Abstract:
The transmission of footfall-excited impact sound is commonly reduced using
floating floors. The most basic of these constructions contains three layers – a resilient
material, a load-bearing floor, and a floating slab.
According to a literature review, a single degree-of-freedom (SDOF) vibration
isolation model theoretically predicts impact sound reduction when assuming harmonic
loading and a rigid load-bearing floor. However, for timber layers excited by transient
loading (e.g. footsteps), sound reduction estimations may contain uncertainties due to
inadequate modeling of footsteps and/or floor components. Therefore, this research
presents a technique for modeling timber floating floors, as multiple degree-of-freedom
(MDOF) systems, using the rigid body dynamics software Working Model 2D®
(WM2D).
WM2D is first used to verify the SDOF case, by comparing software-generated
impact sound reduction plots to graphs found in the literature. Results show agreement
between both sources, though with slight error in predicting resonance values. Next, an
MDOF model is created with a transversely orthotropic and flexible timber load-bearing
floor along with mechanical systems representing the footstep and resilient layer. The
impact sound reduction graph for the MDOF system achieves higher values than the
SDOF case, which can be attributed to additional resiliencies from flexible beams. Also,
regions within the graph resemble the sound reduction plot for the SDOF case.
