lifting torsion on column 1

[Astudy]

Hi all,
I am designing 4-points lifting lugs on columns for a modularized building, because of some restrictions, the lug has to be put on the flange of the column where there is no horizontal beam, and the column is sitting on a longitudinal beam, see the attached. The lug is designed for 25 tons lifting force. My calculations have verified the capacities of the column, lug and connection under vertical lifting force of 25tons. But I am not sure how much the chance is that the lifting load is not applied vertically nd how much the angle is appropriate if considering sideway off from vertical? If the lifting load is not vertically applied, what the ways to restrain column from twisting?
Any thoughts will help. Thank you in advance!

 

[Liam Nesson]

https://www.eng-tips.com/viewthread.cfm?qid=272990#post-1528474

They mention 5 degrees out of plane in the thread above.

Maybe turn the bottom section of the column into a HSS by welding plates between the flanges. Stiffen the column at the lug with 2 horizontal stiffeners between flanges and web.

 

[JLNJ]

The frame you are lifting probably will keep itself square as it’s lifted, but this doesn’t prevent the columns from feeling the eccentricity from the lifted load.

Said another way, the moment caused by the eccentric lift will induce forces and moments in your lifted module and these forces in turn cause flexure in your column.

A few simple calcs should tell you if your module can handle these forces.

 

[dik]

You should have no problem... just need long spreader beams to ensure the loads are uniformly applied.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dhengr]

Astudy:
You guys are always so damn coy in the way you ask an engineering question as to render it impossible to answer, short of guessing at 500 possible answers/solutions. Good on you for the module sketch, but not a single dimension or a few member sizes to give us some sense of scale and proportion. Is it 10’w by 9’h by 40’ long, or what? At 25 tons per lug, that’s 100 tons (200kips) for a module weight, is this already factored up, that seems fairly sizable. What size are the columns and the floor beams? These types of engineering design info. help an experienced engineer visualize the scope/magnitude of the problem. Your problem seems much bigger than just a little torsion in the columns during lifting. You have to argue more strongly for your case, with your other design team members, if they actually want this thing lifted into place, in the end. You shouldn’t have to suck hind tit, after everyone else has satisfied their needs and wants, and still be expected to produce the perfect solution to the lifting problem.

That’s hardly the ideal location for lifting lugs if these units are going to be placed side by side. You could put a saddle of some sort, which the sling would go through, at the top of the column, which would assure a vert. lift at the lugs. You might have two long spreader beams, one each side, which assure a vert. lift, through the saddles. What is your crane size and boom length, in terms of your rigging possibilities above the spreader beams; then, two or four slings to the hook? You might have a rectangular lifting frame which picks vertically at the four module lugs, and slings above that to the crane hook. You can’t always design your lugs for every possible lifting condition. Sometimes you have to dictate some of that. You should usually design your lifting lugs to take some out of plane lifting forces, and 5° seems reasonable for that. That will usually be a bigger issue in the design of your lifting lugs and their welding details, etc. than it will be in the structure you are connecting to.

Why not lift from the top corners with removeable lifting lug systems if you have a bunch of these to do? We know nothing of what this beam/col. detail looks like, but it might be modified a bit to accommodate your needs too. In fact, the lifting lug system might make up the four corners of a rectangular lifting frame. For the four lifting pins which you show right now, make a gusset pl. which is welded to the two fl. bm. flg. tips and to the outer col. flg.; it’s maybe 2’ wide at the bot. flg. of the fl. bm.; then tappers up to a 1’ dia. around the lifting pin at the top. This will help prevent either the col. or the bm. from rotating due to some lateral loading on the pin. This lifting point could be pins, as you show, or trunnions for slings, rather than lifting lugs.

 

[Astudy]

Hi Liam,
Thank you for your response! Yes I added stiffeners.

Hi JLNJ,
Thank you for your help! Yes, As you said what I worried about is the torsional rotation of the column if lifting load is out of plane. But how deep is the calculation should go, should I check the torsion stress? That’s a bit of work.

Hi Dik, Thank you!

Hi Dhengr,
Thank you so much for what your responde! You are absolutely right _ anyone asking questions should provide as much information as possible!
As for my case, the column is W8x67, building is 20ft Wx 12.5ft H x 60ft L. 25T is a factored lifting force, and there are spreaders between slings.

I can not use top of column to lift because the management worries about leaking. Have you ever encountered the leaking problem? How did you solved?

 

[Lomarandil]

Yes, you should check the total stresses (including torsion) for the specified lifting conditions (with some margin for operational error).

Or specify your rigging configuration (spreader bars and sling angles) to prevent any lateral forces from being developed.

I'm not quite sure what you mean by leaking.

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just call me Lo.