Effect of partition walls on the vibration serviceability of cross-laminated timber floors

The current standards need more specific serviceability criteria for Cross-Laminated Timber (CLT) floors. This paper presents a comprehensive analysis of a relevant case study in Norway, which presented unexpectedly high accelerations in the CLT floors after construction. The lack of a sufficiently detailed design process resulted in the poor vibration performance of the floors, which partially compromised their functionality. The paper thoroughly investigates and discusses the experimental dynamic characterization of seven CLT floors within the considered building. The authors estimated the modal parameters and serviceability metrics based on both Eurocode 5 (EC5) and the new draft version of it. Specifically, the authors compared the analytical predictions of the fundamental frequency and the root mean square acceleration against the corresponding experimental estimations. Using a sensor-roving approach, a dense sensor configuration was adopted to describe seven floors' mode shapes and serviceability metrics. These metrics include mean square acceleration and Vibration Dose Value. The scenarios examined in this study shed light on the significance of partition walls, a factor not considered in the practical design for serviceability verifications. The presence of partition walls can enhance the vibration comfort of timber floors by providing a stiffening effect, leading to a significant increase in the first fundamental frequency. A parametric finite element model was developed using OpenSeesPy to investigate this phenomenon further. The model, firstly validated against selected experimental results, is employed to assess the influence of partition walls on floor dynamics. The model predicts the increase in the first frequency caused by randomly generated partition walls. The paper proposes an empirical expression calibrated on the simulated data to estimate the relative increment of the floor's fundamental frequency based on the partition walls' layout. This formulation can be included in the analytical expression enclosed in the EC5 draft to predict the fundamental frequency of timber floors.