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Re: Runway beam

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Stan:

Could you, please, send a sketch showing the crane arrangement, existing
structural framework, spans to be considered, crane capacity etc.  I have
designed  several underhung crane systems and, I might be able to come up with a
solution.  The sketch may be sent as an attachment to e-mail or you may send it
to: P. Rajendran, 4746 Lewis Drive, Bartlesville, OK 74006.

Rajendran

Stan Mulder wrote:

> Thanks for your reply. I was however referring to underslung trolleys
> carrying a hoist. The trolley is running suspended off the bottom flange and
> has to run over a 1.25 ins expansion joint. The crawl beam in question is
> spanning between Boiler Units in a power station. The units are totally
> independent and have expansion gaps between the units.
>
> I don't think that there is a connection devised for expansion joints in
> crawl beams ? The bottom flange is subjected to cross bending and the
> trolley wheel needs to be continuously supported.  The small wheels (~5 to 6
> ins diameter) also cannot move over gaps larger than about 1/8 ins otherwise
> the gap interferes with the with the movement. The flanges also need to be
> perfectly level at joints. Mitring the flange tends to weaken the flange in
> cross bending because the wheels are close to the edges of the flange, with
> a impact load applied at the tip of the taper.
>
> It is often necessary to reinforce the bottom flanges at the joints but even
> if this is possible, I dont think that it will overcome the other problems.
> The other option would be to make the crawl continuous and providing
> longitudinal sliding connections in the top flange support connections.
> However these sliding connection would have to be very free moving even
> under load. I don't feel comfortable doing this.
>
> I would  appreciate any responses.
>
> Thanks.
> -----Original Message-----
> From: Blomberg, Paul <Paul.Blomberg(--nospam--at)Jacobs.com>
> To: seaint(--nospam--at)seaint.org <seaint(--nospam--at)seaint.org>
> Date: 04 February 1999 10:58
> Subject: RE: Runway beam
>
> >I normally provide the expansion joint in between beams and allow the crane
> >rail to span over the expansion joint.  Then, within a few feet of the
> >structural steel expansion joint, I cut a 60 degree angle on the rail to
> >allow the expansion there.  The angle cut allows the expansion but
> maintains
> >positive bearing between the crane wheel and crane rail.
> >
> >It's an old detail.  There may be better approaches.
> >
> >Paul F. Blomberg
> >Jacobs Engineering Group
> >Phoenix, AZ
> > ----------
> >From: Stan Mulder
> >To: seaint(--nospam--at)seaint.org
> >Subject: Runway beam
> >Date: Thursday, February 04, 1999 12:15PM
> >
> >What details are suitable for overhead crawl beam expansion joints. Usually
> >gaps at joints should be kept as small as possible (2 mm or say 1/8 ins) to
> >enable the trolley wheel to pass smoothly over the joint. Sometimes it is
> >necessary to use a long crawl and introduce expansion joints. Possible
> >cutting the bottom flange at 45 degrees and reinforcing the bottom flange.
> >How big can this gap be (3/8 ins) ? Is there some way of making the gap as
> >large as 1 ins ?
> >
> >Thanks..
> >
> >
> >
>