Rooftop Screenwalls ASCE 7-05 Wind Load

[SteveGregory]

ASCE 7-05 section 6.5.15.1 has a factor of 1.9 applied to the Other Structures Eqn 6-28 for rooftop structures and equipment. I think this should include rooftop screenwalls. This is explained in more detail in the commentary on page 300. The commentary is discussing the use of Fig. 6-21. I was using the section on Freestanding Walls and Signs, but I think that Section 6.5.15.1 is more appropriate for rooftop screenwalls now. Screenwalls at ground level should still use the Freestanding Walls and Signs section 6.5.14.

So if I have a pressure of 20 psf from Eq. 6-28, the wind load on the rooftop screenwall should be 38 psf. This includes the windward and leeward suction effects. Is that how everybody else reads this?

 

[steellion]

Yes, but also realize that based on the paragraph of ASCE you listed, this provision is only required for buildings <60 ft high, and the 1.9 can be interpolated down to 1.0 as described.

 

[SteveGregory]

Steellion and others,
Does anyone know what happens to screenwalls on roofs above 60 feet?

 

[steellion]

Seems to me that you would use Eq. 6-28 with the Cf factor from Figure 6-21 and not apply the 1.9 factor. I think that the theory behind the factor increase for low-rise buildings is that they tend to have more surface area than a high-rise building, allowing the wind ebbs to act similar to a ground surface

 

[ARLORD]

See the commentary page 300 for an explanation.