ASCE 7-10 Wind Load MWFRS

[S R P]

Hi,

In ASCE 7-10 there are 2 ways to calculate wind forces on buildings. Directional method and Envelope method. I am using Envelope method for one of my designs which is 56ftx53ftx24ft height flat building. Per ASCE, p = qh[(GCpf) – (GCpi)] (lb/ft2). If my building is partially enclosed, rigid building, can I use p = qh(GCpf) considering cancellation of wind pressure?

 

[DaveAtkins]

If the building is not divided into discrete structures (that is, for MWFRS considerations, it is one building), then yes, the internal pressures cancel out and can be ignored.

DaveAtkins

 

[S R P]

DaveAtkins

Thank you for your reply. My building is rectangular, but in two different roof heights. Each part is also rectangular. Roofs are flat. In that case, can I still use it as a single building? See below.

 

[DaveAtkins]

I think many engineers (myself included) would still say the internal pressures cancel out. However, some might say in the direction perpendicular to the step in the roof that the internal pressures should be included in the analysis of each part of the building--the taller portion and the shorter portion.

DaveAtkins

 

[JAE]

Dave, I think the internal pressures would still cancel out even with a roof step.

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[S R P]

Thank you all.

 

[DaveAtkins]

I agree, JAE, but I was thinking if it is two separate diaphragms, each might have its own contribution from internal pressure.

DaveAtkins