Car port under living space addition 1

[JStructsteel]

Whats your folks though on this? Got to design an addition to an existing house, adding about 400sf and 2 car parking below. Would you attempt this out of wood? No walls for shear either. I was thinking steel W shape with moment connections, adds redundancy, and also impact resistance.

 

[JAE]

There should be code requirements for fire resistance in the residential floor over the parking below - I would think a 5/8" thick gypsum board sheathing would be adequate but I don't know for certain. I do know that is what my own garage has for a ceiling below my occupied space above.


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[SteelPE]

The old soft story. Definitely going to be an issue. If you can't get wood shear walls on the first floor or bracing anywhere then using steel may be the only option. I might look into HSS sections vs WF sections as you can have identical I factors in the X and Y direction making moment connections at corner columns easier.

 

[KootK]

1) Steel moment frames sound reasonable to me so long as you can get the fire rating.

2) Concrete moment frames might appeal as well.

3) If you could brace the sidewalls and shear attach the deck to walls at that storage thing, that might be an option as three sided.

4) While I always hate to be the proponent of knee bracing, that might work for something so small and keep you in timber.

5) You might be able to do this as timber moment frames by running the posts up to the roof level and designating the entire second story wall system the "beams".



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[jayrod12]

I've done Koot's number 5 a few times to get things to work out. That project was in a remote area so steel and concrete beyond the absolutely necessary was forbidden.

 

[XR250]

I usually flagpole HSS members off a big footing in these situations.
Gets rid of the need for moment connections and braces it in two directions.

 

[Ron]

Have done XR250's approach many times with aluminum structures under high wind conditions. Could do the same with steel. Could even do the same in wood by creating a void in the concrete, then encapulating the timber in epoxy within the void.


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[JStructsteel]

Thanks for all the suggestions. I need to run the loads, see what I end up with. In the elevations the Arch does show some knee bracing.

I am worried about redundancy, its a collage residential housing, so when the drunk kid plows thru one of the columns, I need something to support the rest.

 

[XR250]

I am worried about redundancy, its a collage residential housing, so when the drunk kid plows thru one of the columns, I need something to support the rest.

Wood structures (even on poles) are incredibly resilient. Make sure your beams are continuous and you will probably be fine

 

[SlideRuleEra]

Homes and other structures that are 100% elevated are the norm on the southeast US coast (hurricane storm surge flooding). Supports of all types are used... driven piling, wood poles with or without footings, masonry, poured-in-place concrete, etc. FEMA has several publications that can provide tips.

http://www.SlideRuleEra.net

 

[dhengr]

Jrisebo:
As JAE mentioned, fire rating will be a big issue btwn. the car parking area and the living areas. If it is a fully enclosed garage, the interior must be fire rated so as to contain a car fire for some period of time, with 5/8” sheet rock as a staring point. If it is an open carport, the ceiling must be fire rated and then the exterior walls around/above the carport probably need special attention too, since any flames can move out and up the ext. walls. And, regarding protecting the columns (corner columns), make the first 3-4’ above grade a 12-16” concrete column, off the footing, and then put the wood columns on top of those. In effect you are providing something which does more damage to their car, than the car does to the structure (bollards). They’ll learn quicker than they do in the classroom. As for redundancy on corner columns, that’s a tough one.

 

[Rabbit12]

To prevent collapse could you look at the walls above as deep beams cantilevered off the existing? If one of the columns is removed I'd expect damage but you could maybe get enough connection strength to at least prevent total collapse.