Rain Screen Attachment

[SteelPE]

I have a client who would like me to design some attachments of their rain screen product to a precast concrete panel system (basically fancy siding). I am trying to figure out what wind loads I would apply to the the rain screen panel. I am currently using ASCE7-05 C&C loading on a 74' tall structure with a wind speed of 100mph which results in a pressure of 35.8 psf when I use GCpi=0 (I think the system is pretty porous).

I know this is the load that the precast panel must be designed for (not my concern) but I am not sure if the "Skin" of this panel must be designed for the same loading criteria? How would others interpret this condition?

FYI, this load is killing the design of the clips that the panels uses to attach to the precast panel (stress is 183 ksi in the clips with this loading).

 

[XR250]

The rainscereens I design attachments for use 40 to 50 psf typically.
Try to go up in thickness or decrease spacing and take into account some guided cantilever action in the clip legs if you can.

 

[TDIengineer]

assuming you used zone 5 wall pressure coefficients, that sounds about right.

if you study the wind definitons i believe it discusses the allowed tributary area for members and fasteners. and the fasteners should be designed to the smallest TA, thus the largest wind pressure coefficients.