MRI Equipment - Elevated Slab

[slickdeals]

I am currently dealing with a situation where a client wants to locate an MRI equipment on the 3rd floor of a steel framed building.

The floor system consists of 2" metal deck + 3.5" concrete topping supported by W24 beams. The deck spans vary from 7'6" to 9'-6". The unit will finally be located straddling a W24x103 beam.

The unit is 14,000 lb with loads distributed through 4 legs (7" diameter). The legs are placed on a 36" x 30" square.

I have checked the beams and its connection to work, but I am having trouble getting the deck to work when the unit will be wheeled into place. There is a open terrace on which the unit will be delivered. The unit will need to move through at least 3 bays (with the largest span on 9'6") to its final location.

I am trying the metal deck point load distribution calculations (from SDI and NJB) but I find it difficult to justify FOUR 3.5k loads 3' from each other acting as individual point loads as opposed to a single 14k load. What do you guys think?

The building is currently partly occupied. I am not sure what is happening with the second floor.

 

[frv]

Why do you find it difficult? Isn't that what is physically occurring?

 

[rowingengineer]

I think one 14k (factored) is over conservative, I would use four point loads but have an addional saftey factor for wheel being load a little bit exra when wheeling into position.

ANY FOOL CAN DESIGN A STRUCTURE. IT TAKES AN ENGINEER TO DESIGN A CONNECTION.”

 

[Ron]

Use steel plates to distribute the load during move-in and until in place...then don't worry about it if you analysis shows the underlying support is ok.

 

[BAretired]

Will you be rolling this over the floor on a wheeled dolly?

BA

 

[slickdeals]

Yes, see attached.

 

[slickdeals]

@Ron,
Is that based on prior experience? If so what plate thickness and plate width would you recommend?
Will this plate be kind of a "carpet" for the unit to roll on?

 

[paddingtongreen]

I've used 12x12 timbers tracks and Hillman rollers to move much bigger loads, say 35T fan rotors, over elevated and grade slabs. The rollers are similar to the cart shown in the diagram, The plates Ron suggested or railroad ties should do a fine job.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[JLNJ]

I have done just one MRI install and they were crazy about ferris material near the MRI. I believe we even did FRP rebar in the slab (slab on grade). Just out of curiosity, does all the steel in and under your floor give GE or whomever any heartburn?

 

[a2mfk]

I've used Paddington and Ron's methods and some combination to either spread the load out or create a temporary moving bridge as the equipment is moved across the floor. For instance, you can use steel shim plates placed over the existing WF floor beams (location is another chore) and then bridge over top of them with heavy timbers. That is, if you are not comfortable with some combo of heavy timbers and steel plates placed directly on top of the slab to spread out your load.

I once had to do an entire schematic drawing of how this was to be laid out for the entire 200ft journey down a 1930s RC floor slab in an old VA. Fun...

 

[Bobber1]

I have moved heavy machinery using air bearings. Pick an air bearing that is large enough to distribute the load. The nice thing is you can control the loads to your floor system by varying the air pressure.

 

[BAretired]

Air bearings seem like a good solution to the moving problem, but as Bobber says, the area has to be large enough to distribute the load. That would be determined by the weakest floor slab on the route from entry point to final destination.

BA