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A Study on Inelastic Lateral-Torsional Buckling of Stepped I-Beams Subjected to Pure Bending  

Kim, Jong Min (고려대학교 건축사회환경공학과)
Kim, Seung Jun (고려대학교 건축사회환경공학과)
Park, Jong Sup (상명대학교 토목환경공학부)
Kang, Young Jong (고려대학교 건축사회환경공학과)
Publication Information
Journal of Korean Society of Steel Construction / v.20, no.2, 2008 , pp. 237-246 More about this Journal
Abstract
The cross-sections of continuous multi-span beams sometimes suddenly increase, or become stepped, at the interior supports of continuous beams to resist high negative moments. The three-dimensional finite-element program ABAQUS (2006) was used to analytically investigate the inelastic lateral-torsional buckling behavior of stepped beams subjected to pure bending moment and resulted in the development of design equations. The flanges of the smaller cross-section were fixed at 30.48 by 2.54 cm, whereas the width and/or thickness of the flanges of the larger cross-section varied. The web thickness and height of beam was kept at 1.65 cm and 88.9 cm, respectively. The ratios of the flange thickness, flange width, and stepped length of beams are considered analytical parameters. Two groups of 27 cases and 35 cases, respectively, were analyzed for double and single stepped beams. The combined effects of residual stresses and geometrical imperfection on inelastic lateral-torsional buckling of beams are considered. First, the distributions of residual stress of the cross-section is same as shown in Pi, etc (1995), and the initial geometric imperfection of the beam is set by central displacement equal to 0.1% of the unbraced length of beam. The new proposed equations definitely improve current design methods for the inelastic LTB problem and increase efficiency in building and bridge design. The proposed solutions can be easily used to develop new design equation for inelastic LTB resistance of stepped beams subjected to general loading condition such as a concentrated load, a series of concentrated loads or uniformly distributed load.
Keywords
Inelastic Lateral-Torsional Buckling; Stepped Beam; Continuous Multi-span Beam; Increased Flange Size;
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Times Cited By KSCI : 1  (Citation Analysis)
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