===== Steel plasticity with buckling ===== 

This example demonstrates computation of a structural detail, where a girder beam crosses a column. A welded pair of U profiles 300 mm creates both cross-sections of the beam and the column. The geometry and the mesh were created in [[http://www.salome-platform.org|Salome]] and converted to OOFEM input file via [[unv2oofem:unv2oofem|Unv2oofem convertor]]. 

{{:gallery:steel_plasticity.zip|A downloadable zip file}} contains Salome's hdf file, unv file, OOFEM input file and the control file. Although symmetry could have been used and the problem reduced 8//x//, the full-scale simulation is carried out to demonstrate symmetric response.

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This task contains 10 383 nodes and 30 786 linear tetrahedral elements. Perfectly plastic material is assigned to steel with the yield strength of 200 MPa. Arc-length method with IML solver were employed and the computation in eight loading steps took 11.5 min. Maximum axial force 1.58 MN on the column leads to collapse in plastic/buckling mode. Updated Lagrangian formulation ensured updating nodal position after each time increment thus facilitating second-order theory and equilibrium on deformed shapes assuming small strains in constitutive laws.

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//Created 01/2011 by Vít Šmilauer. Acknowledgements belong also to B. Patzák, Z. Bittnar, and T. Roubal.//