Design of Vibration-Sensitive Laboratory Floors: Vibration Criteria and Prediction Methods Compared with Measured Vibrations

Abstract

A vibrating floor can have a direct impact on the usability of sensitive equipment, ranging from mildly annoying, to rendering the equipment readings unusable. Structural vibrations can be caused by mechanical equipment, transportation systems, and building occupants (i.e., footfall traffic) and affect all structures to differing degrees. This paper addresses footfall induced vibrations and their effect on sensitive laboratory equipment. In designing a floor for a vibration-sensitive laboratory the first step is to select the appropriate vibration criterion. Since there are several sources of vibration criteria and prediction methods, this paper provides a discussion of these criteria and methods with respect to measured vibration levels. The accurate selection of vibration criteria and prediction of vibration levels is important in laboratory design because laboratory cost increases as floor vibration levels decrease. Vibration criteria can be determined based on published vibration limits, manufacturer-provided criteria, and subjective tests of vibration-sensitive equipment. For design purposes, floor vibration levels can be predicted by several methods, which include the AISC method, the BBN method, and analytical modal analysis. The accuracy of these prediction methods are compared against measured vibration levels in both a composite and a concrete laboratory floor. In addition, the effect of damping on floor vibrations was analyzed through vibration measurements before and after the installment of interior wall partitions and furniture. NOMENCLATURE