ASCE7-98 vs wind tunnel study

[v2]

it is an existing 45 story high rise.
the addition is an extansion to the restaurant on the 2nd floor. the addition is a canopy half of it is enclosed.

wind pressure by the ASCE7-98 are way high. some 210 psf suction for components.
wind tunnel study is expensive for this addition.

thanks

V2

 

[Lutfi]

ASCE 7 standard does not cover all possibilities and scenarios. Many times, as engineers, we must use our judgment. After all, that is what clients pay us for. If you have an unusual shape building, I would request if not insist on wind tunnel testing to aid you in the design of the structure.

I used wind tunnels in the past. We found out that as you stated, ASCE wind loads are higher. We also found out that ASCE loads were lower at particular parts of the structure due to unusual shapes, angles and protrusions of the building.

If the building were highly unusual, I would recommend to the owner to implement a wind tunnel program. One persuasive argument is that there could be savings in the cost of the structure (of course this could not be guaranteed). Also the structure would be designed for "hot wind spots" that may not be covered in the ASCE standard.

By the way, the load that you mention seems very high for an addition on the second floor! I was involved with a wind tunnel testing for a 246-foot high structure, in Florida, near the ocean. The highest wind uplift was 220 psf.

Good luck