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Wind Loads... Roll up Doors "open" or closed?

Wind Loads... Roll up Doors "open" or closed?

(OP)
I'm working on an intense project where our company interpreted that a building was fully enclosed.  It is a large industrial building with about 10 rollup doors.  Half are on one wall, the rest spread out on two of the other faces.  

Now we are being told by the building designers that we should have known the building was partially enclosed... that we should have interpreted the rollup doors as openings... is this common?  How do you typically treat roll up doors in a scenario like this?  If operable doors in general are to be considered "open" then many buildings would classify as "open"...  They are looking for an immediate response from us.

thank you for the help.

RE: Wind Loads... Roll up Doors "open" or closed?

I assume this is a pre-engineered metal building (aka hay / tractor type barn). If so, the MBMA Low Rise Metal Buildings Manual defines Openings (used to calculate the enclosed / partially open criteria) as "Those areas in the building envelope (wall, roof surfaces) which do not have a permanently attached means for effective closure.

Roll up door should fit the ticket.

The building designers need to be quized as to their qualifications.

RE: Wind Loads... Roll up Doors "open" or closed?

As long as the doors themselves meet the same wind load/speed requirements of the building code as the building shell proper, the building would be classified as enclosed.  If you think in terms of a "design event" for wind being typically 90 mph (most places in the US), most owners would know enough to close the doors well before that level of wind was reached.  
Depending on the distribution of the openings it may be that the building would qualify as enclosed even without wind resistive doors because of the relative opening sizes in multiple walls.  This gets a little misleading since then you are assuming all of the doors are open at the same time.
For a building with a large number of doors and relatively short roof spans there may be some economic advantage to specify the building as partially enclosed and not worry about wind resistive door design, but only if you don't care if some of the contents get wet when the doors blow in.

RE: Wind Loads... Roll up Doors "open" or closed?

Culmechanical,

I agree with jimzpe.  

You need to check for all wind directions the definition of open, enclosed and partially enclosed buildings in section 6.2 of ASCE 7-02.  It depends on the gross area of all walls and roof, and on opening area in each surface.  

First, assume all doors in the building are open. For wind blowing on the wall with 5 doors, you probably meet test 2 in the definition for partially enclosed buildings.  But, with 5 open doors in the windward wall, and 5 more (I've assumed all doors are equal in area) total on sides and leeward, you do not meet test 1 of the definition for partially enclosed buildings.  You need to check this with actual door areas and wall areas.  For wind on any of the other walls (all doors still open), you don't meet test two in the definition. (again, assuming all doors equal size.)

Next, you might consider a case where only some of the doors are open.  If only the 5 doors on one wall are open, and all the others are closed, you may indeed meet test 2.  But, as jimzpe noted, the doors are there to be closed.  If they are closed, they may fail under wind loads, but should not; after all they are to be designed to withstand this same wind.  (were they so designed?  You must check this.)  Are they merely left open?   Is this a normal condition, that some doors are left open and others closed?  In addition, is it reasonable to assume that during this design wind event, that the occupants did not close all the doors?  My opinion is that this is an unreasonable expectation, rather, I expect that the occupants will close the doors.  

So, only in the event that the windward doors alone are open during the design wind event is that building partially enclosed.  You and your colleagues need to determine if that is a possible or a necessary design condition, either if the doors fail, or are left open by the building occupants.  

I hope this helps.


Regards,


chichuck


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