Wind Contributary Area on Grating

[jchi]

I am working on a 160'+ tower and calculating wind loads. Question is what is the contributary area for floor grating blowing perpendicular to the bearing bars. If I figure the area of each bar, like I do with the depth/web of a beam, my reactions become very large.

Will the wind blow against each bearing bar area or blow by due to the close spacing of bars 1 1/4" tall spaced 1 3/16" apart.

Jeff

 

[Ron]

Wind will not blow against each bar except when it impinges at an oblique angle. The impingement angle will be the angle created between the top of one grating bar to the bottom of the adjacent bar. That's somewhat of a "worst case" condition. Most of the time, there will be aerodynamic shading, at least to some degree.