Internal wind pressures - at locations other than internal face of walls 1

[mte12]

Does anyone have experience with internal wind pressures developed on the inside of a building.
For example if you have a portal frame building with an open interior, and structures within, what are the forces experienced by the structures within?

I'm sure it's a complicated subject and depends on factors such as porosity, openings, whether wind is steady or gusty, and so on.
But I haven't seen any guidance on this after a web search.

Did see the following comment in a previous thread:
Folks, I lived in Puerto Rico for 24 years (lots of hurricanes), and I know there was no way to hermetically seal my house. So, during hurricanes, we used to close all windows but those in the “leeward wall.” If we closed all windows/doors, especially those in the leeward wall, we would feel the pressure inside the house trying to blow the windows out. We had an enclosed area in the house with a metal deck roof, which the interior pressure used to lift up. That being said, sometimes it is difficult to comprehend some of the code provisions because it may not really apply to your particular situation, but these things do happen.
Link
Comment is made that pressures are "felt", but is this a physical thing or a perception thing.

 

[jerseyshore]

There are internal and external pressure coefficients in ASCE for this.

Years ago after Hurricane Sandy a building owner had us do some calculations on his now destroyed building. His building insurance said it was flood that destroyed it and the flood insurance company said it was from the wind.

We had to pick one to challenge and since it clearly was damaged from the massive waves crashing into his building, I set off running calcs on all things wind related. That included the internal pressure of the building before and after the windows were blown out by the waves. I think I ran a few scenarios depending if doors were open or closed just to cover all bases. I was pretty proud of myself because as a younger engineer you don't always get to dive somewhat deep into the code. All that time spent and what do you know, both companies still refused to pay him a penny. And most of the building washed into the Atlantic Ocean so there wasn't even anything to salvage.

 

[mte12]

Thanks for responding.
This is regarding areas other than inside part of external walls.

For example at the centre of an enclosed building. In between external walls and in between floor and roof.

 

[ChorasDen]

...both companies still refused to pay him a penny

Ain't insurance great?

Mte12, to your question, I would not expect significant pressure differential within the interior of the structure. Air is a fluid, and with low viscosity, localized effects would be uncommon. Basic concept is energy at exterior of building is equal to energy at interior of building, the difference is that some of the energy at the exterior transitions from pressure to velocity (think of the energy equation you learned in fluids). At the interior, the air has little/no velocity, so the majority of energy is kept as pressure, and thus, we get a differential pressure at the outside of the structure and the inside. I don't expect high wind speeds inside the structure causing differential pressure unless there is a unique phenomenon that hasn't been explained in your post.

 

[mte12]

Thanks for the explanation ChorasDen.

With regards to unique phenomenon, I'm not sure what you mean. My understanding of the velocities/pressures/forces is limited hence the query. Have not seen anything in standards that treat this. The internal pressures are real (at the inside face) but have not seen anything that quantifies forces elsewhere, if applicable that is. And it probably is a function of porosity and openings.