Wind loading on building with courtyard

[manstrom]

Let's say I have a 5-story building, 200'x200' in plan with a courtyard in the middle. The courtyard is 80'x80' and extends the full 5 stories and is open on top. The building is 60' deep on all sides. Basically a fat "tube" of a building.

How would wind pressures be applied the building? I will have windward pressures on the outside of the building, obviously. But would leeward pressures apply on the courtyard face, or on the back of the building? Conservatively, the leeward pressure applies in the courtyard. But I feel like I am penalizing my lateral load design when I am designing roughly 1/2 of the building for the full wind pressure.

This is for a wood building, so I am considering a fairly flexible diaphragm and running the numbers by hand / spreadsheet. I'm sure I could get some help from the back side of the building, but I would need to run a pretty tricky calculation.

Is there something in the ASCE 7 that takes this courtyard condition into account? Could the leeward pressure "jump" over the courtyard?

When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.

-R. Buckminster Fuller

 

[XR250]

My guess is that you would have a vacuum in the courtyard so for MWFRS, you would have windward and leeward pressures for the exposed interior and exterior faces of the "tube".
I guess you would use this for floor and roof diaphragm design.
For shearwalls on the perp. faces, this may not matter as the leeward on the upwind side of the courtyard would partially offset the windward on the downwind side of the courtyard.

 

[MotorCity]

I am more impressed by a 5 story wood building....kudos to you!!

 

[ACtrafficengr]

Pressure in the courtyard would probably not be uniformly low. I'd expect a vertical eddy in the courtyard, with the air going down the downwind wall, in the opposite direction from the wind at ground level and up the upwind side. There would be higher pressure on the far side of courtyard. Probably not as high as the windward outside face.

When the wind was at an angle to the building, it would be even more complicated. Remember the story about the Citibank Tower in NYC? I'd expect outward spreading forces on the downwind courtyard corner.