Parapet C&C - Internal Pressure

[bdlc2k]

Hey everyone
For building h<160ft, does anyone have a good example of what constitutes a porous vs non-porous parapet for C&C loading? What type of parapet would you apply +/-GCpi = 0.18 or 0.55? I can see how a CMU wall or tilt wall may have GCpi=0. What about metal stud parapet?
Most examples is see simply state they are using GCpi=0, non-porous with no real explanation. I read somewhere that internal building pressures may reach the parapet.
Thanks!

 

[r13]

I think you need to provide the "reference" you read, so people realize what is your question and concerns.

 

[Aesur]

Review section C29.5 of ASCE 7-16:

 

[jayrod12]

For parapets, regardless of porosity, I've never accounted for internal pressure or suction since it has pressure/suction on both exterior faces. If pressure/suction were to be present inside of the sheathing, it would cancel out on the global design.

 

[JAE]

jayrod12 - correct- this internal pressure question really only applies to the design of the parapet cladding and its fasteners.

 

[jayrod12]

Fair enough on the cladding attachment. I'm not sure how ASCE handles it, but in our case the NBCC it would classify as category 1 likely therefore minimal contribution to applied loading. And if it were so porous to classify as category 2 or 3, you may as well design the cladding for the same loads as the main structural components.

 

[JAE]

Yes - after typing my answer above I also should state that I've never worried about internal parapet pressures at all.