Existing hoist u-bolt rating
Existing hoist u-bolt rating
(OP)
Hello-
I am analyzing an existing hoist beam and have a question on how to check the u-bolt hoist attachment. In the attached picture you can see the beam cantilever through a concrete wall and at the left end of the beam is a 3/4" u-bolt through both flanges. Both of the existing "hoists" in the picture will be removed and one hoist will be attached to the existing u-bolt with a hook very similar to what is shown in the picture.
So I am thinking I need to check the u-colt for tension, which has two legs, and shear. However for the shear, is it double shear or single shear? Since the new hoist will attach with a hook, it makes me wonder if it would be single or double shear. I am leaning toward single shear just to be conservative but would appreciate some feedback.
Thanks
I am analyzing an existing hoist beam and have a question on how to check the u-bolt hoist attachment. In the attached picture you can see the beam cantilever through a concrete wall and at the left end of the beam is a 3/4" u-bolt through both flanges. Both of the existing "hoists" in the picture will be removed and one hoist will be attached to the existing u-bolt with a hook very similar to what is shown in the picture.
So I am thinking I need to check the u-colt for tension, which has two legs, and shear. However for the shear, is it double shear or single shear? Since the new hoist will attach with a hook, it makes me wonder if it would be single or double shear. I am leaning toward single shear just to be conservative but would appreciate some feedback.
Thanks






RE: Existing hoist u-bolt rating
RE: Existing hoist u-bolt rating
I would consider a pin and a welding eye (http://www.anvilintl.com/products/pipe-hangers-and...) with a published capacity.
RE: Existing hoist u-bolt rating
Thanks for the feedback. Yes, the bending of the u-bolt is a concern, and when I checked it, it is what governs the capacity.
JedClampett-
I agree that a u-bolt is not an ideal hoist attachment, however they are sadly everywhere at most grain elevators in our area. Our client wants a rating for what is existing and then if that is too low, we would look at repairs.
Thanks
RE: Existing hoist u-bolt rating
Some questions for you to answer in the process of evaluating this U-bolt lifting device.... The mat’rl. spec./strength of the U-bolt material; dimensions of the entire system, and some good well proportioned sketches of it; beam size, dimensions, back span length and attachment to the structure, bearing stresses and conditions on the conc. wall, mat’rl. spec. for beam; top flg. bending under the U-bolt nuts and over the beam web; what is it used to lift, and its size and wt. The analysis of the U-bolt itself, involves some bending, shear and axial stresses, and combinations of these at various locations. Take a look at the design of hooks, chain links, curved/bent beams, Hertz bearing stresses, pin plates, as in lifting lugs, and ASME below the hook lifting equipment. Then, add some safety factor for rust, deterioration, your own uncertainty, etc. The large hook seems to fit the U-bolt pretty well, and that’s important for the bending and bearing stress issues. That system may be o.k. for your final application, but that isn’t the way I would detail it, if I could start over by removing the U-bolt, and modifying the tip of the canti. bm.
RE: Existing hoist u-bolt rating