Publications

Ding, GKC 2017, 'Recycling and Reuse of Rainwater and Stormwater' in Abraham, M (ed), Encyclopedia of Sustainable Technologies, Elsevier, USA, pp. 69-76.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Inc. All rights reserved. Rapid population and urbanization have been considered as the main contributor to water scarcity in most regions in the world. Urban development has led to the conversion of land into built-up areas, and impervious surfaces have been widely used to cover the natural ground. Stormwater on one hand provides a valuable alternate source of water, but on the other hand, if not managed properly, it will cause serious flooding, loss of lives, and damage to properties. Conventional stormwater management diverts runoff quickly either to receiving waterways or to municipal drainage systems, accelerating pollutant contamination and degradation of hydrologic ecosystem and causing flooding. Various sustainable management systems have been developed as holistic systems that integrate control, treatment, and protection in the processes. The Best Management Practices as incorporated into these sustainable management systems are tools/technologies not just aiming at preventing urban flooding but also protecting aquatic and native ecological integrity by removing pollutants and treating runoff before discharging the water back into the environment. Rain and stormwater harvesting if planned, designed, and managed properly will become a valuable alternate source of water to address the intensified water stress around the world.

Ding, GKC 2017, 'Wastewater Treatment and Reuse—The Future Source of Water Supply' in Abraham, M (ed), Encyclopedia of Sustainable Technologies, Elsevier, USA, pp. 43-52.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Inc. All rights reserved. Freshwater supply is critical for the survival of humankind. With the rapid growth of population and urbanization we are confronted with serious water scarcity. Wastewater treatment, recycle, and reuse have now become important alternate sources of water supply. Wastewater is used water from domestic, commercial, industrial, and agricultural activities. This water if untreated may be harmful to both the man-made and the natural environment. Treating wastewater requires a comprehensive planning, design, construction, and management of treatment facilities to ensure that the treated water is safe for human consumption and for discharge to the environment. The potential treatments include primary, secondary, and tertiary treatment using mechanical, chemical, and biological processes. Nowadays wastewater treatment plays an important role in providing safe water to ease water scarcity in some areas.

Ding, GKC & Banihashemi, S 2017, 'Ecological and Carbon Footprints—The Future for City Sustainability' in Abraham, M (ed), Encyclopedia of Sustainable Technologies, Elsevier, United Stated, pp. 43-51.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Inc. All rights reserved. Sustainable development has become a concern for people all over the world. The concept of sustainable development is broad and the concerns and actions help ensure long-term growth and prosperity. The environmental aspects of sustainable development include conservation of natural capital stock and the protection of human and the natural habitat. The ecological footprint is a resource accounting tool that has been developed to identify the amount of the biosphere's regenerative capacity used by humans compared with what is available at both local and global scales. The carbon footprint measures the amount of greenhouse gas emissions caused by human activities or accumulated over the life cycle of products. Improving sustainability of cities is important. Therefore, understanding both ecological and carbon footprints will help generate essential information to reduce footprints, identify options for actions, and track progress to ensure resources are available not only for the present generation but also for generations to come.

Ding, GKC & Ghosh, S 2017, 'Sustainable Water Management—A Strategy for Maintaining Future Water Resources' in Abraham, MA (ed), Encyclopedia of Sustainable Technologies, Elsevier, pp. 91-103.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Inc. All rights reserved. Water is a finite natural resource that is essential for our survival. Over the years the reserves of freshwater are running low and some regions in the world are faced with severe water stress. Climate change has impacted the pattern and amount of precipitation and the water shortage has escalated with rapid population growth and urbanization. As a result, we and the natural environment are confronted with a serious water shortage. Sustainable water management is a strategy for maintaining future water resources that include increasing water supply and â managing the way we use freshwater to sustain economic growth for current and future generations. This article aims to discuss the state-of-the-art of managing water supply and demand as a natural resources and what indicators are being developed to identify water scarcity worldwide. The article reviews the technologies that have been developed to implement sustainable water management at the community scale, demonstrated with case studies.

Askari, M, Li, J & Samali, B 2017, 'Cost-effective multi-objective optimal positioning of magnetorheological dampers and active actuators in large nonlinear structures', Journal of Intelligent Material Systems and Structures, vol. 28, no. 2, pp. 230-253.
View/Download from: Publisher's site
View description>>

The optimal number and location of control devices not only play a major role in an effective structural control system but also lead to a cost-effective design. This article presents a multi-objective optimization method based on a new genetic algorithm for simultaneous finding of the optimal number and placement of actuators and magnetorheological dampers, in active and semi-active vibration control of structures. The proposed strategy considers three objective functions to be minimized through optimization, including peak inter-storey drift ratio, peak acceleration and peak base shear force to make sure both human comfort and safety of the structure are guaranteed. Also, by choosing a pre-defined level of performance on dynamic responses of a structure, the designer can decide on decreasing or increasing the number of control devices in a systematic way and minimize the control cost. The approach is then validated through a nonlinear 20-storey benchmark problem. The results from active control system show how a problem that was initially solved with 25 actuators can be solved with less than a quarter of those actuators, having similar results in terms of aforementioned indices. The optimal distribution of different numbers of magnetorheological dampers in the same benchmark building is also studied in this article and compared to those obtained from actuators. Due to highly nonlinear behaviour of these devices, and also the complexity of the under-study benchmark structure, few reported researches have been conducted in this area. Also, the comparison between optimal places of active and semi-active control devices in the same structure has hitherto not been reported in the open literature.

Banihashemi, S, Ding, G & Wang, J 2017, 'Developing a Hybrid Model of Prediction and Classification Algorithms for Building Energy Consumption', Energy Procedia, vol. 110, pp. 371-376.
View/Download from: Publisher's site
View description>>

© 2017 The Authors. Artificial intelligence algorithms have been applied separately or integrally for prediction, classification or optimization of buildings energy consumption. However, there is a salient gap in the literature on the investigation of hybrid objective function development for energy optimization problems including qualitative and quantitative datasets in their constructs. To tackle with this challenge, this paper presents a hybrid objective function of machine learning algorithms in optimizing energy consumption of residential buildings through considering both continuous and discrete parameters of energy simultaneously. To do this, a comprehensive dataset including significant parameters of building envelop, building design layout and HVAC was established, Artificial Neural Network as a prediction and Decision Tree as a classification algorithm were employed via cross-training ensemble equation to create the hybrid function and the model was finally validated via the weighted average of the error decomposed for the performance. The developed model could effectively enhance the accuracy of the objective functions used in the building energy prediction and optimization problems. Furthermore, the results of this novel approach resolved the inclusion issue of both continuous and discrete parameters of energy in a unified objective function without threatening the integrity and consistency of the building energy datasets.

Basack, S & Nimbalkar, S 2017, 'Free strain analysis of the performance of vertical drains for soft soil improvement', Geomechanics and Engineering, vol. 13, no. 6, pp. 963-975.
View/Download from: Publisher's site
View description>>

Improvement of soft clay deposit by preloading with vertical drains is one of the most popular techniques followed worldwide. These drains accelerate the rate of consolidation by shortening the drainage path. Although the analytical and numerical solutions available are mostly based on equal strain hypothesis, the adoption of free strain analysis is more realistic because of the flexible nature of the imposed surcharge loading, especially for the embankment loading used for transport infrastructure. In this paper, a numerical model has been developed based on free strain hypothesis for understanding the behaviour of soft ground improvement by vertical drain with preloading. The unit cell analogy is used and the effect of smear has been incorporated. The model has been validated by comparing with available field test results and thereafter, a hypothetical case study is done using the available field data for soft clay deposit existing in the eastern part of Australia and important conclusions are drawn therefrom.

Basack, S & Nimbalkar, S 2017, 'Numerical Solution of Single Pile Subjected to Torsional Cyclic Load', International Journal of Geomechanics, vol. 17, no. 8, pp. 04017016-04017016.
View/Download from: Publisher's site
View description>>

© 2017 American Society of Civil Engineers. Large structures, such as offshore platforms, wind turbine foundations, wide buildings, bridges, and railway granular embankments, are often supported by pile foundations. These structures are usually subjected to large cyclic loads (in axial, lateral, and torsional modes) arising from actions of waves, ship impacts, or moving trains. Significant torsional cyclic forces can be transferred to the foundation piles due to the eccentricity of the lateral loads. In the past, several theoretical and experimental investigations were carried out on piles under axial and lateral cyclic loads; however, study of the influence of torsional cyclic loads on pile foundations is rather limited. This paper presents a novel numerical model based on the boundary element approach to analyze the response of a single, vertical, floating pile subjected to torsional cyclic load. The nonlinear stress-strain response of soil is incorporated, and the pile material was idealized as elastic-perfectly plastic. The effect of progressive degradation of soil strength and stiffness under cyclic stress reversal is incorporated in the numerical method. Apart from predicting the degradation of torsional pile-soil interactive performance, the profiles for shear stress and angle of twist are also captured by the proposed solution. Validation of the model indicates the suitability and accuracy of the proposed solutions. The frequency, amplitude, and number of cycles play significant roles in torsional cyclic response of piles. The proposed model is also applied successfully to selected case studies on single piles under torsional cyclic loading, and important conclusions are drawn from there.

Booth, N, Davidson, G, Imperia, P, Lee, S, Stuart, B, Thomas, P, Komatsu, K, Yamane, R, Prescott, SW, Maynard-Casely, HE, Nelson, A & Rule, KC 2017, 'Three impossible things before lunch – the task of a sample environment specialist', Journal of Neutron Research, vol. 19, no. 1-2, pp. 49-56.
View/Download from: Publisher's site
View description>>

© 2017 - IOS Press and the authors. All rights reserved. In the course of their day, sample environment professionals can be confronted by numerous technical challenges applicable to a range of scientific questions. This paper presents three successful outcomes from user-posed sample environment challenges for in situ neutron scattering experiments undertaken at the Australian Centre for Neutron Scattering (formerly the Bragg Institute). The sample environments presented here have nothing in common other than their novelty. They may not be the best solution but have been constrained by time, resources and ability. The questions the users posed were: Can we mount a cylinder in cylinder (CIC) rheometer, more regularly used on a small angle scattering instrument, on a diffraction instrument and obtain usable data? Can we supply high-voltage (up to 10 kV) across a sample within the Paris-Edinburgh press while mounted on a powder diffraction instrument? And finally can a Lakeshore 340 and an in-house built liquid conductivity cell do the job of a commercial liquid conductivity meter? This paper presents the engineering and equipment solutions that were used to answer these questions, and in each case the scientific users left with useful, intriguing and, hopefully, publishable data.

Cai, Y, Chen, Q, Zhou, Y, Nimbalkar, S & Yu, J 2017, 'Estimation of Passive Earth Pressure against Rigid Retaining Wall Considering Arching Effect in Cohesive-Frictional Backfill under Translation Mode', International Journal of Geomechanics, vol. 17, no. 4, pp. 04016093-04016093.
View/Download from: Publisher's site
View description>>

n this study, a novel analytical approach is proposed to calculate the passive earth pressure against a rigid retaining wall subjected to the translation mode. Effects of arching in cohesive backfill soils as well as friction mobilized along the wall–soil interface are considered. Analytical expressions of the earth pressure, passive resistance, and its height of application on the backface of the retaining wall were derived based on static equilibrium of forces under passive conditions acting on the failure wedge. A parametric study was undertaken to assess effects of internal friction angle of backfill, wall–soil interface friction angle, surcharge pressure, cohesion, unit weight, and inclination angle of the slip surface on the active earth pressure as well as on the slip-surface angle. The results of the proposed method were then verified against the existing test data as well as the predictions by Coulomb theory and Rankine theory. The results show that the proposed method yields satisfactory results

Chen, SJ, Li, WG, Ruan, CK, Sagoe-Crentsil, K & Duan, WH 2017, 'Pore shape analysis using centrifuge driven metal intrusion: Indication on porosimetry equations, hydration and packing', Construction and Building Materials, vol. 154, pp. 95-104.
View/Download from: Publisher's site
View description>>

© 2017 Porosity is an intrinsic property of many cementitious materials. This study uses a new centrifugation-based low-melting-point metal intrusion technique to characterize and analyze the shape of pores in cementitious materials. Low energy electrons with ultra-long beam dwell time are used to obtain nano meter level resolution of the pore shape. Three descriptors, namely circularity, solidity, and aspect ratio, are proposed to represent the area-perimeter relationship, hydration and packing and 3D shape of the pores, respectively. Circularity is found to hold a consistent power correlation with pore size. Based on this correlation, the Washburn's equation is modified to correct the biased prediction of pore size using mercury intrusion porosimetry (MIP). Solidity, is found to decrease with increased pore size, denser packing of cement particles and more hydration products. Aspect ratio of the observed pores is found to average at about 2 representing an oblate ellipsoid shape of pore in 3D space.

Chua, L, Head, K, Thomas, P & Stuart, B 2017, 'FTIR and Raman microscopy of organic binders and extraneous organic materials on painted ceremonial objects from the Highlands of Papua New Guinea', Microchemical Journal, vol. 134, pp. 246-256.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier B.V. This paper presents a challenging case where organic materials in micro-sized paint samples extracted from mid-20th century ceremonial objects of the Papua New Guinea (PNG) Highlands are characterized using FTIR microscopy, with the aid of solvent extraction and pre-treatment with hydrofluoric acid (HF) targeted for micro-sized samples, as well as Raman microscopy and SEM-EDS. An eclectic range of binder classes including plant-based organic matter, animal fat, wax, natural and synthetic resin, were identified on several ceremonial objects based on spectral signatures. The tree resins detected (tigaso oil and kilt tree resin) are specific to the natural flora from the PNG Highlands. Tannin-rich charred wood forming the base substrate of different ceremonial objects was also identified. In addition, degradation products from metal soaps from both synthetic and biological sources were identified.

Dackermann, U, Yu, Y, Niederleithinger, E, Li, J & Wiggenhauser, H 2017, 'Condition Assessment of Foundation Piles and Utility Poles Based on Guided Wave Propagation Using a Network of Tactile Transducers and Support Vector Machines', Sensors, vol. 17, no. 12, pp. 2938-2938.
View/Download from: Publisher's site
View description>>

© 2017 by the authors. Licensee MDPI, Basel, Switzerland. This paper presents a novel non-destructive testing and health monitoring system using a network of tactile transducers and accelerometers for the condition assessment and damage classification of foundation piles and utility poles. While in traditional pile integrity testing an impact hammer with broadband frequency excitation is typically used, the proposed testing system utilizes an innovative excitation system based on a network of tactile transducers to induce controlled narrow-band frequency stress waves. Thereby, the simultaneous excitation of multiple stress wave types and modes is avoided (or at least reduced), and targeted wave forms can be generated. The new testing system enables the testing and monitoring of foundation piles and utility poles where the top is inaccessible, making the new testing system suitable, for example, for the condition assessment of pile structures with obstructed heads and of poles with live wires. For system validation, the new system was experimentally tested on nine timber and concrete poles that were inflicted with several types of damage. The tactile transducers were excited with continuous sine wave signals of 1 kHz frequency. Support vector machines were employed together with advanced signal processing algorithms to distinguish recorded stress wave signals from pole structures with different types of damage. The results show that using fast Fourier transform signals, combined with principal component analysis as the input feature vector for support vector machine (SVM) classifiers with different kernel functions, can achieve damage classification with accuracies of 92.5% ± 7.5%.

Dadzie, J, Ding, G & Runeson, G 2017, 'Relationship between Sustainable Technology and Building Age: Evidence from Australia', Procedia Engineering, vol. 180, pp. 1131-1138.
View/Download from: Publisher's site
View description>>

© 2017 The Authors. Published by Elsevier Ltd. The overall energy performance of existing buildings is an important consideration in decisions to demolish or refurbish. To refurbish means to use sustainable technologies (STs) to improve energy efficiency, health of occupants, energy cost and environmental sustainability. This paper examines the use of STs to streamline energy efficiency in existing buildings. It analyses various buildings of different ages retrofitted over the last 5 years and the various STs used to enhance energy efficiency through an in-built case study in a survey. The results show that buildings less than 15 years old have been improved with fewer façade technologies compared to those between 16-30 years old. Overall, buildings aged between 16-30 years are the most improved with STs followed by buildings less than 15 years old and those between 31-45 years, in that order. Buildings over 45 years are the least improved with STs for energy efficiency. They had received less than 10% of ST technology injection. The lighting systems, sensors, energy efficient equipment and passive strategies have been applied improve energy efficiency across all ages. However, solar technologies, HVAC systems, façade technologies and building management systems are the least adopted across all ages.

Du, G, Huang, X, Li, Y, Ouyang, Q & Wang, J 2017, 'Performance of a semi-active/passive integrated isolator based on a magnetorheological elastomer and spring', Smart Materials and Structures, vol. 26, no. 9, pp. 095024-095024.
View/Download from: Publisher's site
View description>>

© 2017 IOP Publishing Ltd. This paper reports an investigation on a semi-active/passive integrated vibration isolator utilizing a magnetorheological elastomer (MRE) and spring. To overcome the main shortcoming of passive isolation systems, i.e. lack of adaptability, the semi-active/passive integrated isolator (SAPII) based on an MRE and spring is designed and prototyped. The magnetic circuit is optimized by finite element analysis to fully unlock the unique features of the MRE. The dynamic response characteristic of the SAPII is experimentally investigated under a sweep frequency test. A dynamic model of the SAPII vibration isolation system is established on the basis of the Kelvin model. The model parameters, such as equivalent stiffness and equivalent damping, are identified from experimental data. An ON-OFF control law based on the minimal displacement transmissibility is designed for isolation control of the sinusoid excitation. Two control laws, i.e. ON-OFF control and fuzzy logic control, are designed for vibration isolation of random excitation. Finally, the effectiveness of these control laws is verified by numerical simulation and experiment.

Erkmen, RE & Saleh, A 2017, 'ITERATIVE GLOBAL-LOCAL APPROACH TO CONSIDER THE EFFECTS OF LOCAL ELASTO-PLASTIC DEFORMATIONS IN THE ANALYSIS OF THIN-WALLED MEMBERS', International Journal for Multiscale Computational Engineering, vol. 15, no. 2, pp. 143-173.
View/Download from: Publisher's site
View description>>

© 2017 by Begell House, Inc. The aim of this study is to develop an iterative global-local analysis method to efficiently model the local deformation effects for the nonlinear elasto-plastic analysis of thin-walled beams. Thin-walled members are usually modeled by using beam-type one-dimensional finite elements, which are based on rigid cross-section assumption. Therefore, only deformations associated with the beam axis behavior such as flexural-, torsional-, or lateral buckling can be considered in these formulations, whereas local deformations, namely flange or web local buckling, can be captured by shell-type models. The proposed method allows the local use of shell elements in critical areas to incorporate the local deformation effects on the overall behavior of the thin-walled beam without necessitating a shell model for the whole structure. In this study, the local shell formulation is able to capture the elasto-plastic metal behavior based on the von Mises yield criterion and the associated flow rule for plane stress, which may cause unstable post-buckling response. In order to trace an unstable post-buckling curve, the iterative global-local analysis method is incorporated into the arc-length solution procedure. In order to improve the convergence characteristics, the procedure introduces strong discontinuities in the beam element formulation in the region of the local shell elements. These discontinuities are in the form of an internal enrichment considering additional local degrees of freedom associated with some penalty terms which adjust the tangent stiffness matrix of the beam for the prediction in the next step according to the effects of the local shell model in the previous step. Comparisons with full shell-type analysis are provided in order to illustrate the accuracy and efficiency of the method developed herein.

Far, H, Saleh, A & Firouzianhaji, A 2017, 'A simplified method to determine shear stiffness of thin walled cold formed steel storage rack frames', Journal of Constructional Steel Research, vol. 138, pp. 799-805.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd The shear stiffness of braced frames of thin-walled cold-formed steel storage racks was experimentally and numerically investigated in order to establish the effect of connection flexibility on the accuracy of different analysis methods. The analyses which included a detailed 3D Finite Element model, a 2D frame analysis with beam elements and a simple hand calculation indicated significant variation of results compared with experimental values. A simplified modelling approach for 2D elastic analysis of braced frames was proposed. The approach is aimed at practical applications to account for the flexibility in bolted connections and leads to better approximation of the shear stiffness.

Ghosh, B, Fatahi, B & Khabbaz, H 2017, 'Analytical Solution to Analyze LTP on Column-Improved Soft Soil Considering Soil Nonlinearity', International Journal of Geomechanics, vol. 17, no. 3, pp. 04016082-04016082.
View/Download from: Publisher's site
View description>>

© 2016 American Society of Civil Engineers. In this paper, a mechanical model to idealize the load-settlement response of the load transfer platform (LTP) on column-improved soft soil is proposed. This model simultaneously considers the nonlinear and time-dependent stress-strain behavior of soft soil and the negligible tensile strength of the granular material in LTP. The reinforced Timoshenko beam is adopted to model LTP to consider the shear and flexural deformations. Soft soil is idealized by a spring-dashpot system that includes nonlinear and time-dependent behaviors. The columns and geosynthetics are modeled with linear Winkler springs in the applied range of stresses and rough elastic membrane, respectively. The response function of LTP has been derived for distributed pressure loading in the plane strain condition. The principle of superposition is used to solve the fourth-order differential equations. Parametric studies indicate that the spacing of columns, thickness of LTP, degree of consolidation of the soft soil, and tensile stiffness of the geosynthetics significantly affect the behavior of LTP. This study also evaluates the accuracy of using reinforced Timoshenko theory by comparing the results with Pasternak and Euler-Bernoulli theories.

Ghosh, B, Fatahi, B, Khabbaz, H & Yin, J-H 2017, 'Analytical study for double-layer geosynthetic reinforced load transfer platform on column improved soft soil', Geotextiles and Geomembranes, vol. 45, no. 5, pp. 508-536.
View/Download from: Publisher's site
View description>>

© 2017 The objective of this study is to propose a reasonably accurate mechanical model for double-layer geosynthetic reinforced load transfer platform (LTP) on column reinforced soft soil which can be used by practicing engineers. The developed model is very useful to study the behaviour of LTP resting on soft soil improved with conventional columns such as concrete columns, piles, and deep soil mixing columns. The negligible tensile strength of granular material in LTP, bending and shear deformations of LTP, compressibility and shearing of soft soil have been incorporated in the model. Furthermore, the results from the proposed model simulating the soft soil as Kerr foundation model are compared to the corresponding solutions when the soft soil is idealised by Winkler and Pasternak foundation models. It is observed from the comparison that the presented model can be used as a tool for a better prediction of the LTP behaviour with multi layers of geosynthetics, in comparison with the situation that soft soil is modelled by Winkler and Pasternak foundations. Furthermore, parametric studies show that as the column spacing increases, the maximum deflection of LTP and normalised tension in the geosynthetics also increase. Whereas, the maximum deflection of LTP and normalised tension in the geosynthetics decrease with increasing LTP thickness, stiffness of subsoil, and stiffness of geosynthetic reinforcement. In addition, it is observed that the use of one stronger geosynthetic layer (e.g. 1 × 2000 kN/m) with the equivalent stiffness of two geosynthetic layers (e.g. 2 × 1000 kN/m) does not result in the same settlement of LTP and the tension of the geosynthetic reinforcement when compared to two weaker geosynthetic layers.

Gu, X, Yu, Y, Li, J & Li, Y 2017, 'Semi-active control of magnetorheological elastomer base isolation system utilising learning-based inverse model', Journal of Sound and Vibration, vol. 406, pp. 346-362.
View/Download from: Publisher's site
View description>>

© 2017 Magnetorheological elastomer (MRE) base isolations have attracted considerable attention over the last two decades thanks to its self-adaptability and high-authority controllability in semi-active control realm. Due to the inherent nonlinearity and hysteresis of the devices, it is challenging to obtain a reasonably complicated mathematical model to describe the inverse dynamics of MRE base isolators and hence to realise control synthesis of the MRE base isolation system. Two aims have been achieved in this paper: i) development of an inverse model for MRE base isolator based on optimal general regression neural network (GRNN); ii) numerical and experimental validation of a real-time semi-active controlled MRE base isolation system utilising LQR controller and GRNN inverse model. The superiority of GRNN inverse model lays in fewer input variables requirement, faster training process and prompt calculation response, which makes it suitable for online training and real-time control. The control system is integrated with a three-storey shear building model and control performance of the MRE base isolation system is compared with bare building, passive-on isolation system and passive-off isolation system. Testing results show that the proposed GRNN inverse model is able to reproduce desired control force accurately and the MRE base isolation system can effectively suppress the structural responses when compared to the passive isolation system.

Ho, L & Fatahi, B 2017, 'Axisymmetric Consolidation in Unsaturated Soil Deposit Subjected to Time-Dependent Loadings', International Journal of Geomechanics, vol. 17, no. 2, pp. 04016046-04016046.
View/Download from: Publisher's site
View description>>

© 2016 American Society of Civil Engineers. This paper presents an analytical solution to predict the axisymmetric consolidation in unsaturated soil deposits subjected to different time-dependent loadings. The mathematical procedure uses the separation of variables and Laplace transformation methods to obtain the final solution. A set of polar governing equations of flow are obtained and presented under the partial differential equations (PDEs), and then the variable separation technique is used to alter the PDEs to ordinary differential equations (ODEs) consisting of distinctive variables. Fourier Bessel and sine series are used to present functions of radial and vertical flows, respectively, and the Laplace transformation is used to obtain a function of time. Four primary time-dependent loading functions, including ramping, asymptotic, sinusoid, and damped sine wave, are mathematically simulated and incorporated into the proposed solutions. This study investigates changes in excess pore-air and pore-water pressures as well as consolidation settlement against the air-to-water permeability ratio and various loading parameters. Moreover, changes in suction and net stress induced by ramped and asymptotic loadings are also presented in the worked examples.

Hou, P, Cai, Y, Cheng, X, Zhang, X, Zhou, Z, Ye, Z, Zhang, L, Li, W & Shah, SP 2017, 'Effects of the hydration reactivity of ultrafine magnesium oxide on cement-based materials', Magazine of Concrete Research, vol. 69, no. 22, pp. 1135-1145.
View/Download from: Publisher's site
View description>>

The size of magnesium oxide may greatly affect its behaviour in cement-based materials (CBMs), and this has not been fully investigated. The reactivity of ultrafine magnesium oxide (UFM) of size 40 nm to 20 μm was assessed, and its effects on the compressive strength and volume stability of cement mortar were investigated. The results showed that the hydration of UFM followed the first-order reaction mode in the first 3 d and then slowed down due to the alteration of the reaction to the diffusion-controlled mode. UFM contributed to an increase in compressive strength and a decrease in shrinkage of CBMs at the very early age, but hindered the hydration of cement at later ages, coarsened the microstructure, and decreased the later-age shrinkage to a much smaller extent than normal light-burnt magnesium oxide. The relatively high hydration reactivity of UFM may contribute to the formation of a more compact gel structure around cement particles at the very early age, which may hinder the reaction of cement at later ages, thus leading to the slowed property gain of CBMs at later ages. The findings from this study may help in the selection of magnesium oxide types for achieving a desired CBM with certain properties.

Jamshidi Chenari, R, Fatahi, B, Akhavan Maroufi, MA & Alaie, R 2017, 'An Experimental and Numerical Investigation into the Compressibility and Settlement of Sand Mixed with TDA', Geotechnical and Geological Engineering, vol. 35, no. 5, pp. 2401-2420.
View/Download from: Publisher's site
View description>>

A series of large scale oedometer experiments were carried out to investigate the settlement of sand reinforced with tire derived aggregates (TDA). The parameters studied were five different amounts of TDAs, three aspect ratios and relative skeletal densities, and seven overburden pressures. The volume compressibility coefficient was calculated against different input parameters, and the constraint condition used enabled Poisson’s ratio to be calculated from an “at-rest” coefficient of earth pressure. The triaxial modulus was calculated indirectly and then adopted in subsequent numerical analyses. Finite element analysis and Monte Carlo simulations were used to investigate the settlement of this mixture and to study how the different parameters affected the settlement mixtures of sand and TDAs. The experimental and numerical results reveal that the amount of TDAs is the major parameter which affects settlement, although the overburden pressure and relative skeletal density are also important. The aspect ratio of the shred has almost no effect on volume compressibility parameters as long as constraint compression condition governs. Two index parameters were defined to discuss the type of shred distribution and how it affects settlement of the mixture.

Jozi, B, Braun, R, Samali, B, Li, J & Dackermann, U 2017, 'Limitation of the Lateral Angled Broadband Low Frequency Impact Excitation on the Non-Destructive Condition Assessment of the Timber Utility Poles', International Journal of Advancements in Technology, vol. 08, no. 04, pp. 1-8.
View/Download from: Publisher's site
View description>>

Timber utility poles play a significant role in the infrastructure of Australia as well as many other countries for power distribution and communication networks. Due to the advanced age of Australia’s timber pole infrastructure, substantial efforts are undertaken on maintenance and asset management to avoid any failures of the utility lines. Nevertheless, the lack of reliable tools for assessing the condition of in-service poles seriously jeopardizes the maintenance and asset management. For instance, each year approximately 300,000 poles are replaced in the Eastern States of Australia with up to 80% of them still being in a very good condition, resulting in major waste of natural resources and money. Non-destructive testing (NDT) methods based on stress wave propagation can potentially offer simple and cost-effective tools for identifying the in-service condition of timber poles. Nonetheless, most of the currently available methods are not appropriate for condition assessment of timber poles in-service due to presence of uncertainties such as complicated material properties, environmental conditions, interaction of soil and structure, and an impact excitation type. In order to address these complexities, advanced digital signal processing methodologies are needed to be employed. Deterministic signal separation, blind signal separation, and frequency-wavenumber velocity filtering are the three groups of methodologies, which could most probably provide solutions. In this paper applicability and effectiveness of the blind signal separation methods is investigated through a numerical data obtained from of a timber pole modelled with both isotropic and orthotropic material properties. Principal Component Analysis (PCA), Singular Value Decomposition (SVD), and K-means clustering algorithms are the blind signal separation methodologies that are employed in this research work.

Le, TM, Fatahi, B, Khabbaz, H & Sun, W 2017, 'Numerical optimization applying trust-region reflective least squares algorithm with constraints to optimize the non-linear creep parameters of soft soil', Applied Mathematical Modelling, vol. 41, pp. 236-256.
View/Download from: Publisher's site
View description>>

© 2016 Determination of the creep model parameters is a challenging task particularly when a non-linear elastic visco-plastic (EVP) model is adopted, mainly due to the limited test duration as well as the assumption of the reference time. Therefore, this paper presents an innovative numerical solution to find the EVP model parameters applying the trust-region reflective least square optimization algorithm. The developed approach involves several available laboratory consolidation test results in the optimization procedure with the adopted commencing time to creep as a unit of time. In this paper, the laboratory results of Ottawa clay were employed to demonstrate the limitation of the recent method to obtain model parameters. Furthermore, the developed method is verified against Skå-Edeby clay in the laboratory conditions. The EVP model parameters are obtained by applying the developed method to the available laboratory consolidation results of clay samples. The analysis results of vertical strains and excess pore water pressures demonstrate that the developed method can be a feasible tool to estimate the settlement properties of clays.

Li, J, Hao, H & Wu, C 2017, 'Numerical study of precast segmental column under blast loads', Engineering Structures, vol. 134, pp. 125-137.
View/Download from: Publisher's site
View description>>

© 2016 Elsevier Ltd Constructions with precast technology have seen a fast development over the past several decades. Despite advantages including short construction period, better quality control, less environmental and traffic impact, a lack of study on their behaviour under dynamic loads have prevented the widespread use of precast constructions in high seismic zones and where terrorist attack could be a concern. Among all precast structural components, precast segmental columns have been found one of the construction techniques with great potentials. Intensive research efforts have been spent on investigating the segmental columns under seismic loadings in recent years. During its service life, besides seismic action, structure may subject to other dynamic loads like impact and blast. It is therefore important to perform multi-hazard analyse to better understand structural performance. This study investigates the blast loading resistance capacities of segmental reinforced concrete (RC) columns. RC segmental columns with or without shear keys and energy dissipation bars are considered. Influence of the number of segments and different levels of post tensioning forces on column dynamic performance is also investigated. Commercial code LS-DYNA is used to perform numerical simulations of the segmental columns under different blast loadings. Accuracy of the numerical model is verified against available testing data on RC columns. Numerical results of the segmental columns under different blast loadings are calculated and compared with those of the monolithic RC columns. Discussions on the capabilities of segmental RC columns in resisting blasting loads are made with respect to those of the monolithic RC columns.

Li, J, Wu, C, Hao, H & Liu, Z 2017, 'Post-blast capacity of ultra-high performance concrete columns', Engineering Structures, vol. 134, pp. 289-302.
View/Download from: Publisher's site
View description>>

© 2016 Elsevier Ltd Over the past several decades, iconic and public buildings have become targets of terrorist bomb attacks, but most of these buildings were built without consideration of blast loading scenarios. Key load-carrying elements such as concrete columns are probably the most critical structural components for structural protection against bomb threats. Failures of columns may trigger catastrophic progressive collapse if there is insufficient structural redundancy. In a recent study, novel ultra-high performance concrete (UHPC) material formulated based on reactive powder concrete (RPC) was developed. Field blast tests on columns made of this material were performed. Test results showed that UHPC columns had excellent blast resistant capability, only small mid-height deflection and minor concrete damage was observed after the blasting tests. In the present study, to quantify blast-induced damage and assess residual loading capacity of UHPC columns, static axial loading tests on post-blast UHPC columns were carried out. Undamaged control samples were tested to provide benchmarks. Damage index and residual loading capacity of UHPC columns after various blast loadings were obtained. It was found that column cast with micro steel fibre reinforced UHPC preserved more than 70% of its loading capacity after 35 kg TNT detonation at 1.5 m standoff distance, while high strength concrete column only maintained 40% loading capacity after 8 kg TNT detonation at 1.5 m standoff distance.

Li, J, Wu, C, Hao, H & Su, Y 2017, 'Experimental and numerical study on steel wire mesh reinforced concrete slab under contact explosion', Materials & Design, vol. 116, pp. 77-91.
View/Download from: Publisher's site
View description>>

© 2016 Elsevier Ltd With the rising of terrorism and rapid urbanization around the world, increasingly more structures are exposed to the threats from accidental and hostile explosion loads. To provide adequate structural protection against blast load, novel materials and strengthening techniques are under fast development. In the present study, a composite slab design aiming at high level blast resistance is studied. In the matrix of high strength self-compacting concrete, besides conventional rebars serving as primary reinforcement, steel wire meshes are embedded and served as secondary reinforcements. Moreover, on the concrete cover layer where the tensile cracks locate, steel fibres are added to provide micro crack-bridging effect. Preliminary numerical simulations adopting coupled Finite Element (FE) and Smoothed Particle Hydrodynamics (SPH) are carried out in hydro-code and the results are used as guide for field blast test. Composite slab with optimal design is field tested under 1 kg TNT contact detonation, and the results are compared with slabs made of conventional and ultra-high performance concrete without steel wire meshes. The results demonstrate that slab with steel wire mesh reinforcement develops localized membrane effect when subjected to blast loads and shows better blast resistant capability as compared to the slabs without steel wire meshes.

Li, J, Wu, C, Hao, H, Su, Y & Li, Z-X 2017, 'A study of concrete slabs with steel wire mesh reinforcement under close-in explosive loads', International Journal of Impact Engineering, vol. 110, pp. 242-254.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd Structural responses and damages under blast loading environments are critical to structural and personnel safety. The blast scenarios involving close-in detonations are attracting increasingly more attentions over the last few decades due to the rising of terrorism. Under close-in detonations, structural elements tend to fail in a brittle mode including shear, concrete crater and spall. In such loading scenarios, the structural designated loading capacity which is usually based on flexural deformation assumption is not fully developed. To provide high-level structural protection, high performance concretes with varying fibre additions are now widely investigated and used in blast resistance designs. In the present study, field blast tests results on reinforced concrete slabs under close-in detonations are presented. Performances of slabs made of normal strength concrete and steel fibre reinforced concrete are compared and discussed. Besides conventional steel rebar reinforcement, new reinforcement scheme i.e. hybrid steel wire mesh-micro steel fibre reinforcement is investigated through the laboratory static tests and field blast tests. Furthermore, a numerical study based on Multi-Material ALE and Lagrangian algorithm is carried out to further investigate the field tests’ phenomenon.

Li, W, Huang, Z, Hu, G, Hui Duan, W & Shah, SP 2017, 'Early-age shrinkage development of ultra-high-performance concrete under heat curing treatment', Construction and Building Materials, vol. 131, pp. 767-774.
View/Download from: Publisher's site
View description>>

© 2016 Elsevier Ltd The effects of a novel heat curing regime and longitudinal reinforcement ratio on early-age shrinkage of ultra-high performance concrete (UHPC) were experimentally investigated in this study. The microstructure, porosity and calcium hydroxide (CH) content of UHPC after different heat curing durations were characterized with scanning electron microscopy, mercury intrusion porosimetry and thermal analysis. The results indicate that slight shrinkage was observed when the heat curing duration was less than 60 min and curing temperature reached 48 °C. However, when the heat curing duration approached 70 min and curing temperature was around 55 °C, the early-age shrinkage increased dramatically. It was found that the early-age shrinkage is approximately 450 με after 48 h of heat curing. The results also show that the early-age shrinkage of UHPC significantly decreased by percentage of 33–60% with the increase of longitudinal steel reinforcement ratio from 2.0 to 4.52%. Meantime, after 10 h of heat curing, the cement hydration and secondary hydration in UHPC tend to finish, which consequently leads to dense microstructure and low CH content in UHPC.

Li, W, Li, X, Chen, SJ, Liu, YM, Duan, WH & Shah, SP 2017, 'Effects of graphene oxide on early-age hydration and electrical resistivity of Portland cement paste', Construction and Building Materials, vol. 136, pp. 506-514.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd The effects of graphene oxide (GO) on the early-age hydration process and mechanical properties of Portland cement paste were experimentally investigated in this study. Based on an isothermal calorimeter measurement, the hydration rate of cement was observed to increase with the increase of GO content by nucleation effect. On the other hand, the electrical resistivity development of GO-cement paste was monitored using a non-contact electrical resistivity device. The result showed that electrical the resistivity of GO-cement paste was evidently higher than that of plain cement paste. However, cement paste with excessive amounts of GO exhibited a decreased electrical resistivity due to the massive ion diffusion caused by GO. Compared to plain cement paste, the GO-cement paste exhibited obviously higher compressive and flexural strengths, but the enhancements in compressive strength began to decline when the GO amount was greater than 0.04%. The microstructure characterization indicated that GO can apparently densify the cement pastes with less porosity and hydrates networking, which is consistent with the results of hydration acceleration and strength enhancement.

Li, W, Li, X, Chen, SJ, Long, G, Liu, YM & Duan, WH 2017, 'Effects of Nanoalumina and Graphene Oxide on Early-Age Hydration and Mechanical Properties of Cement Paste', Journal of Materials in Civil Engineering, vol. 29, no. 9, pp. 04017087-04017087.
View/Download from: Publisher's site
View description>>

© 2017 American Society of Civil Engineers. The effects of nanoalumina (NA) and graphene oxide (GO) on the early-age hydration and mechanical properties of portland cement pastes were investigated in this study. The hydration heat release rate and cumulative heat of cement pastes incorporating different dosages of NA and GO were evaluated using an isothermal calorimeter measurement method. Early-age electrical resistivity development was investigated by a noncontact electrical resistivity technique. The results show that both NA and GO could efficiently accelerate cement hydration. As a physical filler, NA significantly accelerates the hydration of tricalcium aluminate (C3A) in cement. On the other hand, GO is able to obviously reduce the dormant period of cement hydration and shift the heat flow peaks to the left by accelerating the hydration of tricalcium silicate (C3S) in cement. Compared to plain cement pastes, both the compressive and flexural strengths of cement pastes incorporating NA or GO are significantly increased. However, when NA and GO contents exceed the optimal amounts, improvements in flexural strength tend to decline, which is probably due to particle agglomeration. NA-cement paste exhibited slightly higher electrical resistivity than plain cement paste during hydration acceleration and deceleration stages. But GO-cement paste clearly showed lower electrical resistivity, which might be attributed to iron diffusion caused by GO with large surface areas.

Li, W, Long, C, Tam, VWY, Poon, C-S & Hui Duan, W 2017, 'Effects of nano-particles on failure process and microstructural properties of recycled aggregate concrete', Construction and Building Materials, vol. 142, pp. 42-50.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd The effects of nano-particles including nano-silica (NS) and nano-limestone (NL) on the crack propagation and microstructure properties of recycled aggregate concrete (RAC) were experimentally investigated in this study. The crack initiation and propagation of nano-particles modified RAC with different nano-particle modification were evaluated using digital image correlation technique (DIC). The microstructures and porosity of interfacial transition zones (ITZ) in nano-modified RAC were also examined using scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP). It was found that the micro-cracks were typically derived from relatively weak ITZs in RAC, and then progressively propagated along the compressive loading direction. The meso-crack developments eventually led to final splitting failure. The results indicated that compared to NL, NS was more effective in improving the microstructure properties and enhance the mechanical strength of RAC. The porosity and water absorption of RAC were obviously reduced by the NS incorporation. However, due to particles agglomeration, NL could not effectively improve the microstructure of RAC for further enhancing the RAC mechanical properties. Furthermore, in terms of severe particles agglomeration, NL was even detrimental to the mechanical strength of RAC especially at the late-age.

Li, W, Luo, Z, Tao, Z, Duan, WH & Shah, SP 2017, 'Mechanical behavior of recycled aggregate concrete-filled steel tube stub columns after exposure to elevated temperatures', Construction and Building Materials, vol. 146, pp. 571-581.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd The compressive mechanical behaviors of recycled aggregate concrete-filled steel tube (RACFST) stub columns after exposure to elevated temperatures were experimentally investigated in this study. The RACFST stub columns incorporating different recycled coarse aggregate (RCA) replacement ratios of 0, 50% and 100% were heated under elevated temperatures of 200 °C, 500 °C, and 700 °C. The results show that the compressive strength and elastic modulus of RACFST columns were relatively inferior to those of the corresponding natural aggregate concrete-filled steel tube (NACFST) columns after exposure to the same elevated temperatures, and the degradations became more pronounced with increasing RCA replacement ratio and higher temperature. This phenomenon might be attributed to the lower resistance of recycled aggregate concrete (RAC) than natural aggregate concrete (NAC) when was exposed to elevated temperatures. However, after elevated temperature exposure, the peak strain of RACFST stub column was relatively higher than that of the NACFST counterpart. Degradation regression formulas of mechanical properties and deformation behaviors of RACFST stub columns after exposure to elevated temperatures were proposed and agreed well with the experimental results.

Li, W, Sun, Z, Luo, Z & Shah, SP 2017, 'Retraction: Influence of Relative Mechanical Strengths between New and Old Cement Mortars on the Crack Propagation of Recycled Aggregate Concrete', Journal of Advanced Concrete Technology, vol. 15, no. 3, pp. 110-125.
View/Download from: Publisher's site

Li, X, Liu, YM, Li, WG, Li, CY, Sanjayan, JG, Duan, WH & Li, Z 2017, 'Effects of graphene oxide agglomerates on workability, hydration, microstructure and compressive strength of cement paste', Construction and Building Materials, vol. 145, pp. 402-410.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd In this study, the effects of graphene oxide (GO) agglomerates on the workability, hydration, microstructure, and compressive strength of cement paste were addressed. The workability of cement paste was reduced because of the presence of GO agglomerates, which entrap a large amount of water. The mini-slump diameter was reduced by 21% with the incorporation of 0.03% by weight GO in cement paste. Hydration of the cement paste was accelerated due to nucleation sites provided by GO agglomerates serving as seeding material in the cement paste. The incorporation of GO refined the pore structure of the cement paste. The incorporation of GO was found to have much greater impact on macropores than on large and small mesopores. At 28 days, the incorporation of 0.04% by weight GO produced a 14% improvement in the compressive strength of cement paste. Below 0.03%, the incorporation of GO had no positive effects on compressive strength.

Li, X, Lu, Z, Chuah, S, Li, W, Liu, Y, Duan, WH & Li, Z 2017, 'Effects of graphene oxide aggregates on hydration degree, sorptivity, and tensile splitting strength of cement paste', Composites Part A: Applied Science and Manufacturing, vol. 100, pp. 1-8.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd It has recently been found the graphene oxide (GO) aggregates form in cement paste due to the chemical cross-linking of calcium cations. Therefore, the effects of GO addition on the properties of cement based materials should be dependent on the properties of GO aggregates rather than GO nanosheets. In this study, GO aggregates were first characterized by particle size measurement. Then, the effects of GO aggregates on the degree of hydration, sorptivity, and tensile strength of cement paste were investigated. The aspect ratio of GO aggregates is much larger than that of the original GO nanosheets. Compared to plain cement paste, the increase of non-evaporable water content of the cement paste was found to be very limited, around 1.17% and 3.90% for cement pastes containing 0.02% and 0.04% by weight GO, respectively. The sorptivity of cement paste, especially the secondary sorptivity, was notably reduced for GO incorporated cement paste. The tensile strength was significantly improved by GO aggregates. Incorporation of 0.04% by weight GO increased the tensile strength by 67% compared to that of plain cement paste.

Li, X, Tao, M, Wu, C, Du, K & Wu, Q 2017, 'Spalling strength of rock under different static pre-confining pressures', International Journal of Impact Engineering, vol. 99, pp. 69-74.
View/Download from: Publisher's site
View description>>

© 2016 Elsevier Ltd A testing method of spalling strength at different static pre-confining pressure is proposed in this paper. Using a modified split Hopkinson bar facility, a static pre-confining pressure was loaded before dynamic loading. The pull-back method is used to calculate the spalling strength and the free surface velocities of the specimen were measured by a laser detector system. The experimental results indicate that the spalling strength is related to the static pre-confining pressures. When the impact loading and rate effect are almost the same, the results demonstrated that the spalling strength decreases with an increase in the confining pressure.

Liu, J, Wu, C & Chen, X 2017, 'Numerical study of ultra-high performance concrete under non-deformable projectile penetration', Construction and Building Materials, vol. 135, pp. 447-458.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd This paper presents a numerical study in evaluating impact response of ultra-high performance concrete (UHPC) cylinder targets under ogive-nosed projectile penetration with broad striking velocities from 300 m/s to 1000 m/s. Steel ogive-nosed projectiles with an average mass of 360 g are launched to penetrate UHPC cylinder targets with 750 mm diameter and 1000 mm length. The Karagozian & Case (K&C) cementitious material model, namely, MAT_Concrete_Damage_Rel3 (Mat_72R3), is implemented into finite element package LS-DYNA for UHPC. In order to accurately predict depth of penetration (DOP) and cratering damage of UHPC cylinder targets, uniaxial compressive and four-point bending testing results are used to validate 3D finite element material model. With the validated numerical model incorporating dynamic increase factors (DIF) of UHPC, parametric studies are conducted to investigate effects of UHPC compressive strength, projectile striking velocity and projectile caliber-radius-head (CRH) ratio on both DOP and cratering damage of UHPC targets. Moreover, an empirical formula to predict DOP is derived according to the simulated data.

Liu, J, Wu, C, Li, J, Su, Y, Shao, R, Liu, Z & Chen, G 2017, 'Experimental and numerical study of reactive powder concrete reinforced with steel wire mesh against projectile penetration', International Journal of Impact Engineering, vol. 109, pp. 131-149.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd This paper presents experimental and numerical studies on impact resistance of reactive powder concrete (RPC) targets reinforced with 44-layer steel wire meshes. Steel ogive-nosed projectiles with an average mass of 330 g and striking velocities ranging from 550 m/s to 800 m/s were launched against the cylindrical RPC targets with 750 mm diameter and 700 mm thickness. The impact responses observed in the tests, including depth of penetration (DOP), crater diameter and volume loss, were investigated and discussed, which indicates an effective impact resistance of steel wire mesh reinforced RPC in comparison with the previous studies on ultra-high performance based cement composites (UHPCC) with additions of fibres and basalt aggregates. Numerical studies based on validated material and element models are also conducted to simulate the impact responses of reinforced RPC targets against high-velocity projectile penetration in explicit hydro-code LS-DYNA. The impact responses, especially for the DOP, are well predicted by using the numerical models. Moreover, further investigation based on the verified numerical models is discussed in the present paper to explore the influence of mechanical and physical properties of steel wire mesh reinforcement on the resistance of projectile penetration.

Liu, Z, Ju, X, Wu, C & Liang, J 2017, 'Scattering of plane P 1 waves and dynamic stress concentration by a lined tunnel in a fluid-saturated poroelastic half-space', Tunnelling and Underground Space Technology, vol. 67, pp. 71-84.
View/Download from: Publisher's site

Liu, Z, Liang, J, Wu, C, Zhao, R & Li, Y 2017, 'The method of fundamental solution for elastic wave scattering and dynamic stress concentration in a fluid-saturated poroelastic layered half-plane', Engineering Analysis with Boundary Elements, vol. 84, pp. 154-167.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd A meshless method based on the method of fundamental solution (MFS) is developed to solve elastic-wave scattering and dynamic stress concentration in a fluid-saturated poroelastic layered half-plane, by utilizing the line sources of cylindrical P I , P II , and SV waves in a poroelastic layered half-plane. The numerical accuracy and stability of the MFS is verified by examining the boundary conditions and comparison with other methods. Subsequently, the amplification effects on displacement, surface hoop stress and fluid pore pressure around a cavity in a three-layered poroelastic half-plane are investigated. Numerical results indicate that the scattering characteristics strongly depend on parameters including the incident frequency and angle, soil-layer porosity and boundary drainage condition. The amplification effects of a cavity in the poroelastic layered half-plane appear to be more significant than the corresponding case of a homogenous half-plane. The amplitude of the fluid pore pressure on the surface of the cavity is amplified up to five times that of the free field, which also considerably aggravates the dynamic stress concentration around the cavity.

Makki Alamdari, M, Samali, B, Li, J, Lu, Y & Mustapha, S 2017, 'Structural condition assessment using entropy-based time series analysis', Journal of Intelligent Material Systems and Structures, vol. 28, no. 14, pp. 1941-1956.
View/Download from: Publisher's site
View description>>

We present a time-series-based algorithm to identify structural damage in the structure. The method is in the context of non-model-based approaches; hence, it eliminates the need of any representative numerical model of the structure to be built. The method starts by partitioning the state space into a finite number of subsets which are mutually exclusive and exhaustive and each subset is identified by a distinct symbol. Partitioning is performed based on a maximum entropy approach which takes into account the sparsity and distribution of information in the time series. After constructing the symbol space, the time series data are uniquely transformed from the state space into the constructed symbol space to create the symbol sequences. Symbol sequences are the simplified abstractions of the complex system and describe the evolution of the system. Each symbol sequence is statistically characterized by its entropy which is obtained based on the probability of occurrence of the symbols in the sequence. As a consequence of damage occurrence, the entropy of the symbol sequences changes; this change is implemented to define a damage indicative feature. The method shows promising results using data from two experimental case studies subject to varying excitation. The first specimen is a reinforced concrete jack arch which replicates one of the major structural components of the Sydney Harbor Bridge and the second specimen is a three-story frame structure model which has been tested at Los Alamos National Laboratory. The method not only could successfully identify the presence of damage but also has potential to localize it.

Ngo, QH, Nguyen, NP, Nguyen, CN, Tran, TH & Ha, QP 2017, 'Fuzzy sliding mode control of an offshore container crane', Ocean Engineering, vol. 140, pp. 125-134.
View/Download from: Publisher's site
View description>>

© 2017 A fuzzy sliding mode control strategy for offshore container cranes is investigated in this study. The offshore operations of loading and unloading containers are performed between a mega container ship, called the mother ship, and a smaller ship, called the mobile harbor (MH), which is equipped with a container crane. The MH is used to transfer the containers, in the open sea, and deliver them to a conventional stevedoring port, thereby minimizing the port congestion and also eliminating the need of expanding outwards. The control objective during the loading and unloading process is to keep the payload in a desired tolerance in harsh conditions of the MH motion. The proposed control strategy combines a fuzzy sliding mode control law and a prediction algorithm based on Kalman filtering for the MH roll angle. Here, the sliding surface is designed to incorporate the desired trolley trajectory while suppressing the sway motion of the payload. To improve the control performance, the discontinuous gain of the sliding control is adjusted with fuzzy logic tuning schemes with respect to the sliding function and its rate of change. Chattering is further reduced by a saturation function. Simulation and experimental results are provided to verify the effectiveness of the proposed control system for offshore container cranes.

Nguyen, L, Fatahi, B & Khabbaz, H 2017, 'Development of a Constitutive Model to Predict the Behavior of Cement-Treated Clay during Cementation Degradation: C3 Model', International Journal of Geomechanics, vol. 17, no. 7, pp. 04017010-04017010.
View/Download from: Publisher's site
View description>>

© 2017 American Society of Civil Engineers. Many researchers have indicated how cementation allows treated soft clays to sustain a higher yield mean effective stress at the same void ratio as its reconstituted state, and thus, the strength of clay treated with cement increases because the cement and clay particles bond together. However, the void ratio of cement-treated clay decreases significantly in isotropic consolidation and triaxial conditions when subjected to a high mean effective stress, particularly beyond the initial yield stress. Laboratory experiments have shown that the cementation of clay gradually diminishes as the mean effective stress increases as a result of the degradation of cementation bonds. Thus, the failure envelope of cement-treated clay gradually merges with the reconstituted clay-cement mixture at high mean effective stresses. Furthermore, the shear strength of cement-treated clay is influenced by the shear degradation induced by shear deformation. In this study, by combining the mean effective stress and shear degradation, a constitutive model, referred to as the C3 model, based on the critical state framework, was developed to simulate the behavior of cement-treated clay. The proposed model includes a modified mean effective stress, a nonlinear failure envelope, a nonassociated plastic potential function, and a general stress-strain relationship to simulate the prepeak and postpeak deviatoric stress states, including the softening behavior of cement-treated clay. In this study, triaxial tests (drained and undrained) were conducted on Ballina clay treated with 10 and 12% cement and Kaolin clay treated with 5 and 10% cement, and the results are reported and discussed. The proposed model was evaluated by comparing its predictions with the triaxial test results reported on the cement-treated Ballina clay and Kaolin clay. The proposed constitutive model gave reliable predictions that agreed with the experimental results and captu...

Pain, A, Chen, Q, Nimbalkar, S & Zhou, Y 2017, 'Evaluation of seismic passive earth pressure of inclined rigid retaining wall considering soil arching effect', Soil Dynamics and Earthquake Engineering, vol. 100, pp. 286-295.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd Evaluation of seismic passive earth pressure is an important topic of research in geotechnical engineering. In this study seismic passive pressure on an inclined rigid retaining wall supporting horizontal cohesionless backfill is estimated considering arching effect. A planar failure surface is considered in the present analysis. Seismic forces are considered to be pseudo-static in nature. The effect of different parameters on the seismic passive earth pressure is studied in details. The normal stress distribution along the depth of the backfill is found to be nonlinear in nature. Friction angle between wall and the backfill soil has the most significant effect on the distribution of normal stress along the depth of the backfill. The point of application of seismic passive pressure shifts gradually downward for higher seismic forces. Present method is validated with the experimental results available in the literature for static conditions. Comparison of present method with other theories is also presented showing the merit of the present study. Arching effect in the backfill should be considered for high values of wall inclination angle as the present seismic passive resistance is found to be the lowest as compared to other theoretical solutions.

Panahian, M, Ghosh, S & Ding, G 2017, 'Assessing Potential for Reduction in Carbon Emissions in a Multi-unit of Residential Development in Sydney', Procedia Engineering, vol. 180, pp. 591-600.
View/Download from: Publisher's site
View description>>

© 2017 The Authors. There is an increase in the construction of multi-unit residential buildings around inner Sydney in the past few years. The energy consumption in Australia has increased by approximately 30% and associated carbon dioxide emissions. This research examines a large multi-unit residential case study located close to the Sydney's Central Business District (CBD). Current energy consumption for the common areas such as the basement, car parks, lobbies, etc. and water usage for gardens are estimated using the actual data on electricity and water usage. Potential for reduction in energy consumption and their equivalent carbon footprint values are examined. Three carbon emissions reduction strategies include: savings from electricity generation from roof solar PV installation; rainwater harvesting from the roof and minimising annual water loss by evaporation in swimming pools reducing energy demand for water supply. In addition, carbon benefits provided by the trees are calculated using an urban forest assessment tool. Recommendations suggest that installation of solar PV on the roof, using an appropriate swimming pool cover, rainwater harvesting and a better tree canopy cover collectively could improve the overall CO2 footprint performance of the selected case study.

Phung, MD, Quach, CH, Dinh, TH & Ha, Q 2017, 'Enhanced discrete particle swarm optimization path planning for UAV vision-based surface inspection', Automation in Construction, vol. 81, pp. 25-33.
View/Download from: Publisher's site
View description>>

© 2017 In built infrastructure monitoring, an efficient path planning algorithm is essential for robotic inspection of large surfaces using computer vision. In this work, we first formulate the inspection path planning problem as an extended travelling salesman problem (TSP) in which both the coverage and obstacle avoidance were taken into account. An enhanced discrete particle swarm optimization (DPSO) algorithm is then proposed to solve the TSP, with performance improvement by using deterministic initialization, random mutation, and edge exchange. Finally, we take advantage of parallel computing to implement the DPSO in a GPU-based framework so that the computation time can be significantly reduced while keeping the hardware requirement unchanged. To show the effectiveness of the proposed algorithm, experimental results are included for datasets obtained from UAV inspection of an office building and a bridge.

Rao, P, Chen, Q, Nimbalkar, S & Liu, Y 2017, 'Laboratory study on impulse current characteristics of clay', Environmental Geotechnics, vol. 4, no. 3, pp. 199-208.
View/Download from: Publisher's site
View description>>

Lightning is recognised as one of the most detrimental natural disasters. While numerous research studies were carried out on the lightning impulse characteristics of the grounding system and the critical breakdown characteristics of soil, little attention was paid to the impulse current characteristics of soils when lightning strikes. In this study, the performance of typical soft soil in Shanghai under the action of lightning is analyzed. Different factors, including the impulse current waveforms, the front time and half peak time of impulse current, the quantity of electric charge and absorption of unit heat, have been studied by performing a series of laboratory tests. The test results show that the variation of impulse current due to lightning strike is time dependent. The higher the soil temperature, the larger the peak impulse current produced during lightning strike. The value of the front time decreases exponentially, while the value of the half peak time decreases linearly with the rise of soil temperature. Novel empirical relationships between the impulse current characteristics of soil and soil temperature are proposed, with the aim of providing useful practical references for the design of a grounding system for lightning strikes.

Rao, P-P, Chen, Q, Li, L, Nimbalkar, S & Cui, J 2017, 'Elastoplastic Solution for Spherical Cavity Expansion in Modified Cam-Clay Soil under Drained Condition', International Journal of Geomechanics, vol. 17, no. 8, pp. 06017005-06017005.
View/Download from: Publisher's site
View description>>

© 2017 American Society of Civil Engineers. This paper presents an innovative semianalytical solution for the expansion of a drained spherical cavity with finite initial radius. The widely known modified Cam-clay model is adopted to capture the nonlinear elastoplastic behavior of soil. The rigorous definitions for the mean and deviator stresses are adopted. The problem is then formulated as a set of first-order ordinary differential equations in the Lagrangian form. The radial and tangential stress and specific volume distribution around the cavity are determined. Extensive parametric study is undertaken to investigate effects of the overconsolidation ratio and relative positioning of elastoplastic interface, among others. The applicability of the proposed theoretical approach is demonstrated by a comparison with laboratory test results.

Shakor, P, Sanjayan, J, Nazari, A & Nejadi, S 2017, 'Modified 3D printed powder to cement-based material and mechanical properties of cement scaffold used in 3D printing', Construction and Building Materials, vol. 138, pp. 398-409.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd Additive manufacturing is a common technique used to produce 3D printed structures. These techniques have been used as precise application geometry in different fields such as architecture and medicine, and the food, mechanics and chemical industries. However, in most cases only a limited amount of powder has been used to fabricate scaffold (structure). In this study, a unique mix of cements (calcium aluminate cement passed through a 150 μm sieve and ordinary Portland cement) was developed for Z-Corporation's three-dimensional printing (3DP) process. This cement mix was blended and the resulting composite powders were printed with a water-based binder using a Z-Corporation 3D printer. Moreover, some samples were added lithium carbonate to reduce the setting time for the cement mixture. The aims of the study were to firstly, find the proper cementitious powder close to the targeted powder (Z-powder); and secondly, evaluate the mechanical properties of this material. Cubic specimens of two different batches with varying saturation levels were cast and cured in various scenarios to enhance the best mechanical properties. The samples were characterised by porosity analyses, compression tests, Olympus BX61 Microscope imaging, 3D profiling Veeco (Dektak) and the Scanning Electronic Microscope (SEM). The maximum compressive strength of the cubic specimens for cementitious 3DP was 8.26 MPa at the saturation level of 170% for both the shell and core. The minimum porosity obtained was 49.28% at the saturation level of 170% and 340% for the shell and the core, respectively.

Shi, W, Chen, Q, Nimbalkar, S & Liu, W 2017, 'A new mixing technique for solidifier and dredged fill in coastal area', Marine Georesources & Geotechnology, vol. 35, no. 1, pp. 52-61.
View/Download from: Publisher's site
View description>>

2016 Copyright © Taylor & Francis Group, LLCOne of the major drawbacks of the conventional method of land reclamation, which involves mixing cement with the dredged soils at the disposal site, is the high cost associated with its manufacturing and transportation. In this study, a new solidified dredged fill (SDF) technique and a new additive are proposed and their practical applications are discussed. Unlike the conventional approach, the dredged marine soils were mixed with the solidifiers using a newly designed mixing technique prior to its transport to site, which would significantly reduce the cost of site machinery and effectively reclaim land with adequate engineering properties necessary for the construction of infrastructure. To evaluate the performance of the reclaimed land using the proposed technique, a series of laboratory and field tests (namely, static and dynamic cone penetration tests, and plate load tests) were conducted on grounds filled with and without solidified dredged marine soils, respectively. The results showed that the engineering behavior of the reclaimed land with dredged marine soils using SDF technique had significantly improved. The SDF technique combined with the newly designed mixing system improved the performance of ground and has thus proved to be both cost-effective and safe.

Stuart, BH & Thomas, PS 2017, 'Pigment characterisation in Australian rock art: a review of modern instrumental methods of analysis', Heritage Science, vol. 5, no. 1, pp. 1-6.
View/Download from: Publisher's site
View description>>

© 2017 The Author(s). The many thousands of Aboriginal rock art sites extending across Australia represent an important cultural record. The styles and materials used to produce such art are of great interest to archaeologists and those concerned with the protection of these significant works. Through an analysis of the mineral pigments utilised in Australian rock art, insight into the age of paintings and practices employed by artists can be gained. In recent years, there has been an expansion in the use of modern analytical techniques to investigate rock art pigments and this paper provides a review of the application of such techniques to Australian sites. The types of archaeological information that may be extracted via chemical analysis of specimens collected from or at rock art sites across the country are discussed. A review of the applicability of the techniques used for elemental analysis and structural characterisation of rock art pigments is provided and how future technological developments will influence the discipline is investigated.

Su, Y, Li, J, Wu, C, Wu, P, Tao, M & Li, X 2017, 'Mesoscale study of steel fibre-reinforced ultra-high performance concrete under static and dynamic loads', Materials & Design, vol. 116, pp. 340-351.
View/Download from: Publisher's site
View description>>

© 2016 Elsevier Ltd In this paper, a three-dimensional numerical model to study the static and dynamic behaviour of ultra-high performance steel fibre reinforced concrete is developed. Ultra-high performance steel fibre reinforced concrete is assumed to be a two-phase model consisting of concrete matrix and steel fibres. The concrete matrix is modelled with homogeneous material and the straight round steel fibres are assumed to be dispersed with random locations and orientations in the matrix. The interfacial transition zone (ITZ) effect is studied based on the single fibre pull-out tests, and parameters describing the fibre-matrix one dimensional bond-slip behaviour are obtained and discussed based on both experimental and theoretical results. After the three-dimensional model is validated with static split tensile tests, split Hopkinson pressure bar (SHPB) split tensile tests are numerically modelled and the stress-time history is interpreted in the mesoscale level. The proposed model qualitatively and quantitatively predicts the material static and dynamic behaviours, and also gives insights on the fibre reinforcement effect in the concrete matrix.

Su, Y, Wu, C, Li, J, Li, Z-X & Li, W 2017, 'Development of novel ultra-high performance concrete: From material to structure', Construction and Building Materials, vol. 135, pp. 517-528.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd This paper investigates effects of nanoscale materials and steel fibres on properties of ultra-high performance concrete (UHPC). Different types of steel fibres including twisted steel fibre (TF), waved steel fibre (WF), and micro steel fibre (MF) together with different kinds of nano materials including Nano-CaCO3, Nano-SiO2, Nano-TiO2 and Nano-Al2O3 are studied in the present research. Material compressive stress–strain relationships, strain energy absorption, the flexural strength and fracture energy absorption of UHPC with different nanoscale materials and steel fibres were compared and discussed. Laboratory static bending tests and field blast tests on structural components made of selected UHPC material composition were carried out, and the results highlighted the superior material ductility and blast resistant capacity of UHPC material developed in the present study.

Sun, W-J, Zong, F-Y, Sun, D-A, Wei, Z-F, Schanz, T & Fatahi, B 2017, 'Swelling prediction of bentonite-sand mixtures in the full range of sand content', Engineering Geology, vol. 222, pp. 146-155.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier B.V. The swelling prediction of bentonite–sand mixtures due to wetting is very important in evaluating the long term performance of the engineered barrier in the high level radioactive waste disposal system and the hydraulic barriers in geoenvironmental constructions. Sun et al. (2015) proposed the swelling prediction model of bentonite-sand mixtures due to full hydration, and predicted the swelling of different types of bentonite-sand mixtures, which was verified, to be consistent with the swelling test results. However, the predicted swelling results of bentonite-sand mixtures with extremely high sand content obtained by the original swelling prediction model have a large deviation from the test results. The reason is that the original model is based on an assumption that all the pores and available water are only associated with bentonite/montmorillonite fraction. However, for mixtures with extremely high sand content, the sand skeleton exists and resists the external stress from the very beginning. At the same time, the bentonite, dispersing in the sand skeleton, in contact with the pore fluid, swells freely to fully saturated state, however, still fails to fill the sand skeleton voids completely. In this research, the original swelling prediction model is extended by introducing the concept of critical filling sand content and critical contact stress. When sand content is more than the critical filling sand content, the deformation of the mixture is mainly due to the sand skeleton deformation. After the stress increases greater than the critical contact stress, the saturated bentonite fills the sand skeleton voids completely, and the swelling can still be predicted by the original swelling prediction model. In the extended model, the swelling prediction can be divided into three zones according to the two limit values of critical sand content and critical filling sand content. In different zones, the distribution ratio of the vertical stress ...

Sun, Y, Chen, C & Nimbalkar, S 2017, 'Identification of ballast grading for rail track', Journal of Rock Mechanics and Geotechnical Engineering, vol. 9, no. 5, pp. 945-954.
View/Download from: Publisher's site
View description>>

© 2017 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences Grading has long been recognised to critically influence the mechanical behaviour of ballast. To identify the ballast grading for heavy-haul rail track, monotonic and cyclic triaxial tests are conducted to assess the performances of different gradings. Permanent deformations, aggregates degradation, resilience, shear resistance, maximum and minimum densities are recorded and analysed. The grading is found to affect the behaviour of ballast in that coarser gradings exhibit relatively better strength, resilience and therefore less permanent deformation. However, ballast degradation increases with the overall aggregate size. Therefore, to identify the grading for ballast with different performance objectives, a grey relational theory is used to convert the multi-objective into single-objective, i.e. grey relational grade. A relatively optimal grading that provides the highest grey relational grade is thus suggested for the improved ballast performance.

Sun, Y, Indraratna, B, Carter, JP, Marchant, T & Nimbalkar, S 2017, 'Application of fractional calculus in modelling ballast deformation under cyclic loading', Computers and Geotechnics, vol. 82, pp. 16-30.
View/Download from: Publisher's site

Tabatabaiefar, HR, Mansoury, B, Khadivi Zand, MJ & Potter, D 2017, 'Mechanical properties of sandwich panels constructed from polystyrene/cement mixed cores and thin cement sheet facings', Journal of Sandwich Structures & Materials, vol. 19, no. 4, pp. 456-481.
View/Download from: Publisher's site
View description>>

Sandwich panels are made of two materials that are relatively weak in their separated state, but are improved when they are constructed together in a sandwich panel. Sandwich panels can be used for almost any section of a building including roofs, walls and floors. These building components are regularly required to provide insulation properties, weatherproofing properties and durability in addition to providing structural load bearing characteristics. Polystyrene/cement mixed cores and thin cement sheet facings sandwich panels are Australian products made of cement-polystyrene beaded mixture encapsulated between two thick cement board sheets. The structural properties of sandwich panels constructed of polystyrene/cement cores and thin cement sheet facings are relatively unknown. Therefore, in this study, to understand the mechanical behaviour and properties of those sandwich panels, a series of experimental tests have been performed and the outcomes have been explained and discussed. Based on the results of this study, values for modulus of elasticity and ultimate strength of the sandwich panels in dry and saturated conditions have been determined and proposed for practical applications.

Vahedian, A, Shrestha, R & Crews, K 2017, 'Effective bond length and bond behaviour of FRP externally bonded to timber', Construction and Building Materials, vol. 151, pp. 742-754.
View/Download from: Publisher's site
View description>>

Despite a large number of studies on estimating the effective bond length from the characteristics of the component materials, key parameters governing the effective bond length for FRP-to-timber joint have not been suggested by any of the current Codes and developed theories to date mostly cover FRP-to-concrete joints. Also, most theoretical bond strength models have been derived based on effective bond length. Therefore, to achieve a satisfactory bonded joint, the effectiveness of bond length is required to be accurately considered. This research study investigates 136 FRP-to-timber joints subjected to pull-out tests in order to determine the stress and strain distribution profiles along the interface and subsequently analyses the results to undertake direct measurement of the effective bond length. In addition, a modified test set up has been developed and is presented. A novel theoretical model has been established through regression analysis of bond length data and accordingly a new predictive model for effective bond length for FRP-to-timber joints has been developed. A comparative analysis between the results of the experimental pull-out tests results and those predicted from the analytical model indicates a satisfactory correlation is achieved between measured and predicted effective bond length, verifying the validity of the new model.

Vahedian, A, Shrestha, R & Crews, K 2017, 'Modelling of Factors Affecting Bond Strength of Fibre Reinforced Polymer Externally Bonded to Timber and Concrete', International Journal of Structural and Construction Engineering, vol. 11, no. 12, pp. 1635-1642.
View description>>

In recent years, fibre reinforced polymers asapplications of strengthening materials have received significantattention by civil engineers and environmentalists because of theirexcellent characteristics. Currently, these composites have become amainstream technology for strengthening of infrastructures such assteel, concrete and more recently, timber and masonry structures.However, debonding is identified as the main problem which limitthe full utilisation of the FRP material. In this paper, a preliminaryanalysis of factors affecting bond strength of FRP-to-concrete andtimber bonded interface has been conducted. A novel theoreticalmethod through regression analysis has been established to evaluatethese factors. Results of proposed model are then assessed withresults of pull-out tests and satisfactory comparisons are achievedbetween measured failure loads (R2 = 0.83, P < 0.0001) and thepredicted loads (R2 = 0.78, P < 0.0001)

Vakhshouri, B & Nejadi, S 2017, 'Compressive strength and mixture proportions of self-compacting light weight concrete', Computers and Concrete, vol. 19, no. 5, pp. 555-566.
View/Download from: Publisher's site
View description>>

Copyright © 2017 Techno-Press, Ltd. Recently some efforts have been performed to combine the advantages of light-weight and self-compacting concrete in one package called Light-Weight Self-Compacting Concrete (LWSCC). Accurate prediction of hardened properties from fresh state characteristics is vital in design of concrete structures. Considering the lack of references in mixture design of LWSCC, investigating the proper mixture components and their effects on mechanical properties of LWSCC can lead to a reliable basis for its application in construction industry. This study utilizes wide range of existing data of LWSCC mixtures to study the individual and combined effects of the components on the compressive strength. From sensitivity of compressive strength to the proportions and interaction of the components, two equations are proposed to estimate the LWSCC compressive strength. Predicted values of the equations are in good agreement with the experimental data. Application of lightweight aggregate to reduce the density of LWSCC may bring some mixing problems like segregation. Reaching a higher strength by lowered density is a challenging problem that is investigated as well. The results show that, the compressive strength can be improved by increasing the of mixture density of LWSCC, especially in the range of density under 2000 Kg/m3.

Vakhshouri, B & Nejadi, S 2017, 'Instantaneous deflection of light-weight concrete slabs', Frontiers of Structural and Civil Engineering, vol. 11, no. 4, pp. 412-423.
View/Download from: Publisher's site
View description>>

© 2017, Higher Education Press and Springer-Verlag GmbH Germany. Construction loading before the age of 28 d can have the most significant effects on the slabs, especially for multi-story structures. The changing properties of the young concrete complicate the prediction of serviceability design requirements also. An experimental investigation is performed on four simply supported Light-Weight Concrete (LWC) one-way slabs subjected to immediate loading at 14 d. Effects of aggregate type, loading levels and cracking moment together with the influences of ultimate moment capacity and service moment on the instantaneous deflection of slabs are studied. Comparison of the obtained results with predictions of existing models in the literature shows considerable differences between the recorded and estimated instantaneous deflection of LWC slabs. Based on sensitivity analysis of the effective parameters, a new equation is proposed and verified to predict the instantaneous deflection of LWC slabs subjected to loading at the age of 14 d.

Van Nguyen, Q, Fatahi, B & Hokmabadi, AS 2017, 'Influence of Size and Load-Bearing Mechanism of Piles on Seismic Performance of Buildings Considering Soil–Pile–Structure Interaction', International Journal of Geomechanics, vol. 17, no. 7, pp. 04017007-04017007.
View/Download from: Publisher's site
View description>>

© 2017 American Society of Civil Engineers. Pile foundations are usually used to transmit foundation loads through soil strata of low bearing capacity to deeper soil or rock strata with a higher bearing capacity and stiffness. The type and size of a pile foundation that supports midrise buildings in high-risk seismic zones can alter the dynamic characteristics of the soil-pile-foundation system during an earthquake due to soil-structure interaction. To investigate these phenomena, a 15-story moment-resisting frame sitting on differently sized end-bearing and floating pile foundations was simulated numerically. The present paper describes a numerical modeling technique for the simulation of complex seismic soil-pile-structure interaction phenomena. By adopting a method of direct calculation, the numerical model can perform a fully nonlinear time history dynamic analysis to realistically simulate the dynamic behavior of soil, pile foundations, and structure under seismic excitations. This three-dimensional (3D) numerical model accounts for the nonlinear behavior of the soil medium, the piles, and the structural elements. Results show that the type and size of the pile elements influence the dynamic characteristics and seismic response of the building due to interaction between the soil, pile foundations, and the structure. The findings of this study can help engineers select the correct size and type of pile foundation while considering the seismic performance of buildings sitting on soft soil and aim at optimizing their design.

Vessalas, K, Sirivivatnanon, V & Baweja, D 2017, 'Influence of Permeability-Reducing Admixtures on Water Penetration in Concrete', ACI Materials Journal, vol. 114, no. 6, pp. 911-922.
View/Download from: Publisher's site
View description>>

Copyright © 2017, American Concrete Institute. All rights reserved. An experimental investigation was carried out on concrete into the effectiveness of integral permeability-reducing admixtures as possible alternatives to the traditional external waterproofers. The efficiency of hydrophobic water repellents and crystalline pore blockers were evaluated in concretes incorporating fixed water-cementitious materials ratio (w/cm) and different cementitious material types covering OPC, fly ash, and granulated blast-furnace slag. Three different test methods were employed to evaluate the water penetration resistance of concrete. To isolate the benefits that are achieved by varying the mixture design parameters, statistical factorial analysis of variances was carried out to discover the significance of each variable. Results indicated that the effect of w/cm and cementitious material is more pronounced compared to the addition of permeability-reducing admixtures. It was also demonstrated that the admixtures can be effective in reducing water penetration; however, their effect is varied in different mixtures. Caution must be exercised when using such admixtures in different concrete mixtures.

Wang, H, Wu, C, Zhang, F, Fang, Q, Xiang, H, Li, P, Li, Z, Zhou, Y, Zhang, Y & Li, J 2017, 'Experimental study of large-sized concrete filled steel tube columns under blast load', Construction and Building Materials, vol. 134, pp. 131-141.
View/Download from: Publisher's site
View description>>

© 2016 This paper investigates blast resistance and residual strength of concrete-filled steel tube (CFST) columns under close-range blast loads. A total of 8 CFST columns, including 4 with circular cross sections and 4 with square cross sections, were tested under close-range blasts. LVDTs were used to record displacement histories and pressure sensors were used to measure pressure histories. The influence of explosive charge weight, steel tube thickness and cross section geometry on dynamic response of CFST columns was analyzed and failure modes of CFST columns were also investigated. Following the blast tests, an experimental study was conducted to investigate residual strength of blast-damaged CFST columns. It was found that the CFST columns were still able to retain a large portion of their axial load capacities even after close-range blast events.

Wang, J, Yang, G, Liu, H, Shrawan Nimbalkar, S, Tang, X & Xiao, Y 2017, 'Seismic response of concrete-rockfill combination dam using large-scale shaking table tests', Soil Dynamics and Earthquake Engineering, vol. 99, pp. 9-19.
View/Download from: Publisher's site

Wu, C & Li, J 2017, 'Structural Protective Design with Innovative Concrete Material and Retrofitting Technology', Procedia Engineering, vol. 173, pp. 49-56.
View/Download from: Publisher's site
View description>>

© 2017 The Authors. Retrofitting technology and high performance construction material are now widely investigated so as to increase structural ductility and robustness under extreme loading conditions. In the present study, some recent developments in structural protection against blast loads are compiled. Metallic foam materials with varying foam density and gradient are used in the cladding design, their energy absorbing capacities and stress-strain relationships are studied based on uniaxial compression tests. These foam material are used to cast sacrificial claddings on the concrete slabs in the field blast tests. Damage and structural deformation are measured to check the effectiveness of the claddings. Besides sacrificial foam cladding, concrete material with new reinforcement scheme including steel wire mesh and micro steel fiber is developed, and the static test results indicates the excellent ductility and crack control ability of this novel design. In the field blast tests, concrete slabs with different steel wire mesh reinforcement are exposed to varying blast loads. The effectiveness of the slab reinforcing design is discussed based on field performance.

Wu, C, Li, J, Hao, H & Li, Z-X 2017, 'Preface', International Journal of Protective Structures, vol. 8, no. 3, pp. 323-324.
View/Download from: Publisher's site

Xia, Y, Wu, C & Bennett, T 2017, 'An analytical model of linear density foam–protected structure under blast loading', International Journal of Protective Structures, vol. 8, no. 3, pp. 454-472.
View/Download from: Publisher's site
View description>>

Aluminium foam is widely known as an energy absorptive material which can be used as a protective cladding on structures to enhance blast resistance of the protected structures. Previous studies show that higher density provides larger energy absorption capacity of aluminium foam, but results in a larger transmitted pressure to the protected structure. To lower the transmitted pressure without sacrificing the maximum energy absorption, graded density foam has been examined in this study. An analytical model is developed in this article to investigate the protective effect of linear density foam on response of a structure under blast loading. The model is able to simulate structural deformation with reasonable accuracy compared with experimental data. The sensitivity of density gradient of foam cladding on reinforced concrete structure is tested in the article.

Xu, J, Wu, C, Li, J & Cui, J 2017, 'Simplified finite element method analysis of ultra-high-performance fibre-reinforced concrete columns under blast loads', Advances in Structural Engineering, vol. 20, no. 1, pp. 139-151.
View/Download from: Publisher's site
View description>>

Ultra-high-performance fibre-reinforced concrete has exceptional mechanical properties including high compressive and tensile strength as well as high fracture energy. It has been proved to be much higher blast resistant than normal concrete. In this article, flexural behaviours of ultra-high-performance fibre-reinforced concrete columns were investigated through full-scale tests. Two 200 mm × 200 mm × 2500 mm columns with and without axial loading were investigated under three-point bending tests, and their load–displacement relationships were recorded and the moment curvatures were derived. The derived moment curvature relationships of ultra-high-performance fibre-reinforced concrete columns were then incorporated into a computationally efficient one-dimensional finite element model, which utilized Timoshenko beam theory, to determine flexural response of ultra-high-performance fibre-reinforced concrete columns under blast loading. After that, the one-dimensional finite element model was validated with the real blast testing data. The results show good correlation between the advanced finite element model and experimental results. The feasibility of utilizing the one-dimensional finite element model for simulating both high-strength reinforced concrete and ultra-high-performance fibre-reinforced concrete columns against blast loading conditions is confirmed.

Xu, S, Liu, Z & Wu, C 2017, 'Numerical simulation and test validation for ultra-high performance steel fiber reinforced concrete-filled double skin steel tube column under blast loading', Zhendong yu Chongji/Journal of Vibration and Shock, vol. 36, no. 1, pp. 45-54.
View/Download from: Publisher's site
View description>>

A 3D FE model was developed to analyze dynamic response and damage mechanism of a UHPSFRCFDST(Ultra-High Performance Steel Fiber Reinforced Concrete Filled Double Skin Steel Tube)column under blast loading, they were validated through comparison of simulated results and blast testing ones of the UHPSFRCFDST column. The effects of main variables including hollow ratios, steel ratios, and thicknesses and strengths of inner steel tube and outer steel one on the blast resistant performance of the UHPSFRCFDST column were investigated by utilizing the 3D FE model. The results indicated that the UHPSFRCFDST column has excellent anti-blast performances, and the proposed 3D FEM model can be used to analyze the dynamic response of the UHPSFRCFDST column under blast loading efficiently; reducing hollow ratio and increasing strength of outer steel tube in certain ranges can enhance effectively the blast resistant performance of the UHPSFRCFDST column; increasing steel ratio and reducing height to thickness ratios of inner and outer steel tubes can significantly improve the blast resistant performance of the UHPSFRCFDST column; the strength of inner steel tube has a little effect on the blast resistant performance of the UHPSFRCFDST column, but increasing the strength of outer steel tube in a certain range can improve the blast resistant performance of the UHPSFRCFDST column significantly.

Xu, S, Wu, C, Liu, Z, Han, K, Su, Y, Zhao, J & Li, J 2017, 'Experimental investigation of seismic behavior of ultra-high performance steel fiber reinforced concrete columns', Engineering Structures, vol. 152, pp. 129-148.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd This paper presents an experimental study on seismic behavior of ultra-high performance steel fiber reinforced concrete (UHPSFRC) columns. Based on a series of cyclic loading tests on 14 UHPSFRC specimens subjected to combined static axial loading and cyclic lateral loading, the investigation and analysis have been carried out on crack status, failure modes, hysteretic loops, skeleton curves, strength and stiffness degradation, energy dissipation capacity and ductility of UHPSFRC columns. The influence of stirrup spacing, type of stirrup, axial compression ratio and shear span ratio on the seismic performance of UHPSFRC columns was also investigated in details. The experiment results show that three typical failure modes are observed, i.e., flexural, flexural-shear and shear failure mode. The existence of steel fiber could prevent the cracked concrete from spalling efficiently and delay the bulking of longitudinal reinforcement further. It noteworthy that the limit plastic drift ratio of all columns changes from 0.036 to 0.061, indicating that the UHPSFRC columns represent a good ductility which is obviously different from the conventional high strength concrete columns that exhibit much more brittleness with the increase of strength.

Zhang, F, Wu, C, Zhao, X-L & Li, Z-X 2017, 'Numerical derivation of pressure-impulse diagrams for square UHPCFDST columns', Thin-Walled Structures, vol. 115, pp. 188-195.
View/Download from: Publisher's site
View description>>

© 2017 Terrorist activities, especially bomb attacks, have become more and more frequent in the past decades which put thousands of innocent lives in danger. The most common failure mode of structures subjected to blast loading is progressive collapse which is mainly resulted from the failure of load bearing columns. In this paper, finite element analysis tool, LS-DYNA is utilized to study the behaviours of ultra-high performance concrete filled double- skin steel tube (UHPCFDST) columns under blast loading. The numerical model is firstly validated against a series of laboratory and field tests and then used to derive pressure-impulse diagrams for UHPCFDST columns in terms of their residual axial load-carrying capacity after being subjected to blast loading. Different parameters are studied to investigate the effects of axial load ratio, steel tube thickness, column dimension and concrete strength on the pressure-impulse diagrams.

Zhang, F, Wu, C, Zhao, X-L, Heidarpour, A & Li, Z 2017, 'Experimental and numerical study of blast resistance of square CFDST columns with steel-fibre reinforced concrete', Engineering Structures, vol. 149, pp. 50-63.
View/Download from: Publisher's site
View description>>

© 2016 Elsevier Ltd In recent years, a large number of studies have been carried out to investigate behaviours of concrete filled double skin steel tube (CFDST) members due to its increasing popularity in the construction industry. This paper firstly presents an experimental study on ultra-high performance concrete filled double-skin tubes subjected to close-range blast loading with cross section being square for both inner and outer steel tubes. It is evident that the proposed CFDST column was able to withstand a large blast load without failure so that it has the potential to be used in high-value buildings as well as critical infrastructures. Then, to further investigate the behaviours of the proposed CFDST column, a number of parametric studies were carried out by using a numerical model which was developed and calibrated based on the data acquired from the blast test along with some laboratory tests. Parameters that affect the behaviours of concrete filled double skin steel tube (CFDST) members against blasts are characterised.

Zheng, J, Li, Y & Wang, J 2017, 'Design and multi-physics optimization of a novel magnetorheological damper with a variable resistance gap', Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, vol. 231, no. 17, pp. 3152-3168.
View/Download from: Publisher's site
View description>>

This paper presents the design and multi-physics optimization of a novel multi-coil magnetorheological (MR) damper with a variable resistance gap (VRG-MMD). Enabling four electromagnetic coils (EMs) with individual exciting currents, a simplified magnetic equivalent circuit was presented and the magnetic flux generated by each voltage source passing through each active gap was calculated as vector operations. To design the optimal geometry of the VRG-MMD, the multi-physics optimization problem including electromagnetics and fluid dynamics has been formulated as a multi-objective function with weighting ratios among total damping force, dynamic range, and inductive time constant. Based on the selected design variables (DVs), six cases with different weighting ratios were optimized using Bound Optimization BY Quadratic Approximation (BOBYQA) technique. Finally, the vibration performance of the optimal VRG-MMD subjected to sinusoidal and triangle displacement excitations was compared to that of the typical multi-coil MR damper.

Aghayarzadeh, M, Khabbaz, H, Fatahi, B & Terzaghi, S 1970, 'Continuum Numerical Modelling Of Dynamic Load Test For Steel Pipe Piles', Proceedings of the International Conference On Advancement of Pile Technology and Pile Case Histories, International Conference On Advancement of Pile Technology and Pile Case Histories, Universitas Katolik Parahyangan, Bali, Indonesia, pp. 1-10.
View description>>

In order to estimate the static axial capacity of driven piles, one-dimensional wave equationanalysis was proposed in 1960, in which pile is simulated by a number of masses attached to each other usingelastic springs, sliders and linear viscous dampers to simulate the visco-elasto-plastic response of the soil. Later,the signal matching technique program, CAPWAP, employing this model, was proposed to overcome theshortcomings of the conventional model. The main objective of this paper is to assess capabilities of so-calledcontinuum numerical model in analyzing dynamic pile load test. In this paper, the static and dynamic load testsof an open-ended steel pipe pile driven into dense sand have been simulated using PLAXIS 2D finite elementsoftware. After carrying out a number of numerical analyses the results of numerical simulation have beencompared to static load test results. The capabilities and challenges of the continuum numerical analysis tosimulate dynamic pile testing of steel pipe piles are briefly discussed.

Bonthu, RK, Pham, H, Aguilera, RP & Ha, QP 1970, 'Minimization of building energy cost by optimally managing PV and battery energy storage systems', 2017 20th International Conference on Electrical Machines and Systems (ICEMS), 2017 20th International Conference on Electrical Machines and Systems (ICEMS), IEEE, Sydney, Australia, pp. 1-6.
View/Download from: Publisher's site
View description>>

The combination of residential photovoltaic (PV) panels and battery energy storage system (BESS) is a promising solution in a building's microgrid. This paper presents an optimal energy management system (EMS) to minimize the electricity bill of residential buildings. The objective is to achieve peak shaving and electrical energy cost minimization for the owner, making use of a dynamic energy pricing model. Due to variability of PV generation and limitations of BESS, the optimization method should account for the utilisation of PV power generation and the conversion losses of power electronics converters. To deal with non-linearities involved, a particle swarm optimization (PSO) algorithm has been developed for minimization of the cost function. Simulation results show that the PSO-based EMS can achieve, as compared to standard schedule for a 24 hour period, a significant saving of daily electricity cost, which prompts for a suitable on-line control strategy

Dang, LC, Khabbaz, H & Fatahi, B 1970, 'An experimental study on engineering behaviour of lime and bagasse fibre reinforced expansive soils', ICSMGE 2017 - 19th International Conference on Soil Mechanics and Geotechnical Engineering, the 19th International Conference on Soil Mechanics and Geotechnical Engineering, ISSMGE, Seoul, Republic of Korea, pp. 2497-2500.
View description>>

This investigation exhibits a series of laboratory tests conducted to evaluate the influences of bagasse fibre and hydrated lime addition on the engineering properties and swelling behaviour of stabilised expansive soils. Bagasse fibre is industrial waste byproduct left after crushing of sugar-cane for juice extraction, used in this study as a reinforcing component for expansive soil stabilisation. The expansive soils used in this investigation were collected from Queensland, Australia. Varying proportions of randomly distributed bagasse fibre of 0.5%, 1.0%, and 2.0% were added to expansive soil and lime-treated expansive soil to investigate the influences of bagasse fibre on the engineering characteristics of stabilised soil. Results of California bearing capacity (CBR), swell potential and one-dimensional consolidation tests after various curing time are presented and discussed in detail. The findings of this experimental investigation indicate that expansive soil reinforcement, blended with bagasse fibre and lime leads to a significant increase in the compressive strength and the bearing capacity of expansive soil. Meanwhile, the swell potential and compressibility of stabilised expansive soils decreased with increasing lime and bagasse fibre contents.

Dong, Y, Li, D, Fatahi, B, Zhang, X & Khabbaz, H 1970, 'Small-strain shear modulus of soft clay treated with Saccharomyces cerevisiae and cement', ICSMGE 2017 - 19th International Conference on Soil Mechanics and Geotechnical Engineering, International Conference on Soil Mechanics and Geotechnical Engineering, pp. 2507-2510.
View description>>

Soil stabilisation by means of microorganisms is an emerging and novel technique in geotechnical engineering. On the other hand, cementation, as one of the conventional ground improvement techniques, has been proved to be an effective method to enhance the engineering properties of soils. Hence, it is believed that the combination of these two approaches can be extremely valuable and offer a novel, cost effective, environmentally friendly and practical engineering solution. In this study, the Saccharomyces cerevisiae, a species of yeast, has been selected owing to abundance and production cost to conduct the experiment in order to investigate its influence on the shear wave velocity and the small-strain shear modulus of cement stabilised clays using bender element test. It is observed that an appropriate amount of Saccharomyces cerevisiae can adequately improve the stiffness of soft clays treated with cement and microorganisms in long term.

Ho, L, Li, D, Fatahi, B & Khabbaz, H 1970, 'Analytical solution to one-dimensional consolidation in unsaturated soil due to time-dependent exponential temperature and external step loading', ICSMGE 2017 - 19th International Conference on Soil Mechanics and Geotechnical Engineering, pp. 757-760.
View description>>

Recent experimental studies demonstrate that temperature changes may significantly influence the deformation of unsaturated soils. Thus, there is an essential need to develop a predictive framework for the unsaturated consolidation capturing non-isothermal effects. This paper introduces analytical solutions to predict the one-dimensional (1D) consolidation of unsaturated soil deposit while incorporating the time-dependent exponential temperature variation. The one-way drainage boundary system and the uniform initial condition are adopted for the mathematical derivation. In this study, governing equations under the non-isothermal condition are first obtained. Then, Fourier sine series and the Laplace transform technique are used to solve these governing equations and obtain the final solutions. This study highlights the combined effects of time-dependent exponential temperature and an external step loading on the excess pore pressures at various depths. It is predicted that the effects of exponential temperature on the dissipation process would be much attenuated at a lower depth.

Huang, B, Fatahi, B & Khabbaz, H 1970, 'Influence of Underground Opening with Stiff Lining on Seismic Response of Buildings', International Conference on Geomechanics and Geoenvironmental Engineering, International Conference on Geomechanics and Geoenvironmental Engineering, Science, Technology and Management Crest 12 Boyer Pl, Minto, New South Wales 2565, Sydney, Australia, Sydney, pp. 125-131.
View description>>

In this study, the influence of an underground opening at different depths on seismic performance of a 15-storey moment resisting building subjected to the 1995 Kobe earthquake is investigated. The numerical model consists of a superstructure, soil medium, and an underground opening, all simulated using finite element method in time domain considering soil nonlinearity and soil-structure interaction. The results are presented in terms of foundation rocking angle, distribution of maximum shear force developed in the structure, maximum lateral deflection as well as inter-storey drifts of the building. The results indicate that the underground opening has a notable influence on seismic response of the building. Particularly, the maximum foundation rocking angle is reduced with the presence of the underground opening with stiff concrete lining and the reduction is more significant when the underground opening is constructed at a lower depth. In addition, for a shallower underground opening, as the foundation rocking decreases, seismic energy dissipation is reduced, which in turn, causes more seismic energy transmitted to the structure and consequently larger shear forces are developed in the structure, which reveals the importance of consideration of underground structure in the seismic design of superstructures. Moreover, according to the results, the building constructed above a shallow underground opening experiences relatively smaller lateral displacement and inter-storey drifts subjected to earthquake excitation.

Li, J & Wu, C 1970, 'Fibre-reinforced strain hardening concrete under static and blast loads', 15th East Asia-Pacific Conference on Structural Engineering and Construction, Xi'an.

Li, J & Wu, CQ 1970, 'Experimental study on steel wire mesh reinforced concrete slabs against close-in detonations', Mechanics of Structures and Materials: Advancements and Challenges - Proceedings of the 24th Australasian Conference on the Mechanics of Structures and Materials, ACMSM24 2016, Australian Conference on the Mechanics of Structures and Materials, CRC Press, Perth, Australia, pp. 567-570.
View description>>

High performance and aesthetic appearance of a structural design is the motivation behind high strength concrete development. As a notable representative, high performance steel fibre reinforced concrete is characterized by a much higher compressive and tensile strength compared with conventional concrete, the low water-cement ratio effectively warrants a low porosity microstructure which in turn enhances its durability. In recent years, with threat from terrorism activities, protection of structures against malicious loads such like explosive detonation is attracting more public concern. Due to its excellent mechanical performance and energy absorption capacity, high performance steel fibre reinforced concrete can be used in the construction of key load-carrying components to mitigate the blast induced structural damage. In current study, slabs made of high strength concrete material are field tested under close-in detonations, different reinforcement schemes including steel fibre reinforcement and steel wire mesh reinforcement are used in the slab design. Comparisons are made with normal strength concrete slab. Brief discussion on the different slab design against blast loads are presented.

Liang, X & Wu, CQ 1970, 'Effect of steel fibre on thermal behavior of concrete under elevated temperature', Mechanics of Structures and Materials: Advancements and Challenges - Proceedings of the 24th Australasian Conference on the Mechanics of Structures and Materials, ACMSM24 2016, Australian Conference on the Mechanics of Structures and Materials, CRC press, Perth, Australia, pp. 79-84.
View description>>

Steel fibre concrete is considered as an ideal material for fire-resistant structures. However, how addition of steel fibre affects thermal behaviors of concrete has rarely been reported. In this study, a meso-scale modelling approach is successfully developed, which models steel fibre and concrete separately rather than treats them as a homogeneous material. Then simulations on how steel fibre content and aspect ratio influence thermal behaviors of concrete are conducted. Simulation results reveal greater steel fibre content contributes to more even temperature distribution but more uneven thermal gradient and flux distributions especially on some local regions where fibre ends present. Besides, bigger fibre aspect ratio has the same effect as greater fibre content, as phenomena observed for mechanical properties. The study also shows that addition of steel fibre up to 2.5% volume fraction has only slight effect on thermal properties of concrete.

Ngoc, TP, Li, D, Fatahi, B & Khabbaz, H 1970, 'A review on the influence of degree of saturation on small strain shear modulus of unsaturated soils', ICSMGE 2017 - 19th International Conference on Soil Mechanics and Geotechnical Engineering, International Conference on Soil Mechanics and Geotechnical Engineering, ISSMGE, Seoul, Korea, pp. 1225-1228.
View description>>

Small-strain shear modulus (Gmax) is an important parameter in the analysis and design of structures resting on liquefiable soils, particularly under dynamic loads such as earthquakes. In real condition, soil layers near the ground surface consistently undergo variation of degree of saturation (Sr) due to the change of weather or loading-unloading processes that lead to the variation of Gmax. To date, this area has received limited attention and still encounters difficulties in evaluating the influence of Sr on Gmax as well as capturing the effect of hysteresis on water retention behaviour. This study concentrates on the relationship between Sr and Gmax based on available experimental data in literature. The results of the analysis show that Sr plays an important role in the magnitude of Gmax for both cohesionless and cohesive unsaturated soils, while it has a greater influence on the latter. In order to predict Gmax for cohesive soils within the full range of degree of saturation, apart from the influence of Sr on the contribution of matric suction (ym), the influence of Sr on the contribution of plastic fines, salt concentration and van der Waals attraction should be additionally included.

Nguyen, HH, Khabbaz, H, Fatahi, B & Hsi, J 1970, 'Effects of installing controlled modulus columns on previously installed columns', ICSMGE 2017 - 19th International Conference on Soil Mechanics and Geotechnical Engineering, the 19th International Conference on Soil Mechanics and Geotechnical Engineering, Seoul, South Korea, pp. 2611-2614.
View description>>

Controlled modulus columns (CMC) ground improvement technique is an attractive geotechnical solution for modification of soft soils. This technique uses a displacement auger during column installation, aiming to reduce the construction cost and disposal of excavated materials. However, lateral and vertical soil movement induced by the installation process may pose potential risks to the adjacent previously installed columns. Only a handful of studies have been attempted in quantifying such effects. This paper presents the results of a numerical investigation on the effects of CMC installation sequence on the already installed columns using the three-dimensional finite difference software package FLAC3D. The results indicate that the installation sequence should be taken into account in the design process to minimise any adverse effects of installing new CMCs on the existing columns.

Nguyen, VV, Li, J & Erkmen, E 1970, 'Numerical investigation of a linkage modelling technique for damage identification using FRF-based model updating', SHMII 2017 - 8th International Conference on Structural Health Monitoring of Intelligent Infrastructure, Proceedings, International Conference on Structural Health Monitoring of Intelligent Infrastructure, Brisbane, QLD, pp. 1243-1252.
View description>>

This paper presents a novel method of identifying the location and severity of damage in a bridge component via model updating where the number of degrees of freedom (DOF) in the finite element (FE) model far exceeds the DOFs measured on a structure. First, the FE model is divided into partitions, each with a predefined Young's modulus. These Young's moduli are used as the updating parameters where the reduction in the Young's moduli is used to indicate damage. The mass and stiffness matrices of the FE model is reduced to a linkage model using the System Equivalent Reduction Expansion Process (SEREP). Then the measured DOFs of the bridge component is expanded to the DOF of the linkage model using the mass and stiffness matrices of the linkage model. Based on the expanded modal data, interpolated FRFs are synthesised and used to form the FRF sensitivity matrix, which is iteratively used to calculate the values of the updating parameters until convergence is achieved. The resulting Young's moduli are used to calculate the damage index for each partition of the FE model. The proposed method is explained and verified using a numerical study. This method has the potential to locate and quantify damage in a structure where sensor instrumentation is otherwise inadequate due to the limitation in sensor availability and access for sensor installation.

Nguyen, VV, Li, J, Yu, Y, Dackermann, U & Alamdari, MM 1970, 'Simulation of various damage scenarios using finite element modelling for structural health monitoring systems', Mechanics of Structures and Materials: Advancements and Challenges - Proceedings of the 24th Australasian Conference on the Mechanics of Structures and Materials, ACMSM24 2016, Australian Conference on the Mechanics of Structures and Materials, CRC Press/Balkema, Australia, pp. 1541-1546.
View description>>

Structural Health Monitoring (SHM) is a developing technology for asset management of structures including bridge assets. A crucial benefit of SHM is its ability to monitor the health status of structures using continuous measurements. As a key in SHM, the application of damage detection algorithms to assess the condition of a structure using vibration measurements can be enhanced by providing structural information under various damaged scenarios, which can be obtained from updated numerical models that realistically represent the in-situ structure. However, the dynamic characteristics of a structure are sensitive to uncertainties of various parameters, including material properties and boundary conditions, which require updating in the Finite Element (FE) model to ensure that the model replicates the actual structure. This study focuses on the development of an FE model for the accurate simulation of a jack arch replica structure of the Sydney Harbour Bridge. An experimental jack arch replica is produced to simulate various damage scenarios for laboratory testing. A matching FE model of the jack arch replica is generated and updated using Genetic Algorithm (GA) based on experimental measurements. Damage is simulated in the updated model and the results are validated using the experimental test results. The successful simulation of damage using updated FE models enables the generation of a large number of damage cases that can be trained into an SHM system to improve its damage detection capabilities.

Phung, MD, Dinh, TH, Hoang, VT & Ha, Q 1970, 'Automatic Crack Detection in Built Infrastructure Using Unmanned Aerial Vehicles', Proceedings of the International Symposium on Automation and Robotics in Construction (IAARC), 34th International Symposium on Automation and Robotics in Construction, Tribun EU, s.r.o., Brno, Taipei, Taiwan, pp. 823-829.
View/Download from: Publisher's site
View description>>

This paper addresses the problem of crack detection which is essential for health monitoring of built infrastructure. Our approach includes two stages, data collection using unmanned aerial vehicles (UAVs) and crack detection using histogram analysis. For the data collection, a 3D model of the structure is first created by using laser scanners. Based on the model, geometric properties are extracted to generate way points necessary for navigating the UAV to take images of the structure. Then, our next step is to stick together those obtained images from the overlapped field of view. The resulting image is then clustered by histogram analysis and peak detection. Potential cracks are finally identified by using locally adaptive thresholds. The whole process is automatically carried out so that the inspection time is significantly improved while safety hazards can be minimised. A prototypical system has been developed for evaluation and experimental results are included.

Shakor, P, Renneberg, J, Nejadi, S & Paul, G 1970, 'Optimisation of Different Concrete Mix Designs for 3D Printing by Utilizing 6DOF Industrial Robot', Proceedings of the International Symposium on Automation and Robotics in Construction (IAARC), 34th International Symposium on Automation and Robotics in Construction, Tribun EU, s.r.o., Brno, Taipei, Taiwan, pp. 268-275.
View/Download from: Publisher's site
View description>>

Additive Manufacturing (AM) technologies are becoming increasingly viable for commercial and research implementation into various applications. AM refers to the process of forming structures layer upon layer and finds application in prototyping and manufacturing for building construction. It has recently begun to be considered as a viable and attractive alternative in certain circumstances in the construction industry. This paper focuses on the utilisation of different concrete mixtures paired with extrusion techniques facilitated by a six Degree of Freedom (DOF) industrial robot. Using methods of Damp Least Squares (DLS) in conjunction with Resolved Motion Rate Control (RMRC), it is possible to plan stable transitions between several waypoints representing the various print cross-sections. Calculated paths are projected via 'spline' interpolation into the manipulator controlled by custom software. This article demonstrates the properties of different concrete mixture designs, showing their performance when used as a filament in 3D Printing and representing a comparison of the results that were found. In this study, the prepared materials consist of ordinary Portland cement, fine sand between (425-450) micron, coarse aggregate ranges (3) mm and chemical admixtures which have been used to accelerate setting times and reduce water content. Numerous tests were performed to check the buildability, flowability, extrudability and moldability of the concrete mixtures. The horizontal test was used to determine the flowability and consistency, while the vertical and squeeze-flow tests were used to determine the buildability of the layers. The extrudability and moldability of the concrete mixtures were controlled by the robot and associated extruder speeds.

Sharbaf, M, Ghafoori, N & Dumitru, N 1970, 'Geogrid in paved and unpaved road systems: A review of mechanisms and design mehods', Bearing Capacity of Roads, Railways and Airfields - Proceedings of the 10th International Conference on the Bearing Capacity of Roads, Railways and Airfields, BCRRA 2017, International Conference on the Bearing Capacity of Roads, Railways and Airfields, CRC Press, Athens, Greece, pp. 1161-1168.
View/Download from: Publisher's site
View description>>

© 2017 Taylor & Francis Group, London. This study has focused on the effect of using Lime (L) from 1.5% to 6.25%; Bagasse Ash (BA) between 6% and 25% and combination of BA-L reached up to 25% on the consolidation characteristic of expansive after the swelling pressure has been determined. The results indicated that the swelling pressure was reduced with increasing BA or L. Furthermore, the results were improved when BA was added to soil treated with L. The swelling pressure of untreated soil decreased from 80 kPa (untreated soil) to 7 kPa (treated with 25% BA-L). In consolidation tests, the pre-consolidation stress has been developed from 180 kPa with untreated soil to 290 kPa with 6.25% lime and 350 kPa when 18.75% BA was added to soil-6.25% L. Furthermore, better results were ascertained when soft clay stabilized with 25% BA-L in comparison with compacted virgin soft clay samples. In addition, the compression indices, and swelling indices decreased 97% and 56%, respectively.

Sirivivatnanon, V, Khabbaz, H & Ayton, G 1970, '“Performance-based Specification of sand for skid resistance of concrete pavements”, ASCP 4th Concrete Pavement Conference, 2017.', ASCP 4th Concrete Pavement Conference, 2017, ASCP 4th Concrete Pavement Conference, 2017.

Sun, WJ, Liu, C, Wei, G, Sun, DA, Wei, ZF, Liu, SQ & Fatahi, B 1970, 'Effect of sand content on undrained behaviour of GMZ bentonite-sand mixtures', Proceedings - IACMAG 2017, 15th International Conference of the International Association for Computer Methods and Advances in Geomechanics, pp. 1497-1503.
View description>>

The hydro-mechanical behaviour was studied by carrying out the constant water content triaxial tests on Gaomiaozi (GMZ) bentonite-sand mixtures with sand content of 70% and 50%, and the stress-strain relationship, deformation and pore water pressure under undrained shear state were obtained, together with the changes of the initial suction, compressibility, suction and strength with the sand content in mixtures. Moreover, the control mechanism was analyzed in microscopic level. The research provides the experimental basis to establish the hydro-mechanical model for unsaturated expansive soils under undrained state, and can be available for reference in proportional optimization design in bentonite based materials used in deep geological disposal system and waste landfills projects.

Tapas, M, Vessalas, K, Thomas, P & Sirivivatnanon, V 1970, 'Role of Supplementary Cementitious Material Composition in its Efficacy to Mitigate Alkali-Silica Reaction', Concrete 2017 Advances in Materials and Structures, Concrete 2017 Advances in Materials and Structures, Adelaide, Australia.

Thomas, P, Ha Hau, WF, Vessalas, K, Sirivivatnanon, V & South, W 1970, 'Assessment of Test Methods for ASR Aggregate Reactivity', Concrete 2017 Advances in Materials and Structures, Concrete 2017 Advances in Materials and Structures, Adelaide, Australia.
View description>>

The paper reports on the initial stages of a study into the use of phase analysis using typical laboratory techniques; thermogravimetric analysis (TG), infrared spectroscopy (FTIR) and x-ray diffraction (XRD) to investigate the alkali silica reaction (ASR) with a view to classifying the relative reactivity of aggregates. Phase analysis of ground aggregates reacted under AS1141.60.1 accelerated mortar bar test (AMBT) conditions in the presence of calcium hydroxide (CH) are reported for aggregates that have been identified as non-reactive, slowly-reactive and reactive according to the AMBT test. Results of the phase analysis correlated the AMBT classifications. The reactivity of the aggregates was also compared to the reactivity of a quartz flour of similar particle size distribution which was found to be less reactive than the reactive and slowly reactive aggregates. The reactivity of the quartz flour and the reactive and slowly reactive aggregate was attributed to the highly reactive conditions used.

Vizcarra, G, Casagrande, M & Nimbalkar, S 1970, 'DEM Three-dimensional modeling of triaxial testing on railway ballast', ICSMGE 2017 - 19th International Conference on Soil Mechanics and Geotechnical Engineering, pp. 1443-1446.
View description>>

This article presents the results of numerical simulations of cyclic loading tests conducted on particles that simulate railroad ballast. The objective of this study was to evaluate the deformation of ballast under a large number of loading cycles and to study the influence of the two different particle size distributions. One of them was according to particle size distribution recommended by Indraratna and co-workers in the past as an improvement to Australian Standard and the other was prepared in accordance with Brazilian standard. The discrete element method offers a new means of studying the response characteristics of railway ballast. The basic idea of discrete element method (DEM) is that arbitrary discontinuities are divided into a set of rigid elements, making each rigid element satisfy the equations of motion, use time step iteration method for solving the equations of motion of rigid elements, and then obtain the overall movement patterns of arbitrary discontinuities. In this study, the discrete element method of analysis has been used to simulate the geotechnical behaviour of railway ballast observed during the testing.

Wang, JJ, Gowripalan, N, Li, J & Nguyen, VV 1970, 'Close-range photogrammetry for accurate deformation distribution measurement', Mechanics of Structures and Materials: Advancements and Challenges - Proceedings of the 24th Australasian Conference on the Mechanics of Structures and Materials, ACMSM24 2016, Australian Conference on the Mechanics of Structures and Materials, Taylor and Francis, Perth, Australia, pp. 793-799.
View description>>

This paper introduces a methodology for improving the accuracy of Deformation Distribution Measurement (DDM) using close-range photogrammetry. After reviewing various algorithms for 2D Digital Image Correlation (DIC), Zero-Normalized Cross-Correlation (ZNCC) is selected for deformation measurement. The impact of several other factors on DIC measurement accuracy has been investigated, including the type of imaging sensors, the contrast and pattern of a specimen, and searching window size. Optimal option of these factors is proposed. The technique is utilized in the experiment of applying static loading on a replica of a concrete structural component used for Sydney Harbour Bridge. Test results presented in the paper include DIC measurements and validation data from conventional sensors.

Wang, W & Wu, C 1970, 'Numerical modelling of FRP-concrete-steel double-skin tubular columns under blast loading', Tubular Structures XVI - Proceedings of the 16th International Symposium on Tubular Structures, ISTS 2017, International Symposium on Tubular Structures, CRC Press, Melbourne, Australia,, pp. 387-393.
View/Download from: Publisher's site
View description>>

© 2018 Taylor & Francis Group, London. This study presents a numerical study on the behavior of hybrid DSTCs under close-in blast loading. Numerical models of hybrid DSTCs were developed and validated. Afterwards, detailed numerical simulations were conducted to investigate the influences of different parameters on the behavior of hybrid DSTCs under blast loading. The mid-span deflection-time history were recorded and analyzed. The numerical simulation results indicate that the inner steel tube plays a key role in resisting the blast loading, while the contribution from outer FRP tube is less significant. Increasing the inner steel tube thickness and hollowness ratio can lead to a decrease of the maximum deflection of hybrid DSTCs. Under a lower axial load level, the maximum deflection will not increase with the increase of axial load. The influences of concrete strength and outer FRP tube thickness are insignificant.

Wu, C & Li, J 1970, 'Structural protective design with innovative concrete material and retrofitting technology', 11th International Symposium on Plasticity and Impact Mechanics, 11th International Symposium on Plasticity and Impact Mechanics, New Delhi.

Xu, R, Fatahi, B & Li, D 1970, 'Effects of Soil Stiffness on Seismic Response of Buildings Considering Soil-Pile-Structure Interaction', The 19th International Conference on Soil Mechanics and Geotechnical Engineering, Seoul, Korea.

Xu, R, Li, D & Fatahi, B 1970, 'Effects of soil stiffness on seismic response of buildings considering soil-pile-structure interaction', ICSMGE 2017 - 19th International Conference on Soil Mechanics and Geotechnical Engineering, 19th International Conference on Soil Mechanics and Geotechnical Engineering (19ICSMGE), Seoul, South Korea, pp. 1619-1622.
View description>>

In this study, a fifteen-storey moment resisting building sitting on an end-bearing pile foundation in soil socketed in rock is selected in conjunction with four values of shear wave velocity. Effects of corresponding shear strength are studied through numerical modelling using finite difference software FLAC3D. Fully nonlinear dynamic analysis under the influence of Northridge earthquake is performed. The results indicate that soil plasticity should be taken into account while conducting dynamic analysis considering soil-pile-structure interaction. However, the dynamic response of the structure regarding base shear, foundation slab rotation, pile lateral deflection and structure lateral deflection is sensitive to the effect of shear strength with the increase in shear wave velocity and corresponding shear modulus. Also, the results show that the dynamic response of structures sitting on end-bearing pile foundations depends not only on base shear attracted by the superstructure but also on the foundation slab rotation. Therefore, to perform realistic seismic analysis and to conduct reasonable seismic design of mid-rise building resting on end-bearing pile foundations, the consideration of foundation slab rotation is essential.

Yeganeh, N, Fatahi, B & Terzaghi, S 1970, 'Effects of shear wave velocity profile of soil on seismic response of high rise buildings', Proceedings - IACMAG 2017, 15th International Conference of the International Association for Computer Methods and Advances in Geomechanics, International Conference of the International Association for Computer Methods and Advances in Geomechanics, International Association for Computer Methods and Advances in Geomechanics (IACMAG), Wuhan, China, pp. 920-928.
View description>>

There is, nowadays, a conspicuous demand for the high rise buildings in the high-density dwellings of the urban areas; in consequence, harnessing the whiz-bang numerical simulations plus conducting the rigorous experimental studies so as to design and construct such prodigious structures would be essential. Thus, the appropriate parameters for modeling the structure and the soil medium in the Soil-Structure Interaction (SSI) system should be selected. The soil-structure interaction is referred to the process in which the soil response is told on by the structure motion whilst the latter is affected by the soil motion. The current research zeroed in on the soil shear wave velocity and its influence on the superstructure performance. Invoking the weighted average shear wave velocity with the aim of calculating the soil shear modulus, which is closely related to the strength and deformation characteristics of the soil, has been a hotly debated issue since the aforesaid parameter was posited by a plethora of codes and regulations to obtain the soil site classification required for the earthquake design. To that end, the numerical model, having two assorted profiles associated with the shear wave velocity, namely, the in situ non-uniform profile (Case A) and the equivalent uniform profile (Case B), was built by means of FLAC3D, capable of analyzing the complex interaction issues via the direct method whereby the entire system of the structure-foundation-soil is modeled and analyzed in one single step. To put it in a nutshell, employing the weighted average shear wave velocity for the entire soil mass in parsing of the 3D seismic soil-structure interaction problems would be accused for ending up with somewhat unreliable results, e.g., underestimated drift ratio and building deformation, which might be the culprit of the damage to the building and possibly the death of the residents residing in the earthquake-prone zones.

Yu, Y, Li, J, Dackermann, U & Subhani, M 1970, 'Development of a portable NDE system with advanced signal processing and machine learning for health condition diagnosis of in-service timber utility poles', Mechanics of Structures and Materials: Advancements and Challenges - Proceedings of the 24th Australasian Conference on the Mechanics of Structures and Materials, ACMSM24 2016, Australian Conference on the Mechanics of Structures and Materials, CRC Press, Perth, Australia, pp. 1547-1552.
View description>>

Aiming at current shortcomings of Non-Destructive Evaluation (NDE) in health condition estimation of timber utility poles, this paper put forward a novel testing method via combination of a portable NDE system, advanced signal processing and machine learning techniques. Primarily, the multi-sensing strategy is employed and incorporated in current NDE technique to capture reflected stress wave signals, avoiding difficult interpretation of complicated wave propagation by only one sensor. Secondly, advanced signal processing methods, such as Ensemble Empirical Mode Decomposition (EEMD) and Principal Component Analysis (PCA), are introduced to extract effective wave patterns that are sensitive to structural damage. Moreover, based on captured signal features, the state-of-the-art machine learning techniques are applied to implement the condition assessment. Finally, field testing results of 26 decommissioned timber poles at Mason Park in Sydney are used to validate the effectiveness of the proposed method.

Yu, Y, Li, Y & Li, J 1970, 'Sigmoid function-based hysteresis modeling of magnetorheological pin joints', 2017 3rd International Conference on Control, Automation and Robotics (ICCAR), 2017 3rd International Conference on Control, Automation and Robotics (ICCAR), IEEE, Nagoya, Japan, pp. 514-517.
View/Download from: Publisher's site
View description>>

© 2017 IEEE. The magnetorheological (MR) pin joint is a semi-active control device which can be installed in the column-beam structures for structural vibration control. Nevertheless, the nonlinear response of the MR pin joint together with its unique rheological nature makes the device modeling difficult and impedes its engineering application. Although many complicated phenomenal models have been proposed to illustrate the dynamic behaviour of MR devices, a large number of model parameters and differential equations bring the challenges for model identification and controller design. In this study, we try to predict the dynamic response of a MR pin joint using a novel and simple phenomenal model, which is comprised of a rotary spring, a rotary damper and a sigmoid function-based hysteresis component. Then, the model parameters are identified using trust-region-reflective least squares algorithm in MATLAB optimization toolbox. Finally, the experimental results under various loading conditions are used to validate the performance of the proposed model.

Yu, Y, Li, Y, Li, J, Gu, X & Royel, S 1970, 'Dynamic modeling of magnetorheological elastomer base isolator based on extreme learning machine', Mechanics of Structures and Materials: Advancements and Challenges - Proceedings of the 24th Australasian Conference on the Mechanics of Structures and Materials, ACMSM24 2016, Australian Conference on the Mechanics of Structures and Materials, CRC press, Perth, Australia, pp. 703-708.
View description>>

This paper presents a novel modeling method to describe the nonlinear and hysteretic characteristics of Magnetorheological Elastomer (MRE) isolator, which is a semi-active control device and used in vibration control of engineering structures such as vehicle suspension system, offshore platform and built infrastructure. In the proposed method, a new single-hidden-layer feed-forward neural network algorithm named Extreme Learning Machine (ELM) is adopted to set up the model, in which the captured responses such as displacement and velocity of the device together with applied current level are employed as model inputs while the model output is the shear force generated according to the external excitation. Finally, the experimental data are utilized to validate the performance of the proposed method.

Zhang, X, Fatahi, B, Khabbaz, H & Zhang, H 1970, 'Investigating effects of fracture density on stress-strain behaviour of jointed rocks using discrete element method', Proceedings - IACMAG 2017, 15th International Conference of the International Association for Computer Methods and Advances in Geomechanics, The 15th International Conference of the International Association for Computer Methods and Advances in Geomechanics, Wuhan, China, pp. 726-732.
View description>>

Adopting discrete element method (DEM) to simulate the behaviour of jointed rocks is becoming more common due to discrete nature of the medium. In this study, the discontinuum based software PFC3D has been employed to analyse the effects of fracture density on the rock mass unconfined compressive strength of jointed rocks. The flat-joint model allowing partial damages at the contact surfaces has been utilised to simulate the mechanical behaviour of the rock, while the smooth-joint contact model has been employed to simulate the sliding effect of fractures. Indeed, 18 jointed rock specimens with different fracture density values ranging from 5 m2/m3 to 240 m2/m3 have been simulated in this study. Via comparing the stress-strain behaviour and failure mechanisms of the jointed rocks subjected to unconfined compression, the impact of fracture density has been investigated. It can be concluded that the rock mass unconfined compressive strength decreased significantly when the fracture density increased to 60 m2/m3 for the simulated medium strength marble, and then reduced gradually and eventually the rock mass unconfined compressive strength of the fractured rock dropped below 5 MPa. The modulus of elasticity also reduced with increasing fracture density.

Ding, G & Forsythe, P Forest and Wood Products Australia 2017, A Study Comparing the Global Warming Potential of Timber and Reinforced Concrete Construction in Office and Apartment Buildings, N/A, no. P NA308a - 1 213, pp. 1-16, Melbourne.
View description>>

Study was undertaken using a life cycle assessment methodology

Forsythe, P & Ding, KG Forest and Wood Products Australia 2017, Increasing wood based office fitout for sustainable life cycle benefits, no. PNA 322-1314, pp. 1-82, Sydney.
View description>>

In large multi-tenanted office buildings there is a common cycle of “fitout-stripout” which occurs regularly over the life of a building. Unfortunately, the physical waste and recurring embodied energy and greenhouse gas emissions (GHG) associated with this cycle are largely ignored. Wood based design solutions are well-placed to provide improved sustainability outcomes which better meet the arising needs and responsibilities of the property industry. This report provides an evidence-based research that aims to quantify and qualify specific aspects of the above problem, and then use this to develop design concepts that aim to solve the problem in a way that allows the property industry to reimagine office fitout using sustainably driven wood based approaches.