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Crane Rail Alignment

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I spoke to the special inspector regarding this issue of plumbness. He
states
that he has not seen any record of survey from the contractor to verify the
construction tolerances of the building frame construction.
I assume an EDM survey crew should have been observing the erection.


Harold Sprague wrote:
   <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.>

Could you define "Too Late". The building is empty, framing and cladding are
all
in place. The bottom portion of the building is precast concrete with metal
siding above. Typical industrial building. What means would they use to
correct
the plumbness? I am hoping the columns are not offset. The error increases
from
a perfect alignment to the 1 1/16" eccentricity. If the crane columns were
placed in the wrong spot or aligned askew. I am also in the awkward position
of
having the SE of Record on vacation in Italy for two more weeks.

Redrilling of the holes solves the friction problem but not the torsion.

Could be worse, I could be a 49er fan with no hope of making the playoffs...
wait a minute ... I am a 49er fan with no hope of making the playoffs

Try it again... could be worse, I could be an Arkansan or Texan dueling it
out
at High Noon on the SEAINT list server.

Thanks for the info Harold, much appreciated as always.

-Gerard


   -----Original Message-----
   From:   "Sprague, Harold O." <SpragueHO(--nospam--at)bv.com>@ENRON@EES
   Sent:   Wednesday, June 07, 2000 1:44 PM
   To:     seaint(--nospam--at)seaint.org
   Subject:  RE: Crane Rail Alignment


   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)