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Re: Gantry Crane Rail Blockout

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I don't mean this as any sort of criticism of anyone, but this discussion reminds me of a situation that occurred in a transit tunnel under downtown Seattle a few years ago:  Planning for future light rail the designers embedded rails in the tunnel floor, even though initial use was only by buses.  When the time came to activate the rails they were found to be inadequate (electrically, for signaling/control purposes IIRC), requiring multi-million-dollar replacement.

Ralph

In a message dated 4/19/07 2:45:06 PM, paul.blomberg(--nospam--at)gmail.com writes:
Daryl,
 
Thanks for the information.  I am specifying a 20 ton crane capacity and there will be worker and forklift traffic across the rail so I'm embedding the track.  Unfortunately, it is a "future" gantry crane so we don't have an awarded supplier and the manufacturers are a little slow providing specific information if there is no sale in sight.
 
So I'm fishing for a generic block out detail that can be installed now and removed in the future and a gantry crane rail installed.  All the discussion I get on the subject is good for me!
 
Paul.

 
On 4/19/07,
Daryl Richardson <h.d.richardson(--nospam--at)shaw.ca> wrote:
Paul,
 
        I have assessed, reviewed, and/or designed a few gantry cranes over the years.  Following are a few thoughts that may (or may not) be helpful.  You are welcome to the helpful ones.
 
        Your first considerations are probably the load rating and type of wheels you want to use.  Some gantry cranes I have been involved with have been on castors, hence, they could be moved anywhere in the building even when they were loaded.  No rails required!  These have included cranes up to two ton rating.
 
        For intermediate cranes (say three ton to seven or possibly ten ton) you could consider using solid rubber wheels which do not require a rail but probably do require a dedicated runway location in order to have adequate foundation to avoid cracking the slab.
 
        For larger design loading, say above seven or ten ton, you will probably opt for a rail system.  Whether you use a block-out or not is another question.  this, of course brings up the question "do you use a solid bar for a rail or do you go to an actual ASCE rail?"  This will affect what type of block-out, if any, you design.
 
        You haven't indicated why you need a block-out.  I'm speculating that you want to avoid a tripping hazard or provide some type of cross rail access for a vehicle or a dolly or some other wheeled transporter.  If you can use the solid bar rail you can probably use a channel cast into the floor toes up (either a C or an MC shape) according to the depth you require.  I'm sorry; I don't have a detail for a larger cast crane block-out.
 
        Hope this is helpful.
 
Regards,
 
H. Daryl Richardson



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