Rainbowtrout
Structural
- May 8, 2014
- 36
There was an older tread two years back but was unfortunately was closed. See Roof Pressure in Design Wind Load Cases thread507-322346
It looks like ASCE 7-10 didn't do much more explaining than 7-05 did. In my view, it seems to be fair not to add the roof wind pressure up, but to rearrange them so they reflect the new wind direction. The intent of this additional load case is not to over-design the roof structural members by 1.5 at selected locations, but to ensure columns have enough biaxial and torsional capacity (for a simple structure anyways).
If anything, using 0.75 Px and 0.75 Py implies the wind velocity pressure remains the same: 0.75 * sqrt(2) = 1.06 = 1.0, which again proves my point that roof wind pressure shouldn't be added up.
Thoughts?
It looks like ASCE 7-10 didn't do much more explaining than 7-05 did. In my view, it seems to be fair not to add the roof wind pressure up, but to rearrange them so they reflect the new wind direction. The intent of this additional load case is not to over-design the roof structural members by 1.5 at selected locations, but to ensure columns have enough biaxial and torsional capacity (for a simple structure anyways).
If anything, using 0.75 Px and 0.75 Py implies the wind velocity pressure remains the same: 0.75 * sqrt(2) = 1.06 = 1.0, which again proves my point that roof wind pressure shouldn't be added up.
Thoughts?