Measurement of the Vibration Reduction Index, Kij on Free-Standing Masonry Wall Constructions

Abstract

In the determination of coupling parameters between concrete/masonry walls in the laboratory there are potential advantages in using free-standing test constructions instead of flanking laboratories. To assess this potential, free-standing masonry walls were built in the laboratory to test two common types of rigid T-junction. The measured modal overlap factors were typically less than unity over the frequency range 50Hz – 1kHz. In this range, empirical rules imply that it is not possible to state with statistical confidence that there is any significant difference between the two types of junction connection. Below 1kHz many solid concrete/masonry separating elements are likely to have modal overlap factors less than unity in both the laboratory and the field. This is problematic for laboratory measurements because the vibration reduction index, Kij is unlikely to be a ‘situation invariant’ parameter when determined with elements that have low modal overlap.