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RE: Crane Rail Alignment

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It sounds like the contractor made a bad problem worse.  There are other
(better) ways to correct for an out of plumb column.  You can abandon the
holes and have new holes burned and reamed to size or have them use a mag
drill.

If it is not too late, I would have the iron workers back to plumb and align
the building.  Just because the iron is in the air does not mean it is too
late to re align and plumb the iron.  

The added torsion can play hell with the bridge crane (and that is a big
bridge crane), the girders, brackets, and all kinds of stuff.  It is also a
function of the duty cycle of the crane.  If it is a stand by service crane,
it is a concern.  If it is a steel mill crane, it is a show stopper.

Regards,
Harold Sprague


> -----Original Message-----
> From:	Madden, Gerard [SMTP:Gerard_Madden(--nospam--at)enron.com]
> Sent:	Wednesday, June 07, 2000 12:09 PM
> To:	'seaint(--nospam--at)seaint.org'
> Subject:	Crane Rail Alignment
> 
> I have a situation where a 105 kip crane (self weight) with a lifting
> capacity of 90 kips, spans 79 ft across the building. The crane rails rest
> on crane girders which in turn are supported on built up columns along
> side
> the building columns. The building was an addition with one side of the
> crane support along the (e) bldg.  The building is in seismic zone 4, less
> than 2km from a type b fault.
> 
> During installation, the contractor installed the crane rails directly
> over
> the centerline of the crane girders at the existing building. At the new
> building side, the contractor has skewed the crane rails to maintain the
> 79
> ft center to center dimension. This meant that the had to burn the holes
> to
> a slotted condition in order to fasten the rail to the girder. I believe
> the
> problem was due to the new columns not being installed plumb, creating a
> sweep horizontally, which shortened the span.
> 
> This creates two problems immediately recognized.
> 1. Burned holes... they were not reamed and the slot means that proper
> tensioning of the rail clamp friction connection is essential.
> 
> 2. The alignment of the crane rail creates eccentricities relative to the
> centerline of the crane girder. The offset is as great a 1 1/16" Per AISC,
> the max. tolerance is 1/4" from the centerlines.
> Torsion is now present in the crane girder (W36x245). I am very sure the
> beam can take the load under normal conditions, however, this is a fatigue
> design condition which makes me cautious.
> 
> All comments are welcome along with any other issues that I may be
> overlooking as a consequence to this.
> 
> Thanks,
> -Gerard
> 
> Gerard Madden, P.E.
> Civil Engineer/Structural Designer
> 
> The Bentley Company,
> A Division of Enron Energy Services North America, Inc.
> Email: gmadden(--nospam--at)enron.com
> Ph: 510.661.0527 (Fremont)
> Fx: 510.661.0528 (Fremont)
> Ph: 925.543.3810 (San Ramon)
> Fx: 925.543.3551 (San Ramon)
>