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Modeling Impact Plastic Deformation in Large section I beam with two intermediate Transverse Stiffener to Web section Welds that failed  

Question asked by Gerhard Beckmann on Feb 2, 2018

Hello I am planning to use  SW.


I am working with an experienced SW professional to develop a plastic deformation model of a 54' long x 24 inch high I beam with 12" flanges 3/4" nominal thickness -  Bridge beam - that has two intermediate stiffeners along the length which are welded at web of I beam.  These connect to the next beam, etc, for a total of 12 which form the support of the roadbed and utility, sidewalk, etc... .


the top flanges are fixed into concrete roadbed and ends are secured at abutments, I am going to assume ridged- ?


The 'last' beam of the network was 'impacted' at a location approximately 1/3 of its length outwardly (but between the stiffeners) approximately and underwent a significant amount of plastic deformation over at least 20' of its length (with significant local plastic deformation at point of impact) - bottom flange , which was point of impact, rotated nearly to 45 degrees at the point of impact and displaced on the order of 11" from its starting position on the 'bottom' of I Beam ( i.e. a Bent Ribbon) - the welds at the intermediate stiffeners 'unzipped' and failed where web underwent plastic deformation (all but ~2" at top of stiffener to web) , the beam bowed over much of its length and there is axial torsion as described above.




unzipped weld:




My goal -


I wish to model the force required to produce the resultant observed plastic deformation?


i.e. beam web axial torsion at impact point and the influence of the failure of the welds at the I beam web that 'unzipped'  - only about 2" of the ~12" of weld remains intact, where the web of I beam is near where it was rigidly embedded in concrete roadbed ,


I want to establish a representative force to produce the observed impact damage - (impact velocity was <55 mph) - FIRST on just the beam sans welded stiffeners , and SECOND the beam with welded stiffeners for which welds failed ('unzipped') , which I assume will be a higher force, as energy was dissipated in fracture of welds.


I am working with an experienced CAD/FEM modeler , I just want to be sure I pose problem requirements correctly so as to be most efficient - thank you, appreciate any/all inputs comments/suggestions, experiences,  ------


These forces will be compared to 'likely candidate' impacters :-)