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Strain Distribution in Locally Slender Structural Steel Cross-sections Seif, M., Schafer, B.W. Civil Engineering at JOHNS HOPKINS UNIVERSITY

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Acknowledgments AISC Faculty Fellowship Program Professor Ben Schafer The thin-walled structures research group at JHU

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Overview Motivation Cross-section stability Design methods FE parametric study Strain Distributions Ongoing work

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AISC definition of locally slender Motivation

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AISC Q-factor AISI Effective Width AISI Direct Strength App. 1

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Column curve

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Overview Motivation Cross-section stability Design methods FE parametric study Strain Distributions Ongoing work

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ABAQUS elements S4 10 elements

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Residual stresses Galambos and Ketter (1959)

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Material modeling Barth, White, Righman, & Yang (2005)

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Geometric imperfections

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LOCAL slenderness W14FI: W14x233 with variable Flange thickness, varies Independently from all other dimensions W14FR: W14x233 with variable Flange thickness, but the web thickness set so that the Ratio of the flange-to- web thickness remains the same as the original W14x233 W36FR: W36x330 with variable Web thickness, but the flange thickness set so that the Ratio of the flange-to-web thickness remains the same as the original W36x330 W36WI: W36x330 section with variable Web thickness, that varies Independently from all other dimensions c

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LOCAL slenderness

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Results Columns

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Results Columns App. 1

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Overview Motivation Cross-section stability Design methods FE parametric study Strain Distributions Ongoing work

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Results W36x330 x x x W36WI Thicker Original W36x233 Thinner Displacement, in. P n, kips

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Deformed shape Thinner web Original W36x330 Thicker Web

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Membrane longitudinal stress Thinner web Original W36x330 Thicker web ~ Zero = Yield

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Membrane plastic strain Thinner web Original W36x330 Thicker web ~ 10 y ~ Zero

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3D2D

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S4 - Element 3D x x

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Thinner flange Thicker flange 2D Stress/Strain distributions

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2D Effective Area NO !!!!

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Equilibrium Clear height

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W14 FI: Strain Energy Distribution Thinner ThickerOriginal W14x233

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W14 FI: Postulated Effective Width Distribution Thinner ThickerOriginal W14x233

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W14 FR: Strain Energy Distribution Thinner ThickerOriginal W14x233

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W14 FR: Postulated Effective Width Distribution Thinner Original W14x233 Thicker

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W36 FR: Strain Energy Distribution Thinner Original W36x330 Thicker

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W36 FR: Postulated Effective Width Distribution Thinner Original W36x330 Thicker

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W36 WI: Strain Energy Distribution Thinner Original W36x330 Thicker

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W36 WI: Postulated Effective Width Distribution Thinner Original W36x330 Thicker

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Ongoing work Strain Distributions Effective Areas DSM for Structural Steel

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Work continues….. more at:

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