Application of ASCE 7 C&C to mesh/open components

[NYCStructuralEng]

Am designing for wind loads to mesh paneling that is attached to a high rise. It has approx 50% opacity to wind. I trust that it is best to utilize the Components and Cladding approach utilizing velocity pressure of the height of the building for leeward wind.

My question is: do you apply the Cpe/Cpi factored pressure to only the solid area or do you ignore the 50% opaque part and treat it as a solid panel?

I am confused - the open signs/lattice framework section allows for the use of a solidity ratio to determine an appropriate Cf and apply the calculated pressure to the solid area only. Components and Cladding makes no reference to the area to apply the pressure - solid or gross?

 

[thaidavid40]

I don't know the location or elevation of your mesh, but many of us allow for at least some area coverage from hanging banners - or wind-blown debris - which could inadvertently cover the mesh, thus making it suddenly 100% solid (opaque). You might want to investigate that possibility if it looks like a real potential.
Dave

Thaidavid

 

[NYCStructuralEng]

Thanks Thaidavid - this is for the ground floor and yours is a good point. Additionally the benefit of 50% voidage if using a solidity ratio based Cf is somewhat marginal in this case.

 

[WARose]

I am confused - the open signs/lattice framework section allows for the use of a solidity ratio to determine an appropriate Cf and apply the calculated pressure to the solid area only. Components and Cladding makes no reference to the area to apply the pressure - solid or gross?

The coefficients in the C&C section of the code take into account the relationship between effective area and pressure coefficients. So whatever design pressure you come out with would be multiplied by the effective area (i.e. 50% in your case).

 

[brut3]

I would recommend taking a look at the international perforators association website link below. Typically you have a substantial loss in strength whenever you're removing almost 50% of the material area. If you're going to go the route of reducing the wind pressure by the open area percentage, then you will also have to reduce the allowable strength of the material itself.

http://www.iperf.org/perforating/kn...ifiers-and-buyers-handbook-perforated-metals/