Edinburgh Napier University

  The vibrational behaviour of structural timber flooring systems can result in serviceability problems due to discomfort experienced by the occupants. However, the dynamic response of such structural systems cannot be easily determined by hand calculations and as a result, finite element method (FEM) was used, which provides a suitable tool for numerical modelling for evaluation of dynamic parameters. In this study, timber flooring structures constructed with I-joists and particleboard decking were modelled for eigenproblem analyses to predict the most critical modal frequencies with corresponding modal shapes and also the static deflection under a point load. Joint elements were introduced at the interfaces between deck and joists to account for the spring stiffnesses due to the connection with metal fasteners. Spring stiffnesses were also assigned to the supports considering slip and withdrawal effects. Some sensitivity studies were then performed to identify the influence of introducing the spring stiffness in the individual translational directions and to determine the appropriate withdrawal stiffness. This paper presents the details of the modelling and also the correlation of predicted and measured results of six full-scale timber I-joist flooring systems. It shows the capability of the model in determining the most critical frequencies (e.g. of the first five principal first order modes), accurately in particular the fundamental frequencies and the modal shapes as well as good prediction of deflections under static point loads.