partially enclosed vs enclosed

[structuralnerd]

I am trying to determine if my large warehouse I am designing is classified as "enclosed" or "partially enclosed." There are some very large overhead doors in the project all in a row along one wall. Do you consider overhead door so be an "opening?"

 

[dgkhan]

yes

 

[CTSeng]

no

 

[jike]

See C6.5.9 and if you figure out what it says, please tell the rest of us. They could not have written it to be more confusing...

It says holes in the building envelope which are designed as "open" during a wind event. I would hope that during a 90 mph wind event, one would want to close the doors. Are we suppose to assume all doors are open?

 

[cvg]

in my opinion, doors and windows are not permanent openings in a building envelope, even if they are large or there are many of them.

 

[structuralnerd]

But what if the doors or windows are blown out? I have a call into the International Code Council. I left a message, so when they get back to me I'll let you know.

 

[FSS]

A door (or window) is not an opening as far as wind is concerned unless you have glazing and the project is in the wind-borne debris region. Then the glazing has to be protected or else it is considered an opening.

 

[DaveAtkins]

I used to think of overhead doors as openings. But I think FSS may be correct--all of the pre-engineered steel building designs I see call the building enclosed, even when there are multiple overhead doors on one side of the building.

DaveAtkins

 

[ronster]

Design as enclosed, the overhead door should be designed to handle the wind load so it does not blow out.

 

[Structures33]

The way it was explained to me --

If you consider the windows and doors as closed during a storm, and the building is thus classified as enclosed, the doors and windows need to be able to take the impact.

If the storm hits and the openings blow out, will the building be "open"? If the answer is yes, and you want to design as "enclosed", you need to specify impact resistant doors and windows.

An alternative in coastal regions (at least in the residential industry) is to have plywood to cover each opening on the premises. If the builder does not install impact resistant (which they typically don't because of the cost), they must provide plywood to cover the openings before a storm.

 

[hokie66]

When you compare the strength of overhead doors, even the ones which are supposed to be "hurricane proof", to the rest of the wall system, it is usually obvious that the doors will fail first. So I am wary of neglecting door openings. Remember, someone else is designing the doors, and if they fail, there goes your design assumption.

 

[jike]

I dug into this one time with the architectural specs and the overhead door manufacturers. It seems that, at least in my area, they are not designed to the required loads. Check the architectural performance specs and then discuss with the door manufacturer!

I agree with hokie66.

 

[haynewp]

I have gotten into this before too. I think the building should be able to be considered enclosed if the doors are designed to take the wind load. The other issue I have debated is whether the doors would be left open during a hurricane. I would state on the drawings that the doors have been considered to be closed during the design wind event for the design of the building.

For very large doors hangar type doors, I have read about pressure leakage and the partially enclosed assumption is more realistic. I think this suggestion may also be found in the ASCE commentary.

 

[CTW]

How can anyone guarantee that the overhead doors will be closed during a major wind event? Ensuring the doors are closed is not up to the engineer, and I doubt most building owners are trying to open or close doors during a storm to satisfy the engineer's original design intent.

 

[haynewp]

So I guess you also design all buildings if all the windows are open during a design wind event too?

 

[FSS]

Look in the Guide to the Use of Wind Load Provisions that ASCE publishes. Their examples don't even consider the concept of partially enclosed until the wind speed is 120 mph or above (i.e. wind borne debris). So unless you have a barn or something with permanent openings, don't sweat the partially enclosed stuff outside wind borne debris regions.