Vibration of existing slab-on-grade due to large commercial laundry drier

[ajk1]

Given:
An existing installation consists of 3 large commercial laundry driers sitting on a 5" ± thick
housekeeping pad which in turns sits on a 5" (125 mm) thick slab-on-grade reinforced with welded steel wire mesh. The driers are not bolted to the housekeeping pad. The driers are in a nursing home.

Problem:
The issue is that the slab-on-grade can be felt to vibrate when the driers are on.

Questions:
1. Would it reduce the slab vibration if the driers were bolted to the housekeeping pad?
2. How can the vibration of the slab be reduced?
3. Is this something that anyone on this forum has encountered, and how did you address it?

I realize that this may require spring/pad vibration isolators under the driers and this may require retaining a vibration specialist to advise (or perhaps a mechanical engineer who has dealt with this issue).

The drier manufacturer seems unable to help.

Any help that someone on this forum could provide, particularly if you have experience in vibration mitigation, would be appreciated.

I wonder if this question might be better posted on another of the forums? What do you think?

 

[ajk1]

If bsee isolation is to be used, attached is my preliminary concept of what it would be. Of course would have to work the details out with a vibration specialist, but are there any comments on the attached?

 

[WARose]

Question: Do you think that installing a grid of micropiles, say about 2 m down into the existing 8 m deep engineered fill under the existing 125 mm thick slab-on-grade, perhaps at 1.7 m centres would reduce this transmission to the rest of the building by damping it, or could it make it worse?

An analysis will tell you that.

If bsee isolation is to be used, attached is my preliminary concept of what it would be. Of course would have to work the details out with a vibration specialist, but are there any comments on the attached?

I think the base isolation system (shown) is probably your best bet. (Among the options available.)

 

[Canuck65]

My 2 cents worth ... I would consider removing the slab-on-grade in the area that the washers sit and building an isolated, thicker slab for the washers to sit on, with the isolators that you show. Then make sure the joint between the new pad and the existing slab-on-grade has some form of separation, perhaps filled with a compressible material that will not transmit vibrations. Vibrations can be very pervasive.

 

[canwesteng]

Isolators should be low tuned for the dryer, what is the natural frequency of the dryer? If very low, you might be helping much. The system is pretty complex, I would go with the same idea as canuck - cut up the slab so that the dryers are independent, add mass as required. Hopefully not enough vibration is transmitted to the building through the soil.