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Euler Buckling using NL Analysis

Question asked by Andy Krispie on Mar 1, 2010
Latest reply on Mar 1, 2010 by Andy Krispie

I've been doing some buckling analysis using simulation NL analysis, and after a bit of initial rigging have been quite pleased with the results.


I wanted to verify that my boundary conditions were behaving as expected, so I decided to conduct a basic buckling analysis of a W-Section (ie I-Beam) and compare it to the critical Euler buckling load.  I used a W150x30 section (Iy=5.56e6 mm^4, ry=38.2mm).  Assuming a slenderness ratio of kL/r=200, L=7640mm.  Plugging that into the Euler critical buckling equation, Pc~188kN.  I'm using 350W steel (E=200000MPa, Fy=350MPa) as a material.


I applied a constant lateral load of 2kN to create some initial displacement that would instigate buckling (worked out to ~3mm in this case).  Attached are some images of my setup.


While I'm pleased with the buckling shape (visually K~1.0), the failure load of 547kN (+/- 5kN) is well above the critical buckling load.  I've tried creating a very stiff material to use as the rocker component and increasing the lateral load but the failure results were within 5%.  I would think simulating Euler buckling should be fairly simple, and I'm making a silly mistake.  I thought someone out there might have some suggestions from past experience.