Flexural capacity of W-Beam with plate welded on both flange?
Flexural capacity of W-Beam with plate welded on both flange?
(OP)
I am checking the flexural capacity of a W12x65 beam, its un-braced length Lb<Lp, because its flange is noncompact, so I welded a 10"-width by 0.25"-thick A36 plate on both flanges. My question is with this welded plate, can I now take the beam as compact I-shape member and use AISC-13th Part16, Section F2(page 16.1-47) to calculate its flexural capacity? (without these two welded plate, I have to use section F3. to do calculation.)
Attached is my calculation. Can anybody tell me if my calculation is correct (or if it meets AISC-13th code)?
Thanks a lot!
Attached is my calculation. Can anybody tell me if my calculation is correct (or if it meets AISC-13th code)?
Thanks a lot!






RE: Flexural capacity of W-Beam with plate welded on both flange?
RE: Flexural capacity of W-Beam with plate welded on both flange?
RE: Flexural capacity of W-Beam with plate welded on both flange?
To StructuralEIT: Yes I know compact flanges has nothing to do with unbraced length. But with Ld<Lp, I don't need check LTB, and I can just check yielding use plastic section modulus Z. My question is for those non-compact or slender W-beam, after we welded a plate on its non-compact or slender element, can we take it as if it were a solid compact member with the combined thickness as its flange or web thickness?
RE: Flexural capacity of W-Beam with plate welded on both flange?
You also don't have two individual plates either as the stitch welds at the ends of the cover plate do force the two to act somewhat together in terms of second order buckling under flexural compression.
So my response would be that you have "something in between" a fully combined plate and two separate plates.
Since you don't know for sure where "between" you are - you should tend towards the conservative and assume that the original flange plate is still the same b/t.
The cover plate would follow section B4.2.c where it says that the distance b would be the distance between the stitch welds. For your 1/4" cover plate this is even worse than your original b/t of the W12 flange alone.
The cover plate can buckle away from the flange plate per the attached sketch (with stitch welds). If you had continuous welds you could still buckle the top plate away from the top flange but in a spherical (hump) shape. How you would develop a b/t for that and utilize the given b/t limits I wouldn't know.
Again - where you don't have solid direction in the specs/codes you should tend toward the conservative assumption.
RE: Flexural capacity of W-Beam with plate welded on both flange?
RE: Flexural capacity of W-Beam with plate welded on both flange?
RE: Flexural capacity of W-Beam with plate welded on both flange?
RE: Flexural capacity of W-Beam with plate welded on both flange?