Wind Loads - Interior Pressure Coefficient

[xez]

Hello all

In a scenario where steel cladding is installed directly over the exterior of a concrete tilt up wall, can the interior pressure coefficient for wind loads be eliminated since the concrete tilt up wall is effectively withstanding the interior pressures?

Thank you

 

[Agent666]

I guess in my opinion it depends on whether there is an air-path from the "interior" of the building to the cavity between the concrete and the cladding. If there was then the cavity would in my opinion be considered to be subject to internal pressures. If not (if the cavity was fully sealed from the "interior" of the building), then I'd probably just consider the exterior pressure coefficients being applied.

I'd say in most situations it would be quite hard to guarantee that there was no air-path to the interior of the building though unless that panel formed part of some fully sealed envelope. Often you'll be at the mercy of the architectural detailing and/or contractors construction quality to achieve this

 

[liam1369]

Can you provide a section through? I can imagine the steel cladding is tied to the concrete wall via a number of ties? Thus the loading will be transferred to the cladding regardless, without getting too technical with energies etc I would consider external and internal pressure coefficients.

 

[r13]

Do you mean wind pressure inside the void space between the concrete and steel panels? Depending on how the steel cladding is attached, but I doubt there will be significant pressure built up inside the panel, except near the edges.

 

[xez]

There would be a hat channel rail system installed onto the concrete wall. The steel cladding would then install onto the hat channels. I would think the wall would be sufficient to keep internal pressures from getting to the exterior cladding and the cladding would only see the exterior pressures but I'm not sure if I'm just not thinking of something.

 

[BridgeSmith]

Just as with the building as a whole, the ratio of area open to the interior vs. the exterior would be the key metric. If air can freely get from the interior of the building to behind the cladding, but it can't get out to the exterior side, then you'd have interior pressure behind the cladding. Otherwise, the interior pressure on the cladding would not be significant.

Rod Smith, P.E., The artist formerly known as HotRod10