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Re: Cranes and earthquake loads

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>I have been asked whether a crane in a steel-frame building
>we have been designing needs to be designed for earthquake
>loads.
Only if you don't want it to collapse under load or drop off the rails. 
The reason you don't design cranes with the building code is that they 
don't respond like buildings. Service loads are very important, and 
ultimate load design will get you in serious trouble when the fatigue 
gremlins come calling. Various crane manufacturer's standards (CMAA-70 or 
some of the ASME Standards for starters)  has some information. My own 
opinion is that response spectrum methods are best for crane seismic 
analysis. Static accelerations taken from the building coeds don't really 
reflect how cranes respond to dynamic loading.

Christopher Wright P.E.    |"They couldn't hit an elephant from
chrisw(--nospam--at)skypoint.com        | this distance"   (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)
http://www.skypoint.com/~chrisw