Impact of sound-insulated joints in the dynamic behavior of Cross-Laminated Timber structures

Abstract

Cross-Laminated Timber (CLT) has gained an increasing success and widespread diffusion among wood products. Due to the novelty of the components and the dry-assembling techniques, certain aspects of its behavior and performance remain unexplored; among these, the use of sound-insulated joints and brackets, along with their possible drawbacks on mechanical performance.In this paper the authors discuss the results of dynamic identification (ID) tests carried out on twin full-size CLT mockups (two-story), one of which was furnished with sound-insulation details based on an elastomeric interlayer. Ambient (white noise and random excitations) and forced vibration (mass shaker) tests were carried out to identify modal parameters.The paper mainly aims at: i) assessing potential differences in the overall dynamic behavior of the two mockups, likely due to the introduction of acoustic insulation, ii) detecting possible drawbacks of insulation layers on mechanical performances, iii) increasing the knowledge about dynamics of CLT structures.The results of Operational Modal Analysis (OMA) are presented and the variations in the dynamics between the mockups are discussed. The construction of finite element (FE) models and their calibration – with joint properties variations – are then presented. The outcomes revealed a drop of modal frequencies values (at least 20 %) upon the introduction of elastomeric insulation, whilst no significant alteration was observed in the mode shapes. Model updating based on the FE models demonstrated that the dynamic response and the frequency variations were mostly associated with wall-to-wall and wall-to-diaphragms joints, and hold-down connections.