Vibration monitoring 7th floor of a building

[milkshakelake]

A client wants to monitor vibrations of the top floor of his building (7th) due to vibrations from adjacent construction. I've never done this before; I always monitor foundations, because that's where vibrations would start. Technically I could do it, and use non-construction times as a baseline to see what is caused by construction. However, I'm afraid that putting it so high up will weaken the link between vibrations and construction activity, because confounding factors like wind and mechanical equipment start getting involved. It might not be accepted if it's peer reviewed or lands in court if there are damages. I also wouldn't know the criteria; the code here (New York City) has a limit of 0.5 in/sec for alerting and 1.0 in/sec for stopping construction, but I've always assumed that's for foundations.

Is it okay to put vibration monitoring this high up for monitoring adjacent construction? And does anyone have general resources about where to put vibration monitoring?

 

[271828]

Best I can tell, when the delicate items or finishes are on an upper floor, you can measure at that floor and use the same limits such as your 0.5 in./s. This is a fairly coarse type of testing program. The PPV isn't exactly splitting gnat hairs. LOL

Perhaps you could measure the velocity at the base and at the top floor. It would be interesting to see if there is amplification.

 

[milkshakelake]

Do you know if there's any references for this? I'm just afraid I have no way of separating factors like wind, and building torsion due to wind.

It's a good idea to measure it at the ground floor as well. If the peaks are lining up, that can certainly give a clue about the cause.

 

[271828]

0.5 in./s is some pretty serious vibration. My last testing program used 0.1 in./s. I did some comparisons to put that in perspective and I'm pretty sure that level of vibration would be readily perceptible. IIRC, people can feel 0.02 in./s.

Take some ambient measurements when there's no construction activities going on. If the vibrations during construction are indiscernible from those, then the vibrations are probably in the "who cares" category.

One of the most informative articles I've seen is "Vibration Limits for Historical Buildings and Art Collections" (2015) by Arne Johnson and Robert Hannen.

There are a lot of documents that mention PPV limits, etc., but it's a disorganized body of knowledge, best I can tell. It's hard to pin down limits and standard testing protocols with great precision. Lots of judgment is required.

 

[milkshakelake]

Thank you. I just looked up that article and it's pretty informative.