This thesis characterizes the behaviour of Structural Insulated Panels (SIPs) under fire conditions. The composite construction material addressed here has a sandwich configuration; the core is made from Expanded Polystyrene (EPS) and the face sheets are Magnesium Oxide (MGO) boards. It is a modular lightweight system, prefabricated to meet requirements of the end-user. While the quantitative results shown herein are relevant to the specific product studied, the general analysis and observations are applicable to any multi-layer composite panel. There is vast information that explains the structural behaviour of SIPs at ambient conditions. However, the number of studies on fire performance is less extensive. Previous research has focused on performing standard tests aimed at determining the fire resistance (to fulfil regulatory requirements) for specific products or on measuring flammability parameters to assess the impact they may have upon compartment fire dynamics. Moreover, common design for fire safety is done only from a prescriptive point of view, where the fire resistance rating is the only basis for design. This perspective is ill conceived, since it relies fully on the capacity of the face sheets (e.g. MGO) to provide encapsulation to a combustible core (e.g. EPS). Encapsulation is a strong function of combined thermal and mechanical behaviour; hence, the combined action of temperature and load needs attention. Nevertheless, this combined action of mechanical loading and increasing temperature rarely has been investigated, and therefore the performance of SIPs during or after fire is not fully understood. Fire performance and structural behaviour are two mutually affecting processes. Thermal degradation of load bearing materials causes a reduction in the capacity of the system to carry loads and provide a sound structural performance. In a similar manner, a compromised mechanical integrity diminishes its fire performance because the capacity to encapsulate the combustible core is reduced. To explain such complex interaction, this research study uses a combination of structural mechanics principles, heat transfer modelling and experiments to develop a composite analysis that describes the thermomechanical behaviour of the panels. SIP's failure mechanisms at ambient temperature were determined by conducting experiments on full-scale samples as well as modified specimens. These were compared with the observations of similar tests conducted on samples tested under residual conditions (i.e. heated and cooled down prior to testing). By performing independent experimentation on each comprising material (EPS, MGO) viii Financial support This research was partially funded by the linkage project LP13 "The design and construction of quality, sustainable and affordable pre-made housing in Australia-Optimisation and Interaction",
