Building Under Negative Pressure 3

[SteelPE]

I am currently looking at a project where the building will be put under negative pressure. The reason for this is so the client can make sure the air that leaves the facility is properly filtered/cleaned. I am wondering how this would be handled in regards to building loading? I am guessing that you would just need to manipulate GCpi in some way, but I am wondering what the proper approach is. Are there any recommendations on how to handle this situation within ASCE-7?

 

[ukbridge]

I'm surprised there isnt any literature on this subject.

Its probably worth spending half a day trawling the ASCE, ICE for relevant articles or seeing if theres a CIRIA guide out there.

 

[Compositepro]

Negative pressure to ensure that leaks are inward is really no different that the normal pressure changes that any building experiences, except that the ventilation is design to not allow positive pressure. These pressures are measured in hundredths of an inch of water column. This should not affect structural design. If you get a negative pressure that affects the structure you will have difficulty opening and closing doors. High negative pressure will also cause leakage, which then must be treated and exhausted. So this is a non-issue. Nothing more than what a gable fan will do.

 

[KootK]

Don't hold out on us KootK....what's the story?

Once upon a time, in a land far away, I was responsible for the design of a hospital addition. I didn't even register the pressurization as a design requirement I'm afraid.

So the drawings went out showing typical, sparse wall connections to the composite steel deck above. The contractor tested the pressurization as part of the mechanical commissioning exercise which resulted in a stud wall failing at it's top connection and flopping over.

Nobody was hurt but the owner of my firm opted to pay for the remediation out of pocket rather than engage our insurance. I was not reprimanded in any way which was a testament to the kind of leader that he was. I presented the incident at an internal lunch and learn thing to keep others from making the same error.

Then I slayed a few more dragons, kidnapped a princess with flowing chestnut hair, and high tailed it back to the kingdom of Canadia to be with the spirits of my ancestors.

 

[SteelPE]

Not my operation, so I will not be buying a Gulfstream anytime soon... not even sure I can afford to ride in one.

It's a good point in regards to doors. If the pressure is too high no one will be able to open them.

So I guess the point of the story is, while the pressure may be an issue, it more than likely isn't as the pressure is so small. In regards to the consultant, he is probably feeding the owner and the AHJ a bunch of BS just to justify his high consulting fees (A consultant who will probably be buying a Gulfstream soon).

 

[azcats]

KootK - Thanks for sharing. Any idea how much pressure the wall actually saw before it failed?

 

[KootK]

Any idea how much pressure the wall actually saw before it failed?

Nope. I don't even recall how much the design pressure was. It's one of those moments from my youth where what was happening around me seemed so blisteringly important that I couldn't fathom ever forgetting a single detail. And then I had kids.