Flanking sound transmission in connected panels of cross-laminated-timber at low frequencies

Abstract

The sound transmission between adjacent rooms can be dominated by the structure-borne sound transmission in the flanking walls. A wall can be defined as a subsystem of the overall system based on two coupled rooms. These subsystems show local modes, if they are not connected to each other. In contrast, connected subsystems result in global modes showing a high response of both subsystems, if the comparable local modes have similar eigenfrequencies. The flanking sound transmission especially at low frequencies is reduced, if a generation of such global modes can be suppressed. As a consequence, the flanking sound transmission in buildings can be mitigated significantly using a proper design of the walls (geometry, material, etc.). The principles and the impact of this effect are studied in this paper using numerical models based on the finite element method. Selected constructions are implemented in real size 2D- and 3D-models of two adjacent rooms. Panels of cross-laminated-timber are used because the variable composition of the single layers of a panel allows an extensive variation of the vibration response of the single walls. The results confirm the applicability of the described effect for common practical situations.

Strategies for a Safe Integration of Water-Bearing MEP Systems in Prefabricated CLT Room Modules

“…The capacity of such prefabrication facilities in Austria ranges up to 2000 modules per year per plant. While research efforts have been focused on aspects such as structural design, joining techniques, and building physics (e.g., Brandner et al, 2016, Merz, 2018, Buchegger et al, 2018, almost no attention has so far been paid to the integration of mechanical, electrical, and plumbing (MEP) systems. For this reason, current MEP installation practices in room modules do not take into account possibilities offered by modularity and prefabrication; neither do they provide precautionary measures to protect the wooden structures from potential water leaks.…”