Web stiffeners
Web stiffeners
(OP)
I am trying to make a strong beam that is low in height. Two W12x72's side by side, stitch welded together, then attach 3/4" plate top and bottom. I want to use only fillet welds along the sides of the plates to attach them to keep cost down. I am looking at flexure, stress in the weld at the interface between plate and beam, and web shear capacity.
There are two loading conditions, point load in center, and symmetric loads separated by 10 ft.
I have analyzed the flexure and the capacity of the fillet welds. I am stuck understanding how to analyze and design the web stiffeners. I know the web is not sufficient by itself. I would like to just have transverse stiffeners on the outsides instead of both sides of each web. Can anyone point me in the right direction?
There are two loading conditions, point load in center, and symmetric loads separated by 10 ft.
I have analyzed the flexure and the capacity of the fillet welds. I am stuck understanding how to analyze and design the web stiffeners. I know the web is not sufficient by itself. I would like to just have transverse stiffeners on the outsides instead of both sides of each web. Can anyone point me in the right direction?






RE: Web stiffeners
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Web stiffeners
RE: Web stiffeners
I’ll second what KootK suggests. I’d fabricate a box beam/girder with a single top flg. of 42-50ksi mat’l., two thicker webs of 36-42ksi mat’l., and a single bot. flg. of 50-65ksi mat’l. Fillet welds, both sides on webs to top flg., and single fillet welds from the outside only at the webs and bot. flg. You start the fab. with the top flg. upside down on a stiff fab. table and apply the webs. You can apply cross stiffeners, were you want/as needed, clipped corners and welded to the top flg. and webs with fillets. You want to be able to roll the member from side to side for welding. Then, roll it over onto the bot. flg. to complete the bot. flg. welds. With those magnitudes of loads, you have to pay attention to top flg./web bearing stresses and may nibble bevels 12-16" long in the top of the webs at the load application regions to increase the weld metal area for the concentrated cross web loading. You must distrib. those line loads over some length of the webs. Then, you have essentially the same bearing type problems at the reaction points on the bot. flg. You have to pay attention to deflection under loading, and camber due to the fab./welding process.
RE: Web stiffeners
RE: Web stiffeners
Ix 2651 in4 Zx 470 in3 Sx 384 in3 Q 127 in3
Rotate W12 90 degree option
Iy 1720 in4 Zy 314 in3 Sy 255 in3 Q 108 in3
Per the information, I doubt the beam strength, deflection and the weld.
RE: Web stiffeners
RE: Web stiffeners
The diagram I clipped just shows the capacity of the beam in flexure with no regard to other factors. I included it mostly to show the load configurations that we are considering. The dual point load is what we expect for the engines, and the single point load is a worst case scenario that we evaluate in order to put a load rating on the assembly for general use without regard to engineering analysis. This company is a crane and rigging company and we would need to put a rating on the part just for general use because it could eventually be used for other jobs with unforseen configurations.