Optimal Design of Prefabricated Timber Flooring System Based on Structural Performance

There has been an increasing trend in the construction industry to use timber as a viable alternative to steel and concrete in recent years. Timber is considered for a wide range of construction applications from low-rise buildings to high-rise structures by incorporating various structural elements into the overall design. One such structural element, timber cassette floor, is particularly significant and widely popular among builders worldwide including in Australia, especially for low-rise construction applications. However, the current practices for using cassette floors heavily rely on manufacturer catalogues as they are treated as proprietary products. This reliance may not be sufficient for mid-rise or high-rise constructions as the application of cassette floors needs enhancement to support variety of loading conditions. This study aimed to gain a comprehensive understanding of cassette floor systems, their functionality, and performance behaviour, as well as to propose a design optimisation methodology and solutions. This included evaluating the structural capacity, investigating internal member strength and connections, developing finite element models, and proposing a method and framework for optimal designs and verification. This research evaluated the structural capacity of parallel chord webbed cassette floors and investigated the strength of internal members and inter-component connections. Modelling of cassette floors and components in finite element software was conducted to analyse their behaviour and evaluate their performance. Additionally, a full-scale simplified structural model was developed in commercial structural design and analysis software, and its accuracy was confirmed through validation against experimental test data. This validated model was utilised for analytical purposes to study timber cassette floors of various sizes and under different loading conditions. Consequently, a comprehensive investigation was conducted to analyse the impact of various structural measures on the performance of cassette floors. Finally, a parametric study was conducted, comparing different configurations and categorising parameters of the cassette floor and its members to examine the influence of each change on the overall capacity and performance. This study produced important findings to understand the function of cassette floors, confirming that they generally have excess capacity, which allows for optimisation in required areas. It outlined the failures observed in cassette floors and identified possible causes based on the experimental test results. Furthermore, simplified modelling techniques were introduced to model the cassette floors for extended analytical and design purposes. Ultimately, the study proposed an investigation framework that can be utilised to select appropriate member sizes for optimal designs or provide valuable insights for designers addressing design assessments in cassette floor systems. Despite challenges encountered in modelling a detailed finite element model in the study, data from the component-level model and the full-scale simplified model can be utilised in preliminary design checks and engaged in analytical applications to study timber cassette floors of various sizes and under different loading conditions.