CC Wind Pressures on Cladding Elements

[brut3]

I am designing cladding elements that will be installed on the exterior ground floor of an existing high rise (500ft mean roof height). The maximum height that the cladding elements will be installed on the building will not exceed 20 ft above grade level.

Ideally, my client would like to use the 20 ft height when determining the wind pressures for the elements that will be installed. I'm leery of taking this approach without having something to substantiate my wind pressure calculations. My question is, has anyone ran across an area of the code or commentary that addresses this issue. Or is there anywhere in the code that explicitly states that the overall mean roof height of the building must be used when determining the CC pressures. I forgot to mention that I'm working with ASCE 7, but would be open to other design codes guidance if this is specifically addressed.

 

[phamENG]

my client would like to use the 20 ft height when determining the wind pressures

Of course they would. It costs less now, and your insurance will pay for it when it fails. Win-win for them.

You need to look at the whole building to determine your coefficients. The wind doesn't care where your cladding is attached, it cares about the shape of the building its going around.

If they want to pay for a wind tunnel test, then have it. Otherwise, stick to the full procedure and use the whole building.

 

[driftLimiter]

I agree 100% with PhamENG, it isn't really up to the owner to decide how minimum loading is determined. Interestingly looking at the code ASCE 7 16 Ch30. Part 3. I found two instances of a type regarding roof height. It says h > 60ft (h < 18.3m) in the text of paragraph 30.5 and 30.5.2. It is clear however that this is the only section of Ch 30 that applies to buildings over 60ft.