Equipment Anchorage & Thermal Movement

[BatMan]

Be nice guys....Here we go.
I'm doing an anchorage of an equipment in a region with high seismicity. The equipment is not considered essential and is used in industrial warehouse (stubby, not very heavy).
However, the client in concerned that anchoring the supports to existing slab will cause cracking due to thermal expansion/contraction as the equipment is exposed to high operating temperature (not near the support).
I've suggested to box it in with anchored angles around the equipment. Is there more clever way to handle this? Letting the equipment breathe in/out while restraining from sliding all over the place? I'm guessing the thermal movement is on the order of an inch or less

 

[MikeHalloran]

Some shops put all their machine tools on rubber mounts like these or similar:

http://www.royalproducts.com/product.cfm?catID=10

They reduce transmission of vibration into the floor from the machines, make the machines fairly simple to relocate and level when needed for process flow changes, and stick to the floor well enough to keep the machines from moving around by themselves. ... but probably not well enough to deal with seismic motions. I suppose you could tie them down with angles, but probably somebody would want to see calculations and such, and maybe that's not necessary because...

Seismic isolators exist:

https://www.google.com/search?q=seismic+isolators&ie=utf-8&oe=utf-8

Many of which might be overkill for your machinery, but perhaps therein lies a basis for further discussion with your customer.





Mike Halloran
Pembroke Pines, FL, USA

 

[dhengr]

Hjk25:
Why not ask the machine manufacturer, there aren’t a lot of people who should know their equipment much better than they do. They’ve likely looked at these issues, or already corrected and accounted for them where they were a problem.

Furthermore, concrete and steel are reasonably compatible w.r.t. thermal expansion and contraction. A 10' piece of steel expands about .078" over 100 ̊F temp. increase/change; while concrete over that same length and temp. change expands about .066"; .012" is not much difference in the scheme of things. Then, you will have temp. changes/differences over the size/length of the machine, and you will also have flexural adjustments within/btwn. the various parts and levels of the machine.

 

[MotorCity]

Even if the equipment is hot, does that heat transfer to the supports? If it does transfer to the supports, I would be surprised if it caused thermal expansion/contraction of the supporting structure since concrete is a very poor conductor. Thermal movement of an inch due to heat from equipment? That's pretty significant. Is there expansion/contraction of the equipment itself due to the heat generated?

 

[JStephen]

Possibly use slotted bolt holes in the base plate with nuts left loose.
If you can use smaller-diameter bolts attached up higher on the equipment, you may be able to accommodate the thermal movement with elastic deflection in the bolts.
Anchor straps might accomplish the same thing.
You can get Teflon slide plates for applications like this if critical.

 

[BigInch]

As JStephen says, slotted holes ... on one end should work just fine.

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