Effective Wind Area for Components & Cladding

[DTS419]

In ASCE 7-16 Figure 30.1-1 is the Effective Wind Area the area of the entire wall, or is it for each zone 4 & 5 individually?

For example, if building walls were 10' tall and 50' long, would the effective area be 500 SF for both, or would it be 40 SF for Zone 5 (a * h) and 420 SF for Zone 4 (500 - 2 * a * h)?

 

[RobertHale]

Its the area of the componet/element you're designing. If you had an element that had portions of both zones, I would calculate a single Ae, calculate the respective pressures for each zone, and finally apply the pressures to the areas of the zones. I think you were just pulling random numbers for your example, but I would caution you about pulling an area for an entire wall like you are suggesting. Even if it was a continuous concrete wall, I would the "floor" set in the definition of Effective Wind Area (Chap. 26) so that your A = (1/3)*H^2 and design a unit strip of the wall for those pressures.r

 

[DTS419]

RobertHale, thank you for your reply. In my example, it would be a matter of where the individual component is located. But to calculate the pressures and use Fig 30.1-1, is it the tributary area of the part, or is it the area of the wall depending on which zone the part is located in?

 

[Lomarandil]

The tributary area of the part itself.

 

[271828]

it would be a matter of where the individual component is located...

No, the effective wind area is only a function of the span and spacing. See the definition in Section 26.2.

Example: Wall studs 14 ft tall at 16 in. spacing all around the perimeter of your building.

Effective wind area = max of (14 ft)(1.33 ft) OR (14 ft)(14 ft / 3). The second one controls, so Ae = 65.3 ft2

Go to Figure 30.3-1. Some of the studs will be in Zone 4 and some in Zone 5, but they would all have Ae = 65.3 ft2.