Construction on an existing hospital campus has the potential to affect ongoing activities in neighboring buildings, particularly those that contain vibration-sensitive areas like operating rooms and imaging suites.

Hospital planners would like to know the potential impact of construction early on so that contingency plans can be made to accommodate any disruptions. Unfortunately, the accurate prediction of the impact of construction-related vibration is not trivial, in large part because of the uncertainties associated with vibration propagation in dense settings.

While analytical predictions can be useful to obtain a ballpark estimate of potential impact, more accurate predictions can be obtained with live tests using full-scale equipment. Such tests involve the use of real construction equipment to generate vibrations at the planned construction site while the vibrations are measured inside nearby sensitive spaces. This approach minimizes uncertainty by using real construction equipment, operating at the actual location on the actual soil; with the vibrations propagating through the actual soil into the actual buildings. Unfortunately this approach also requires the cost and logistics to mobilize real construction equipment.

If full-scale tests are not practical, useful propagation data can be reliably obtained using a drop weight as a vibration source. Even though the actual source is not used to produce the vibration, this method still provides an excellent model of the soil propagation and building response characteristics. The vibrations produced by the drop weight can then be adjusted to predict the vibrations from representative equipment.

Jeffrey A. Zapfe, PhD, is Director, Noise Vibration Group, at Acentech. For more information, visit www.acentech.com.