2 floor garage

[WillR]

I am in the process of designing a 2 floor garage. My question applies to the top floor design.

The floor measures 26.5' x 26.5'.

The floor will be supported by 4-12"x6.5" steel beams every 5', that are resting on filled block pilasters that are integrated into the 12" block wall below the floor.

The Engineer at the Steel distributor chose this steel so I did not have to use center columns in the bottom basement.

The floor will be poured on top of Steel Corrugated pan.

The top floor will also sit on top of the 12" block with a 6" "lip" all the way around. There are no "holes" in this floor passing through to the basement.

My question. I plan on using fiber reinforced concrete and was wondering is it still recommended that I use rebar in this floor?

My load will only be 2-3500lb cars, but I have to keep in mind if I ever sell the house, the next owner may pull something bigger in the garage.

Thanks for reading.

 

[JedClampett]

A couple of questions: What is the thickness of the concrete? Does the corrugated pan have composite properties, (i. e. does it have some mechanism for transferring shear at the concrete/steel interface so that they will act together)?
I'd still have a structural engineer review the design. There are several issues such as deflection, lateral bracing of the top flange, etc. that need to be addressed. It will be money well spent.

 

[WillR]

Sorry I missed that.

From what I understand, the Corrugated pan depth changes 2", so the concrete will be 4" - 6" deep.

Also I understand that the Corrugated pan is all bolted (or) spot welded together so it is one piece, but it just floats on top of the steel and the side walls.

The outside form on top of the sidewalls is 2 course of 6" block that sits on top of the 12" wall, giving a 6" lip that the floor and metal pan sits on. (the weight of the 2X4 walls carrying the roof system for the garage top level will sit on top of this 6" block.

The concrete floor has material used in expansion joints around the outside edge where it meets the block wall.

This garage is being built into a hill, so 3 of the sidewalls have dirt against them, as well as the pilasters on the inside. (Located in PA).

I am working with someone who has done this before, but I also am "reviewing" his recomendations. (he is not an Engineer) I have seen others build this same style garage in the past (only smaller) using plywood forms underneath the floor with jack walls installed to hold up the plywood until the concrete set.

Thanks

 

[RG88]

I would press the steel distributor on this one. If he designed it, he can seal it. If he can't seal it because he is not licensed, well that is illegal. Steel distributors usually have retained engineers to prepare shop drawings on projects that the distributor is supplying.

100% agree with Jed Clampett on the hiring of a structural engineer. Call the local building inspections department and ask them about the engineers in the area...some who have done this before.

Unfortunately you have several issues with this that cannot be addressed without physically being involved in the project. Such as:

Foundation capacity and concrete reinforcement.
Beam pockets...Bearing plates, reinforcement.
Min bearing length of beams in pockets.
Unbraced length of the beams (26' is a lot of unbraced length for 12" deep beam).
Interface between decking and beams.
Moment capacity of decking (with/without rebar, studs, puddle welds, etc). Style and concrete thickness are just the beginning.
Location of control joints.
There is not engough room to list them all.....

The engineer is well worth it in this case. The chances of failure, especially catastrophic failure are just too great. I respect your detailed involvement in your project, but if there ever was a justification to hire a structural engineer on a residential project, this is it.

One question, why does your building inspector not require engineering on this? I know of no building code that permits this without supporting engineering from a design professional.

 

[WillR]

RG88 wrote
One question, why does your building inspector not require engineering on this? I know of no building code that permits this without supporting engineering from a design professional.

That’s just the way it is where I live. I have already spoken to him about my plans; he will review the plans as part of the permit, and maybe make suggestions, but does not require an engineering seal. I guess this is part of living in Amish country.

You guys have opened up a lot of questions in my mind. I will be having an engineer check out my ACAD drawings after I have finished them. I just hope to have everything "correct" before the engineer sees the drawings.

I don't mind paying an Engineer to show me what I need to change on my drawings. I need to find the right engineer; as I can't afford to pay for hours of research.

I believe the theory it’s cheaper to do it right the first time compared to redoing it.


Thanks again.

 

[boo1]

Woww, what a starter project!

GOOD LUCK