Area calculation ASCE 7-05

[SteelPE]

I am tasked with designing some insulated foam metal panel (sandwich panel) and cold formed girts for a 3 story building. I am somewhat familiar with how to design these items as I have a large background in the design of industrial buildings.

The client has sent me the allowable span table that he wants to use such that he is using side joint fasteners only to attach the panels to the girts. Usually this table does not govern the design but today it is so I would like to make sure I get things correct.

The span table indicates an allowable span of 5’-10” for a wind pressure of 35 psf and 5’-2” for a wind pressure of 40 psf. My question is in relation to what area I need to be using to check this table. My wind pressures are:

10 square feet = -38 psf
20 square feet = -35 psf
50 square feet = -32 psf

The panel is 12 feet tall by 3.5feet wide. Should I be using the total area for the panel (42 square feet) or the area for each fastener (approx. 21 square feet)? I’m inclined to use the total area of the panel but I am not 100% confident in this.
Code is ASCE 7-05.

 

[KootK]

Seems to me that your real world "span" will be the span from girt to girt. A such, I'd use an area that is consistent with that: girt spacing x panel width.

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.

 

[DETstru]

For Components and Cladding calculations for panel design, you need not use an area less than the larger dimension squared divided by three.
So for the panel design, can use the pressure based on the area of 12²/3 = 48 square feet

For the fastener design, you must use the area tributary to each fastener, 21 square feet.

See the definition of "Effective Wind Area, A" in the beginning of Chapter 6 in ASCE 7-05.

 

[KootK]

Based on the information supplied, I assume that the 12' dimension is not the structural span but, rather, the length of individual panels. As such, I'd recommend the following depending on how many girts you have breaking up the span:

- 1 girt; 2 span; L = 6'; Effective area = 21 SF
- 2 girt; 3 span; L = 4'; Effective area = 12 SF

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.