Vibratory Evaluation of Material Damping Performance of Cross-Laminated Timber Panels

Abstract

Serviceability is one of the governing parameters for the use of cross laminated timber (CLT) panels in floor systems for multi-storey buildings. The low comparative density of CLT products against steel and concrete systems can attract low damping and acoustical performance. Referring to the transient impulse response of a material, damping is a product of the boundary conditions (BCs) and material properties such as stiffness and density. There currently exists minimal understanding of the performance of CLT products in regards to damping as well as methods by which damping can be quantified and furthermore, the BCs under which these assessments should be conducted to ensure representative results to the intended application. The aim of this study was to investigate a vibratory assessment method to evaluate the damping performance of CLT panels for a range of conditions that may affect the damping response for a floor surface area equal to the tested CLT panel (3.0 x 3.0 m). 75 mm and 125 mm CLT panels were assessed for their damping response for a fully clamped (CCCC) BC to the influence of an impacting force with respect to a dropped weight of variable mass and drop height. The results of the damping response indicate a higher rate for impact tests at the boundary supports while the mid-span locations produced lower damping; while this was consistent across both panel types, the 125 mm CLT produced consistently higher damping rates compared with the 75 mm CLT, suggesting that the added material assists with damping. In addition to this the sound transmission difference between the surface to the underside of the panels were measured using appropriately positioned microphones and found a complimentary result to the damping where the transmission difference was lower for higher drop heights and varied with weight. © ACAM 2021. All rights reserved.