ASCE 7-10 Ch. 30 Part 3

[SoFloJoe]

Hi All,

Quick question, may already know the answer to this. But following ASCE 7-10 Part 3 for buildings > 60ft....

I have a high rise with Exposure Classification D. I am only interested in zone 4 and 5 for impact windows, but I do not see where this process takes into account the exposure classification. The closest thing I found is on Figure 30.6-1 under notes item #6 which references Fig. 30.4-2A,B & C but these only apply to zones 1-3. So is it safe to say that exposure does not effect zones 4 and 5? My gut is saying that it still should be, with something like either a Lambda coefficient (like part 2) or EAF (like Part 4).

Thanks in advance!

 

[NJ92]

Your gut is correct that the pressure should be affected by the exposure.

Figure 30.6-1 only provides the value for (GCp) for each of the zones. This value then needs to be plugged into equation 30.6-1 to get the design pressure on the zone. The 'q' variables in that equation are calculated from Chapter 26 which include kz, kzt & kd which account for the height, exposure, terrain and directionality. It may be helpful to look at Table 30.6-1 (pg 262 of the 3rd printing) which shows the steps to use Ch 30 Part 3. The wind chapters can get rather confusing since each section seems to have a slightly different method for determining the design pressure so the tables highlighting the steps are usually the first place I look to make sure I'm not missing anything.

 

[SoFloJoe]

Ahh its Kz I was missing. Thank you!