The reinforcement of a timber floor with a concrete layer properly connected to produce a composite system represents not only an improvement in the stiffness but also a foreseeable change in the modal frequencies of the floor. In order to assess that change, a typical timber floor, which was subsequently reinforced with a concrete layer to produce a composite, was tested at both stages in the research reported in this paper. Additionally, composite beams taken from the original floor were also tested. The results showed a significant decrease (44%) in the fundamental frequency after the reinforcement. In order to obtain the mode shapes and frequencies of the floor, finite-element (FE) models of the floors and beams were created. The FE models accurately matched the experimental results. Having validated the model, a parametric study was carried out to compare the results provided by the proposed FE model with a numerical model from the bibliography and to understand the influence of the most relevant structural parameters on the fundamental frequency of the composite floor.

Timber floors suffering from poor serviceability performance can be upgraded with a concrete topping to form a timber–concrete composite. The upgrade stiffens the floor, reducing the perception of a vibration response to dynamic excitation. Despite timber–concrete composites becoming an established research area in recent years, relatively little is known about the vibration response of these floor types. This paper explores how the vibration response of a timber floor changes when upgraded with a concrete topping, with particular attention given to the fundamental frequency of vibration. An analytical model, utilising the gamma method of Eurocode 5 (EN 1995-1-1), is used to predict how the fundamental frequency of vibration changes with the addition of a topping. The model is compared with experimental testing of timber–concrete panels before it is used to conduct a parametric study to establish the effect of common factors. It is found that high interaction between the topping and timber floor, identifying a suitable topping thickness and considering the change in transverse stiffness are key to a successful upgrade. It is suggested that topping upgrades which are thin (20 mm or less) are suitable for this application.