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Re: Crane Design; SE v. ME

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On Thu, 11 Mar 1999 13:53:10 -0500 "Drew A. Norman, S.E."
<DNormanSE(--nospam--at)email.msn.com> writes:
<snip>
>
>The (preliminary) calculations we have seen to date include NO seismic
>analyses whatsoever.  I had a "chat" with the ME for the supplier this
>morning.  He asserts that dynamic forces created by the crane starting 
>and
>stopping under load are generally greater than any which might occur 
>in an
>earthquake, but I think agreed to submit a seismic analysis (under ME, 
>not
>CE or SE signature) to prove it. 
><snip>
<snip>
>Resolution of the issues on this particular project may be complicated 
>by
>the fact that it is being done as a design-build.  Contractually, our 
>firm
>is structural consultant to the architect, who is working for a 
>general
>contractor.  Even though our design documents are clear, if what we 
>are
>asking for exceeds the minimum standards of governing code we may be 
>asked
>to defend them to the contractor, who is after all our client's 
>customer.
>It is for this reason that my client and I are particularly interested 
>in
>(a) relevant legal, building code and/or safety requirements, (b) 
>standards
>of practice (what is everyone else out there doing), and (c) 
>experiences
>anyone out there might have had with problems due to improperly 
>designed
>bridge cranes (particularly in re their performance in earthquakes).
>
>Drew Norman, S.E.
>Drew A. Norman and Associates

__________________________________

Sounds like all is not lost.  The crane code does require all runways to
be braced or otherwise attached to resist lateral and longitudinal loads.
 The building codes require, as a minimum, that equipment above ground
level be secured to resist 2 x 0.30 W = 0.6W loads.  That alone will give
you 4-6 times the lateral/longitudinal connection strengths as compared
to the crane codes.  They owe you at least that much.  Beyond that, you
may be able to insist they address, by dynamic calculations, the
amplified building motions at the point of crane attachment.
alternatively, you may declare that I = 1.25 to be appropriate for
critical safety.   And you have also specified that an SE sign and stamp
the final product.  No SE will "rubber stamp" an ME's work, so that alone
may get you most (if not all ) of what you want for the crane/building
interface.

The the crane itself....................that's a whole nother problem.

--- Russ Nester
     rnester(--nospam--at)juno.com

 

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