moment frame drift due to wind

huangyhg

moment frame drift due to wind
i'm sure this has been posted before but i can't seem to find any old posts.  what are people using for drift limits for moment frames loaded from wind?
this depends mostly on what your cladding system is as this is more of a serviceability issue.  look at aisc design guide #3 (serviceability design considerations for steel buildings) pages 38-42 for some good recommendations.
also, when checking drift you should use the ten-year wind, not the 50-year wind that you use when you check strength.
if your wind speed is 90-100 mph, the 10-year wind is .84*50-year wind, and you should use 0.71*50-year wind forces (since v is squared in the force equation - 0.84*0.84 = 0.71).
if your wind speed is >100mph, the 10-year wind speed is 0.73*50-year wind speed and the factor for forces is 0.53*50-year wind force (0.73*0.73 = 0.53)
the type of cladding (or other controlling features such as cranes)has a great deal to do with determining the appropriate limits: glazing, brick, gyp and studs, metal wall panels, etc.
you might also take a look at asce 7-02, cb1.2.
here's a few past links on the topic: