directions for improved calculation of I-Section member flexural resistances are suggested for cases where the influence of web distortion is significant.
Donald W White - One of the best experts on this subject based on the ideXlab platform.
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effect of web distortion on the buckling strength of noncomposite discretely braced steel i Section members
Engineering Structures, 2007Co-Authors: Donald W White, Sekwon JungAbstract:The influence of the web distortional flexibility typically is not addressed explicitly in standards for flexural design of steel I-Section members. This is due in part to the fact that there are no simple closed-form solutions that account for these effects, whereas closed-form solutions are well established for elastic lateral-torsional buckling using thin-walled Open-Section Beam theory. Thin-walled Open-Section Beam theory is of course based on the assumption that the cross-Section profile does not distort. Furthermore, accurate strength predictions are obtained for a wide range of experimental tests without explicit accounting for web distortion in the lateral-torsional buckling calculations. Nevertheless, it is clear from prior research studies that the web distortional flexibility can lead to a substantial reduction relative to the Beam theory lateral-torsional buckling resistance for I-Sections with torsionally-stiff flanges and relatively thin webs. [AASHTO. AASHTO LRFD bridge design specifications. 3rd ed. Washington (DC): American Association of State and Highway Transportation Officials; 2004; AISC. Specification for structural steel buildings. Chicago (IL): American Institute of Steel Construction; 2005 [in press]] give specific limits on cross-Section geometry and yield strengths aimed at controlling the unconservative errors due to the neglect of web distortion effects. This paper evaluates the effectiveness of these limits. Potential future directions for improved calculation of I-Section member flexural resistances are suggested for cases where the influence of web distortion is significant.
Youngjong Kang - One of the best experts on this subject based on the ideXlab platform.
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stability of continuous welded rail track
Computers & Structures, 2003Co-Authors: Namhyoung Lim, Nam Hoi Park, Youngjong KangAbstract:Abstract As the use of continuous welded rail (CWR) increases in track structures, derailing disasters associated with track buckling also increase in great numbers due to high compressive thermal stress. A three-dimensional CWR track model is developed in the present study to be used for extensive buckling analysis of CWR tracks subjected to temperature load. The analysis model is encoded into a special purpose program using the finite element method. The CWR track model consists of four elements: a mono-symmetric thin-walled Open Section Beam element with 7 degrees of freedom per node to represent the rail; a solid Beam-on-elastic-foundation element having 6 degrees of freedom per node to simulate the tie, including vertical and/or longitudinal ballast resistance; an elastic spring element with two nodes and zero length to stand for pad-fastener system; and spring elements for the lateral or longitudinal ballast resistances. Also, two types of significant nonlinearity are included in the track model: the geometric nonlinearity of the rail element, and the materially nonlinear resistance of the ballast. The validity of the present study is strictly verified through a series of comparative analyses with those by others. The nonlinear analysis results have shown that buckling of the track is a three-dimensional problem, and the 2-D rail–tie model and Beam model overestimated the CWR track stability.
Namhyoung Lim - One of the best experts on this subject based on the ideXlab platform.
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stability of continuous welded rail track
Computers & Structures, 2003Co-Authors: Namhyoung Lim, Nam Hoi Park, Youngjong KangAbstract:Abstract As the use of continuous welded rail (CWR) increases in track structures, derailing disasters associated with track buckling also increase in great numbers due to high compressive thermal stress. A three-dimensional CWR track model is developed in the present study to be used for extensive buckling analysis of CWR tracks subjected to temperature load. The analysis model is encoded into a special purpose program using the finite element method. The CWR track model consists of four elements: a mono-symmetric thin-walled Open Section Beam element with 7 degrees of freedom per node to represent the rail; a solid Beam-on-elastic-foundation element having 6 degrees of freedom per node to simulate the tie, including vertical and/or longitudinal ballast resistance; an elastic spring element with two nodes and zero length to stand for pad-fastener system; and spring elements for the lateral or longitudinal ballast resistances. Also, two types of significant nonlinearity are included in the track model: the geometric nonlinearity of the rail element, and the materially nonlinear resistance of the ballast. The validity of the present study is strictly verified through a series of comparative analyses with those by others. The nonlinear analysis results have shown that buckling of the track is a three-dimensional problem, and the 2-D rail–tie model and Beam model overestimated the CWR track stability.
