Response to students' questions on NSCP 2010 wind loading provisions

These are actually in the comments, but I thought I should promote them to a full post. The first asks about leeward wall pressures:
Are the values for the Leeward wall pz really constant with elevation?
My reply: NSCP 2010 Figure 207-6 answers your question. :)

Another student asks,
We are estimating wind loads on the MWFRS of the bldg. The building is a low-rise type and the calculations will be done using Method 1 of NSCP 2010. It is said that Method 1 is applicable to both gable type and flat roof type buildings. The one indicated on Figure 207-2 of NSCP is a gable type building where there are wind pressures applied on Zones A, B, C, D, E, F, G, and H. First: what will happen to the loads on Zones B and D for flat roof types of buildings? According to the table provided by NSCP there are negative horizontal pressures on these zones but since the eave height is equal to the height of the structure, I think B and D should be zero. Second: will there be no pressure applied on the rear side of the building?
My answer: I think the NSCP is quite clear on what the answers to your questions are. :D  However, as I have emphasized in class, make sure to consider at least 4 wind directions!

A third student asked:
In your example problem, shouldn't the roof pressure coefficient values be multiplied by 0.80 to account for area reduction? So -0.18 should be -0.144? :)
My answer: The NSCP 2010 appears to say that the 0.80 reduction factor for area should be applied only to -1.3 and not to -0.18. The NSCP 2001 did not specify a -0.18 coefficient but it did say that the reduction factor applies only to the -1.3 coefficient. You can check the ASCE7-05 provisions to verify.


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