Partially Enclosed Building

[ron9876]

If you have a building with three solid walls and one completely open wall it meets the requirements of a partially enclosed building per ASCE7. However it seems to me that the intent of ASCE7 is for a building with openings not a completely open wall. I think that the value of the internal pressure coefficient should be the stagnation pressure coefficients not 0.55. Any opinions?

 

[ron9876]

Let me add that for wind parallel to the opening I would use 0.55.

 

[slickdeals]

See attached. It will provide you more clarity.

 

[steellion]

A similar building to what you are describing would be a hangar. Hangars are designed as partially enclosed buildings in accordance with the UFC.

 

[ron9876]

slickdeals the attached is for MWFRS and since the values are near 0.55 it is easy and reasonable to use the largest value. But what about C&C? There the values can be well above 0.55.

steelion that condition is for "leaking". To me the 0.55 makes sense for that condition. But in a condition where there is no wall then it seems to me that the stagnation pressure makes sense.

That is my real question-is reasonable/necessary to treat the two conditions differently.

 

[a2mfk]

slick- what is that document? Nice to know I've been thinking about it right all of these years. I have always thought of hangars, garages, and any other three-walled structures as the worse when it comes to wind. Like a paper grocery bag laid flat, the air can enter in but has a hard time leaving, thus causing the large internal pressures.

This has been confirmed forensically after damaging wind events where garage doors were blow inwards and then windows, doors, or worse case, walls/roofs are then blown outward. Though that document did not spell it out, it should also be clear the left-right wind direction will produce your worse case uplift on the roof due to the large internal pressure and upward pressure on the ceiling (if its there) or on the underside of the roof....

In Florida this has led to better garage doors, better tracks, and even stiffener posts and beams that can be quickly installed prior to a hurricane. Some systems have a pre-drilled hole(s) in the slab where you insert a pin/dowel to stiffen the bottom of the garage door. During the busy season of 2004 in Central FL, I put a couple of garbage cans filled with water in front of my old-school outward swing door, and the same on the inside. Some people parked their cars next to their doors inside and tied them off to the bumper...

 

[csd72]

different code, but when I designed industrial sheds in Australia the code there specified an internal pressure depending on the relation of the dominant opening to all the other openings. At worst it could be equal to the external pressure at that opening (calculated as if it wasnt there).

 

[ron9876]

csd72 that is what I mean when I say stagnation pressure.

 

[a2mfk]

Ron- maybe I am confused by your question (or by ASCE), seems that you agree now that +/- 0.55 internal be used for this situation. I would use that plus your worse case cladding pressure coefficients:

The +/- algebra can get confusing so I fudged the CC to cut to the chase...

Windward direction towards door opening, back wall pressure = +.55 internal + CC suction on leeward side of back wall

Leeward direction towards back wall, opposite of door opening = -.55 internal - CC positive pressure on leeward side of back wall

 

[ron9876]

I was agreeing with 0.55 for MWFRS since the GCpf factors are close to 0.55. But C&C factors aren't close thus my question.