Numerical study on the structure-borne sound propagation through the junctions with blocking-masses.

Abstract

The characteristics of structure-borne sound propagation through the various types of junctions without or with blocking-masses like beams and columns are studied numerically when the bending wave or the longitudinal wave is normally incident on the junctions. The following facts are found. In the case of one typical building structures made of dense concrete, almost all the energies of bending and longitudinal waves are reflected at the junction by the blocking-masses above 1000Hz, and the effects of blocking-masses are little below 50Hz. In the case of the bending wave incidence, much energy transmits through the junction at a frequency peculiar to the junction because of the existence of the blocking-mass. When the longitudinal wave is incident on, the characteristics of propagation greatly depend on whether the structure, i. e., a plate, is or not on the extension line of the plate on which the wave is incident. In the case of junctions intersected at an arbitrary angle, it is found that the wave of different type from the incident one is generated gradually with increase of the turning angle.