Finite element modelling of bracket-connected cross-laminated timber plates to calculate vibration reduction indices

Several modelling approaches have been developed to predict flanking sound transmission through Cross-Laminated Timber (CLT) junctions, typically assuming idealised connections. However, research has shown that the configuration of fasteners significantly influences flanking sound transmission in these junctions. Predicting such effects requires versatile models where connectors are modelled accurately. This paper presents an experimentally validated Finite Element Method (FEM) model of an L-junction mock-up, where the angle brackets connecting CLT plates are represented in detail. As part of the validation, the Vibration Reduction Index Kij is reported for two different configurations of the L-junction, with plates being either in direct contact or separated by an air gap. The mechanical contact at plates’ interface has been modelled accordingly with coupling stiffness matrices. Numerical results showed a good correlation to experimental data in one-third octave bands, with deviations of less than 5 dB up to 3150 Hz. Analysis identified that: (1) an interrelationship exists between connectors and contact mechanics at the plates’ interface; (2) connectors can be modelled using this methodology, although they cannot be reduced to mere rigid point connections; (3) modelling connectors in detail is necessary for accurate predictions, especially when the plates’ contact interface is far from rigid.