1.75" .120 hrew tube deflection

[ColeHous]

I'm new to the site and was hoping someone could help me. I'm in the process of building a project and need some help. I'm using 1.75"hrew .120 wall. It will be attached on both ends and the center will have a 4" mounting surface that a winch will be mounted on for lifting small loads. Can anyone help me figuring out how much weight this will safely lift and how much it will "bow" under load. It will be welded on both ends and the weight hanging from center. Thank you in advance.

 

[MikeHalloran]

hr = hot rolled, suggesting a yield around 36ksi for steel (not specified).
ew = electric welded, I think, which has no effect unless it fails
So you've got a tube, supported, maybe fixed, at both ends,
and loaded at the center if you just hang a hook there,
or maybe loaded at two places near the center if you mount the hoist with some kind of bracket; maybe that's the 4 inches.

Get out your Machinery's Handbook. If you don't have one, buy one, and never lend it.
Find I for a tube with your dimensions.
Find deflection for the load case you have given,
using 36 29 ksi for E (that's not the same thing as the yp, despite the units) and the I you have calculated,
and an arbitrary load plus the weight of the hoist.
Find stress for that same condition. If the stress exceeds yp, change something and recurse.




Mike Halloran
Pembroke Pines, FL, USA

 

[hokie66]

Mike,
E of steel is about 29000 ksi.

 

[MikeHalloran]

Oops, brain fade.
ColeHous, Hokie is right.
Thank you, Hokie.


Mike Halloran
Pembroke Pines, FL, USA

 

[transmissiontowers]

I believe E (Young's Modulus) is 29,000 ksi for steel. I might use a safety factor of 2.0 for load if you are just doing some hand calculations for a load limit and I would not stand under the load. If the OP has an AISC steel manual, there are beam formulas and member properties.

_____________________________________
I have been called "A storehouse of worthless information" many times.

 

[ColeHous]

Thank you all for the pointers.