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RE: Wind Load Net Pressure vs. Design Load Case

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I agree with your interpretation that the roof load ought to be included 
with the cases shown in figure 6-9.  I guess I've never really thought 
about it much, because 95% of the buildings I do are commercial buildings 
with flat roofs, so it doesn't really factor in.  But if you have a 
monoslope or gable with a significant horizontal component to the force, 
that should be added to the wall pressures.

Yes, more clarity in the complicated procedures that have become a part of 
our code would always be welcome.

-- Joel

the structural alliance
Joel Adair, PE, LEED AP
T  469.330.5200 x-204

-----Original Message-----
From: seaint-seaosc(--nospam--at) [mailto:seaint-seaosc(--nospam--at)] On 
Behalf Of Polhemus, William Sent: Thursday, January 16, 2014 6:36 PM
To: seaint-seaosc(--nospam--at)
Subject: RE: [SEAINT-SEAOSC] Wind Load Net Pressure vs. Design Load Case

Okay, let me clarify what's bugging me about interpreting this.

You state here - and I agree - that you come up with "magnitudes of 
pressures applied to each surface" which includes the windward, leeward, 
and side walls, and the roof, as illustrated in Fig. 6-6/27.4-1.

So for example typically you're going to have a varying pressure on the 
windward face calculated from q-sub-z*G*C-sub-p, and uniform pressures on 
the other three walls from q-sub-h*G*C-sub-p, and a pressure profile on the 
 roof similarly.

But then when you go to Fig. 6-9/27.4-8, and look at CASE 1 it illustrates 
pressures on windward and leeward walls ONLY, and in fact Note 3. of that 
figure explicitly calls those "Windward/Leeward face design pressures". So 
where are the pressures on the roof and the side walls in that 
illustration? Okay, I guess the side walls cancel each other out. But what 
about the roof load? Do you take for example the roof loads in each 
direction, and ADD them together for CASES 3 and 4 (multiplied by their 
respective reduction coefficients in each CASE)?

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