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Originally Posted by norustplease
Only just seen your workshop project and as a thought, would comment that most steel building frames are bolted together using junction plates and have some diagonal bracing inserted both in vertical and horizontal planes to prevent the structure lozenging. Quicker than welding and also makes it easier to dismantle if alterations or relocation needed. Your cladding may give some diaphragm effect, but diagonal bracing is more certain.
Also what stops the building lifting off if you are caught in a gale with the doors open? Are you infilling the floor frame with concrete or some kind of precast unit ? If not, you could probably do with a few foundation pads around the perimeter in mass concrete to hold the building down. Don't underestimate the power of the wind! The problem with most lightweight structures is not just holding them up, but holding them down in storm conditions.
Generally (in UK) smaller buildings on dodgy ground are built on a reinforced concrete raft.
Apologies if you have thought of all this already.
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Thanks for your comments. One of the main reasons for posting on a forum is for feedback.
I have thought a bit about wind loading. The problem with any project like this is that you can get lost in the details (which is a particular problem for me). Sometimes when building things like this for the first time it is only when you start converting your plans from ideas and scribbles on the back of fag packets into a real structure that you realise that things need to be made a bit differently.
I have already reached the conclusion that I need more steel cross bracing even though there will be a wooden exoskeleton around parts of the steel onto which double skinned OSB will be fixed...
...the other thing that is apparent is that I need some more gussets at the welded joints as I'm now not happy with just a butt welded joint.
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Back to the wind =>
Self weight - despite the flimsy steel box sections - is not trivial. So far sleepers, steel and wood for the walls will weigh about 12 tons. (Floor not yet decided)
On a roof with an area of 100 square meters a lifting pressure would have to be in excess of 100kg per square meter. I expect all of the crap I will put in this workshop will be about 5 tons of assorted goodness knows what before I put in two vehicles.
I don't think it is going to go any where in a hurry. (A prolonged earthquake would probably do much more damage)
I doubt it is hurricane proof but on the whole we're quite lucky here with that. In a strong wind situation I'd expect a tree or two to fall over and damage the workshop before there is a technical problem with the wind loading.
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With the welded structure I have been worried about thermal expansion. Two sides of the shed will never see the sun (when it is really hot), whereas the other sides will. To counteract thermal expansion differences between wood and steel I plan to encase the steel in as much insulated wood as I can afford and hope for the best.
There is as always an element of hoping for the best in the absence of months of 3D solid works computer modelling (!) - {Alternatively months and months of digging through civil engineering text books and managing to not get irritated by their crappy guestimation assumptions that are more often than not NOT at all rigorous like "real engineering" <= Now there's controversy for you!}