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Judging Vibrations

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Vibration velocities (peak particle velocities) and their frequencies are the measure by which the relative vibration damage potential is judged (see Vibration Standards for additional information on this point).  One cannot easily know vibration velocities just by feel. These must be determined by vibration monitoring studies, carefully done and properly interpreted.

However, in the majority of construction vibration damage situations, vibration monitoring is either not done at all, done only selectively and incompletely after a damage report, done so poorly that it has limited scientific value, or is not fully produced to the homeowner by the construction contractor, often even when under court order. Thus, it is difficult for many people to know if felt vibrations are capable of causing damage until after the damage appears, either immediately for particularly high velocity vibrations or later for somewhat lower velocity ones. The delayed appearance of damage may contribute to additional damage from subsequent vibration events.

Separating the Injurious from the Irritating

Since people are more sensitive to vibration perception than homes are to vibration damage, it is important to understand how one might begin to make a distinction between likely non-damaging vibrations and those which might have damage potential. This can be important when no vibration monitoring studies are done or are done without real-time feedback to the homeowner or construction crew.

Following are a few tips on how to assess vibrations with respect to damage potential. These tips are neither quantitative nor definitive, since vibrations from a given source type can vary substantially in velocity. They should not be used for quantitative purposes. However, within their limitations, I hope they will help give some rough guidance and aid to homeowners who must decide what actions they might take after the vibrations occur.

Vibrations which are often "safe"

  • Isolated vibrations which you simply notice, like those from sonic booms or the occasional large passing truck are unlikely to be damaging, even if they are irritating.
  • Vibrations caused by the activities of people (jumping, running, exercising, etc.) have, at the very worst, local effects centered within perhaps a ten foot radius of the vibration site. They are not strong enough to produce structure-wide damage.
  • Vibrations caused by the neighbor's (or your own) home or car sound system can be highly irritating and, if bass-boosted, closer to home resonance frequencies than one would like, but are usually non-damaging.
  • Vibrations caused by nearby construction using powered or hand tools like those used in framing and finishing a new home or remodel are usually not of concern for vibration damage.
  • Any "strong" vibration occurring once and lasting less than a few seconds is unlikely to produce immediate damage, but should be seen as a need for some monitoring if it is likely to be repeated.

Vibrations which may indicate a need for follow-up measures

  • Vibrations which are sufficiently intense to be "scary" are ones which might require further investigation, such as doing your own monitoring with a cell phone or tablet computer, as described the CVDG chapter, Vibration Monitoring.
  • Vibrations which cause easily visible (as opposed to barely noticeable) flexing in and out of window panes
  • Vibrations in which you can hear regular variations in the intensity of the house vibration suggest the possibility of resonant amplification and, thus, should be investigated.
  • Any vibration which causes dislodging of items hung on walls should be of concern.
  • Any vibration causing swinging of chandeliers or other light fixtures may be worth a more careful consideration.
  • Any vibration caused by the operation of heavy equipment within 100 feet of the home should be noted and documented, particularly those caused by ground impact-like operations such as demolition, pile driving and vibratory compaction (like that shown in the video frame capture above).
  • Vibrations caused by repeated and frequent heavy traffic, particularly when operating at high speeds (e.g. tractor-trailer rigs near freeways) may cause long-term damage.
  • Any vibration causing cracks in the soil should be cause for further inquiry.
  • Any unsettling vibration lasting minutes to hours or more is potentially cause for concern.

There are many other possible vibration situations not discussed here, as these are only some of the most commonly found. A vibration meeting any of these guidelines is neither proof of damage potential, nor its absence. In the end, such criteria should help people know when further monitoring may be justified or necessary.

Following Up on Troubling Vibrations

In the typical construction vibration situation where there is no vibration monitoring to establish actual vibration velocities, these tips can also, perhaps, help set your mind at ease - or give you some encouragement to document and investigate further. Those types of vibrations noted as concerns should trigger further investigation and, perhaps, immediate documentation of the condition of your home.

You should investigate whether monitoring is being done on the nearby project, and, if not, arrange to do your own monitoring, if the vibration is sufficiently concerning or has already produced damage. Having your own vibration information, either seismograph vibration velocities from a retained vibration monitoring firm or your own acceleration data from a smartphone or tablet computer's built-in acceleration sensors, can be extremely valuable in the all-too-common situation in which the contractor entirely denies (usually without evidence) producing damaging vibrations.

A clear bottle or other container filled with water, as at left, can be a useful means of demonstrating the presence of vibrations. However, such a visualization method cannot be used to measure the velocity of vibrations numerically nor can it be used to draw any meaningful conclusions about such numbers.

The PDF and Pro versions of the CVDG have an Appendix B - Warnings Signs which addresses vibration concerns from the standpoint of visible effects on the home. Its content is complementary to this section of the CVDG and should probably be read by those who have read this information.


 

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Last modified: 05/15/17