ASCE 7-16 C&C pressures (part 1 method)

[BrianApex]

Hey guys,

Right now I'm trying to automate a wind pressure chart for my company and using the part 1 method so they can enter in all the information and it spits out pressures for the different zones. I'm using the formula in the book p=q_h[(GC_p)-(GC_pi)]. I'm comparing that number with the part 2 method which has the values in the book. The positive number I get right on the money but the negative number is higher then what is in the book. I'm assuming the q_h value is correct otherwise I would get the positive value correct.

I'm not sure if i should just use the higher negative pressure that I'm getting or use a factor to get close to the number in the book. Let me know what you guys think.

To give an example of what I'm getting:

Zone 4 walls positive
My pressure = 40.48
Chart pressure = 40.5

Zone 4 walls negative
My pressure = -43.91
Chart pressure = -38.2

 

[BrianApex]

Found the issue, there is a typo in the ASCE 7 manual where the 140 mph pressures are the same as the 150 mph on page 353. The 140 pressures are correct but the 150 are not.