M.E. help needed: Optimum cantilever beam shape?

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The Artist formerly known as Turbo84
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Clinging to my guns and religion in KCMO.
Just got back from a long road trip to the land of KWPLOT and TimAT. (I promise to contact you guys some time when I know in advance when I'll be up there.) Was motoring down the highway trying to figure out some stuff I want to try out (structure wise), and was contemplating some loads that are supported in only a cantilever fashion. Given a few different shapes (square, rectangular, and round) of the same length and especially weight, what is the most efficient shape? I can come up with arguments for each shape, and I've got most of my old mechanical books boxed and taped up for the move in progress, so I can't look up anything in them.

I appreciate the help, or any additional items to consider in the process here.
Mike
 
I'm no M.E. but a triangle is the strongest shape. A square or rectangle can be easily deformed with pressure on a corner. Round can be flattened with pressure anywhere around the outer circumference.

Look at those big overhead cranes (other than the one that collapsed just north of KC), they are all triangles with a cable supported by triangles running down the spine.
 
Thanks, guys. I'll confess my embarassment for not even thinking about a triangular shape. I was too focused on standard material shapes one can buy at a local welding/steel supply shop. I'm certainly not shy about fabricating a custom shape if that ends up being the strongest, yet lightest part.

Thanks again!
Mike
 
I'm no M.E. but a triangle is the strongest shape

I second that opinion.

That you're no Mechanical Engineer.?;)


This Electrical Engineer is going to vote for the I beam.

for a given amount of material and conversely weight, the I beam can be made taller which resists momental force better.

better get out your text books and brush up.
 
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...This Electrical Engineer is going to vote for the I beam.

for a given amount of material and conversely weight, the I beam can be made taller which resists momental force better.

better get out your text books and brush up.

Agree.

No engineer, rather a builder here, and don't know for sure how this applies to your needs, but when supplemental steel is required in cantilevered structures we either go with flitch plates sandwiched between lumber or I-beams depending on the application. Our last large cantilever was on a FLLW/Prairie School styled home finished last year, and measured 8' x 72', wrapping around the corners at both ends w/o any posts or columns whatsoever.
 
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:stirpot:Isn't an I beam a member, and a triangle a structure?
 
:stirpot:Isn't an I beam a member, and a triangle a structure?

naw, the thing between my legs is a member.

If you use a triangle you want the base of the triangle to be shorter than the other sides Isosceles (non equilateral). That will more closely simulate an I beam structure.
 
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so when is the get together at your new house :bounce:

This fall, or maybe next spring. Until the house here sells (and stuff ain't selling terribly quickly down here), it'll be a while before we get moved up there. I'll be sending out a garage-warming party announcement when things finally happen. Adult beverages will be provided.
 
so when is the get together at your new house :bounce:

This fall, or maybe next spring. Until the house here sells (and stuff ain't selling terribly quickly down here), it'll be a while before we get moved up there. I'll be sending out a garage-warming party announcement when things finally happen. Adult beverages will be provided.

I don't think houses are moving very well anywhere :amazed:

We will be watching for the party invites :thumbs::bounce:
 
I don't think houses are moving very well anywhere :amazed:

We will be watching for the party invites :thumbs::bounce:


Houses move VERY FAST on the great plains.......:fishing::fishing::tomato::tomato::eek::twitch:
 
I don't think houses are moving very well anywhere :amazed:

We will be watching for the party invites :thumbs::bounce:


Houses move VERY FAST on the great plains.......:fishing::fishing::tomato::tomato::eek::twitch:

:smash:Yep. Just ask Kevin

Yeah when them tornados come through,the houses move like a bat out of hell,i'm still fixing damage from the last one that went through here :huh:
 
I don't think houses are moving very well anywhere :amazed:

We will be watching for the party invites :thumbs::bounce:


Houses move VERY FAST on the great plains.......:fishing::fishing::tomato::tomato::eek::twitch:

:smash:Yep. Just ask Kevin

Yeah when them tornados come through,the houses move like a bat out of hell,i'm still fixing damage from the last one that went through here :huh:
OH shit, sorry man, THAT ain't funny....

I do think that I would build underground out there though....anybody do that??

:twitch::amazed:
 
Yeah there are quite a few earth'n homes around here,all you can see of them is the roof sticking above the ground,except for the S.E side,you can see the front of the house,the rest of it is below ground.Cut's down on building cost you only have to put windows on one side of the home.
 
...This Electrical Engineer is going to vote for the I beam.

for a given amount of material and conversely weight, the I beam can be made taller which resists momental force better.

better get out your text books and brush up.

Agree.

No engineer, rather a builder here, and don't know for sure how this applies to your needs, but when supplemental steel is required in cantilevered structures we either go with flitch plates sandwiched between lumber or I-beams depending on the application. Our last large cantilever was on a FLLW/Prairie School styled home finished last year, and measured 8' x 72', wrapping around the corners at both ends w/o any posts or columns whatsoever.


72 FEET?? what in hell you building there, a bowling alley??? jeebus.....
 
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