20130927

Another NSCP 2010 Erratum

This one is actually a question asked by a former student.. from back in 2010! She says:
I came across with Method 1 - Simplified Procedure, and in Equation 207-2, pnet=lambda*Kzt*w*pnet9, where pnet9, as given in the definitions, is the net design wind pressure for Exposure B at h=9m and Iw from Figure 207-3. I turn to Figure 207-3, and in the label of Figures 207-3 it states that it is "pnet (Exposure B at h=10m with Iw=1.0 and Kzt=1.0)". My question is if the Figure 207-3 is already the net design wind pressure (pnet) or is it the pnet9 (net design wind pressure)? Also, if the values are for a 10m high building or 9m high building?

Thankfully I've been looking at the NSCP 2010 recently and noticed these, too. My answers to her questions are as follows:
  1. Figure 207-3 provides pnet9 values.
  2. Figure 207-3 are the values for a 9m-high building in Exposure B, with Iw=1.0, and Kzt=1.0.
Additionally, I caution her (and all of you) that there are no negative pnet9 values provided in Figure 207-3 for Zone 2 (V = 200 kph). But in my opinion, you can assume the negative pnet9 values for Zone 2 as being the average of the values for Zones 1 and 3. It's great that we have 50 kph increments in basic wind speeds for the zones now. :)

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