Effects of pile driving vibrations on computer servers.

[FleetwoodInt]

I've got a project in NW Washington State. There is an existing 100' x 100' prefab steel office building. The customer needs more office space but the only place to go is up. We’ve decided to straddle the existing building with a completely new free standing building over top of the existing space. Our geotechnical engineer has determined that good bearing is at about 15’ – 20’. The best method for the foundation seems to be driven closed end steel piles and the exterior pile would need to be as close to the existing building as possible. A concern has come up over the effects of the pile driving on the company’s computers and computer servers. We know that if we bore a hole before inserting and driving the piles that the vibration effects will be greatly reduced. For the interior piles we are planning on coring the slab to accept the piles and possibly utilize the Air/Vacuum Potholing technique. This is a working office and ideally we plan to have no office shutdowns during construction.
We could go completely the Air/Vacuum Potholing route with poured concrete but this seems like a slow and costly route.
Does anyone know what the effects of pile driving vibrations on computer servers are and is this a valid concern with our driving method?
Does anyone have a better way of supporting the new structure without driving piles?
Are "H" piles a better way to go?

 

[Ron]

It's a valid concern; however, there are likely no reliable data to help you evaluate. I would suggest that you remount the servers on isolation pads or use isolation mounts on the whole cabinet.

I have done this for a permanent vibration installation (mounted the "show" dvd/audio disk players for a "major theme park" on isolation mounts as the ride itself produced significant building vibrations).

Take precautions during construction as you have noted. You might also consider augered concrete piles (Augercast). These will reduce vibrations over driven piles.

I would also monitor the vibrations (using alarm triggers) during the construction to help prevent damage.

 

[FleetwoodInt]

Thanks Ron,
We have thought about Auger Cast piles and may try to utilize them on the exterior but for the interior supports, I think that they would be way to invasive and disruptive. That’s also a good call on the isolation mounts; there’s an attached manufacturing plant with heavy machinery, so they may already have isolation mounts.
Thanks again

 

[PEinc]

Is it possible to install helical screw piles inside the building? You probably would need to get into the building with a Bobcat or mini excavator to screw in the helical piles. A hand held installation unit would need something to brace against, such as a nearby column or sturdy wall. You could drill micropiles inside the builting but that would be messier than helicals.

http://www.PeirceEngineering.com

 

[ishvaaag]

Micropile machines should be able to do the thing inside the building with no much fuss.

 

[steve1]

on page 5 of this reference they provide some displacement, velocity, acceleration, and frequency limits for computer systems:

http://www.vulcanhammer.net/svinkin/BLST-CRT.pdf

 

[dgillette]

The server mfrs might be able to help on tolerable vibrations (in the form of peak acceleration, or peak velocity).

 

[BigHarvey]

I have already been confronted to this situation on a dynamic compaction job. I was given a document written by IBM which was an abacus giving limits in terms acceleration and displacements as a function of the weight of the computer.
For transient vibrations 17 to 150 Hz and 200 kg : 0.06 g , for a few kg and same range of frequency : 0.08 g

but first answer I got was obviously 0 vibrations !