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Re: Crane Design; SE v. ME

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>Bottom line is that the crane manufacturer needs NO
>ENGINEERING LICENCES to build and sell a crane.
This may be an oversimplification of the intent of that wretchedly stupid 
'manufactured' or 'standard' product clause in most engineering laws. 
There are two other features of the model law, one defining those areas 
requiring professional engineering services and the other requiring such 
services where public safety is an issue. These latter two could and 
should supercede language slipped in by manufacturers concerned about 
limits on the shoddy crap they could ship. (BTW, does the Arizona 
engineering law still exclude the mining industry from its purview?) 

I got involved in a matter once where an electrician was killed when a 
badly designed hoist drive failed. One of the points at issue was whether 
the hoist manufacturer was practicing engineering unlicensed. Another 
involved the competency of the AE firm supervising the project to oversee 
the design and installation of the hoist. It's unfortunate that this case 
settled so quickly, it might have made the point that engineering has 
changed some since the days when the engineer was a master builder who 
could sketch and do arithmetic.

>In general, most building cranes will withstand zone 4 seismic loads... 
> Also suspect might be the runway beams.
If you mean the specified static horizontal accelerations, 0.3 g doesn't 
even come close to matching the dynamic loading on a crane structure 
during a quake. Response isn't confined to a single fundamental frequency 
and the frequency range of amplified ground motion usually includes one 
or more of the significant modes. There are also uplift and sliding 
issues that need to be addressed too. And I've found that runway beams 
stiff enough to be usable (because they're so long) are usually not the 
problem; if I had to pick just one area I'd say connections.

>The loads you have been supplied by the crane engineer do not include
>seismic, as you have suspected.
Don't assume this, either. CMAA doesn't specify the methodology, but that 
doesn't mean that someone hasn't done a seismic analysis. You just need 
to be able to assess what you've been given. If it were me and the guy 
handed me a set of reactions based on a static acceleration, I think we'd 
have a sort chat about dynamics and sufficiency.

I'd be very interested in seing the paper, Russ.
4903 Royal Oaks Drive, Minnetonka MN 55343 Or email a copy of the 
document, if that's handier.

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