Infrastructure Engineering - Theses
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ItemLandfill phytocap development and performance evaluation using Australian native plants( 2010)The aim of the research presented in this thesis is to improve Australian landfill phytocap performance outcomes by enhancing our understanding of factors influencing the function of the phytocap plant community. The landfill phytocap presents a soil-plant alternative to the traditional barrier cap paradigm and relies on the capacity of a porous layer of soil to store water, and the combination of evaporation and the natural transpiration abilities of vegetation to control the percolation of water into a landfill. Despite the vegetation component having at least an equal role as the soil in determining phytocap performance outcomes, to date there has been a far greater emphasis in phytocap research on the configuration of the soil profile relative to the plant community. Furthermore, the majority of full-scale field studies on phytocap performance have been conducted in semi-arid or arid sites in the northern hemisphere with different climatic patterns and plant species. This research evaluates the hydrological behaviour and performance of a phytocap system within an Australian context. Greater emphasis is placed on the phytocap plant community and the potential effects that landfill processes have on performance outcomes including the impact of a lysimeter. Initial chapters focus on the selection and trial of native plant species in the field and glasshouse as part of phytocap development while later chapters evaluate the performance of the developed phytocap using full-scale test sections. The first stage of phytocap development was substrate characterisation and site assessment to inform native plant selection. A transferable methodology was demonstrated that can be applied to other landfill sites to improve plant selection outcomes, and was strongly supported by the successful establishment of a native plant community. Responding to the need for greater consideration of plant performance during phytocap design, a glasshouse trial was conducted to assess the species specific effects of substrate compaction on plant water use and root growth. This trial enabled the identification of an optimum phytocap substrate compaction range (75-83% of standard maximum dry bulk density) which optimises plant water use and effective rooting depth. This specification can be broadly prescribed to future phytocap designs. The hydrological performance of a monolithic and capillary barrier design were evaluated with lysimeters and found to perform exceedingly well. As both designs recorded very low percolation and were capable of effectively limiting percolation within the second year of monitoring, no distinction was made between designs in terms of performance. Evapotranspiration was found to be the most significant element of the water balance and the system was strongly limited by the availability of water such that evapotranspiration was high throughout the year, including the winter months. Limitations of lysimeters were assessed through comparative monitoring of unlined test sections installed directly on top of the landfill. Lysimeters were found to exclude adverse landfill gas and temperature effects, prevent assessment of plant sensitivity to the landfill environment and obstruct the interaction between the substrate design and the landfill including the landfill gas extraction system. Another significant limitation of lysimeters identified, was their inability to differentiate between phytocap designs; while there was no distinction between the performance of the monolithic and capillary barrier designs when monitored with lysimeters, when the designs were monitored on unlined test sections the performance of the capillary barrier design was clearly hydrologically and ecologically inferior. These limitations have significant implications for the interpretation of data obtained from studies based solely on lysimeter monitoring. They also suggest that comparative modelling of designs based on lysimeter data may not be meaningful for the employment of the designs on a full-scale phytocap. Overall, this thesis highlights the complexity of the interactions present within a full-scale phytocap and suggests that the inability of lysimeters to incorporate interactions which. strongly impact upon phytocap performance makes them an inadequate tool for performance evaluation of these systems. For that, alternative performance evaluation tools to lysimeters need to be considered.
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ItemInterpreting destination descriptions for navigation services( 2011)People move from one location to another to complete their daily activities. Finding the destination and determining a way that leads to the destination is a demanding task, particularly in an unfamiliar environment. Destination descriptions are referring expressions in natural language that uniquely describe the destination of a route in an environment. As a wayfinder, you may be able to identify your current location, and have some information about the destination, but you may only have coarse spatial knowledge about how to get there. There are local people in the streets, who can understand where you are headed and help you find the way to your destination. However can you still reach your destination efficiently if only asking help from a navigation service? This research intends to answer this question by exploring intelligent navigation services that simulates human behavior and understands requests in natural language. Route communication includes three phases between wayfinders and informants: the initial phase is when wayfinders ask information for directions from the start point to the destination, the center phase where informants offer information, and the last phase is confirmation and closing. While much research in this area has converged on the center phase, the focus of this research is in completing the initial phase. The initial phase of route communication is vital to complete route communication. This is because during the initial phase, a wayfinder and an informant make an agreement on the start point and destination. If an agreement cannot be successfully made, the informant cannot provide directional information and the wayfinder cannot close the communication and act. However, wayfinders often find difficulties with current navigation systems at the initial phase because they cannot deal with destination descriptions in general. This lack of spatial semantics in the fundamental mechanism of navigation systems motivates this research. An intelligent navigation system should have capabilities to imitate human route communication behaviors and make sense of place descriptions at the initial phase. This research firstly explores how humans perceive and express urban environment in natural language, and investigates the structure of destination descriptions. It secondly investigates the solutions to semantically matching destination descriptions with geospatial data. This research then formalizes an interpretation model, which works in the initial phase of route communication with navigation services. The input of the model is a destination description in natural language, i.e., plain English. This model filters the available data using spatial reasoning, and offers the most relevant reference matching the destination description as a result. Collected from Victorian gazetteer data, real data are prepared with all the required attributes for use. A simple natural language processing tool is employed to parse and identify place names and spatial relation entities for the model. Running the automatic interpretation model behind, two experiments are designed to evaluate its performance. The assessment is done by comparing the interpretation of results from human destination descriptions to a state-of-the-art navigation service. It was observed from the results that compared to current interpretation models, a spatially enabled semantic interpretation model of destination description can improve the performance of inferring destinations. This research contributes to the field of spatial cognition in general and to research on spatial reasoning of destination descriptions in particular.
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ItemDevelopment of a pavement maintenance effectiveness model for management of road networks( 2011)The development of efficiency models for road network management is challenged by three aspects: reliable future performance predicting capability, effective and efficient optimization modelling, and ability to accommodate constraints faced by the roads authority. This research aims to answer these challenges by analyzing pavement maintenance effectiveness of a road network leading to the development of effective models. The effectiveness of routine, periodic and rehabilitation maintenances are investigated, resulting in the development of a new quantification method. Further, these quantification results form inputs for the development of a stochastic based performance prediction model (Markov Chains) and optimization model (Markov Decision Processes/MDP). The results and discussions of the maintenance effectiveness analysis are utilized and then directly converted into Transition Probability Matrices (TPM) as main inputs of the Markov Chains. A very important discussion and outcome of this thesis is the development of graphical/visual presentations of the Markov Chains and their interpretations. The methods for presenting the results of the Markov Chains analysis for the performance prediction of different types of pavement maintenance are put forward as an enhanced way to present such information. The analysis and presentations developed in this thesis in part address the previous limited information or discussions on the visual presentations of the Markov Chains in road network management applications. Another important idea put forward in this thesis is an implementation of additional constraints into the MDP optimization analysis. An average cost method is selected for a solution of the MDP and is solved using dual linear programming. These additional constraints (i.e. budget and proportion constraints) are discussed through development of different scenarios, leading to development of optimal maintenance policies. Finally, this thesis demonstrates the implementation of the maintenance policies obtained in the optimization process into a road network under case study. Ultimately; this thesis aims to provide tools for road authorities to select optimal maintenance measures based on a more informed network level performance prediction model, given the uncertainty of pavement behaviours.
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ItemReal-time data visualisation in collaborative virtual environment for emergency management( 2011)A Collaborative Virtual Environment (CVE) is a shared virtual environment used for collaboration and interaction of many participants that may be spread over large distances. Although CVE has been widely used in emergency management, especially for education, training and assessment, there are some drawbacks and challenges in existing CVEs: 1. The authenticity of emergency simulation in CVE still needs improvement. 2. Delivery of up-to-date information cannot be guaranteed in currently available CVE. 3. The problems with usability of CVE are common, including the user collaboration and scenario creation. A review of the current literature reveals that, until now, these problems have not been well addressed. This thesis focuses on the design and implementation of a prototype system that facilitates emergency management via a Collaborative Virtual Environment using real-time spatial information. The system, Spatial Information Exploration and Visualisation Environment – Virtual Training System or SIEVE-VTS, was developed based on a game engine. It automatically integrates real-time data from multiple online sources, then models and simulates emergency incident scenarios using such data. The prototype system provides the capability of simulating dynamic scenarios in the virtual environment, extends the traditional technique of real-time data collection from 2D maps to the 3D virtual environment, manipulates spatial information efficiently and effectively, and enhances collaboration and communication between users. It improves the processes and outcomes of emergency management by increasing engagement and supporting decision making of potential users, including first responders, emergency managers and other stakeholders.
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ItemBehaviour of precast reinforced concrete columns in moderate seismic conditions( 2011)This research project contributes towards fulfilling a long-term objective of appropriate seismic evaluation of building structures in regions of low to moderate seismicity such as Australia. Structures such as unreinforced masonry (URM) walls, soft-storey buildings, gravity structures and non-structural components which include free-standing objects are well known to be non-ductile and yet commonly found in regions of low-moderate seismicity. Potential significant degradation in strength in these structural systems in projected earthquake scenarios has been a cause for concern. As the structure, or component, is excited into large displacement (and experiences “rocking” behaviour pertaining to overturning) its effective natural period value is expected to be lengthened into the high period range well above the initial natural period value (as a result of strength and/or stiffness degradation). Consequently, the risk of collapse of the structure is essentially controlled by response spectral parameters in the high period range. Therefore, displacement-controlled behaviour phenomenon applicable to conditions of low to moderate seismic regions has formed the basis for performance evaluation of the structures in this thesis. When the conditions of displacement controlled behaviour are reached the seismic displacement demand on the structure, or component, can become insensitive to any further increase in the natural period of the structure. Seismic assessment is hence much simpler and direct, particularly when the natural period of the structure is variable or difficult to estimate. According to this phenomenon, structures are deemed seismically safe if their displacement capacity exceeds the imposed displacement demand irrespective of their strength and energy dissipation capacity. Results of the tests and complementary analytical simulations of rigid body objects experiencing rocking behaviour revealed that earthquake induced overturning hazards were best represented by the peak displacement demand (PDD) parameter. The increase of probability of overturning with decreasing size of the object has been clearly established from developed fragility curves, importantly demonstrating size effect phenomenon. A conservative model based on the worst scenario of magnitude 7 earthquake and class D site for 5% probability of overturning has also been developed. The understanding of rocking behaviour of rigid objects as observed from the shaking table experiments and analytical simulations was extended to precast reinforced concrete (RC) columns supporting soft-storey system which are nominally connected to the rest of the structure. Field tests conducted on a four-storey soft-storey building supported by precast RC columns in Melbourne, Australia revealed that the columns maintained their gravity load carrying capacity up to a drift of about 8% under quasi-static conditions. The force-displacement relationships of the columns as estimated by a numerical model in Ruaumoko (Carr, 2008) have been found to be in good agreement with those observed from the field tests. It has been found from the developed fragility curves that the probability of failure of precast columns decreases with increasing size of the column, demonstrating the size effect phenomenon. A comparative evaluation study of one low rise (4 storey above ground level) and a high rise (20 storey above ground level) buildings, each with a soft-storey at ground floor level, was conducted which involved assessing existing building stocks using both the conventional force-based procedure as stipulated by current codes of practice (AS1170.4, 2007; AS 3600, 2009) and the more realistic displacement-based procedure which involved non-linear THA of SDOF systems. The risks of collapse of the twenty-storey building were found from the dynamic analyses to be much lower than that of the four-storey building. However, both buildings failed to comply with conventional force-based design requirements. The displacement based approach has highlighted the importance of the effect of size upon the vulnerability to failure of precast RC columns which has not been well captured by conventional force based method.
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ItemBehaviour of outrigger braced tall buildings subjected to earthquake loads( 2011)Modern tall buildings have become more flexible and taller than in the past owing to the growing use of high-strength or lighter-weight materials and advanced construction techniques. As a result, these tall buildings are more sensitive to dynamic excitations by wind or seismic loads. Especially in the analysis of tall buildings in high seismic regions, the seismic loads play an important role in the design of such structures. The outrigger braced tall buildings are very common around the world these days and 73% of the tall buildings constructed in 2000s over the world have been adopted core and outrigger system as the lateral load resisting system as per Council for tall and urban habitat. Therefore in this study, the behaviour of outrigger braced tall buildings is considered although there are many other structural systems are available to resist lateral loads. Even though the failure mechanism of ordinary frame and core systems are thoroughly identified in the past, due to the higher stiffness in the outrigger beams, the general weak beam strong column concept cannot be accepted in these buildings. Therefore, this study attempted to find the failure mechanisms associated with outrigger braced buildings and guidelines are provided about the failure locations of such buildings. It is concluded that the external columns above and below the outrigger locations should be clearly designed and detailed to have sufficient ductility to undergo deformations in a large earthquake. Further due to the greater height in these tall buildings, the higher mode participation is much more significant compared to other low to medium rise buildings. Therefore the general concept of first mode governs the behaviour, no longer cannot be accepted. In this study, the higher mode participation in tall buildings under seismic loads was methodically studied. In addition, the period lengthening of these tall buildings influence the overall behaviour of the structure and it is proposed that the lengthened higher modes periods should be included in the seismic design for an economical design. Moreover the higher mode participation is very much significant when structures are subjected to long duration earthquakes and this phenomenon was investigated with real long duration ground motions such as Mexico 1985 and Tohoku 2011 earthquake records. Although there are several methods available in the design of structures for seismic loads, the recent development of performance based design methods have been well accepted within the engineering community especially in the design of tall buildings. The recommended method of analysis for tall buildings is generally given as nonlinear dynamic analysis with compatible time history records. However, this process is tedious and time consuming, even with the use of new faster computer systems. Therefore this study aimed to develop a simple and versatile method which can be adopted in the preliminary design stage for the outrigger braced buildings. Recently developed direct displacement based design method was used as a base for the proposed methodology and a simple form of expressions and guidelines for representing higher mode effects are included in the design of outrigger braced buildings. Even though a comprehensive experimental program was outside the scope of this study, the validations of the outcomes were performed with the use of some past research experimental investigations and parametric studies.
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ItemManagement of Sodic soils under reclaimed water irrigation( 2011)Land application of raw sewage or partially treated wastewater has been practiced widely around the world over the past few decades. But regulatory authorities, concerned about water quality, environment and public health, are restricting the uncontrolled and direct disposal of these wastes into water bodies. However, current management practices related to wastewater and/or reclaimed water irrigation are mainly targeted at volumetric application rates and controlling nutrient levels and pathogens. There has been limited effort in understanding the long-term consequences on soil physical properties caused by cations, particularly sodium (Na), which is dominant in many of the wastewaters and reclaimed waters applied to land. Sodium is also the dominant cation in soil profiles of Australia and many other parts of the world. Leaching these soil profiles by irrigation water or rain leads to the formation of sodic soils. Once formed, irrigating these already salt-affected soils also results in the build-up of Na salts, leading to the formation of saline-sodic soils. This is also true in the choice of irrigation water quality, frequency and overall management. Consequently, irrigation management in these soil profiles is intrinsically linked to the management of soil sodicity. With increasing percentage of arable land being salt-affected or increasing percentage of salt-affected soils having to be brought under cultivation, proper management of these soils are vitally important in order to maintain agricultural productivity. The Western Treatment Plant (WTP) at Werribee, Victoria, Australia, had been employed to treat sewage/wastewater for over a hundred years (since the 1890s). Partially treated sewage/wastewater was used to irrigate pastures and to graze cattle and sheep. In 2003 the application of wastewater ceased and reclaimed water irrigation commenced. In response to climate change and drought induced reclaimed water shortage further land and water use changes are proposed. These are likely to consist of an increasing amount of rotational cropping and a decline in animal production. Of key interest is the fate of soil organic matter (SOM) and its role in these changes and associated sodicity impacts. As land and water use at WTP has been managed and monitored for 100 years it provides a useful study site to ascertain the amount and value of OM in this landscape. For example, the primary production system supporting direct land application of wastewater resulted in the formation of a thick sludge/Organic Matter (OM) mat. An estimate of the contribution of wastewater to this mat gives an idea as to how significant the impact of reclaimed water irrigation practice at WTP would be. With the change in irrigation water quality at WTP, the aim of this study was to investigate the changes it would bring to the soil properties of these salt-affected soils. One key change was the reduction in soil organic carbon (OC) contents since the cessation of wastewater irrigation. This reduction had led to the search for an alternative OM source. As a result the possibility of using wet and dry biosolids had been explored together with the impact of different quality irrigation water. Controlled laboratory experiments had been carried out with samples of top-and subsoils collected from designated parts of the WTP. The laboratory experiments comprised of 36 weeks of actual treatment (in terms of irrigation and biosolids application) and analysis. At the end of this study it was concluded that irrigating these salt-affected soils with reclaimed water, while depending on rain fed irrigation during certain months, was still a good option for these soils as long as there are OM inputs to these soils to compensate for the previous input of OM coming from wastewater irrigation. The dosage for such inputs had also been identified. Given that the on-site biosolids are to be used, the volume of generated biosolids and possible application rates had also been checked to determine the feasibility of the suggestions made. Since heavy metal concentrations in biosolids are an important concern, these application rates had been checked against other application rates with similar heavy metal concentrations in other studies in Australia. However, the current study did not measure phosphorus and/or any metals for the application rates suggested and further study can be carried out before finalising such application rates for the WTP soils. Some of the trends in soil properties could not be established beyond reasonable doubt or with significant statistical validity. Running field experiments and for longer periods would be a possibility which could not be done in this particular study due to limited resources.
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ItemPolymeric coatings for enhanced protection of reinforced concrete structures from the effects of blast( 2011)Reinforced concrete (RC) structural systems dominate the construction of buildings and infrastructure in Australia, as well as in most parts of the world. The increase in terrorist activities, accidental explosions and proliferation of weapons in recent years has made these structures more vulnerable to extreme impulsive loadings. Due to these developments, structural and material engineers are seeking to develop innovative and technically feasible protective solutions to protect critical RC infrastructure and to mitigate the damage resulting from such extreme loading events. This research evaluates the potential of using an elastomeric polymer (i.e. polyurea) to develop an innovative structural retrofitting application to enhance the resistance of RC structural elements to blast effects. The polymeric material is applied on to the structure as a protective coating, by using a spray-on procedure. The overall research involved comprehensive experimental, analytical and numerical investigation programs to evaluate the effectiveness and technical reliability of this technique. Experimental investigations were undertaken to evaluate the contribution of enhanced strain rates on the mechanical properties and behaviour of polyurea in comparison to its quasi-static properties. The findings were used to establish the stress–strain characteristics and other dynamic mechanical properties of the polymer in the strain rate ranges of 0.006 to 388 s-1. It was observed that the stress–strain behaviour of polyurea at high strain rates was considerably non-linear and exhibited significant rate dependency. Subsequently, constitutive equations were developed to characterise the dynamic increase factor (DIF) of various mechanical properties of this material at higher strain rates. The second experimental program involved the assessment of several unretrofitted and polyurea coated panels in a series of blast trials. The polyurea coatings applied on each of the retrofitted panels were unique in terms of coating thickness and location combinations. The findings of these trials indicated that polyurea coating contributes significantly in reducing the damage to the structural elements from the blast effects. Furthermore, it was also observed that the location of application of the protective coating play a major role in the level of protection offered by the retrofitting scheme. The experimental findings were also utilised in verifying the finite element (FE) models developed in the numerical analyses stage. The FE analyses were performed using the explicit solver of the non-linear FE code, LS-DYNA. Six different material models available in LS-DYNA were selected to model and simulate the behaviour of the polyurea, and the feasibility of each of this material model in representing the comprehensive strain rate parameters of the polymer were emphasised. The significance of the constitutive equations developed to model the DIF of various mechanical properties of the polyurea was also highlighted in this exercise. Based on the findings of the FE analyses, one of the material models was identified as the most suitable to represent polyurea. The verified FE models were subsequently used as the foundation to perform the parametric analyses to evaluate and identify the main parameters that contribute towards the overall effectiveness of the retrofitting scheme. The influence of location of application of coating, and the coating thickness, as well as various combinations of the two parameters were meticulously assessed in this exercise. Furthermore, the effectiveness of the retrofitting technique was also evaluated on a full-sized structural RC panel. The findings of the parametric studies were used to establish the functional configurations that could be practiced to optimise the level of protection offered by the proposed retrofitting scheme.
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ItemEucalypt leaf-flush detection from remotely sensed (MODIS) data( 2011)The apiary industry in Australia is unique from the rest of the world in that it is dependent upon tree species to provide the nectar for honey production, whereas the rest of the world utilises meadow vegetation and shrub species for nectar supply. Consequently, the apiary industry in Australia relies upon the ecosystem-dominant eucalypt trees within closed-forest, forest, open-forest, and woodland environments that have more complex ecosystem interactions than the meadow and shrub ecosystems outside Australia. Therefore, the Australian apiarists are dependent upon acquiring knowledge of greater complexity pertaining to forest ecosystem dynamics, such as including successional-ecology, interactions with different understorey community types, herbivory defoliation-events, and fire. This study has found it is possible to detect changes in vegetation indices over successive images, and between seasons, to correlate with honey-yield data. The supplied honey-yield data is used as a covariate for flowering intensity of eucalypt communities. Due to the lack of numerical honey-yield data (the supplied data was categorical/ordinal), modelling of the remote sensing vegetation indices with honey yield could not be done, and the analyses rely upon interpretation of graphical and rate-of-change values. This Master-by-Coursework project is a preliminary component of a larger project attempting to find a method of predicting flowering intensity of eucalypt ecosystems, and therefore potential honey yield, using the freely-available MODIS data. The data used for this project was the NDVI, EVI, Pixel Reliability, and VI Quality information extracted from images accessed from the MOD13Q1 product. With access to numerical honey-yield data, and weather and ecosystem data (available from the Bureau of Meteorology and the Department of Sustainability and Environment respectively), along with the MODIS data, it should be possible to perform a detailed analyses using multiple-regression techniques to model the flowering intensity of eucalypt ecosystems based upon prior leaf-flushing events. Predicting potential honey yield from MODIS data coupled with weather and ecosystem data will allow apiarists to determine the most likely site and time to place their beehives in order to maximise production.
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ItemModelling and performance of RC frames with masonry infill under in-plane and out-of-plane loading( 2011)Reinforced-concrete moment-resisting frames have been widely used in many parts of the world. In such buildings, exterior masonry walls and/or interior partitions, usually regarded as architectural elements, are built as an infill between the frame members, namely beams and columns. It is common practice in structural design that the interaction between the frame and infill panel is ignored. This is based on the assumption that the frame and infill panels are separated. However, the behaviour of such structures observed during past earthquakes has indicated that the actual response of the infill-frame is significantly different to that of a bare frame. This research focuses on developing a generic three-dimensional finite-element model of reinforced-concrete frames with masonry infill using ANSYS. A thorough review of previous research on the behaviour of masonry and reinforced-concrete materials is presented. Also, a large number of prior studies related to infill-frames are critically reviewed. A specific strategy is proposed for modelling reinforced-concrete and masonry. Results from models using these strategies are verified by the available experimental results from the literature. Detailed discussions are provided on how the proposed material models are implemented in ANSYS. Advanced analysis features of ANSYS, which have been employed for the constructed models in this study, are discussed in detail. The modelling strategies for reinforced-concrete and masonry are further combined to construct a generic FE model of an infill-frame, at a micro level, for the analysis of such structures under in-plane and out-of-plane loading. Appropriate experimental data available from the literature are identified and utilised to verify the proposed FE model of infill-frames under in-plane and out-of plane loading separately. The advantages as well as limitations of the present model are discussed, and the reasons for possible discrepancies between the FE and experimental results are scrutinised. Detailed explanations are provided on how damage progresses as the level of external load increases. Based on the results of the constructed FE models, the reasons behind some of previously observed damage to infill panels are also given. In order to successfully implement the solution phase, a simple method is proposed in order to overcome convergence issues, which are related to the solution of the highly nonlinear models using the Newton-Raphson algorithm. Given the inherent high variability of the masonry material properties, sensitivity analyses are conducted to investigate the effect of variability of the selected parameters on both in-plane and out-of-plane behaviour of infill-frames. It is shown that the constructed FE model can be employed to predict the behaviour of the infill-frame over a wide range of drift, and to interpret its response at various stages of in-plane or out-of-plane loading. This will be a useful tool for the assessment of existing buildings against the requirements of seismic retrofit/design codes in future studies.