Wind Load/Lateral Analysis (ASCE 7-02)

[dvwil]

For a structure that meets all the condition of Section 6.4 of ASCE 7-02, we use Method 1-"simplified procedure" for Lateral analysis:

Ps=adjustment factor*Importance factor* simplified wind pressure for exposure B.

What happens if the structure doesn't meet the condition, it meets the condition of Section 6.5, Method 2-"analytical procedure." Do I use the equation provided:

p=q(GCp-GCpi) for Lateral analysis? Is this equation for uplift? Do I use this both for Lateral analysis and uplift analysis?

 

[DST148]

I have ASCE 7-02. MWFRS: For design wind pressures on the windward, leeward, side walls, the roof, and the parapet, use eqns. (6-17) through (6-20) as applicable.
Components and Cladding - For uplift analysis of the roof proper, use wind pressures given by eqns. (6-22) or (6-23,) as applicable.

 

[dvwil]

Thanks, so MWFRS is for lateral analysis and C&C is for uplift? Is that right?

 

[DST148]

MWFRS is for lateral load analysis for the entire structure (in a global sense). So if you are checking foundations for uplift then you would use reactions from MWFRS wind pressures.
C & C is for designing individual elements of the building envelop(local level) like walls, girts, the roof system etc. If you are checking uplift on the roof members, you would use C & C wind pressures.

 

[dvwil]

I am a recent graduate and I just started working in a residential firm. I have no work experience, but I have read the IBC and ASCE multiple times. The firm outsource the structural calculation (mostly residential) and architectural drawing, sometime the boss make me check it before he himself approve and stamp it.

A common thing I see in their lateral analysis is they use the equation:
Ps=adjustment factor*Importance factor* simplified wind pressure for exposure B (Eq 6-1)
for MWFRS even when it is in exposure C (They use this to compare it to V=CsW, to see which govern wind or seismic). Then they check roof, floor diaphragm, and shear wall using which ever govern.

And then for uplift they use the equation:
P=q(GCp-GCpi) where q=0.00256*Kz*Kzt*Kd*V^2*I

Is this right? Should they be using P=q(GCp-GCpi) for lateral analysis? I'm frustrated. I think they are using Method 1 for lateral analysis and Method 2 for Uplift.

 

[dvwil]

Typo:

A common thing I see in their lateral analysis is they use the equation:
Ps=adjustment factor*Importance factor* simplified wind pressure for exposure B (Eq 6-1)
for MWFRS even when it is in exposure C (They use this to compare it to V=CsW, to see which govern wind or seismic). Then they check roof, floor diaphragm, and shear wall using [the Ps or V].