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Re: Crane Runway Earthquake Loads - Urgent !

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>In order to design a Crane Runway I need to include the Earthquake load 
>among other loads.
>Particulary, I need to know how much of the lateral  force I must consider 
>in one side ( 50 %  or 100 % ).  I suppose it depend on the vertical 
>aceleration and the wheel system.
You might want to check the list archives--this topic was discussed last 
March. Usually the crane is less than 10% of the building mass so all you 
really need is some notion of accelerations to expect at the level where 
the crane is mounted. Ground acceleration is not much good. Ideally you 
should have a floor response spectrum. I feel pretty strongly that you 
should assess the crane dynamically--it doesn't respond much like a 
building so the pseudo-static method won't be right. There's pretty good 
evidence that it's not only not right, it's unconservative. A response 
spectrum analysis will also give you accurate loads for the supporting 

You'll also want to be careful that you've considered the possibility of 
uplift and sliding. Typically wheel loads are carried by one rail or the 
other, not both, because the wheel flanges only engage the rail on one 
side at a time. And be certain you address uplift to keep the machine on 
the rails.

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