horizontal distribution of wind loads to vertilal elements

[cantthinkofaname]

Hi there,
With seismic loads, and a rigid floor diaphragm I apply the load at the center of mass and let the computer distribite the force to the braces according to theirrelative stiffness's.
Is wind load on a building with rigid diaphragms applied in the same way? Or is wind load applied to the braces accoring to tributary no matter what type of diaphragm?

thanks

 

[JAE]

With rigid diaphragms,

Seismic loads are applied at the center of mass, and distributed to the braces based upon their relative rigidities.

Wind loads are applied at the center of the exposed area, and distributed to the braces based upon their relative rigidities.

 

[WillisV]

Yup - Wind loads applied at Center of Pressure point which may or may not coincide with the Center of Mass depending upon your gravity load distribution.

 

[rb1957]

center of pressure is the centroid (center of area) if you assume a uniform pressure load.

the caveat in an earlier post was "if you have rigid diaphragms" ... i guess the alternative is a diaphragm that doesn't resist wind ?

 

[DaveAtkins]

rb1957,

The alternative is a flexible diaphragm, which distributes loads to resisting elements without regard to relative stiffness.

DaveAtkins

 

[JAE]

Or if you are a truly anal engineer....the diaphragms are all somewhere in between completely flexible and totally rigid and you perform a 3D FEM analysis of the whole model!

 

[swivel63]

it's based on the stiffnesses of the member, the EI of each member and also takes into account overturning and stuff like that. it should also take into account torsional loads if the CM isn't the same as the CR.

 

[cantthinkofaname]

Thanks you all for those great answers.