anchor bolts...do I need them.

[mark416]

Hey;

Is it stated any where in a code that a structure must be anchored down, specifically, anchored with anchor bolts to a foundation? I have a small shack (40ft long x 12ft wide x 12ft high, approximatly 41,000 lbs heavy.). Do I need to anchor it to the foundation per any codes in Canada even if wind loads cannot move it. There will be no issue for uplift since wind can not get underneath the shack.

Thanks,
M.

 

[csd72]

What stops it sliding horizontally
How do they erect the columns with no anchor bolts?

 

[COEngineeer]

it can still tip over. It is like pushing a box, you can still have upflift when it rotates.

Never, but never question engineer's judgement

 

[hokie66]

Wind doesn't have to get underneath to lift. Suction can do the job. But if your "shack" truly weighs 41000 pounds, that is about 85 psf, so it shouldn't blow away.

 

[lkjh345]

JMHO:

Why would you want to be the guy who goes out on the limb? A few well place anchor bolts would be of neglible cost, and would provide a lot of piece of mind.

Also, keep in mind, if there is a problem, it might be hard to prove that you followed a 'standard of care' consistant with what other engineers would do, as I believe most engineers would put in some anchor bolts.

JMHO.

 

[mikesg]

Not being an American, but what about OSHA? IIRC, there was a requirement about 4 bolts and a minimal load on top.

Mike

 

[frv]

I agree with the others.

Why take the risk?

 

[hokie66]

Mark,

Note that I am not "the others". If your structure is as heavy as you say it is, it doesn't need to be anchored.

 

[UcfSE]

Are you a structural engineer?

 

[hokie66]

UcfSE,

To whom is your question directed?

 

[UcfSE]

mark, the OP.

 

[hokie66]

He can answer for himself, but I think he is, based on his previous posts.

 

[DonPhillips]

To answer the OP, yes, both the 2006 IBC and IRC has a requirement for anchor bolts (or straps) for conventional framing (prescriptive). Otherwise, you follow ASCE 7 to determine your uplift and lateral force to determine the anchorage requirement and figure out how to meet the performance requirement you calculate.


Don Phillips

http://worthingtonengineering.com

 

[lkjh345]

I'm not sure that there would be all that high of a factor of safety to the shack moving.

Since the OP doesn't state what type of building this is, and what kind of foundation it is on, for the sake of discussion, I am going to suppose it is a steel framed ( or at least steel base plates) building on some type of concrete foundation.

I'm not at the office at the moment so I can't look up the coefficient of friction of steel on concrete, but supposing it is around 0.3, then the toal resistance to slideing is 41,000 lbs * 0.3 = 12,300#. 12,300#/ (41'long x 12' tall) = 25 psf wind needed to move the shack.

Not probable as I guess you could say this is part of the 'Main Force Resisting System' but its not a entirely out of the realm of possibility either in a severe wind event. Either way, its cutting it pretty close.

Of course, until I get back to the office, I'm guessing at the coefficient of friction. Or my assumptions about the type of framing could be off too.

JMHO.

 

[csd72]

ljkh345,

Actually the friction will be reduced by the suction on the roof so the resistance to sliding is actually even less.

 

[civeng80]

We have alot of shipping containers which are used as storage sheds and temporary structures. They are quite heavy and require no anchor bolts. So my answer to the OP would be if the structure is heavy enough then there is no need for anchor bolts.

 

[msucog]

what does 28 bolts cost? $40-$60 (u.s. $)? how much does the shack cost all together?

hmmm...let's throw out any engineering design and code arguments and just consider the cost versus any small advantage that could possibly be gained by putting them in. it's a no brainer (at least to me).

although, i don't really care if you put them in or not...i can't see it from here in the south anyway. but if by some chance you get a wild wind that is strong enough to move it, how many times will you kick yourself for now sticking a few bolts in there. if you don't want to put them in during pouring, spend twice as much and drill them in after the fact. either way, i'd suggest doing "something".

 

[msquared48]

msucog:

At the minimum of 6' on center in the US, I count even fewer bolts - 18. Probably 1/2" diameter.

Has to be less than $50.00 US. Oh, pardon me, that was yesterday... $100.00 today.

Just put 'em in.

Mike McCann
MMC Engineering

 

[gwynn]

Can't say I do any buildings, but my first response would be to check the National Building Code of Canada for any requirements. If they aren't there check the provincial and municipal codes for the building location. In some cases these are more strict than the national codes.

Assuming a steel structure, $50 bucks for anchorage bolts seems to me to be neglecting fab costs on the steel columns and installation, but I could be wrong (base plates, welding, drilled holes etc seem to me to be well over $50). To give the OP the benifit of the doubt, there is also the possibility of an existing or already built slab without the bolts in it. Costs can certainly go up depending on the situation.

Normally though the only cases where I would not add anchor bolts are with embedded columns.

 

[oneintheeye]

looking at it logically you probably dont need them. Temporary port a cabins etc are this size and are just lifted off lorry and placed on ground, pads etc (think site office accomadation). These dont go taking off in wind.
But to be sure by comparing the cost/risk to you personnaly, just put em in.