Infrastructure Engineering - Theses
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ItemA framework for micro level assessment and 3D visualisation of flood damage to a building( 2016)Flood Damage Assessment (FDA) is the key component of the flood risk management process. By highlighting the potential consequences of floods, FDA allows for an evidence-based risk management by employing optimal risk reduction measures in the community. FDA is generally performed in three main scales namely Macro, Meso and Micro. For assessing the potential flood damages at different levels, various categories of vulnerable elements (e.g. roads, people, buildings, etc.) are accounted for. Among these elements, buildings are the most notable and are considered in nearly all the current FDA methods due to their significance to the economy. In addition, with increasing risks of floods due to the climate change effects, the attention to improve the flood resilience of buildings is increasing. This leads to the need for a more profound understanding of the fluid-structure interactions and assessing the potential damages and risks to the building from floods in the early design and planning stages. Amongst the FDA methods, in contrast to the aggregated land use as the inputs of Macro and Meso models, only those Micro level assessments can provide separate analysis for the buildings. However, the current micro-level FDA models cannot account for the distinct characteristics of each building and its unique behaviour against floods. Therefore, they are associated with high uncertainties. Additionally, the current models only account for either damage from the flood loads or those as the result of floodwater contacting with water-sensitive components. This leads to incomplete outputs and further increase in the uncertainty of the results. Moreover, the existing FDA models mostly focus on the quantitative assessment of damages and do not communicate the mode/type of damage to important decision makers (e.g. designers and engineers). This inhibits the optimal selection of measures for reducing the risk to buildings. While the need of larger-scale applications are well satisfied by the existing FDA methods, the highlighted limitations hinder the use of these methods to effectively assess the damage and risks in situations where individual buildings are the focus of the analysis. To address the aforementioned limitations of the previous models, in this multidisciplinary research by adopting the Design Science Research Methodology an FDA framework was developed. This framework allows for a detailed micro-level assessment and 3D visualisation of flood damage to a building and according to its unique characteristics and behaviour against floods. The proposed processes in the framework were designed in detail according to the well-established theories in a number of related domains. Moreover, by developing a new BIM-GIS integration method, rich inputs about a building and flood parameters could be provided for the framework to effectively overcome the data input limitations of the current FDA models. The framework was realised by development of a prototype system and on the basis of the proposed guidelines. The dual evaluation of the framework using the internal validity checking as well as the use of a case study underlined the feasibility of implementation and the effective application of the framework for solving real-world problems. The benefits of the proposed framework for assessment and communication of flood damage at the building level was also highlighted to a variety of users. The framework can be employed as a complementary approach to the current FDA models for improving the resilience of the community towards floods and their adverse impacts.
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ItemPerformance of steel framed domestic structures subjected to earthquake loads( 1997)This thesis investigates the performance of cold formed steel framed domestic structures subjected to earthquake loads. These structures generally include one and two storey houses, comprising steel wall framing, exterior veneer cladding and internal lining. The dynamic, non-linear performance of such structures during earthquakes is simplified to static linear behaviour for design purposes using the structural response modification factor, Rµ. This factor is defined as the product of the structural ductility reduction factor, Rµ, and the over-strength of the system, Ω. This thesis develops a rigorous technique for the determination of Rµ and the application of this technique is demonstrated for a proprietary framing system. This is achieved using novel non-linear, transient dynamic finite element models of these structures subjected to earthquake loads. The model parameters are estimated from unique experiments conducted on representative structures using a shaking table. It is shown that the framing system considered is non-ductile (ie Rµ≈1). This result directly contradicts the assumed ductile behaviour of these framing systems as specified in the Australian earthquake loading standard, AS 1170.4. The significance of this is that current design practices are unconservative and therefore underestimate the earthquake loads on these structures.
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ItemDuctility of one-way slabs constructed with class L mesh, Grade 500 steel, under support settlement( 2005)This study investigates the impact of new class L Grade 500 Australian steel on the behaviour of suspended reinforced concrete slabs. An experimental program consisting of two one-way full-scale slabs constructed with class L steel was carried out. The key focus of the test program was to examine the response of slabs under imposed support settlements, which could occur for various reasons in the life of a structure. The experimental results were compared with the numerical results obtained by using the computer software prepared by Dr. Rebecca Gravina at The University of Adelaide, SA. Two continuous one-way slabs, with spans more than 4 m and 5 m respectively, constructed with class L steel were tested under imposed support settlement. A typical value of support settlement was used to raise the intermediate support of one test slab and to lower the intermediate support of the other. The results recorded using various techniques were used to establish the load-deflection curves, moment-rotation curves, degree of moment redistribution, failure loads and crack patterns at different load stages during the tests. A comparison of the experimental results with the numerical study carried out by Dr. Rebecca Gravina using software developed in her PhD studies showed a good agreement between the two results. This study showed that the test slabs were able to resist a load higher than the design load, even when subjected to support settlements of a magnitude expected in practice. Also the test slabs developed significant cracking in the spans as well as over the intermediate support regions before failure. The load deflection curves showed little sign of ductility. Moreover, the failure in each case was in a catastrophic manner by fracture of steel in the negative moment region, with no sign of compressive concrete crushing. This study has provided a detailed experimental investigation about the behaviour of class L steel under support settlement effects. However, it is limited to one-way slabs and has used reinforcement provided one steel manufacturer. It can be further extended to two-way slabs and also to class N steel for comparison with class L behaviour.
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ItemA competitive estimating and tendering strategy model for use in the civil engineering construction industry( 1996)The Australian civil engineering construction industry does not have a formal methodology for setting margin (markup) on project tenders. A need exists to structure and formalise the decision-making process used in setting margin, since the margin-size decision is critical to a company's success in winning work and its subsequent profitability. Despite the number of software systems available for cost estimating, none has features to help in making the margin-size decision. Numerous competitive tendering strategy models for setting margin have been developed, but very few are used in practice. A number of disadvantages in the features of these models make them unsuitable and difficult to apply. The objective of this thesis is to improve the procedures and tools available for use in the competitive tendering process in the civil engineering construction industry. This objective is achieved primarily by the development of a competitive tendering strategy model. The competitive tendering strategy model uses fuzzy set theory, a modelling technique designed for handling linguistic and approximate information, to model the margin-setting process and provide recommendations of margin size. The use of fuzzy set theory allows assessments to be made in qualitative terms, which suit the subjective nature of the margin-size decision. The goal of the competitive tendering strategy model is to help a company achieve its objectives in tendering. The model provides over ninety factors that may influence the choice of margin size, and enables the company to assess the impact of those that are relevant to its tender situation. The competitive tendering strategy model formalises the decision-making process and provides a standard methodology for setting margin on civil engineering project tenders, which can be tailored to suit the individual practices of each company. The implementation of the model in the form of a software system, named PRESTTO, makes the model quick and easy to use. The PRESTTO software system can increase the efficient use of the brief time available for setting margin. The competitive tendering strategy model provides accurate recommendations of margin size, based on its validation with actual project tenders collected from a survey of the Australian construction industry. The model therefore reflects current sound decision-making practices in setting margin and can be used with confidence as a guide to setting margin. The objective of this thesis is also achieved by the development of a theoretical framework that defines a standard methodology for the integration of cost estimating, tendering, and cost control, for use by both clients (owners) and contractors. The competitive tendering strategy model is placed in the context of this overall framework, since the margin-size decision is not made in isolation. This framework provides the theoretical basis for the implementation of a fully integrated software system. The PRESTTO software system, which consists of a cost estimating module integrated with a tendering module, is a partial implementation of this fully integrated system. A major conclusion of this thesis is that fuzzy set theory can be applied successfully to model the margin-size decision. Fuzzy set theory is an enhancement on previous modelling techniques because it allows assessments to be made in qualitative and approximate terms, which suit the nature of the margin-size decision. The competitive tendering strategy model developed, which supports subjective judgement and experience, can help civil engineering contractors gain a competitive edge in tendering. By providing them with a standard methodology to improve the quality of their decision-making, this model can help contractors reduce the uncertainty associated with setting margin, resulting in a more competitive bid.
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ItemSeismic performance of concrete beam-slab-column systems constructed with a re-usable sheet metal formwork system( 2007)This report describes an investigation of seismic performance of a ribbed slab system constructed with an innovative re-usable sheet metal formwork system. Experimental results from quasi-static cyclic lateral load tests on half-scale reinforced concrete interior beam-slab-column subassemblages are presented. The test specimen was detailed according to the Australian code (AS 3600) without any special provision for seismicity. This specimen was tested up to a drift ratio of 4.0 %. Some reinforcement detailing problems were identified from the first test. The damaged specimen was then rectified using Carbon Fibre Reinforced Polymer (CFRPs), considering detailing deficiencies identified in the first test. The repaired test specimen was tested under a lateral cyclic load as per the original test arrangement up to a drift level of 4%. The performance of the repaired specimen showed significant improvement with respect to the level of damage and strength degradation. The results of the rectified specimen indicate that the use of CFRPs may offer a viable retrofit/repair strategy in the case of damaged structures, where this damage may be significant. Two finite element analysis models were created and results of the first test were used to calibrate the FE model. The second FE model was used to obtain detail information about stress and strain behaviour of various components of the beam-column subassemblage and to check the overall performance before carrying out expensive lab tests. It was concluded that finite element modelling predictions were reliable and could be used to obtain more information compared to conventional type laboratory tests. Time-history analyses show that the revised detailing is suitable to withstand very large earthquakes without significant structural damage.