Applying ASCE 7 Wind Loads
Applying ASCE 7 Wind Loads
(OP)
The attached sketch shows two buildings that by ASCE 7 definition are considered enclosed buildings. When designing the MWFRS, the wind loads are applied to the "projecting area" according to figure 6-9 of ASCE 7-05. Even though the pole building has open area, I have been applying the loads to full area as shown. I have some coworkers that believe you only need to apply the loads to the solid areas. I don't see anywhere in ASCE 7-05 where this is stated.
I don't have my new copy of ASCE 7-10 yet, so I apologize if it is covered in the new standard. Thank you for your comments in advance.
I don't have my new copy of ASCE 7-10 yet, so I apologize if it is covered in the new standard. Thank you for your comments in advance.






RE: Applying ASCE 7 Wind Loads
RE: Applying ASCE 7 Wind Loads
That being said, let's take the pole building example to more of an extreme. If it's 30' tall and only has 3' of wind surface at the top I don't think I would look at it with a full wind surface. That doesn't make sense.
RE: Applying ASCE 7 Wind Loads
RE: Applying ASCE 7 Wind Loads
The pole building as drawn is neither partially enclosed or open. In order for it to be open all sides must be at least 80% open. Even the gable end, with just the gable sheathed, is less than 80% open.
Intuitively it does not make sense to think of the pole building as anything but open. I am guessing ASCE could not cover every possible "openness" case. So, if the structure is not completely open, it is conservatively lumped into the enclosed case. I am guessing this is the reason. Of course you could do wind tunnel testing.
RE: Applying ASCE 7 Wind Loads
RE: Applying ASCE 7 Wind Loads
I have and will always say that our wind loading procedures are a bit of black magic for most buildings out there. But it seems to work.
Back to the post - yes, I would conservatively apply it to the entire surface.
RE: Applying ASCE 7 Wind Loads
Other than that, I look at the way the wind acts against each wall like I would any other structure. If there is no surface for the wind to hit, then why would we pretend it is there?
Maybe I am missing something here....
RE: Applying ASCE 7 Wind Loads
RE: Applying ASCE 7 Wind Loads
RE: Applying ASCE 7 Wind Loads
RE: Applying ASCE 7 Wind Loads
EIT, New York, NY
RE: Applying ASCE 7 Wind Loads
In addition, a Minimum Pressure of 10 psf applied on projected areas is required. I assume this is intended to apply to the gross projected area, regardless of openings.
IMHO, ASCE 7 is not clear enough on the issue. Without clarification from ASCE, it may be prudent, even if overly conservative, to use the full projected areas.
RE: Applying ASCE 7 Wind Loads
On the other hand, you could have a smooth interior surface and the wind cleanly blows right through the barn, but it is noted that even our air duct systems (sheet metal) has calculated resistance to air speed.