Parapet Design - ASCE 7 - Roof Pressures?
Parapet Design - ASCE 7 - Roof Pressures?
(OP)
Per Section 6.5.12.4.4 of ASCE 7-02 two wind load cases shall be considered for parapet design. The first involves positive wall pressure to the front surface and negative corner zone ROOF pressure to the back surface.
The commentary describes this principle of using roof pressure as "based on the idea that the zone of suction caused by the wind stream separation at the roof eave moves up to the top of the parapet when one is present. This the same suction which acts on the roof edge will also act on the back of the parapet wall"
Using both windward and leeward wall pressure makes sense to me, but windward and roof suction seems very conservative and hard to visualize conceptually occuring. Does anyone have any references regarding this issue? (I searched other post but wasnt' able to find anything)
Please let me know your thoughts. Thanks!
The commentary describes this principle of using roof pressure as "based on the idea that the zone of suction caused by the wind stream separation at the roof eave moves up to the top of the parapet when one is present. This the same suction which acts on the roof edge will also act on the back of the parapet wall"
Using both windward and leeward wall pressure makes sense to me, but windward and roof suction seems very conservative and hard to visualize conceptually occuring. Does anyone have any references regarding this issue? (I searched other post but wasnt' able to find anything)
Please let me know your thoughts. Thanks!






RE: Parapet Design - ASCE 7 - Roof Pressures?
RE: Parapet Design - ASCE 7 - Roof Pressures?
This is primarily due to the reason you mention. Roof uplift loads are based on being perpendicular to the roof surface. Simply assuming this same load applies at a 90 degree angle seems very odd.
I visualize wind moving over the parapet and 'pulling' it similiar to the same way it would pull the leeward side of a building as it moves over the roof edge. This is why it would seem more logical to me to use the leeward suction load. This is, however, typically a much lower load than that of the roof uplift.
Any others have thoughts on this topic?
RE: Parapet Design - ASCE 7 - Roof Pressures?
RE: Parapet Design - ASCE 7 - Roof Pressures?
RE: Parapet Design - ASCE 7 - Roof Pressures?
http
RE: Parapet Design - ASCE 7 - Roof Pressures?
RE: Parapet Design - ASCE 7 - Roof Pressures?
RE: Parapet Design - ASCE 7 - Roof Pressures?
RE: Parapet Design - ASCE 7 - Roof Pressures?