Experimental investigations of connections for robustness of mass timber buildings

Abstract

Recent growth in mass timber construction has raised concerns about preventing disproportionate and progressive collapse, emphasizing the need for performance-based design due to general lack of understanding the behaviour of mass timber connections under extreme load and deformations. The aim of the research presented was to expand on the current understanding of the mechanical properties of common floor panel-to-panel cross laminated timber (CLT) connections and subsequently floor systems under combined bending and tension, as typically observed under catenary action through experimental analysis. The thesis develops the methods for component-level and full-span substructure tests for CLT floors under extreme deformations that allow for distillation of the necessary parameters. The novelty of the study lays specifically in analysing the changes in these parameters due to increasing tension utilisation of the connections, which is instrumental for robustness performance analysis and has not been previously investigated. The component test developed uses a fraction of resources needed for the standard full-span testing while aiming to provide the same information about the connection behaviour, which can be used in design calculations and modelling alike. Full-span testing was performed to verify the component test results through numerical methods, as well as introducing further parameters such as continuous spanning panels and wall detailing. In total five types of CLT floor-to-floor connections were investigated, including four most commonly used currently in the industry as well as a novel tube connector.