Plate Girder Design with AISC 13th Edition
Plate Girder Design with AISC 13th Edition
(OP)
Hello all,
Does anyone know why the plate girder design chapter (Chapter E) in the ASD 9th edition was omitted in the 13th edition? With that being said, how would all of you go about designing a tapered plate girder with the current edition? Thanks.
Shaylon
Does anyone know why the plate girder design chapter (Chapter E) in the ASD 9th edition was omitted in the 13th edition? With that being said, how would all of you go about designing a tapered plate girder with the current edition? Thanks.
Shaylon






RE: Plate Girder Design with AISC 13th Edition
E7 for computing Pn of a slender section. You'll also need E4 if flexural-torsional or torsional buckling applies.
User note at first of Ch. F for selecting the correct section for Mn. You can end up in F3, F4, or F5 depending on what's slender--the flange and/or web.
See G2 and G3 for shear strength without and with tension field action.
RE: Plate Girder Design with AISC 13th Edition
RE: Plate Girder Design with AISC 13th Edition
RE: Plate Girder Design with AISC 13th Edition
With that said, you should refer to DG 25 for tapered members as others mentioned, which just came out. I read it while it was still in draft (Dr. White was my grad steel professor), and the moral of the story is mainly to use the direct analysis method (which is also advocated in 360-10).
Structural Design Engineer
New York, NY
RE: Plate Girder Design with AISC 13th Edition
I'm confused
RE: Plate Girder Design with AISC 13th Edition
RE: Plate Girder Design with AISC 13th Edition
AISC Engineering Journal
First Quarter 2009 Volume 46, No.1
"Design Aids for Built-Up I-Shaped Beams with Slender Webs" by Paul P. Nasados, Jr.
RE: Plate Girder Design with AISC 13th Edition
RE: Plate Girder Design with AISC 13th Edition
RE: Plate Girder Design with AISC 13th Edition
I apologize if my comment caused some confusion.
Structural Design Engineer
New York, NY
RE: Plate Girder Design with AISC 13th Edition
I think the main reason they use the DM is to avoid dealing with Kx. It's easy for them to push the initial geometry to H/500 to one side, reduce AE and EI and run the analysis.
RE: Plate Girder Design with AISC 13th Edition
RE: Plate Girder Design with AISC 13th Edition
However, I admit that, even as a specialist in this sort of thing, I find DG25's formulations to be somewhat baffling and counterintuitive. The average design engineer who's very familiar with the AISC Spec. will find it frustrating.
Now that I think of it, the Lee et al. documents might be a lot easier for a typical design engineer to pick up and use. Not sure if one needs the Lee et al. documents. Just look at Appendix F of the 1993 AISC Specification.
RE: Plate Girder Design with AISC 13th Edition
I believe most of the metal building guys had programs that extended their software beyond those limitations. But, what criteria did they use to do that? There was never a clear specification on how to do this. Therefore, every company probably did this a little differently. At least now, we should get to the point where there is some consistent guidance on how these members should be designed.
RE: Plate Girder Design with AISC 13th Edition
RE: Plate Girder Design with AISC 13th Edition
Overall analysis: First-order using stiffness matrices for tapered members.
KL/ry buckling: doesn't change significantly due to taper, so use the Spec. as is.
KL/rx buckling: use rx at a magic distance from the smaller end (something like 0.57L IIRC) and treat the member as prismatic. Compute Kx using analytical formulas or eigenvalue analysis within their program.
Accounting for slenderness in the axial strength calcs: evaluate at stations.
Flexural Yielding or FLB: this is a station by station check, so no mods reqd.
Flexural LTB: Evaluate at closely spaced stations and use prismatic member equations.
Interaction equations: station by station check.
Shear check: station by station check, so no mods required. I think most did/do subtract the vertical component of flange force per Blodgett's method, although this method is mentioned as unverified in DG25.
Sorry for typos and poor grammar--in a hurry.