Infrastructure Engineering - Theses

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    Bio-inspired cross-laminated timber for protective structural applications
    Le, Van Tu ( 2021)
    Major blast events have occurred annually in several regions around the world. Accordingly, building codes, design standards and structural design recommendations are of paramount importance to protect occupants and property against unpredictable blast events. Cross-laminated timber (CLT) has recently emerged as a sustainable and lightweight engineered wood product. CLT offers several advantages as a construction material, in terms of both mechanical properties and environmental protection, including a high stiffness-to-weight ratio, a high two-way stiffness, and a low embodied carbon footprint. The increasing use of CLT in structural members combined with emerging threats highlight the importance of improving its resilience to blast loads. The study on the performance of CLT under blast loadings is significant to protect important structural elements and improve their resilience to blast loads. CLT possesses a lamellar structure, similar to that of marine seashells such as conch shells. A conch shell is primarily composed of brittle minerals (over 99% aragonite) but boasts a high fracture toughness due to its unique lamellar structure. By taking inspiration from the striking resemblance between the lamellar structure of the conch shell and CLT, this research aims to develop an innovative bioinspired CLT structure with superior resilience to blast loadings. Specifically, three main research areas are reviewed, namely blast loading, bio-inspired armour systems and cross-laminated timber. A comprehensive review is conducted on these topics to highlight the significance of protective structures against blast loading, the toughening mechanisms of biological armour systems, and the need for enhancing the performance of CLT under blast loadings. The review emphasises the lack of studies on the behaviour of CLT under blast loadings to improve its toughness and resilience in an explosion. Moreover, a striking resemblance between CLT and biological structures such as conch shell offers innovative solutions for increasing the toughness of CLT through bio-mimicking techniques. With this knowledge, the feasibility of mimicking the micro architecture of the conch shell on a larger scale to enhance the toughness of conch-like CLT is investigated. Programable 3D printing instructions were used to manipulate the 3D printer to develop tough conch-like prototypes. The prototypes were tested under single-edge notched tension to investigate their fracture behaviour. Then, a numerical model was developed and validated using these experimental data and an analytical solution. The model employed to examine the toughening mechanisms in the innovative proof of concept conch-like structure. A parametric study was also conducted to investigate the effect of different parameters on the toughening behaviour of the conch-like prototypes. A finite element (FE) model was proposed to simulate the behaviour of CLT under both quasi-static and dynamic loadings. The FE model was validated using experimental results and subsequently employed to simulate the bio-inspired CLT panel under both quasi-static and blast loads. An analytical solution was also proposed to capture the behaviour of CLT panels under blast loadings to validate the FE model. This validated FE model was used to conduct a numerical study on the performance of bio-inspired CLT under blast loading. In this study, the lamellar arrangement in the conch shell structure was mimicked to improve the toughness of a conch inspired CLT panel subjected to blast loadings. Several key parameters from the conch shell were also mimicked to enhance the toughness of CLT panels, namely the lamellar arrangement and the interlocking mechanisms. These bioinspired CLT panels were investigated by conducting numerical simulations of four-point bending tests. As such, several design recommendations were provided to enhance the performance of the conch-inspired CLT including changing the cross-section of timber planks in the middle layer of a CLT panel, introducing carbon fibre composite layers for ductility improvement, using pins to enhance interlocking mechanisms and adjusting the mechanical properties of the bonding adhesive. The bioinspired CLT panel was shown to exhibit several performance benefits over its benchmark counterpart, namely increased stiffness, strength and toughness. Finally, the conclusions of this research project and directions for future work are also provided.
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    Improving building energy efficiency: biomimetic adaptive façade and computational data-driven approach
    Bui, Dac Khuong ( 2020)
    The urbanisation and population growth are resulting in a significant increase in energy consumption in buildings, leading to a substantial increase in greenhouse gas (GHG) emissions. During the operation of buildings, a massive amount of GHG emissions are released due to the process of building heating, cooling, and lighting, which accounts for the most significant proportion in building energy consumption. Therefore, energy-efficiency design and operation will play an essential role in reducing GHG emissions in buildings. Facade systems are one of the most critical aspects regarding the efficient management of heating, cooling, and lighting energy in buildings. A facade system is a barrier and exchanger (simultaneously) for temperature, light, and air between the building indoor environment and the outside environment. Therefore, the proper design and operation of the facade can effectively save substantial energy. For decades, engineers and researchers from all over the world have been in search for the intelligent design and operation of the facade systems to improve energy efficiency and sustainability in buildings, and to not compromise a pleasant indoor environment for building occupants. Subsequently, they have found that many natural systems have developed a highly efficient biological structure to adapt to dynamic and extreme environments over millions of years. These natural systems now have become great inspirations for the research community in the quest for building energy efficiency solutions, and the biomimetic adaptive facade (BAF) system is one of those remarkable examples of adopting bioinspiration in buildings. The BAF system is considered as a potential solution to improve the performance of conventional facade systems. The BAF system has an ability to adapt its functions, features, or behaviour for dynamically varying climatic conditions, providing buildings with the operational flexibility to act in response to different climate scenarios. Nonetheless, the practical application of a BAF in buildings remains limited due to the absence of a comprehensive design platform that can facilitate the widespread adoption of BAF systems. Most studies on BAFs remain at a conceptual stage of development, and an effective platform that can effectively assist the design and operation of BAF is still lacking. This thesis proposes and develops a methodology for enhancing building energy efficiency using the design of BAF systems, and thereby supports the transition to next-generation facades. Specifically, the objective of this thesis is to develop, test, and evaluate a computational data-driven optimisation approach in assisting the BAF design. The thesis presents a multidisciplinary approach that combines building energy modelling, metaheuristic optimisation, and data-driven methods. The goal of the proposed approach is to minimise the total energy consumption in buildings, including heating, cooling, and lighting energy, but still maintain the indoor environmental quality in terms of thermal and visual performance. A comprehensive analysis of the proposed computational data-driven optimisation approach is provided in the thesis. In summary, this study has proposed a computational data-driven approach based on building energy simulations, optimisation processes, and machine learning algorithms. The proposed approach is used to assist the design and operation of BAFs for building energy efficiency and analyse the interactions between energy-saving and indoor environmental quality. These significant findings demonstrate the potential of BAFs to enhance the energy efficiency of buildings, and the developed platform can be used as an effective tool to support BAFs in both design and product development.