Fixing a 3000 lb on an I-beam

[Karish]

Here is my scenario.

we have a frame, 34 feet tall and 23 feet long.
the columns are 12x12x0.375, Beam is W24x229.
This is built to proof load up to 70 kips in point loading in the center of the beam (ultimate factor of 5).
There are no lateral bracing for the beam and the columns are braced at the top. we are looking to purchase a wench (hoist unit) which weighs 2889 lb hoist & bottom block and 500 lb sheave assembly. problem is we do not know how to actually mount it on the bottom of the I-beam. The bottom block is 70 inches by 27 inches and it will most likely be over hanging giving us torsion which on an I beam is never good. The sheave also has 9 inches of play over 34 feet which is not bad but still would give us extra torsion in beam. I even called DEMAG engineers and the guy told me he never mounted one like that on an I-beam and told me to shove off till we actually purchase one.
What is the best way to mount the wench accounting for the wench load and the torsion the starting and stoping of the electric motor will cause?

 

[PEinc]

Mount a wench? This is too risque for this forum!

 

[PEinc]

Do you have an erection plan?

 

[JAE]

You could possibly add cover plates to the W24 to create a box shape - adding greatly to its torsional ability. Then, perhaps a WT on the bottom, sized to work with the hoist.

I would also consider looking at additional lateral bracing of the beam to help with the eccentric loads.

Finally, get a structural engineer to look at it if you aren't comfortable with this design or aren't qualified in structural. Based on the actual in-place conditions and details, they could probably solve your design problem here without too much trouble.

 

[Karish]

Thanks for the reply guys.
my boss is a structural engineer and i am a civil one.
we thought about mounting a big ass plate on the bottom and using counter weights but he is not sold on the idea. I was also thinking about boxing in the whole beam on both sides making it a closed section and hence better at torsion resistance. I posted this to see if anyone had experience with fixed wenches. Lateral bracing for the beam is not an ooption by the way otherwise we would be sitting good with. Our logistics are not in the best place but that was beyond our control.

 

[JStephen]

I'm not real clear on the details of your installation, actually.

But first off, a "winch" is a hoist, and a "wench" is a woman from olden days. Hence the suggestive responses above.

The approach to the moment would be to delete the moment, not support it. You should be able to mount the winch in some way so that it pulls directly from the centerline of the beam. If that won't work, try hanging the hoist from a swivel, as opposed to rigidly supporting it from the beam.

Moment from the motor starting and stopping should be negligible, I would think.

 

[Karish]

Thanks for the reply guys.
i did not know wench ment women
I will try to look at the winch hanging instead of mounting to the bottom of the flange and see what i come up with.

Any more suggestions feel free to post them.

 

[boo1]

Would a pad eye work if welded in plane with the Ixx axis?

 

[steve1]

Any chance of arranging the lifting apparatus such that any eccentricity is along the axis of the beam rather than normal to it?

 

[Karish]

The winch is 34 feet high so the sheav has a maximum movment along one axis of 9 inches or 4.5 inches each way if u center it half way down. I can set it up where it will be along the Ixx axis but the winch will be perpendicular do the I beam (which is ok). However that would preduce an axial load on the columns due to the 4.5 inch eccentricity.
The majore problem is my boss is not sold on the idea and i am trying to convince him otherwise. the only practical way to proof load tools in a timely manner is with a winch.
So how do you suggest connecting the winch perpendicular to the bottom flange? weld a plate to the top of the winch and then weld it to the flange along with supports welded all the way to the web on both sides?

 

[apsix]

I don't know what a W24x229 beam actually is, but if it is 24" deep it will be working hard with 70 kips (if my conversion is right). Have you considered the consequence of failure?
Also, a proof load hanging from the bottom flange does not accurately replicate loading at top flange level.

 

[Karish]

A 24x229 is 26 inch deep with 13.1 inch flange of 1.73 thickness. with the unbraced length we got it can handle 1.47 Mft-lb of moment. It can handle the load pretty good. The beam was already purchased so we have to use it. Now accuratley analyzing the hoist and sheave at the bottom is the problem at the moment. It seems to me that it's the way to go i just have to prove it to my boss.

 

[steve1]

Karish,

I don't think you need worry much about additional axial load on the columns due to a 4.5 inch eccentricity along the centerline of the beam.

An interfacing framework is often used when connecting machinery to its supports. One side of the interface is designed to mate with the machine, and the other with the support. That is what you must come up with. I would imagine that it would consist of plates, welds, stiffners, etc.

Kinda hard to be more specific without seeing the geometry of the machine (winch and sheav).

 

[ehcet]

Hi

I am not surprised by DEMAG answer.
I worked for DEMAG in Canada for 3 decades, designing cranes
supporting structures etc.
Without having some sketch or picture about your winch and also what you want to lift, it is very difficult to give advice.
Question! If you use only one beam why dont you purchase
a underruning hoist and placed on the lower flange. They are designed to have the bottom block in the center of the
vertical axis. But, you have to check the lower flange local
stresses. (no brainer).
If you can be more specific and supply sketch I would be
able to tackle your problem.
Regards
EHCET

 

[Karish]

Thanks for the reply guys

today a salesman for air winches came by and showed us a catalog. the air winches have a point load without laterl moving cables. With more information (which we are waiting on) that could solve our problem. two air winches at 1/3 span will lower our moment significantly.