This thesis presents the findings from an investigation of the vibration performance of in use Timber Concrete Composite flooring systems under walking loads. The investigation includes the in-situ collection and processing of accelerations, finite element model creation and calibration and parametric analysis.

Modern architectural design has shifted towards buildings with large open areas, which require floors to span longer distances. This shift has had a negative impact on the vibration performance of floors, particularly from human actions such as walking. Therefore, extensive research has been conducted on the vibration performance of flooring systems, culminating in a number of guides being completed on the issue. However, most of the research has been done on concrete and steel floors, and therefore these guides are tailored towards these materials. With a number of timber flooring options becoming available commercially there is a need to corroborate this research for timber floors. A popular option amongst these modern timber floors are Timber Concrete Composite flooring systems. Modern Timber Concrete Composite (TCC) floors have been developed as a design solution for spanning long distances, whilst still maintaining a low self weight due to efficient use of materials. Despite success commercially, there is limited research on TCC flooring systems’s in-situ vibration performance.

Finite element analysis has been an accurate way of predicting the dynamic properties of floor- ing systems. Its prevalence in past research has resulted in the aforementioned guides including suggestions for the modelling flooring systems,still with a focus on steel and concrete floors. With- out validation, the accuracy of timber floor models following these recommendations is unknown. The first objective of this thesis is to develop and calibrate a model for the dynamic properties

of TCC flooring systems through in-situ testing of real case study buildings. A complete and accurate model of TCC flooring systems can then be used to determine the system’s most impactful components with regard to vibration performance, with the purpose of improving the design of TCC systems and suggesting appropriate retrofit strategies. The secondary objective of this thesis is to undertake a modal parametric analysis leading to design and retrofit suggestions.

The in-situ data was collected from two real in use buildings. The vibration response was collected, from both buildings, using accelerometers with the excitation being provided by heel drops. The Frequency Domain Decomposition method was used to extract the dynamic properties from the acceleration response. The in-situ results showed adequate vibration performance. The models calibrated using this data proved a good representation of the real response of the floor. The parametric analysis identified the timber joists as the most influential component of the TCC flooring system with regard to frequency. Throughout the research the impact of partitioning on the dynamic response is clear; it is an easy, yet potentially undesirable retrofit option.