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Re: Structural steel--isolated joints

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Christopher,

I knew you'd have good information... and you didn't even say anything to
offend me, what's the world coming to? ;-).

You are right this is no toy and it moves very fast down a long runway which
when the rail is not in good alignment  causes a lot of vibration to
anything attached. The column that the rail beam is attached to has the
primary function of supporting the center span of the metal bldg frame. It's
a 6" .140 wall pipe (pretty thin). It's been in service for 25 yrs. The rail
beam is nominally attached with a thin plate to lend some lateral stability
(globally) to the beam. But in effect what it has done is focus the inertial
load from the crane into this thin wall pipe. I'm planning on replacing the
pipe with a 6"TS column with .5" wall and reattach to the crane rail to lend
it global lateral support but the thought is to allow some give in the
reattachment so that every rattle does not transmit directly into the
column. Are you saying in this case lateral softness is a bad thing?

Thanks,
Rand


----- Original Message ----- 
From: "Christopher Wright" <chrisw(--nospam--at)skypoint.com>
To: "SEAOC Newsletter" <seaint(--nospam--at)seaint.org>
Sent: Monday, August 09, 2004 12:59 PM
Subject: Re: Structural steel--isolated joints


> > Does anyone
> >have any leads that would help me fine tune this design?
> A 32 ton crane is a big machine, with big inertia loads. The kind of
> shock mounts you're talking about work OK on small equipment, but not for
> something that weighs 32 tons. They work by softening the system, which
> is not what you need. You should be using the AISC fatigue design
> provisions for service loading.
>
> Christopher Wright P.E.    |"They couldn't hit an elephant at
> chrisw(--nospam--at)skypoint.com        | this distance"   (last words of Gen.
> ___________________________| John Sedgwick, Spotsylvania 1864)
> http://www.skypoint.com/~chrisw
>
>
>
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