Browne, RW, Bloom, MS, Schisterman, EF, Hovey, K, Trevisan, M, Wu, C, Liu, A & Wactawski-Wende, J 2008, 'Analytical and biological variation of biomarkers of oxidative stress during the menstrual cycle', Biomarkers, vol. 13, no. 2, pp. 160-183.
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Little information is available on the intra-individual variability of oxidative stress biomarkers in healthy individuals and even less in the context of the menstrual cycle. The objective of this study was to characterize the analytical and biological variability of a panel of 21 markers of oxidative damage, antioxidant defence and micronutrients in nine healthy, regularly menstruating women aged 18-44 years. Analyses included measurement of lipid peroxidation, antioxidant enzymes and antioxidant vitamins. Blood specimens were collected, processed and stored using standardized procedures on days 2, 7, 12, 13, 14, 18, 22 and 28 in one cycle for each subject. Replicate analyses of markers were performed and two-way nested random effects ANOVA was used to describe analytical, intra-individual and inter-individual variability. No statistically significant differences at α = 0.05, or temporal effects across the menstrual cycle were observed. Analytical variability was the smallest component of variance for all variables. The ICC among replicates ranged from 0.80 to 0.98. Imprecision based on quality control materials ranged from 1 to 11%. The critical differences between serial results varied greatly between assays ranging from 6 to 216% of the mean level. These results provide important initial information on the variability of biomarkers of oxidative stress, antioxidant defence and micronutrients across the menstrual cycle.
Chindaprasirt, P, Rukzon, S & Sirivivatnanon, V 2008, 'Resistance to chloride penetration of blended Portland cement mortar containing palm oil fuel ash, rice husk ash and fly ash', CONSTRUCTION AND BUILDING MATERIALS, vol. 22, no. 5, pp. 932-938.
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Choi, FC, Li, J, Samali, B & Crews, K 2008, 'Application of the modified damage index method to timber beams', Engineering Structures, vol. 30, no. 4, pp. 1124-1145.
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2007, Australia Received 31 August 2006; revised 16 July 2007; Accepted 16 July 2007. Available online 21 August 2007. Abstract In this paper the use of two existing algorithms developed for global nondestructive evaluation to locate and evaluate localised damage in timber beams is investigated using a finite element model. These damage localisation algorithms were found, through this investigation, not to be effective in locating multiple damage scenarios and unable to evaluate the severity of damage. Hence, modifications on damage index algorithms as well as a hybrid algorithm are proposed to overcome the problems. In this study, experimental modal analysis (EMA) was used as a tool to extract mode shapes for calculating the damage index in the proposed method which utilises changes in modal strain energy between the undamaged and the damaged timber beam model. The modified damage index (MDI) method normalises the mode shape curvature and the hybrid algorithm combines the modified damage index and changes in flexibility algorithms which reflect the changes of natural frequency and mode shape. Analytical evaluations were performed to compare and verify the ability of original and modified damage localisation algorithms in locating single and multiple damage in timber beams. The modified damage index (MDI) algorithm and the hybrid damage algorithm are also used in the experimental studies to validate the effectiveness of the methods to locate and evaluate damage within timber beams by laboratory experiments.
Choudhury, D & Nimbalkar, SS 2008, 'Seismic Rotational Displacement of Gravity Walls by Pseudodynamic Method', International Journal of Geomechanics, vol. 8, no. 3, pp. 169-175.
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Darestani, MY, Thambiratnam, DP, Nataatmadja, A & Baweja, D 2008, 'Influence of vehicular positions and thermal effects on structural behaviour of concrete pavement', JOURNAL OF MECHANICS OF MATERIALS AND STRUCTURES, vol. 3, no. 3, pp. 567-589.
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Structural response of concrete pavements is influenced by the position of the axle loads and if critical load positions are not considered in concrete pavement analysis, the design may be inadequate and lead to early failure of the pavement. Whilst there has been a great deal of research conducted on concrete pavement performance and deterioration under vehicular loads and environmental forces, there is a lack of adequate information on effects of vehicular load positions on pavement responses. Critical positions of different axle groups in uncurled and curled jointed concrete pavement with different configurations were determined in the current study. Results indicate that structural performance of concrete pavements is significantly affected by boundary conditions between concrete slab and base. Corner loading was found to be critical in bonded concrete pavement. Corner loading is also critical when a separation occurs between unbonded concrete slab and base. Furthermore, the benefits offered by unbonded boundary condition cease at a certain differential temperature. Hence, a particular care needs to be considered in projects constructed in extremes of heat or cold. In presence of high differential temperature together with axle loading, joint faulting in unreinforced concrete pavements is affected by concrete slab thickness.
Ding, GKC 2008, 'Sustainable construction—The role of environmental assessment tools', Journal of Environmental Management, vol. 86, no. 3, pp. 451-464.
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Construction has been accused of causing environmental problems ranging from excessive consumption of global resources both in terms of construction and building operation to the pollution of the surrounding environment, and research on green building design and using building materials to minimise environmental impact is already underway. However, relying on the design of a project to achieve the goal of sustainable development, or to minimise impacts through appropriate management on site, is not sufficient to handle the current problem. The aim for sustainability assessment goes even further than at the design stage of a project to consider its importance at an early stage, before any detailed design or even before a commitment is made to go ahead with a development. However, little or no concern has been given to the importance of selecting more environmentally friendly designs during the project appraisal stage; the stage when environmental matters are best incorporated. The main objectives of this paper are to examine the development, role and limitations of current environmental building assessment methods in ascertaining building sustainability used in different countries which leads to discuss the concept of developing a. sustainability model for project appraisal based on a multi-dimensional approach, that will allow alternatives to be ranked is discussed in detail in the paper. © 2007 Elsevier Ltd. All rights reserved.
Ha, QP, Kwok, NM, Nguyen, MT, Li, J & Samali, B 2008, 'Mitigation of seismic responses on building structures using MR dampers with Lyapunov-based control', STRUCTURAL CONTROL & HEALTH MONITORING, vol. 15, no. 4, pp. 604-621.
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As losses of human lives and damages to buildings frequently occur during earthquake periods, it is crucial to mitigate structural vibrations. This paper describes the development of a Lyapunov-based control approach for magnetorheological (MR) dampers integrated in building structures to suppress quake-induced vibrations. In this work, MR dampers are used as semi-active devices, taking the advantages of the fail-safe operation and low power consumption. The control of MR dampers is, however, hindered by their hysteretic force-velocity responses and usually leads to indirect strategies compromising controllability and performance. To enhance the system performance, a Lyapunov-based controller is proposed here for direct control of the supply currents to the dampers for a multi-storey building. The dampers are configured in a differential mode to counteract the force-offset problem from the use of a single damper. The effectiveness of the proposed technique is verified, in simulations, by using a building model subject to quake-like excitations. Copyright © 2007 John Wiley & Sons, Ltd.
Hao, H, Deeks, JA & Wu, C 2008, 'Numerical simulations of the performance of steel guardrails under vehicle impact', Transactions of Tianjin University, vol. 14, no. 5, pp. 318-323.
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Road side barriers are constructed to protect passengers and contain vehicles when a vehicle crashes into a barrier. In general, full-scale crash testing needs to be carried out if a geometrically and structurally equivalent barrier has not previously been proven to meet the requirements of containing the vehicle and dissipating sufficient impact energy for passenger protection. As full-scale crash testing is very expensive, the number of data that can be measured in a test is usually limited, and it may not always be possible to obtain good quality measurements in such a test, a reliable and efficient numerical simulation of crash testing is therefore very useful. This paper presents finite element simulations of a 3-rail steel road traffic barrier under vehicle impact. The performance levels defined in Australian Standards AS5100 Clause 10.5 for these barriers are checked. The numerical simulations show that the barrier is able to meet low performance levels. However, the maximum deceleration is higher than the acceptable limit for passenger protection. If present, a kerb launches the vehicles into the barrier, allowing for the possibility of overriding the barrier under certain circumstances, but it redirects the vehicle and reduces the incident angle, which reduces impact force on the barrier. Further investigation into all common kerb profiles on roads should be carried out, as only one kerb profile is investigated in this study.
Indraratna, B, Muttuvel, T, Khabbaz, H & Armstrong, R 2008, 'Predicting the Erosion Rate of Chemically Treated Soil Using a Process Simulation Apparatus for Internal Crack Erosion', Journal of Geotechnical and Geoenvironmental Engineering, vol. 134, no. 6, pp. 837-844.
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Chemical stabilization is an effective ground improvement technique for controlling erosion. Two stabilizers, lignosulfonate and cement, were used to study how effectively they could stabilize erodible silty sand collected from Wombeyan Caves, NSW, Australia. To conduct this research, four dosages of cement 0.5, 1, 1.5, and 2% and four dosages of lignosulfonate 0.1, 0.2, 0.4, and 0.6% by dry weight of soil were selected. All treated and untreated soil specimens were compacted to 90 and 95% of their maximum dry density to study the effect of compaction level on erodibility. The erosion characteristics of treated and untreated soil samples were investigated using a process simulation apparatus for internal crack erosion designed and built at the University of Wollongong. The findings of this study indicated that both chemical stabilizers increased the resistance to erosion because of their cementing properties. It was also found that the critical shear stress increased linearly with the amount of stabilizer, and the coefficient of soil erosion decreased as a power function of the critical shear stress.
Indraratna, B, Trani, LDO & Khabbaz, H 2008, 'A critical review on granular dam filter behaviour – from particle sizes to constriction-based design criteria', Geomechanics and Geoengineering, vol. 3, no. 4, pp. 279-290.
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Over emphasis on tests results involving base soils with increasing coefficient of uniformity (Cu) makes the reliability of an empirical particle-based criterion for effective filters questionable. Extra measures such as regrading of base soil are then necessary in order to capture the effectiveness of filter constriction sizes in trapping eroding fines. Recent studies which focused on the role of the sizes of filter voids on overall filtration behaviour have deployed constriction size approaches that were shown to be equally acceptable methods for distinguishing between effective and ineffective filters. This paper examines the evolution of this approach, starting from past empirical and mathematical investigations and proceeding to the eventual development of geometric-probabilistic methods with special reference to embankment dams. Models based on dominant and controlling constriction sizes are introduced, and subsequently the constriction-based retention criteria for granular filters are presented. The proposed retention criteria were verified based on extensive experimental data taken from small- and large-scale filtration tests carried out by various authors. The integration of filter compaction, porosity and Cu, together with the incorporation of analytical principles, provides alternative and rigorous design approaches that remove most limitations of the conventional particle-based criteria, thus making the models essentially more comprehensive and quantifiable.
Ip, KH, Stuart, BH, Ray, AS & Thomas, PS 2008, 'A spectroscopic investigation of the weathering of a heritage Sydney sandstone', SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY, vol. 71, no. 3, pp. 1032-1035.
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Infrared spectroscopy has been employed in a study of the degradation of heritage Sydney sandstone used in St. Mary's Cathedral in Sydney, Australia. Spectra were used to characterise the clay components taken from weathered and unweathered sandstone blo
Ip, KH, Stuart, BH, Thomas, PS & Ray, AS 2008, 'Thermal characterization of the clay binder of heritage Sydney sandstones', JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY, vol. 92, no. 1, pp. 97-100.
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Thermal analysis has been employed in a study of the degradation of heritage Sydney sandstone used in St Mary's Cathedral in Sydney, Australia. TG and DSC have been used to characterise the clay components removed from weathered and unweathered sandstone. Two types of kaolin clays - kaolinite and its polymorph, dickite - have been identified. A higher amount of dickite present in the clay of weathered sandstone indicates that a kaolinite-to-dickite transformation occurs upon weathering. XRD hot stage analysis was also used to demonstrate the presence of a more thermally stable polymorph of the kaolinite.
Liu, A, Wu, C & Schisterman, EF 2008, 'Nonparametric sequential evaluation of diagnostic biomarkers', Statistics in Medicine, vol. 27, no. 10, pp. 1667-1678.
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AbstractWe consider evaluation and comparison of the diagnostic accuracy of biomarkers with continuous test outcomes, possibly correlated due to repeated measurements. We develop nonparametric group sequential testing procedures to evaluate and compare the area of biomarkers under their receiver operating characteristic curves, with either independent or paired test outcomes. These procedures rely on the construction of a two‐dimensional statistic of Whitehead (Statist. Med. 1999; 18:2271–2286) so that design methods based on Brownian motion can be applied. Copyright © 2008 John Wiley & Sons, Ltd.
Liu, A, Wu, C & Yu, KF 2008, 'Point and Interval Estimation of Primary and Secondary Parameters in a Two-Stage Adaptive Clinical Trial', Journal of Biopharmaceutical Statistics, vol. 18, no. 2, pp. 211-226.
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Investigated in this paper is the point estimation and confidence intervals of the treatment efficacy parameter and related secondary parameters in a two-stage adaptive trial. Based on the minimal sufficient statistics, several alternative estimators to the sample averages are proposed to reduce the bias and to improve the precision of estimation. Confidence intervals are constructed using Woodroofe's pivot method. Numerical studies are conducted to evaluate the bias and mean squared error of the estimators and the coverage probability of the confidence intervals. Copyright © Taylor & Francis Group, LLC.
Liu, A, Wu, C & Yu, KF 2008, 'Two-stage procedures for selecting the best diagnostic biomarkers', Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol. 366, no. 1874, pp. 2293-2299.
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Considered in the paper is the problem of selecting a diagnostic biomarker that has the highest classification rate among several candidate markers with dichotomous outcomes. The probability of correct selection depends on a number of nuisance parameters from the joint distribution of the biomarkers and thus can be substantially affected if these nuisance parameters are misspecified. A two-stage procedure is proposed to compute the needed sample size that achieves the desired level of correct selection, as so confirmed by simulation results.
Nimbalkar, S & Choudhury, D 2008, 'Seismic design of retaining wall by considering wall-soil inertia for active case', International Journal of Geotechnical Engineering, vol. 2, no. 4, pp. 319-328.
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Effect of both the wall and soil inertia must be considered for the design of retaining wall under seismic conditions. In this paper, by considering pseudo-dynamic seismic forces acting on the soil wedge and the wall, the required weight of the wall under seismic conditions is determined for the design purpose of the retaining wall under active earth pressure condition. The method proposed considers the movement of both shear and primary waves through the backfill and the retaining wall due to seismic excitation. A rigid vertical retaining wall supporting cohesionless backfill with horizontal ground has been considered in the present analysis by considering planar rupture surface. Results in graphical form show the variations of proposed design factors viz. soil thrust factor (F ), wall inertia factor (F ) and combined dynamic factor (F ) with respect to horizontal seismic acceleration coefficient (k ), required for the design of the wall under seismic conditions. Also the effects of variation of parameters like soil friction angle, wall friction angle, vertical seismic acceleration, period of lateral shaking and amplification factor on combined dynamic factor have been studied. A comparative study between the present theory and available pseudo-static results has shown the merits of the present analysis. T I w h
NIMBALKAR, SS & CHOUDHURY, D 2008, 'EFFECTS OF BODY WAVES AND SOIL AMPLIFICATION ON SEISMIC EARTH PRESSURES', Journal of Earthquake and Tsunami, vol. 02, no. 01, pp. 33-52.
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To design a retaining wall, conventional Mononobe–Okabe method, which is based on the pseudo-static approach and gives the linear distribution of seismic earth pressures in an approximate way, is used to compute the seismic earth pressures. In this paper, pseudo-dynamic approach is used to compute the seismic earth pressures on a rigid retaining wall by considering the effects of time, phase difference in shear and primary waves and soil amplification along with the horizontal and vertical seismic accelerations and other soil properties. Design value of the seismic active earth pressure coefficient is found to increase with increase in the seismic accelerations, phase difference in body waves and soil amplification, whereas the reverse trend is observed for the passive case. Influence of various soil parameters on seismic passive earth pressure is more significant than that for the active case under harmonic seismic loading. Results are provided in the combined tabular and graphical non-dimensional form for both the seismic active and passive earth pressures. Present results are compared with the available results in literature to validate the proposed non-linearity of seismic earth pressure distribution.
Oehlers, DJ, Haskett, M, Wu, C & Seracino, R 2008, 'Embedding NSM FRP Plates for Improved IC Debonding Resistance', Journal of Composites for Construction, vol. 12, no. 6, pp. 635-642.
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Onishi, A, Thomas, PS, Stuart, BH, Guerbois, JP & Forbes, SL 2008, 'TG-MS analysis of the thermal decomposition of pig bone for forensic applications', JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY, vol. 92, no. 1, pp. 87-90.
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In order to investigate the potential of thermal analysis for the determination of post-mortem age, rib bone specimens were collected from the remains of a number of slaughtered pigs that were allowed to decompose in the Australian bush in a controlled site under a range of conditions for time periods ranging from 1 to 5 years. The bone specimens were cut in cross-section with the compact bone collected for analysis. TG-MS curves were collected by heating bone samples to 1100°C in an argon atmosphere. The TG-MS data showed significant differences for the pig bone specimens derived from the different environments and showed trends in peak size correlating with age. The reported data suggest that TG-MS has significant potential for the identification of origin as well as the ageing of skeletal remains in a forensic context.
Phat, VN & Ha, QP 2008, 'New characterization of controllability via stabilizability and Riccati equation for LTV systems', IMA JOURNAL OF MATHEMATICAL CONTROL AND INFORMATION, vol. 25, no. 4, pp. 419-429.
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This paper presents a new characterization of controllability via stabilizability and Riccati equation for linear time-varying systems. An equivalence is given between the global null controllability, complete stabilizability and the existence of the sol
Quick, GW & Sirivivatnanon, V 2008, 'Predicting iron staining of siderite-bearing microsyenites intended for dimension stone use', CONSTRUCTION AND BUILDING MATERIALS, vol. 22, no. 3, pp. 257-263.
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Samali, B, Dowling, DM & Li, J 2008, 'Dynamic Testing and Analysis of Adobe-Mudbrick Structures', Australian Journal of Structural Engineering, vol. 8, no. 1, pp. 63-75.
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Traditional, unreinforced adobe-mudbrick houses are highly susceptible to damage and destruction during seismic events. Research at the University of Technology Sydney has included shake table testing of 10 scale model (1:2) u-shaped adobe wall units to assess the performance of different reinforcement systems and evaluate the response to out-of-plane seismic forces. This paper describes the qualitative and quantitative performance of one unreinforced and two reinforced adobe structures. Results confirm the importance of using appropriately time-scaled input spectra to ensure dynamic similitude and induce damaging near-resonance conditions. The testing and analysis revealed both internally and externally reinforced structures to be effective at impeding initial cracking, as well as delaying major structural damage and ultimate collapse. The system incorporating external vertical reinforcement performed significantly better and has the clear advantage of being simpler to construct, as well as being a viable option for the retrofit-strengthening of existing dwellings. © Institution of Engineers Australia, 2008.
Samali, B, Dowling, DM & Li, J 2008, 'Static and Dynamic Testing of Adobe-Mudbrick Structures', Australian Journal of Structural Engineering, vol. 8, no. 2, pp. 159-170.
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Smallwood, AG, Thomas, PS & Ray, AS 2008, 'Characterisation of the dehydration of Australian sedimentary and volcanic precious opal by thermal methods', JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY, vol. 92, no. 1, pp. 91-95.
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Smallwood, AG, Thomas, PS & Ray, AS 2008, 'Comparative analysis of sedimentary and volcanic precious opals from Australia', Journal of the Australian Ceramic Society, vol. 44, no. 2, pp. 17-22.
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Precious opal is Australia's national gemstone, with Australian opal fields providing 90% of world production. The sedimentary geological environment, associated with Cretaceous sediments of the Great Artesian Basin, is the source of most precious opals in Australia. The deposit of precious opal at Tintenbar in northern New South Wales is the only known commercial occurrence of precious opal in volcanic environment in Australia. Differences in silica structure of opal previously classified by x-ray diffraction (XRD) in the 1960's by Jones and Segnit identified three types of opal structure - amorphous opal-A, opal-CT with a poorly crystalline intergrowth cristobalite and tridymite and opal-C showing the cristobalite structure. Recent papers have suggested that all precious opal from a sedimentary environment is Opal-A, and all precious opal from the volcanic environment is opal-CT. This paper examines the differences between sedimentary precious opals from Coober Pedy, South Australia, and volcanic precious opal from Tintenbar, NSW using XRD, scanning electron microscopy and thermal analysis.
Sofi, M, Mendis, PA, Lie, S & Baweja, D 2008, 'Early age concrete thermal and creep effects: Relevance to anchorage zones of post-tensioned members', Electronic Journal of Structural Engineering, vol. 8, pp. 90-96.
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Highly concentrated stresses are imposed on maturing concrete slab local anchorage zones when post-tensioning (PT) load is applied. The prime nonlinear phenomena of the concrete while hydrating are the evolution of stiffness, the thermal strains, the visco-elastic nature of the concrete and cracking. Thermal and visco-elastic effects are more pronounced in early ages due to a higher rate of hydration reaction and the different phases present. The stresses associated with these effects may cause minor cracks in concrete, even prior to the application of the PT load. Finite Element simulation of early-age concrete behaviour is presented representing about four days of concrete curing in a plywood box. The thermal evolution is validated using experimental data obtained for the same mix. Results demonstrate that hydration reaction and visco-elastic effects can produce tensile stresses at critical times when the PT load is being applied. These stresses can have significant effects to the 'spalling' stresses when a concentrated load is applied to the concrete section.
Su, Y, Wu, C & Griffith, M 2008, 'Mitigation of blast effects on aluminum foam protected masonry walls', Transactions of Tianjin University, vol. 14, no. S1, pp. 558-562.
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Terrorist attacks using improvised explosive devices (IED) can result in unreinforced masonry (URM) wall collapse. Protecting URM wall from IED attack is very complicated. An effective solution to mitigate blast effects on URM wall is to retrofit URM walls with metallic foam sheets to absorb blast energy. However, mitigation of blast effects on metallic foam protected URM walls is currently in their infancy in the world. In this paper, numerical models are used to simulate the performance of aluminum foam protected URM walls subjected to blast loads. A distinctive model, in which mortar and brick units of masonry are discritized individually, is used to model the performance of masonry and the contact between the masonry and steel face-sheet of aluminum foam is modelled using the interface element model. The aluminum foam is modelled by a nonlinear elastoplastic material model. The material models for masonry, aluminum foam and interface are then coded into a finite element program LS-DYNA3D to perform the numerical calculations of response and damage of aluminum foam protected URM walls under airblast loads. Discussion is made on the effectiveness of the aluminum foam protected system for URM wall against blast loads.
Thomas, PS, Smallwood, AS, Ray, AS, Briscoe, BJ & Parsonage, D 2008, 'Nanoindentation hardness of banded Australian sedimentary opal', JOURNAL OF PHYSICS D-APPLIED PHYSICS, vol. 41, no. 7, pp. 1-6.
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Nanoindentation hardness data in continuous stiffness mode are reported for banded potch and play of colour opals sourced from Lightning Ridge in New South Wales and Andamooka in South Australia. Despite the significant visible heterogeneities observed and the significant differences in origin and microstructures, as observed by SEM, and subtle differences in the elemental distributions between bands within specimens, little difference was observed in the mechanical properties. Specimens were found to be mechanically homogeneous and values of the hardness and moduli were found to be similar between samples. The creep behaviour of the specimens was also observed to be similar. It was concluded that the similarities in mechanical properties were due to the similarities in the silica morphology of the specimens, formed in similar geological environments, as differences in microstructure and trace element distribution were found not to significantly influence the observed bulk mechanical properties
Vessalas, K, Ray, AS, Thomas, PS, Sri Ravindrarajah, R, Joyce, P & Haggman, J 2008, 'Pitchstone fines pozzolanic activity assessment as partial Portland cement (PC) replacements', Journal of the Australian Ceramic Society, vol. 44, no. 1, pp. 7-12.
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Mined pitchstone fines (PF), derived as a waste by-product from expandable perlite production in Australia, are a viable, environmentally friendly aluminosilicate supplementary cementitious material (SCM) suitable for partial Portland cement (PC) replacement, thus reducing greenhouse gas emissions resulting from PC manufacture. This paper reports on the findings of pozzolanic activity exhibited at 10%, 20% and 40% replacement levels of PC, through compressive strength determinations of mortar after 1, 7 and 28 days ageing, using strength activity index (SAI) criteria. Additionally, flows and wet densities have been examined using a polycarboxylic based high-range water-reducing admixture (HRWRA) superplasticiser and fixed water content relative to cementitious material present for all PF substitution levels.
Wu, C & Hao, H 2008, 'Numerical derivation of averaged material properties of hollow concrete block masonry', Engineering Structures, vol. 30, no. 3, pp. 870-883.
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Wu, C, Oehlers, DJ & Whittaker, A 2008, 'FRP retrofitted RC slabs using finite difference model', Transactions of Tianjin University, vol. 14, no. 5, pp. 344-347.
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Current guidelines recommend using single-degree-of-freedom(SDOF) method for dynamic analysis of reinforced concretec (RC) structures against blast loads, which is not suitable for retrofitted members. Thus, a finite difference procedure developed in another study was used to accurately and efficiently analyze the dynamic response of fibre reinforced polymer (FRP) plated members under blast loads. It can accommodate changes in the mechanical properties of a member's cross section along its length and through its depth in each time step, making it possible to directly incorporate both strain rate effects (which will vary along the length and depth of a member) and non-uniform member loading to solve the partial differential equation of motion. The accuracy of the proposed method was validated in part using data from field blast testing. The finite difference procedure is implemented easily and enables accurate predictions of FRP-plated-member response.
Aboura, K, Samali, B, Crews, K & Li, J 1970, 'Stochastic Deterioration Processes for Bridge Lifetime Assessment', 2008 Third International Conference on Broadband Communications, Information Technology & Biomedical Applications, 2008 Third International Conference on Broadband Communications, Information Technology & Biomedical Applications, IEEE, Pretoria, South Africa, pp. 437-442.
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The Markov chain model can be found in the maintenance and repair problems since the early 60's, is introduced to the maintenance of road infrastructure in the 1980's, and is made to drive the current bridge maintenance optimization systems. While this model results into solvable programming problems and provides a solution, there are a number of criticisms associated with it. In this article, we highlight the shortfalls of the Markov model for bridge infrastructure lifetime assessment and promote the use of stochastic processes. We use examples from a study for the modeling of the condition of bridges that considers more than 15 years of data. We argue for the applicability of the gamma process and other stochastic processes. © 2008 IEEE.
Aboura, K, Samali, B, Crews, K & Li, J 1970, 'Stochastic processes for modelling bridge deterioration', Futures in Mechanics of Structures and Materials - Proceedings of the 20th Australasian Conference on the Mechanics of Structures and Materials, ACMSM20, Australasian Conference on the Mechanics of Structures and Materials, Taylor and Francis Group, Toowoomba, pp. 533-538.
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Traditionally, bridge management systems were designed using Markov chain models. Recently, researchers applied the gamma process successfully to structural deterioration problems. The stochastic process captures the temporal variability of degradation, and has been applied to a range of problems in structures. We report on a study for the modelling of the condition of bridges in the state of NSW. The study encompasses large amounts of data spanning more than 15 years. We argue for the applicability of the gamma process and other stochastic processes. While the gamma process has been adopted in the past decade on grounds of mathematical tractability and physical motivation, we also observe another distribution for the deterioration at different times. The finding promotes the stochastic process modelling direction taken in the past decade and brings forth new models for the time-dependent reliability analysis of bridges. © 2009 Taylor & Francis Group, London.
Anderson, D & Crews, K 1970, 'Bridging the Gap – A Design Process Case Study for an “Intelligent” Footbridge', IABSE Conference, Helsinki 2008: Information and Communication Technology (ICT) for Bridges, Buildings and Construction Practice, IABSE Conference, Helsinki 2008: Information and Communication Technology (ICT) for Bridges, Buildings and Construction Practice, International Association for Bridge and Structural Engineering (IABSE), Helsinki, Finland, pp. 1-10.
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This paper presents details of a research project that has been undertaken at the University of Technology, Sydney by a multidisciplinary team to develop a framework model that synthesises architectural, engineering and construction processes for intelligent buildings with sustainable performance characteristics. A significance aspect of this project is the bridging of the traditional gap that exists between Architecture, Engineering and Construction professions in Australia. The focus of the first stage of this research has been to undertake design of a complex form footbridge using various software packages to undertake concept design using digital architecture, visualisation and modelling of structural performance of the finished bridge. In order to achieve this synthesis in design, a number of interoperability issues have been identified. The paper presents details of the project and discuss how various design and knowledge creation issues have been addressed, as well as how it is proposed to develop the framework model in the future, for more complex problems.
Aoki, Y, Sri Ravindrarajah, R & Khabbaz, H 1970, 'Environmentally friendly sustainable pervious concrete', Futures in Mechanics of Structures and Materials - Proceedings of the 20th Australasian Conference on the Mechanics of Structures and Materials, ACMSM20, Australasian Conference on the Mechanics of Structures and Materials, Taylor & Francis Group, Toowoomba, Queensland, Australia, pp. 567-570.
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Portland cement is considered as one of the environmentally unfriendly materials due to its contribution to the increased liberation of carbon dioxide to the environment during production. In addition to its impervious nature, when it is used for pavement application, it contributes to increased stormwater runoff to drainage systems, over-burdening the infrastructure and causing excessive flooding in built-up areas. This paper presents the results of an experimental investigation associated with quantifying the properties of pervious concrete containing fly ash, up to 50% as partial replacement for cement. The main goal of this research is to promote the utilisation of fly ash for developing durable and sustainable pervious concrete, which creates less negative environmental impacts. © 2009 Taylor & Francis Group, London.
Choi, F, Li, J, Samali, B & Crews, KI 1970, 'Non Destructive Testing of a Timber Beam using Vibration-Based Approach', The 9th International Conference on Motion and Vibration Control, Technique Universaetet, Munich.
Choi, F, Li, J, Samali, B & Crews, KI 1970, 'Overview of Dynamic Based Damage Detection for Timber Bridges', On-Site Assessment of Concrete, Masonry and Timber Structures - Volume 2, On Site Assessment of Concrete, Masonry and Timber Structures, RILEM Publications, Varena, Italy, pp. 1125-1135.
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Asset management of bridges throughout the world faces increasing challenges as a result of aging infrastructure and inadequate funding. Replacement of an old bridge is neither viable nor sustainable in many circumstances. As a consequence, there is an urgent need to develop and utilise state-of-the-art techniques to assess and evaluate the 'health state' of existing bridges and to be able to understand and quantify the effects ofdegradation in regard to public safety. This paper presents an overview of experimental work for a project in developing and implementing several dynamic methods for evaluation of damage in timber bridges. The technique of detecting damage involved the use of modal strain energy commonly referred to in the literature as damage index methods. The project started with simple beams subjected to single and multiple damage and then was extended to a scale timber bridge constructed under laboratory conditions. It was found that after modification on the damage index method, it was well suited to detect single and multiple damage scenarios for a one-dimensional beam. For the laboratory bridge, the damage index method developed for plate-like structures was successful in detecting single and multiple damage with an acceptable degree of accuracy.
Crews, K & MacKenzie, C 1970, 'Development of grading rules for re-cycled timber used in structural applications', 10th World Conference on Timber Engineering 2008, pp. 231-238.
Crews, KI 1970, 'An overview of the development of on-site assessment for timber structures in Australia', On-Site Assessment of Concrete, Masonry and Timber Structures: 1st International RILEM Symposium Proceedings, On Site Assessment of Concrete, Masonry and Timber Structures, RILEM Publications, Varena, Italy, pp. 1113-1124.
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Crews, KI 1970, 'Rehabilitation designs on sometimber heritage bridges in Australia', Proc. 12 th International Conference Structural Faults and Repair 2008, 12 th International Conference Structural Faults and Repair 2008, Strucural Faults and Repair, Edinburgh Scotland, pp. 1-11.
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Australia has some 27,000 timber bridges, representing about 65% of the total national bridge stock [1]. Most of these are small span bridges made from round hardwood girders and located in regional areas. However, a small number of these are larger and arguably more significant truss structures spanning up to 36.6m (or 120 feet). These include some notable early examples of Allan and Dare trusses built around the turn of the 19th century. Over recent years, most of these truss bridges have been designated as Heritage structures, which are deemed to be of national significance in terms of the Engineering heritage represented by the original bridge. Whilst Heritage listing is often a popular decision for local communities, it poses some interesting problems for Structural Engineers who have to comply with modern design code requirements, whilst at the same time adhering to Heritage Council restrictions on changing the material and / or section geometry of truss components. This paper discusses the development of assessment and design procedures that meet this challenge and presents an overview of some timber truss bridge rehabilitation projects that have been recently undertaken in Australia.
Crews, KI & Mackenzie, C 1970, 'Development Of Grading Rules For Re-Cycled Timber Used In Structural Applications', Proceedings of WCTE2008-10th World Conference on Timber Engineering, World Conference on Timber Engineering, WCTE, Miyazaki, Japan, pp. 1-8.
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Until recently, the usual method of disposal of timber used in structures has been demolition and disposal. For example, at the time of writing, Australians are placing approximately 1 million tonnes of wood waste into landfill sites. However, reduced availability of native hardwoods has created a situation where use of recycled timber has significant environmental and economic potential, particularly where recycled products can be incorporated into new construction or in some cases retro-fitting of existing buildings and structures. Currently, there are no standards or recommendations for assigning design properties for structural reuse of wood and the use of recycled timber in decorative products tends to rely on subjective application of visual grading rules developed for new timber. In order to address this problem and utilise the recycled timber resource effectively and reliably, the authors have undertaken a research project (funded by the Forest and Wood Products Association). The aim of this project is to develop appropriate (visual) grading systems that take into account the properties of recycled timber; in particular, how the history and previous use of the timber has effected its properties in terms of being fit for purpose in a re-use application. The paper will present the findings of this project involving research to quantify the mechanical properties and develop appropriate (visual) grading systems that take into account the properties of recycled timber; for use in both structural and aesthetic applications.
Dackermann, U, Li, J & Samali, B 1970, 'Structural damage identification utilising PCA-compressed frequency response functions and neural network ensembles', Futures in Mechanics of Structures and Materials - Proceedings of the 20th Australasian Conference on the Mechanics of Structures and Materials, ACMSM20, Australasian Conference on the Mechanics of Structures and Materials, CRC Press, Taylor & Francis Group, Toowoomba, pp. 803-809.
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This paper presents a damage detection method that utilises FRF data to identify damage in beam structures. The proposed method uses artificial neural networks (ANNs) to map changes in FRFs to damage characteristics. To obtain suitable patterns for ANN inputs, the size of the FRFs is reduced adopting Principal Component Analysis (PCA) techniques. A hierarchy of neural network ensembles is created to take advantage of individual differences from sensor signals. To simulate field applications, the time history data are polluted with white Gaussian noise. The method involves finite element modelling of undamaged and damaged steel beams. By performing transient analysis with the numerical beams, the time histories are obtained and subsequently polluted with different levels of white Gaussian noise. FRFs are determined and compressed utilising PCA techniques. The PCA-reduced FRFs are then used as input patterns for training and testing of neural network ensembles giving the characteristics of the damage. © 2009 Taylor & Francis Group, London.
Dalvand, H, Nguyen, MT, Kwok, NM, Ha, QP & IEEE 1970, 'A New Hybrid Filter for Power Quality Improvement in Unbalanced Load Conditions', 2008 10TH INTERNATIONAL CONFERENCE ON CONTROL AUTOMATION ROBOTICS & VISION: ICARV 2008, VOLS 1-4, International Conference on Control, Automation, Robotics and Vision, IEEE, Hanoi, Vietnam, pp. 1027-1032.
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This paper presents the design of a new hybrid filter for quality improvement of power systems in unbalanced conditions. This filter includes a variable passive filter in parallel with an active filter. The passive part is designed with a varying inductance to reduce the rating of the active part. By using this proposed filter it is possible to compensate for the current harmonics and unbalanced loads with a lower rating active filter compared with conventional ones. Also a simple and accurate method is used to generate the harmonic reference current in the active part of this filter which makes it efficient in unbalanced load conditions. Furthermore, an intelligent hysteresis band current controller is utilized to generate inverter pulses owing to its quick current controllability and easy implementation. Simulation results using the MATLAB Simulink Power System Toolbox show the efficiency and effectiveness of the proposed hybrid filter in elimination of harmonics and balance of the utility current with a desired level of load balancing. © 2008 IEEE.
Ding, GK 1970, 'Environmental assessment of residential buildings in China', Proceedings of the 2008 World Sustainable Building Conference, World Sustainable Building Conference, ASN Events, Melbourne, Australia, pp. 494-501.
Fang, G, Kwok, NM & Ha, Q 1970, 'Automatic Fuzzy Membership Function Tuning Using the Particle Swarm Optimization', 2008 IEEE Pacific-Asia Workshop on Computational Intelligence and Industrial Application, 2008 Pacific-Asia Workshop on Computational Intelligence and Industrial Application (PACIIA), IEEE, Wuhan China, pp. 324-328.
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Fuzzy logic controllers (FLCs) are developed to exploit human expert knowledge in designing control systems. While the fuzzy rules are relatively easy to obtain, fuzzy membership function (MF) tuning could be a time consuming exercise. In this paper the particle swarm optimization technique is employed to automatically tune the MFs of a Mamdani-type of fuzzy controller. The effectiveness of the proposed controller is demonstrated by the control performance of such an FLC of a nonlinear water tank system. The results are compared favourably to a PSO tuned PID controller.
Fang, G, Kwok, NM & Ha, QP 1970, 'Swarm Interaction-Based Simulation of Occupant Evacuation', 2008 IEEE Pacific-Asia Workshop on Computational Intelligence and Industrial Application, 2008 Pacific-Asia Workshop on Computational Intelligence and Industrial Application (PACIIA), IEEE, Wuhan China, pp. 329-333.
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The understanding of occupant responses during an evacuation is crucial for improving the design of effective escape routes. An approach, incorporated the swarm behaviour, for simulating the evacuation of occupants from an enclosed environment is proposed in this paper. This method complements the research in evacuations adopting the cellular automatic and lattice gas models. In particular, it is shown that the trajectories followed by evacuees under panic could be mimicked by the social interaction among them and self-experiences of the individuals. Simulation results of the evacuation from a single exit enclosure are included to illustrate the feasibility of the swarm behaviour-based approach in imitating evacuation phenomena such as jamming and clogging.
Fatahi, B, Indraratna, B & Khabbaz, H 1970, 'Numerical and Experimental Study of Tree Influence on the Ground', GeoCongress 2008, GeoCongress 2008, American Society of Civil Engineers, New Orleans, USA, pp. 694-701.
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A mathematical model for the rate of root water uptake has been developed considering ground conditions, type of vegetation and climatic parameters. The three independent features in the root water uptake model incorporated in detail are soil suction, root distribution, and potential transpiration. A two dimensional finite element approach has been employed to solve the transient coupled flow and deformation equations in vicinity of a tree. To validate the model, an array of field measurements and the data have been compared with the numerical predictions. The predicted results acquired from the numerical analysis have been compared favourably with the field and the associated laboratory measurements, justifying the assumptions upon which the model has been developed. Copyright ASCE 2008.
Fatahi, B, Khabbaz, H & Indraratna, B 1970, 'Analysis of Matric Suction Effects Induced by Tree Roots on Rail Track Subgrade', Conference Proceedings: CORE2008 Conference on Railway Engineering, Conference on Railway Engineering, RTSA, Perth, WA, Australia, pp. 599-610.
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This study investigates the eflects of vegetation on soil matric suction and ground deformation. This paper highlights the inter-related parameters contributing to the development of a conceptual evapo-transpiration and root water uptake equilibrium model that is then incorporated in a comprehensive numerical model. The developed numerical model based on the finite element analysis (ABAQUS) considers fully coupled flowdeformation behaviour of soil. The model formulation is based on the effective stress approach developed for unsaturated soils. Based on the proposed model, the distribution of the matric suction proflle adjacent to the tree has been numerically anaiysed. To validate the model, an array of field measurements conducted at Miram site in Victoria, Australia have been compared with the numerical predictions. Then behaviour of a single tree on improving soil behaviour underneath rail tracks has been described. II is found that root water uptake and associated matric suction stabilise the soft soil beneath railway lines and a pattern of trees grown systematically along rail corridors may olter a cost eltective and environmentally attractive solution for the soft ground improvement in the long-term.
Gerber, C, Crews, K & Sigrist, C 1970, 'Understanding the composite characteristics of stressed-skin panels', 10th World Conference on Timber Engineering 2008, pp. 2213-2218.
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The composite properties of stressed-skin panel (SSP) systems are characterised by the interaction - composite action - and the portion of the sheathing acting with the joists - the tributary width. A discussion on the tributary width forms the focus of this paper. An analysis, which has been conducted considering the pattern of the strain distribution in the sheathing(s), is presented. It uses laboratory data of a major research project conducted at the University of Technology, Sydney, between 2002 and 2007 (Gerber 2007). This analysis indicates that under strict conditions, in particular structurally glued interlayers, a large portion of the sheathing contributes to the structural behaviour of SSP structures. A better use of the mechanical properties of the panels is also achieved. This paper also presents an analysis on the effects of discontinuities in the sheathing. It has been identified that such event causes a significant reduction of the sheathing contribution.
Gerber, C, Crews, KI, Sigrist, C & Samali, B 1970, 'A numerical approach for assessing the behaviours of timber stressed panels', Proc. ASEC 2008, Australian Structural Engineering Conference, The Meeting Planners, Melbourne, pp. 1-11.
Gilbert, RI & Nejadi, S 1970, 'An Experimental Study of Flexural Cracking in Reinforced Concrete', ASEC 2008, Australian Structural Engineering Conference, The Meeting Planners, Melbourne, pp. 1-10.
Indraratna, B, Khabbaz, H & Fatahi, B 1970, 'Conceptual development and numerical modelling of vegetation induced suction and implications on rail track stabilisation', 12th International Conference on Computer Methods and Advances in Geomechanics 2008, International Conference of International Association for Computer Methods and Advances in Geomechanics, Indian Institute of Technology, Bombay, Goa, India, pp. 4335-4344.
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The effects of tree roots on soil suction and ground settlement are investigated. This paper highlights the inter-related parameters contributing to the development of a conceptual evapo-transpiration and root water uptake equilibrium model that is then incorporated in a comprehensive numerical model. The developed numerical model based on the finite element analysis (ABAQUS) considers fully coupled flow-deformation behaviour of soil. Field measurements obtained by the authors from a field site in western Victoria and from past literature are used to validate the model. The predicted results show acceptable agreement with the field data in spite of the assumptions made for simplifying the effects of soil heterogeneity and anisotropy. The numerical analysis proves that the proposed root water uptake model can reliably predict the region of maximum matric suction away from the tree axis. The paper also compares the natural favourable effect of tree roots with the stabilising mechanisms of geosynthetic vertical drains subjected to vacuum pressure. Although this analogy is only justified for shallow vertical drains, the comparison still emphasises the obvious economical advantages of native vegetation.
Ip, KH, Stuart, BH, Thomas, PS & Ray, AS 1970, 'Thermal characterization of the clay binder of heritage Sydney sandstones', JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY, 8th Mediterranean Conference on Calorimetry and Thermal Analysis, SPRINGER, Palermo, ITALY, pp. 97-100.
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Li, J, Ma, G & Yu, M 1970, 'Penetration analysis for geo-material based on unified strength criterion', International Journal of Impact Engineering, Elsevier BV, pp. 1154-1163.
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Li, J, Samali, B & Xu, YL 1970, 'A new modal based damage detection approach utilising added mass', Futures in Mechanics of Structures and Materials - Proceedings of the 20th Australasian Conference on the Mechanics of Structures and Materials, ACMSM20, Australasian Conference on the Mechanics of Structures and Materials, CRC Press Taylor and Francis Group, Toowoomba, Australia, pp. 789-793.
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To reliably detect structural damage and estimate damage severity at its early stage poses a great challenge to engineering community. Despite a great deal of research and development in the areas of damage detection and health monitoring, there are very few successful applications in real life damage detection in engineering practices. One of the main obstacles for successful application of damage detection algorithms to real life civil infrastructure is the complex nature of structures and the uncertainties associated with modelling and measurement. This paper presents a new modal based damage detection approach aiming to provide an effective means to improve reliability and accuracy of damage detection. The proposed approach requires measurement data from two states of the structure, i.e. data from the structure 'as-is' and data from the structure after adding a known mass. By means of experimental modal analysis (EMA), the modal parameters of the structure with and without added mass can be obtained. With modal parameters of the said two states and the known added mass, the proposed method will be able to produce the 'in-service' system stiffness matrix. With the element connectivity being known a priori (or assumed reasonably), the 'in-service' element stiffness can be obtained. Location of damage as well as damage severity of the structure will therefore be known. Experimental verification of the proposed method was carried out using a three storey shear building model. The experimental results show that the proposed damage detection method is superior in both damage localisation and damage severity estimation. © 2009 Taylor & Francis Group, London.
Li, Y & Wang, J 1970, 'Experimental study on PID control of MagnetoRheological shock absorber under impact load', 15th International Congress on Sound and Vibration 2008, ICSV 2008, pp. 3022-3028.
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Magneto-Rheological fluids (MRF), with their fast, reversible and repeatable change of rheological behaviour in response to an external applied magnetic field, have for about a decade been the most fascinating subject of widespread interest. Many investigations have been fulfilled and prototypes have also been fabricated to undertake experiments, mainly in the transportation application such as automobile suspensions, heavy truck seats, and racecar suspensions and seismic protection in civil engineering and wind-rain-induced load mitigation in Cable Bridge. In recent years, the applications of MR devices under high shock and impact load have got increasing attentions because of its widely potentials in the engineering. Although there are researches focusing on the structure design and the dynamics of impact-use MR shock absorber, still very few investigations concerning the semi-Active control of the MR shock absorber under impact load have been explored. The primary purpose of this paper is to experimentally investigate the effectiveness of PID control policies on large-scale Magneto-Rheological (MR) shock absorber subjected to impact load. In this paper, three pre-estimated controllers, which are PID controller, PI controller and P controller, are developed to mitigate the peak shock response of MR shock absorber when it subjected to high impulsive load. An impulsive test rig that uses a fixed amount powder to produce the impact force is introduced. Comparative test results show that the P control has the best control results to restrain the peak response of damping force and inner pressure of MR shock absorber.
Li, Y, Li, J, Samali, B & Wang, J 1970, 'Theoretical and experimental studies on semi-active smart pin joint', Futures in Mechanics of Structures and Materials - Proceedings of the 20th Australasian Conference on the Mechanics of Structures and Materials, ACMSM20, Australasian Conference on the Mechanics of Structures and Materials, Taylor & Francis Group, Toowoomba, Queensland, Australia, pp. 723-728.
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An intelligent structural system equipped with smart structural members that are controllable in real-time is one effective solution to prevent structural damage and failure during hostile dynamic loadings, thereby leading to effective protection of structures and their occupants. The primary purpose of this study is to design, fabricate and characterise a prototype smart member, namely a semi-active magnetorheological (MR) pin joint, through theoretical modelling and experimental investigation. Design of prototype smart pin joints includes theoretical analysis relating to the rotary plate radius, the property of MR fluids and the gap between the rotary plate and the casing based on the requirements of the dynamics of MR pin joints. It is verified that an MR pin joint with a diameter of 180 mm can produce a torque of up to 30 Nm, which is deemed adequate for realisation of the semi-active control for multi-storey building models in the next stage of research. © 2009 Taylor & Francis Group, London.
Li, Y, Wang, J & Hu, H 1970, 'Effect of fluted flow channel on magnetic field in Magneto-Rheological damper', Proceedings of the World Forum on Smart Materials and Smart Structures Technology, SMSST'07, p. 574.
Li, Y, Wang, J, Hu, H & ASME 1970, 'Comprehensive study on controllablity of a large-scale MR shock absorber under high impact load', PROCEEDINGS OF THE ASME INTERNATIONAL DESIGN ENGINEERING TECHNICAL CONFERENCE AND INFORMATION IN ENGINEERING CONFERENCE, VOL 1, PTS A-C, ASME International Design Engineering Technical Conferences/Computers and Information in Engineering Conference, AMER SOC MECHANICAL ENGINEERS, Las Vegas, NV, pp. 1803-1808.
Nimbalkar, SS & Choudhury, D 1970, 'Computation of point of application of seismic passive resistance by pseudo-dynamic method', 12th International Conference on Computer Methods and Advances in Geomechanics 2008, pp. 2636-2643.
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Computation of seismic passive resistance and its point of application is an important aspect of seismic design of retaining wall. Several researchers in the past had obtained seismic passive earth pressures by using the conventional pseudo-static method. In this pseudo-static method, peak ground acceleration is assumed as constant and seismic passive pressure thus obtained shows the linear variation along the height of the retaining wall. There is hardly any scope to find out the point of application of seismic passive resistance by pseudo-static approach but to assume it to act at one-third height from the base of the wall. Rectifying these errors, in recently developed pseudo-dynamic method of analysis, all these factors are considered to compute seismic passive earth pressures. In this paper, an attempt has been made to compute the point of application of seismic passive resistance using limit equilibrium method of analysis with pseudo-dynamic approach. Effects of variation of parameters like wall friction angle, time period of earthquake ground motion, seismic shear and primary wave velocities of backfill soil, soil amplification and seismic peak horizontal and vertical ground accelerations on the seismic passive earth pressure are studied.
Raja, S, Thomas, P, Stuart, BH & O'Brien, C 1970, 'Thermal analysis of bones in forensic applications', International Association of Forensic Sciences 18th Triennial Meeting Book of Abstracts, 18th Meeting of the International Association of Forensic Sciences, New Orleans.
Samali, B, Li, J & Aboura, K 1970, 'Monitoring Bridge Deterioration Using Sensors', 2008 Third International Conference on Broadband Communications, Information Technology & Biomedical Applications, 2008 Third International Conference on Broadband Communications, Information Technology & Biomedical Applications, IEEE, Pretoria, South Africa, pp. 64-69.
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Structural health monitoring is a vital part in the management of bridges, particulary as the structures begin to age. Detecting structural faults through the use of sensors is an emerging field that has seen considerable efforts this past decade. Similarly, the use of sensors in bridge management systems provides valuable data on the condition of bridges and external factors affecting the deterioration of bridges such as the traffic load endured by the structures. We review both cases of visual and vibration based monitoring of bridges and showcase an on-line monitoring system for the collection of traffic information. © 2008 IEEE.
Smallwood, AG, Thomas, PS & Ray, AS 1970, 'The thermophysical properties of australian opal', Australasian Institute of Mining and Metallurgy Publication Series, International Congress foe Applied mineralogy, Australasian Institute of Mining & Metallurgy, Brisbane, Australia, pp. 557-560.
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The characterisation of the surface area and porosity of opals derived from Tintenbar, a volcanic environment, and Lightning Ridge, a sedimentary environment, using nitrogen gas adsorption at -196°C is reported. Both opal types were found to have relatively low surface areas and displayed little porosity. The low surface areas observed is indicative of the ability of silica to infill voids and interstices. Thermogravimetric analysis of the samples before and after degassing was carried out to determine the amount of water removed by the degassing process. Negligible difference was found in the water content before and after degassing in the case of the Lightning Ridge sedimentary opal, while the Tintenbar volcanic opal was found to have lost more that 60 per cent of its water during the degassing process. These differences were ascribed to the differences in the silica structure of the opals with the Lightning Ridge opal having a denser cage structure, which traps the molecular water, while a more open structure is postulated for the Tintenbar opal, allowing the water to be relatively easily removed.
Tran, TH, Ha, QP & IEEE 1970, 'Fast Algorithm for UGV Wheel-Terrain Interaction Analysis', 2008 10TH INTERNATIONAL CONFERENCE ON CONTROL AUTOMATION ROBOTICS & VISION: ICARV 2008, VOLS 1-4, International Conference on Control, Automation, Robotics and Vision, IEEE, Hanoi, Vietnam, pp. 674-680.
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On-line prediction of unmanned ground vehicle (UGV) behaviour during interactions with terrain is essential for autonomous and safe operations of skid-steering UGVs. This paper presents a fast and accurate algorithm for a new interaction model to predict performance of a UGV running on a particular terrain. By approximating nonlinear relations involved in the interaction between the vehicle and terrain, a closed form of the interaction model is obtained to enable on-line computation. The minimum absolute error criteria are applied to secure accuracy for the proposed method. The development is compared with the other models in terms of both computation speed and accuracy. © 2008 IEEE.
Vessalas, K, Ray, AS, Thomas, PS, Joyce, P & Haggman, J 1970, 'Characterisation of Portland cement blended with pitchstone fines aiding carbon dioxide emission reduction', Australasian Institute of Mining and Metallurgy Publication Series, International Congress for Applied Mineralogy, Australasian institute of mining & Metallurgy, Brisbane, pp. 255-258.
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Climate change and global wanning present a significant challenge as unsustainable levels of greenhouse gas emissions arising from human activities continue to be emitted. The cement industry is responsible for between five and ten per cent of annual world carbon dioxide emissions; most arising from the manufacture of Portland cement (PC). An effective way of reducing emissions is by incorporating supplementary cementitious materials (SCMs) as partial PC replacements. SCMs are silicate or aluminosilicate based pozzolanic materials which, in finely divided form, combine with water and calcium hydroxide (lime), liberated by cement hydration, to form compounds exhibiting cementitious properties. Pitchstone is such an aluminosilicate and has the potential to act as an effective pozzolan for partial replacement of PC. In North Queensland, Australia, a vast deposit of pitchstone is mined and processed for expandable perlite aggregate. During the classification stage of the excavated natural material, waste pitchstone fines (PF) less than 0.5 mm in size are generated. This study evaluates the waste PF as a viable, eco-friendly pozzolan for the partial replacement of PC. The reactivity of the PF is compared to fly ash (FA), using the pozzolanic compressive strength activity index (SAI) after seven, 28, and 91 days ageing at 20 per cent and 40 per cent PC substitutions. PF was found to be comparable to FA as a pozzolan at 20 per cent PC substitution at all ages tested. However, for the 40 per cent substitution blends significant strength was only achieved at 91 days ageing for the FA blend. The pozzolanic reactivity was also investigated using thermogravimetric analysis to determine the degree of free lime present after 91 days. In all cases where an SCM was added, the free lime was observed to be consumed with increasing age.
Wang, Y, Li, J, Samali, B & Choi, EC 1970, 'A new non-destructive damage detection method for reinforced concrete beams based on modal strain energy', Futures in Mechanics of Structures and Materials - Proceedings of the 20th Australasian Conference on the Mechanics of Structures and Materials, ACMSM20, Australasian Conference on the Mechanics of Structures and Materials, CRC Press, Toowoomba, pp. 773-779.
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This paper presents a new non-destructive damage detection algorithm to predict locations and severities of damage in concrete beams based on modal strain energy. The new method only relies on the measured mode shapes from damaged and undamaged states. Furthermore, theoretical development of the new method requires only a simple assumption, that is, structural mass invariability before and after damage. After brief introduction of the new method, Finite Element (FE) models of RC beam are constructed. Structural vibration response time histories of RC beam models are obtained from transient analysis under impact loading. To simulate real life applications, various levels of noise are added to the response time histories. The results from both numerical work and experimental work show that the new method is not only sensitive to damage, but also simple and robust in locating and estimating the severity of damage. © 2009 Taylor & Francis Group, London.
Wang, Y, Li, J, Samali, B & Sri Ravindrarajah, R 1970, 'A New Damage Detection Method for Reinforced Concrete Beams Based on Modal Strain Energy', Proceedings of the 9th International Conference on Motion and Vibration Control, International Conference on Motion and Vibration Control, Technische Universitaet Muenchen, Munich, pp. 1-10.
Wang, Y, Samali, B & Sri Ravindrarajah, R 1970, 'Non-destructive damage detection in reinforced concrete beams based on modal strain energy', Proceedings of Australasian structural Engineering Conference, Australasian structural Engineering Conference, The Meeting Planners, Melbourne, pp. 1-8.
Yeoh, D, Fragiacomo, M, Buchanan, A, Crews, K, Haskell, J & Deam, B 1970, 'Development of semi-prefabricated timber-concrete composite floors in Australasia', 10th World Conference on Timber Engineering 2008, pp. 2152-2159.
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An integrated research project on timber-concrete composite (TCC) floors in Australasia comprises of four primary objectives involving the University of Technology, Sydney; the University of Canterbury, Christchurch; and the University of Sassari, Italy together with several other industry partners. New applications of timber in multi-storey buildings are being sought by the timber industry in both Australia and New Zealand. Current development and testing of medium to long span flooring systems are highlighted. A semi-prefabricated TCC floor system that is economical, practical and easy to construct is proposed and four major phases of extensive investigations for short- and long-term involving full scale T-strip floor beams are described. The experimental results of phase one, short-term monitoring of beams are reported and compared with a uniaxial finite element model which was specially developed for long-term and collapse analysis of TCC beams. Overall, the validations were found to be within good accuracy except for some cases with acceptable experimental deviations. Other parameters observed were different construction variables and type of concrete.
Yeoh, D, Fragiacomo, M, Ghafar, A, Buchanan, A, Deam, B & Crews, KI 1970, 'Behaviour of Timber-concrete Composite Floor Systems', Australasian Structural Engineering Conference 2008: Engaging with Structural Engineering, Australian Structural Engineering Conference, The Meeting Planners, Melbourne, Australia, pp. 92-102.
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Timber-concrete composite (TCC) floor systems utilise composite action between a timber joist and a concrete topping to increase their span. Their overall structural performance is significantly influenced by the load-slip relationship, strength, stiffness and positions of the connectors providing the composite action. The relatively low elastic modulus of timber, however, may affect the dynamic (vibration) performance of medium to long-span TCC floors. Three broad areas are currently under investigation at the University of Canterbury: (1) the choice of the best type of connection: (2) the collapse behaviour under static (gravity) loads; and (3) the vibration susceptibility. This paper presents preliminary results of experimental tests used to characterise the connection systems as they are tested to failure under monotonic loads. Based on those outcomes, a semi-prefabricated composite floor system is proposed. The system is constructed from prefabricated panels made from timber joists and plywood sheets, and by a concrete slab cast-in-situ on top of the panels. Two different types of connection systems are shown to perform satisfactorily: notches cut from laminated veneer lumber (LVL) joists and reinforced with coach screws, and toothed metal plates pressed into LVL joists. Finally, an overview of the extensive experimental programme currently ongoing is provided.
Yeoh, DE, Fragiacomo, M, Buchanan, A, Crews, KI, Haskell, J & Deam, B 1970, 'Development of Semi-Prefabricated Timber-Concrete Composite Floors in Australasia', Proceedings of WCTE2008-10th World Conference on Timber Engineering, World Conference on Timber Engineering, WCTE, Miyazak, Japan, pp. 1-8.
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An integrated research project on timber-concrete composite (TCC) floors in Australasia comprises of four primary objectives involving the University of Technology, Sydney; the University of Canterbury, Christchurch; and the University of Sassari, Italy together with several other industry partners. New applications of timber in multi-storey buildings are being sought by the timber industry in both Australia and New Zealand. Current development and testing of medium to long span flooring systems are highlighted. A semi-prefabricated TCC floor system that is economical, practical and easy to construct is proposed and four major phases of extensive investigations for short- and long-term involving full scale T-strip floor beams are described. The experimental results of phase one, short-term monitoring of beams are reported and compared with a uniaxial finite element model which was specially developed for long-term and collapse analysis of TCC beams. Overall, the validations were found to be within good accuracy except for some cases with acceptable experimental deviations. Other parameters observed were different construction variables and type of concrete.
