effective area of fastener

[delagina]

can you help me determine the correct effective area for this fastener schedule. purlin spacing is 5'.
from my understanding, it's 5' x 0.5' for zone 1,2 and 3
0.5' is the approximate tributary width of the middle fasteners
thanks,

 

[dik]

I would consider the tributary spacing of the fasteners to be from the middle of the flat lower portion to the middle of the high raised portion. Wasn't fully understanding the question... if that's it.

Dik

 

[delagina]

I'm designing the fastener against wind uplift. Making sure I got the correct effective area for c&c wind.

 

[KootK]

X2 for dik's recommendation. Multiplied by the out of the page spacing of course.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[delagina]

when should I use zone 1 and 2? zone 3 has higher value.

 

[Once20036]

I had a conversation like this with some of the tech folks at MetlSpan recently. They manufacture IMP walls and have a knowledgable engineering department.
They indicated that for these calculations, they use the tributrary area of the panel*the purlin spacing to get the fastener uplift force.

Zone 1 vs zone 3? Are you talking about the wind zones? Not sure what code you're looking at, but zone 1 is the typical interior of the roof, zone 2 is the edge of the roof, and zone 3 is the corner. Take a look at ASCE 7-10 figure 30.4-2a. The width of the edge/corner regions is defined there.

 

[rb1957]

not my area, but sounds like you'd use an area of 3' by 5', reacted by 6 fasteners (looks like each fastener would react the same load, supported by 0.5' width quoted in the OP).

another day in paradise, or is paradise one day closer ?

 

[delagina]

Once20036, I meant for fastener design, it seems Zone 3 psf will govern and all fasteners are typical size. I know about different Zone areas for c&c but it seems Zone 1 and 2 will not govern for fastener design.

 

[brut3]

I would defer to the definition for Effective Area in Chapter 26 of ASCE 7-10.

"For cladding fasteners, the effective area shall not be greater than the area that is tributary to an individual fastener"

I take this as meaning: EA = [(1/2 x Distance between fasteners at high flute) + (1/2 x Distance between fasteners at low flute)] x Purlin/Joist Spacing. Based off of the depth of the metal panel profile I would be highly surprised if you were able to use anything other than the minimum 10ft² for buildings <= 60 ft or 20ft² for buildings with greater mean roof heights.

 

[xez]

For fastener calculations, I'd consider the effective area to be 5 ft times the distance between the middle of the high rib to the middle of the flats.

The Zone 1, Zone 2 and Zone 3 loads can be used to design its respective configurations. Not all purlin spacings and purlin thicknesses have to be the same across the board all the time. Different loads can allow different configurations. However, Zone 3 would always have the worst case loads so if the design is typical across the roof (i.e. same fastening pattern and 5 ft purlin spacing), then this load should be used.