Civil Engineering - Theses
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ItemFire performance of GFRP facade systems( 2015)Glass façades became preferable in contemporary architecture in last few decades due to its superiority in transmitting light and aesthetic appearance. In the recent past, more attention has been transformed to alternative “greener” materials like fibre reinforced polymer composites (FRPCs). Metallic materials require high amount of energy owing to their manufacture at extremely high temperature. Furthermore, FRPC has lighter weight than any type of aluminium and steel, which surpasses one advantage of aluminium and steel in buildings. Lower weight and higher strength are two critical key properties that make FRPC “greener” than aluminium and steel. However, the fire performance of FRPC facade systems has not been systematically investigated in recent research. Fire retardancy is an issue as FRPC is sensitive to elevated temperatures and the failure of the composite structure should be studied comprehensively to ensure the security for the occupants in fire incidents. Consequently, it is important to conduct a research which focuses on the performance of FRPC as a member of facade systems to identify the potential risks, to provide basic guidelines for appropriate FRPC in building application as well as to offer solutions for FRPC facades to meet the available standards for building materials. This thesis presents analytical, experimental and numerical investigations of fire performance of FRPC façades. Experimental testing is conducted to evaluate the performance of the material in accordance with safety codes and standards as well as to validate numerical simulation. Numerical simulation, in turn, accounts for evaluations where experimental testing is limited owing to cost and time commitment. The analytical study is conducted to provide the background theories required for the research and to design the experimental testing and support numerical simulation. These components are integrated in Chapter 3 – 7 to provide an understanding of the influence of flame retardants and generally the performance of GFRP composite façades subjected to fire conditions. These five main chapters consist of peer reviewed journal publications which have been either published or under review in international science and engineering journals. FRPCs enable the design of complex façade systems with low embodied energy, thus they have drawn substantial attention from façade designers worldwide. Nevertheless, there are many types of FRPCs with varying properties and manufacturing costs, resulting in some difficulty in selecting the suitable materials for the façade elements. Additionally, one of the key drawbacks of FRPCs is their relatively low fire resistance, which still requires comprehensive investigations in order to be applied in façade systems subjected to strict fire safety specifications. To address these concerns, the thesis explores the potential applications of FRPCs in modern façade systems, with a special focus on their fire performance. A case study of the fire performance of GFRPs is conducted numerically on a fire dynamic model established for glass fibre reinforced polyester, vinyl ester, epoxy and phenol composites without flame retardants in order to achieve a rapid assessment on the practicability of this configuration. A commercially available flame retardant, namely aluminium trihydroxide, is also tested and simulated comprehensively. The high concentration of conventional flame retardant triggers failure in the manufacture and deters other properties such as mechanical strength. Nanoclay is introduced in this study, as a novel flame retardant for glass fibre reinforced polymer (GFRP) composite. A comprehensive study covering types of thermosetting resins, types of nanoclay at different concentrations and methods to incorporate nanoclay into the composite is successfully conducted to predict the optimum combination. An analytical method using Taguchi design of experiment is employed with the newly proposed two-step GLM ANOVA. Resin and clay types are found to have significant effects on the ratio of peak of heat release rate (PHRR) to time to reach PHRR (Tp) as well as the total heat release (THR) responses of the composite. The fabrication procedure using ultrasonic agitation seems to yield better fire performance due to the better nanoclay distributions. Various challenges in the modelling include designing the accurate simulation of the combustion process for the multilayer and multi-materials composition such as the organoclay-composite. The proposed Component-layer model addresses the aim to capture very well the fire growth index (FGI) evolution and the FGI peak value. The validated analytical-numerical model is then applied in full-scale fire scenarios specified in ISO 9750-1:2013 and a selected case study (City Office building in Utretch, Netherlands). This building is one of the first buildings in the world integrated with GFRP façade and results have shown that the presence of nanoclay at 5% concentration prevents flash-over from happening and also the flame from spreading in the horizontal direction of the GFRP façade. Important parameters relevant to building members subjected to fire, in all the selected configurations of the City Office building are found to be well below the threshold to be used in building environment according to EN 13501-1:2007.