Publications

Anthony, TTC & Ha, Q 2018, A Quadratic Constraint Approach to Model Predictive Control of Interconnected Systems, Springer, Germany.
View description>>

This book focuses on the stabilization and model predictive control of interconnected systems with mixed connection configurations.

Plant, R, Maurel, P, Barbe, E & Brennan, J 2018, Les terres agricoles face à l’urbanisation —De la donnée à l’action, quels rôles pour l’information ?, Update Sciences Technologies, Éditions Quae, Versailles.
View description>>

La perte de terres agricoles liées à l’urbanisationconstitue l’une des facettes de la consommation des terres. Commencé dans lesannées 1970, ce phénomène – essentiellement dû à l’étalement urbain –prend des proportions jusque-là inégalées. Les conséquences de ces processusd’artificialisation sont multiples et portent à la fois sur la production etsur la sécurité alimentaire ainsi que sur la perte de biodiversité. Cesprocessus interrogent aussi les formes de solidarité territoriale entre lesvilles et les espaces péri-urbains et ruraux.Issu d’une collaboration scientifique lancée au début desannées 2010 entre l’Université de technologie de Sydney (University ofTechnology Sydney, UTS) et l’Institut national de recherche en sciences ettechnologies pour l’environnement et l’agriculture (Irstea), cet ouvrage abordedes points clés de la problématique de la consommation des terres en sefocalisant sur les terres agricoles en France et en Australie. Plutôt que d’offrirune analyse comparative approfondie de la planification des terres agricolespériurbaines entre les deux pays, il propose une exploration des « boîtesà outils » de l’ingénierie territoriale développées et mobilisées pourfaire face à l’enjeu de la perte de terres agricoles liée à l’urbanisation. Iloffre également un « arrêt sur image » dans un panorama de champs derecherche en pleine évolution, autant du point de vue théorique queméthodologique.

Wu, C, Li, J & Su, Y 2018, Development of Ultra-High Performance Concrete against Blasts: From Materials to Structures.
View description>>

Development of Ultra-High Performance Concrete against Blasts: From Materials to Structures presents a detailed overview of UHPC development and its related applications in an era of rising terrorism around the world. Chapters present case studies on the novel development of the new generation of UHPC with nano additives. Field blast test results on reinforced concrete columns made with UHPC and UHPC filled double-skin tubes columns are also presented and compiled, as is the residual load-carrying capacities of blast-damaged structural members and the exceptional performance of novel UHPC materials that illustrate its potential in protective structural design. As a notable representative, ultra-high performance concrete (UHPC) has now been widely investigated by government agencies and universities. UHPC inherits many positive aspects of ultra-high strength concrete (UHSC) and is equipped with improved ductility as a result of fiber addition. These features make it an ideal construction material for bridge decks, storage halls, thin-wall shell structures, and other infrastructure because of its protective properties against seismic, impact and blast loads.

Brennan, J & Murrell, A 2018, 'La disponibilité des données sur les sols en Australie' in Plant, R, Maurel, P, Barbe, E & Brennan, J (eds), Les terres agricoles face à l’urbanisation De la donnée à l’action, quels rôles pour l’information ?, Quae, pp. 91-106.
View description>>

This chapter takes a closer look at both the extent to which urban sprawl and soil sealing are already mapped in Australia, and the accessibility of soil information through soil databases such as the New South Wales Soil and Land Information System (SALIS). Urban sprawl and associated soil sealing are a worldwide phenomenon, which greatly affects the availability of agricultural land. Hence, land use planning requires a far greater understanding of these phenomena and consideration of soil quality than what is currently the practise. In order to make soil information more accessible, it can be used to create soil landscape maps incorporating constraints and limitations imposed by different soil and geological conditions. Soil capability maps are examples for this, and provide easily accessible information on soil quality for planners.

Ding, GKC 2018, 'Embodied Carbon in Construction, Maintenance and Demolition in Buildings' in Pomponi, F, de Wolf, C & Moncaster, A (eds), Embodied Carbon in Buildings, Springer International Publishing, pp. 217-245.
View/Download from: Publisher's site
View description>>

Due to the rapid growth of the construction industry during the last decades, building-related waste has become a major source of concern from governments both nationally and internationally. Construction, maintenance and demolition waste is often neglected as it is perceived as less important than waste generated from operating activities. However, research studies reveal that waste is generated at all different stages of the building’s lifecycle and this has a profound impact not only in terms of increasing project cost but also adding to environmental pollution as the common type of treatments for wastes is landfilling and/or incineration. Reducing waste will reduce energy use, minimise degradation of the environment and reduce embodied carbon emissions. This chapter reviews the nature, characteristic and magnitude of construction, maintenance and demolition waste of buildings and their associated embodied carbon emissions. It also examines policies, initiatives and international regulations in dealing with the problem of waste and the calculation methods for the assessment of embodied carbon of waste in the various stages of a building’s life; it ends with a discussion on strategies of reducing waste and a case study.

Plant, RA, Maurel, P, Ruoso, LE, Barbe, E & Brennan, J 2018, 'Synthèse : de la donnée à l’intelligence collective sur les terres agricoles péri-urbaines – quels rôles pour l’information, les savoirs et l’action ? [Synthesis: from data to collective intelligence on peri-urban agricultural land – what roles for information, knowledge and action?]' in Plant, R, Maurel, P, Barbe, E & Brennan, J (eds), Les terres agricoles face à l’urbanisation —De la donnée à l’action, quels rôles pour l’information ? [Agricultural land facing urbanization — From data to action, what roles for information?], Éditions Quae, Versailles.
View description>>

Keeping peri-urban farmland and associated activities close to growing urban centers is a global concern. In the face of ever-increasing demand for land development, the challenge of conserving peri-urban farmland - our main concern in this book - continues to be debated.The recent literature presents various initiatives that have, or could be, adopted to protect and conserve these lands. For example, Akimowicz et al. (2016) have critically assessed the merits of the Greenbelt Act in Ontario (USA) regarding farmers' adaptation and investment strategies. Inwood and Sharp (2012) reported on the resilience of farms in peri-urban areas by studying the succession patterns and adaptation of farms in the United States. As such, this study does not propose initiatives that could be put in place to protect and conserve peri-urban agricultural land, but rather an analysis of how to explain the maintenance of farms in peri-urban areas. From the study of conflicts around agricultural uses in the Greater Paris region, Darly and Torre (2013) analyze the experiences of farmers and the media coverage of, and present innovative mechanisms for conflict resolution.

Tri Tran C., A & Ha, Q 2018, 'Quadratic Constraint for Decentralised Model Predictive Control' in Studies in Systems, Decision and Control, Springer Singapore, pp. 31-57.
View/Download from: Publisher's site
View description>>

© 2018, Springer Nature Singapore Pte Ltd. The asymptotically positive realness constraint (APRC) and quadratic dissipativity constraint (QDC) are introduced in this chapter as an effective tool for designing decentralised control systems, especially the decentralised model predictive control, in the discrete-time domain. We derive the convergence conditions for interconnected systems on the grounds of global system dissipation, subsystem dissipation, coupling structure, and dissipation-based constraints (APRC or QDC in the case of quadratic constraints) of all controlled subsystems. These conditions are suitable for the decentralised and distributed control of interconnected systems that prohibit artificial constraints on the unmeasurable coupling vectors. A convex quadratic constraint on the current-time control vector is subsequently developed from the dissipation-based constraint and applied to the model predictive control (MPC) as an enforced attractivity constraint. The attractivity constraints for controlled subsystems can be fully decoupled in this approach. Only linear-time-invariant (LTI) interconnected systems are under the scope of this chapter.

Basack, S & Nimbalkar, S 2018, 'Measured and Predicted Response of Pile Groups in Soft Clay Subjected to Cyclic Lateral Loading', International Journal of Geomechanics, vol. 18, no. 7, pp. 04018073-04018073.
View/Download from: Publisher's site
View description>>

© 2018 American Society of Civil Engineers. Major offshore and onshore structures, including transport corridors and high-rise buildings, resting on soft compressible clays are often supported by pile foundations. Apart from the usual vertical loading from the superstructures, these piles are usually subjected to large cyclic loads arising from the actions of waves, ship impacts, or moving vehicles. Under such circumstances, vertical and lateral modes of cyclic loading are predominant and affect overall stability. Such repetitive loading on piles leads to reversal of axial stresses in the adjacent soft clay, initiating progressive degradation in soil strength and stiffness that deteriorates the pile capacity with unacceptable displacements. Although several studies have been carried out to investigate the response of a single pile, a detailed investigation on a pile group in soft soil subjected to cyclic lateral loading, which is of immense practical interest to field engineers, had yet to be conducted. In this paper, extensive laboratory model tests with steel-pipe-pile groups in soft cohesive soil were conducted followed by the development of a numerical model that was based on a two-dimensional (2D) dynamic finite-element (FE) approach. The degradation of both axial and lateral capacities of the pile group and the pattern of the degradation with variations in the cyclic-loading parameters were studied. Comparisons of the experimental data with the computed results validated the numerical analysis. The study indicates that both the axial and lateral pile capacities and displacements were significantly influenced by the cyclic-loading parameters (number of cycles, frequency, and amplitude). Relevant design recommendations are presented.

Chen, Q, Zhou, Y & Nimbalkar, S 2018, 'Closure to “Estimation of Passive Earth Pressure against Rigid Retaining Wall Considering Arching Effect in Cohesive-Frictional Backfill under Translation Mode” by Yanyan Cai, Qingsheng Chen, Yitao Zhou, Sanjay Nimbalkar, and Jin Yu', International Journal of Geomechanics, vol. 18, no. 7, pp. 07018012-07018012.
View/Download from: Publisher's site

Chen, Q, Zhou, Y & Nimbalkar, S 2018, 'Closure to 'Estimation of passive earth pressure against rigid retaining wall considering arching effect in cohesive- frictional backfill under translation mode' by Yanyan Cai, Qingsheng Chen, Yitao Zhou, Sanjay Nimbalkar, and Jin Yu', International Journal of Geomechanics, vol. 18, no. 7.
View/Download from: Publisher's site

Chen, X, Li, Y, Li, J & Gu, X 2018, 'A dual-loop adaptive control for minimizing time response delay in real-time structural vibration control with magnetorheological (MR) devices', Smart Materials and Structures, vol. 27, no. 1, pp. 015005-015005.
View/Download from: Publisher's site
View description>>

© 2017 IOP Publishing Ltd. Time delay is a challenge issue faced by the real-time control application of the magnetorheological (MR) devices. Not to deal with it properly may jeopardize the effectiveness of the control, even lead to instability of the control system or catastrophic failure. This paper proposes a dual-loop adaptive control to address the response time delay associated with MR devices. In the proposed dual-loop control, the inner loop is designed to compensate the time delay of MR device induced by the PWM current driver. While the outer loop control can be any structural control algorithm with aims to reducing structural responses of a building during extreme loadings. Here an adaptive control strategy is adopted. To verify the proposed dual-loop control, a smart base isolation system employing magnetorheological elastomer base isolators is used as an example to illustrate the control effect. Numerical study is then conducted using a 5 -storey shear building model equipped with smart base isolation system. The result shows that with the implementation of the inner loop, the control current can instantly follow the control command which reduce the possibility of instability caused by the time delay. Comparative studies are conducted between three control strategies, i.e. dual-loop control, Lyapunov's direct method based control and optimal passive base isolation control. The results of the study have demonstrated that the proposed dual-loop control strategy can achieve much better performance than the other two control strategies.

Chenari, RJ, Fatahi, B, Ghorbani, A & Alamoti, MN 2018, 'Evaluation of strength properties of cement stabilized sand mixed with EPS beads and fly ash', Geomechanics and Engineering, vol. 14, no. 6, pp. 533-544.
View/Download from: Publisher's site
View description>>

The importance of using materials cost effectively to enhance the strength and reduce the cost, and weight of earth fill materials in geotechnical engineering led researchers to seek for modifying the soil properties by adding proper additives. Lightweight fill materials made of soil, binder, water, and Expanded polystyrene (EPS) beads are increasingly being used in geotechnical practices. This paper primarily investigates the behavior of sandy soil, modified by EPS particles. Besides, the mechanical properties of blending sand, EPS and the binder material such as fly ash and cement were examined in different mixing ratios using a number of various laboratory studies including the Modified Standard Proctor (MSP) test, the Unconfined Compressive Strength (UCS) test, the California Bearing Ratio (CBR) test and the Direct Shear test (DST). According to the results, an increase of 0.1% of EPS results in a reduction of the density of the mixture for 10%, as well as making the mixture more ductile rather than brittle. Moreover, the compressive strength, CBR value and shear strength parameters of the mixture decreases by an increase of the EPS beads, a trend on the contrary to the increase of cement and fly ash content.

Chuah, S, Li, W, Chen, SJ, Sanjayan, JG & Duan, WH 2018, 'Investigation on dispersion of graphene oxide in cement composite using different surfactant treatments', Construction and Building Materials, vol. 161, pp. 519-527.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd Graphene oxide (GO) is a novel class of two-dimensional nanoscale sheet material due to its excellent dispersibility in water, high aspect ratio and good intrinsic strengths. In order to obtain a well-distributed GO-reinforced cement composites, the dispersion of GO in water, alkali and several ionic species are investigated with the aid of UV–vis spectroscopy. High alkalinity and calcium ions are key factors inducing the agglomeration of GO in cement system. Dispersion of GO in simulated pore solution is the culmination of the alkali and salt experiments. Agglomeration of GO occurred when GO contacted with the simulated pore solution, highlighting the necessity to protect GO against such aggressive media. The test on surfactant compatibility was then carried out to ensure GO was effectively dispersed in polycarboxylate, air-entrainment and Gum Arabic admixtures within the pore solution. Polycarboxylate-based superplasticisers gave the most promising results to disperse GO in cement alkaline environment. Flexural experiments was performed to highlight the importance of fabrication protocol on the mechanical properties of GO-cement composites. The result shows that the amount of 0.03% GO by weight of cement can increase the flexural strength of GO-cement composite up to 67%.

Dadzie, J, Runeson, G & Ding, G 2018, 'Determinants of sustainable upgrade for energy efficiency – the case of existing buildings in Australia', Energy Procedia, vol. 153, pp. 284-289.
View/Download from: Publisher's site
View description>>

© 2018 The Authors. Published by Elsevier Ltd. The impact of existing buildings on the environment is on the rise; thus to achieve environmental sustainability requires sustainable upgrade (SU) of existing built facilities. Over the years, SU has focused on technologies with little attention given to the nature and conditions of existing buildings. The purpose of this paper is to identify existing building characteristics that impact SU. A detailed literature review on the nature and characteristics of existing buildings, as well as energy and environmental performance was undertaken. A survey questionnaire with all the determinants of existing buildings was administered to sustainability and construction professionals in Australia. The results show that size of building, age of building, U-value of wall, U-value of ceiling, area of external wall, thickness of insulation materials, occupancy, size of window opening, life span of sustainable technologies, and the type of building impact sustainable upgrade of existing buildings for energy efficiency.

Dadzie, J, Runeson, G, Ding, G & Bondinuba, F 2018, 'Barriers to Adoption of Sustainable Technologies for Energy-Efficient Building Upgrade—Semi-Structured Interviews', Buildings, vol. 8, no. 4, pp. 57-57.
View/Download from: Publisher's site
View description>>

© 2018 by the authors. Globally, only 2% of existing building stock is built yearly; the remaining 98% already exist. Energy consumption and indoor thermal comfort of the existing building stock are not encouraging. This is due to many challenges associated with existing buildings; the challenges range from cracks, leakages, poor insulation, heat losses and high rate of unsustainable technologies. This paper investigates possible barriers facing the adoption and application of sustainable technologies (STs) for sustainable or energy-efficient upgrade of existing buildings. New STs are manufactured on a regular basis to meet improved energy efficiency standards, yet there are minimal actions/attempts to adopt and apply improved technologies in existing buildings for energy efficiency. Indeed, there are limited studies focused on the use of qualitative approaches to identify barriers to adoption and use of STs. Thus, a semi-structured interview approach was adopted and applied using sustainability/energy efficiency professionals, building services engineers, project managers, architects, and facility managers in Australia. The results indicate that barriers to the adoption and application of sustainable technologies are perceived benefits in demolish-and-build, age of building, cost of STs, perceived poor payback time, unreliable energy-savings projections, existing design, hidden and overall cost of renovation, and cost of STs.

Dong, Y, Fatahi, B, Khabbaz, H & Zhang, H 2018, 'Influence of particle contact models on soil response of poorly graded sand during cavity expansion in discrete element simulation', Journal of Rock Mechanics and Geotechnical Engineering, vol. 10, no. 6, pp. 1154-1170.
View/Download from: Publisher's site
View description>>

© 2018 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences The discrete element method (DEM) has been extensively adopted to investigate many complex geotechnical related problems due to its capability to incorporate the discontinuous nature of granular materials. In particular, when simulating large deformations or distortion of soil (e.g. cavity expansion), DEM can be very effective as other numerical solutions may experience convergence problems. Cavity expansion theory has widespread applications in geotechnical engineering, particularly to the problems concerning in situ testing, pile installation and so forth. In addition, the behaviour of geomaterials in a macro-level is utterly determined by microscopic properties, highlighting the importance of contact models. Despite the fact that there are numerous contact models proposed to mimic the realistic behaviour of granular materials, there are lack of studies on the effects of these contact models on the soil response. Hence, in this study, a series of three-dimensional numerical simulations with different contact constitutive models was conducted to simulate the response of sandy soils during cylindrical cavity expansion. In this numerical investigation, three contact models, i.e. linear contact model, rolling resistance contact model, and Hertz contact model, are considered. It should be noted that the former two models are linear based models, providing linearly elastic and frictional plasticity behaviours, whereas the latter one consists of nonlinear formulation based on an approximation of the theory of Mindlin and Deresiewicz. To examine the effects of these contact models, several cylindrical cavities were created and expanded gradually from an initial radius of 0.055 m to a final radius of 0.1 m. The numerical predictions confirm that the calibrated contact models produced similar results regarding the variations of cavity pressure, radial stress, deviatoric stress, volumetric ...

Fatahi, B, Van Nguyen, Q, Xu, R & Sun, W-J 2018, 'Three-Dimensional Response of Neighboring Buildings Sitting on Pile Foundations to Seismic Pounding', International Journal of Geomechanics, vol. 18, no. 4, pp. 04018007-04018007.
View/Download from: Publisher's site
View description>>

© 2018 American Society of Civil Engineers. Seismic pounding occurs when the separation gap between buildings and structures is not wide enough, particularly during major earthquake events; this can cause them to collide, causing local damage or, in extreme cases, collapse. This study investigated the impact that this separation gap has on the seismic response of midrise buildings supported on piles while considering seismic soil-pile-structure interaction (SSPSI). To achieve this aim, three 15-story reinforced concrete buildings sitting on pile foundations and with five different separation gaps under excitations from the 1994 Northridge and 1995 Kobe earthquakes were numerically simulated. This study used three-dimensional numerical modeling to simultaneously capture the effects of seismic pounding and SSPSI. Because the considered structure, pile foundation, and soil deposit are three-dimensional in nature, the adopted three-dimensional numerical modeling can provide a more realistic simulation to capture the seismic behavior of the system. The nonlinear behavior of structural elements was included, and the dynamic soil properties were obtained from field data and backbone curves. A contact pair interface with small-sliding surface-to-surface formulation between buildings was used to capture possible seismic pounding, and contact interfaces with a finite-sliding formulation were used to simulate the interaction between the piles and the soil. The results, including lateral building deflections, interstory drifts, structural shear forces, foundation rocking, lateral pile deflections, and the distributions of bending moments and shear forces of the piles, are presented and discussed. The findings of this study will give engineers a better insight into the possible effects of seismic pounding on the seismic performance of buildings, and the response of endbearing piles in soft soils.

Haydar, H, Far, H & Saleh, A 2018, 'Portal steel trusses vs. portal steel frames for long‐span industrial buildings', Steel Construction, vol. 11, no. 3, pp. 205-217.
View/Download from: Publisher's site
View description>>

AbstractPortal frames and portal truss structures are two of the most cost‐effective and sustainable structural forms for the design and construction of long‐span industrial buildings. Although the use of both structure types as steel‐clad structures is widely accepted, due to frame complexity and variation of frame types for use in single‐storey buildings with spans > 30 m, literature providing a comprehensive investigation of the concepts of portal trusses and portal frames is scarce. This study compares the behaviour of a portal truss configuration with pitched portal frames for use in industrial buildings with spans > 30 m, focusing on weight, costs and construction time. Furthermore, this study entails a numerical investigation that utilizes the SAP2000 computer program to model and structurally optimize the member properties for both portal frame and portal truss configurations. Based on the results obtained from the investigation, it has become apparent that, due to the smaller sections used, the portal truss configurations are lighter and cheaper to fabricate and construct in comparison to the pitched portal frames, which, however, require a shorter construction time.

Ho, L & Fatahi, B 2018, 'Analytical solution to axisymmetric consolidation of unsaturated soil stratum under equal strain condition incorporating smear effects', International Journal for Numerical and Analytical Methods in Geomechanics, vol. 42, no. 15, pp. 1890-1913.
View/Download from: Publisher's site
View description>>

SummaryThis paper proposes closed‐form analytical solutions to the axisymmetric consolidation of an unsaturated soil stratum using the equal strain hypothesis. Following the 1‐dimensional (1D) consolidation theory for unsaturated soil mechanics, polar governing equations describing the air and water flows are first presented on the basis of Fick's law and Darcy's law, respectively. The current study takes into account the peripheral smear caused by an installation of vertical drain. Separation of variables and Laplace transformation are mainly adopted in the analytical derivation to obtain final solutions. Then, the hydraulic conductivity ratio, the radius of influence zone and smear parameters influencing time‐dependent excess pore pressures, and the average degree of consolidation are graphically interpreted. In this study, a comparison made between the proposed equal strain results and the existing free strain results suggests that both hypotheses would deliver similar predictions. Moreover, it is found that the smear zone resulting from vertical drain installations would hinder the consolidation rate considerably.

Ho, L, Fatahi, B & Khabbaz, H 2018, 'Analytical Solution to One-Dimensional Consolidation in Unsaturated Soil Deposit Incorporating Time-Dependent Diurnal Temperature Variation', International Journal of Geomechanics, vol. 18, no. 5, pp. 04018029-04018029.
View/Download from: Publisher's site
View description>>

© 2018 American Society of Civil Engineers. Several experimental studies have demonstrated that temperature changes may significantly influence the deformation of unsaturated soils. Thus, there is an essential need to develop a predictive framework for unsaturated consolidation capturing the nonisothermal effect. This paper presents an analytical solution to the one-dimensional (1D) consolidation of unsaturated soil deposit in response to temperature variation. A set of governing equations of flow incorporating the nonisothermal condition were first obtained. Then, Fourier sine series and the Laplace transformation were used to derive solutions based on these governing equations. This study highlighted the effect of diurnal temperature variation on pore pressures and soil deformation at different depths while considering two conditions of interest: (1) no external applied load, and (2) application of step loading to the ground surface. In addition, the thermal diffusivity characterizing the consolidation behavior of unsaturated soils was also investigated and is discussed in this paper. It is predicted that a decrease in thermal diffusivity would attenuate the effects of diurnal temperature on the unsaturated consolidation.

Ke, G, Li, W, Li, R, Li, Y & Wang, G 2018, 'Mitigation Effect of Waste Glass Powders on Alkali–Silica Reaction (ASR) Expansion in Cementitious Composite', International Journal of Concrete Structures and Materials, vol. 12, no. 1.
View/Download from: Publisher's site
View description>>

© 2018, The Author(s). The effects of different contents and particle sizes of waste glass powder on alkali–silica reaction (ASR) expansion of cementitious composite bar were investigated in this study. Waste glass powder with particle size less than 300 μm exhibits an excellent mitigation effect on ASR expansion. With larger content and smaller particle size, the mitigation effect of waste glass powder on ASR expansion gradually increases. The mitigation effect of waste glass powder with particle size ranging from 38 to 53 μm and 20% by weight of cement seems relatively better than that of fly ash. When the waste glass powder content reaches 30%, the mitigation effect is still effective and almost the same as that of fly ash. However, the waste glass powder with particle size larger than 300 μm presents negative mitigation effect on ASR expansion when the replacement rate is larger than 30%. On the other hand, the waste glass powder and calcium hydroxide (CH) further react, and produce more calcium–silicate–hydrate gels, which apparently reduce the amount of CH. Moreover, the increasing content of waste glass powder results in a lower pH value in the pore solution of cementitious composite.

Keshavarzi, A, Shrestha, CK, Zahedani, MR, Ball, J & Khabbaz, H 2018, 'Experimental study of flow structure around two in-line bridge piers', Proceedings of the Institution of Civil Engineers - Water Management, vol. 171, no. 6, pp. 311-327.
View/Download from: Publisher's site
View description>>

Previous investigations indicate that local scouring is one of the most common causes of waterway bridge failure. The scour mechanism around bridge piers is complicated by the interaction of flow and structure. To explore the local scouring process, it is therefore essential to study the flow–structure interaction around bridge piers. Most previous studies have been based on this interaction around a single pier; however, in practice, many bridges are wide and comprise a number of piers aligned in the flow direction that together support the loading. In this study, a particle image velocimetry technique was used to investigate two-dimensional flow–structure interaction around two in-line bridge piers with different spacings. Various influencing flow characteristics including turbulence intensity, turbulent kinetic energy and Reynolds stresses were calculated in different vertical planes around the bridge piers. Results indicated that the flow characteristics around two in-line bridge piers are very different than for a single pier and the spacing between two in-line piers significantly influences the flow characteristics, particularly in the rear of the piers. Furthermore, for spacing in the range of 2 ≤ L/D ≤ 3, stronger turbulence structures occurred behind pier 1 and, as a result, a higher scour depth can be expected around pier 1.

Lei, B, Li, W, Li, Z, Wang, G & Sun, Z 2018, 'Effect of Cyclic Loading Deterioration on Concrete Durability: Water Absorption, Freeze-Thaw, and Carbonation', Journal of Materials in Civil Engineering, vol. 30, no. 9, pp. 04018220-04018220.
View/Download from: Publisher's site
View description>>

© 2018 American Society of Civil Engineers. The effect of cyclic loading deterioration on freeze-thaw and carbonation resistances of concrete were experimentally investigated in this study. A novel loading method was designed, which simultaneously considers both mechanical loading and environmental actions for concrete. It shows that with the increase of cyclic compressive loading, the porosity and water absorption of concrete initially decrease but then increase when the stress is above a threshold level because of the cracking initiation caused by cyclic compression. With the increase of concrete porosity, both dynamic elastic modulus loss and carbonation depth obviously exhibit an increasing trend. On the other hand, under the same stress level, the freeze-thaw and carbonation resistances of high-strength concrete are relatively superior to those of low-strength concrete. Compared with the unloaded concrete, the carbonation depth and dynamic elastic modulus loss after mechanical loading below the stress level threshold are lower. This is probably due to the denser microstructure compacted by the compression. However, if the loading level becomes above the threshold level, both the carbonation depth and dynamic elastic modulus loss dramatically increase, which is due to the cracks initiation and propagation after cyclic loading deterioration. Therefore, the combination of mechanical and environmental actions is more severe than a single environmental action without considering the mechanical loading.

Lei, B, Li, W, Tang, Z, Tam, VWY & Sun, Z 2018, 'Durability of recycled aggregate concrete under coupling mechanical loading and freeze-thaw cycle in salt-solution', Construction and Building Materials, vol. 163, pp. 840-849.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd In this study, a novel coupling testing protocol with separated repetitive loading and freezing-thaw cycles in salt-solution is designed to simulate coupling mechanical loading and complex environmental effects on durability and deterioration of recycled aggregate concrete (RAC). The Micromechanical properties and porosity of RAC were also characterized by scanning electron microscopy (SEM) and microhardness. The results show that the number and width of cracks of RAC and NAC under freeze-thaw cycles obviously increased with the increase of alternating times of repetitive load and the compressive stress level. The compressive strength losses for both RAC and NAC increase with the increase of compressive stress level and alternative times of repetitive load. However, the compressive strength of natural aggregate concrete (NAC) became lower than that of RAC after freeze-thaw cycles. It was found that the freeze-thaw resistance of RAC seems even better than that of NAC under the same freeze-thaw attacks and cyclic mechanical loading. It indicates that after freeze-thaw cycles in salt-solution, the durability of RAC is better than that of NAC. On the other hand, the microhardness and SEM characterization results indicate that the interface transition zone (ITZ) was a weak part in both RAC and NAC, and the ITZ in NAC obviously deteriorated faster than that of RAC.

Li, J & Wu, C 2018, 'Damage evaluation of ultra-high performance concrete columns after blast loads', International Journal of Protective Structures, vol. 9, no. 1, pp. 44-64.
View/Download from: Publisher's site
View description>>

As emerging advanced construction material, ultra-high performance concretes have seen increasing field applications over the past two decades to take advantages of their ultra-high mechanical strength and durability; yet the systematic study on its dynamic behaviour under impact and blast loads is not commonly seen. This article presents an experimental and numerical study on the static and dynamic behaviour of an existing ultra-high performance concrete material. Experimental study on its flexural behaviour under static loads is conducted and an inverse study is carried out to derive its uniaxial tensile constitutive law. The derived relationship is used in the material model in hydro-code LS-DYNA together with dynamic material properties to study ultra-high performance concrete columns under blast loads. The residual loading capacity of the column is studied and pressure–impulse diagrams for assessing the ultra-high performance concrete column damage under blast loads are proposed. Parametric study on effects of ultra-high performance concrete strength, column height, cross-section size and reinforcement ratio is performed and analytical equations are proposed for generating pressure–impulse diagrams for generic ultra-high performance concrete columns.

Li, J, Wu, C & Liu, Z-X 2018, 'Comparative evaluation of steel wire mesh, steel fibre and high performance polyethylene fibre reinforced concrete slabs in blast tests', Thin-Walled Structures, vol. 126, pp. 117-126.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd Concrete is the most widely used construction material in the modern construction practice. Due to its relatively low tensile resistance, concrete tends to experience tensile failure and cracking under external loads. To enhance the tensile performance and ductility of concrete material, possible solutions including fibre reinforcement and steel mesh reinforcement are investigated in the present study. Steel fibre, ultra-high molecular weight polyethylene (UHMWPE) fibre and steel wire meshes were mixed with varying volume fraction in the concrete matrix. Static material tests including uniaxial compression and flexural bending tests showed that the steel fibre addition yielded better strength enhancement while UHMWPE fibre provided better material ductility. Concrete samples with hybrid steel fibre-steel mesh reinforcement showed high strength and ductility. Field blast tests are designed to study the behaviour of reinforced concrete slabs under close-in detonations. Different damage profiles are observed from the blast tests. The advantages and disadvantages of using different reinforcing materials are discussed. From the results, the advantages of replacing steel fibre with UHMWPE fibre or steel wire mesh were demonstrated.

Li, J, Wu, C, Hao, H, Liu, Z & Yang, Y 2018, 'Basalt scale-reinforced aluminium foam under static and dynamic loads', Composite Structures, vol. 203, pp. 599-613.
View/Download from: Publisher's site
View description>>

© 2018 Elsevier Ltd In this paper, mechanical performance and deformation behaviour of basalt scale-reinforced closed-cell aluminium foams are investigated. Quasi-static uniaxial compressive tests on the constitutive alloy material reveal that after basalt scale reinforcement, the alloy elasticity modulus and yield strength show noticeable enhancement. Quasi-static compression tests on the foam material show that while basalt scale-reinforced aluminium foam has higher plastic crush stress and plateau stress, the densification strain is lower than non-reinforced foam. A method based on energy absorption efficiency is adopted to accurately measure the densification strain for both foam materials. In the subsequent split-Hopkinson pressure bar tests, dynamic compressive behaviour of basalt scale-reinforced aluminium foams with relative densities ranged from 14% to 33% is studied experimentally under strain rate ranging from 480/s to 1720/s. Clear material rate sensitivity is noted from the dynamic tests. The results indicate that the plateau stress of aluminium foam increases with relative density and strain rate. In addition, with the increase in strain rates, an increase in the energy absorption capacity is observed and this characteristic is beneficial when the foam material is used to absorb impact energy. A mesoscopic model based on the X-ray CT for the aluminium foam material is developed. The simulations and the test data agreed well for the quasi-static loading case. However, it is noted that the mesoscale model without consideration of the base material rate sensitivity and the entrapped gas underestimated the strength enhancement under dynamic loading scenario.

Li, L, Nimbalkar, S & Zhong, R 2018, 'Finite element model of ballasted railway with infinite boundaries considering effects of moving train loads and Rayleigh waves', Soil Dynamics and Earthquake Engineering, vol. 114, pp. 147-153.
View/Download from: Publisher's site
View description>>

© 2018 Elsevier Ltd This paper proposes a three-dimensional model incorporating finite element (FE) meshes with infinite element (IE) boundaries for ballasted railways. Moving train loads are simulated with sliding motions of moving elements which have hard contact feature at the interface with supporting rails. Dynamic responses of ballasted railway under different train speeds are investigated in time domain and frequency domain to identify the predominant frequency and critical speed. Rayleigh wave (R-Wave) propagation is simulated using the combined FE-IE model to determine the velocity of R-Wave in the layered embankment model and its relationship with the critical speed of the ballasted railway. The proposed model is successfully validated against the results of Euler-Bernoulli Elastic Beam (E-BEB) model.

Li, W, Luo, Z, Sun, Z, Hu, Y & Duan, WH 2018, 'Numerical modelling of plastic–damage response and crack propagation in RAC under uniaxial loading', Magazine of Concrete Research, vol. 70, no. 9, pp. 459-472.
View/Download from: Publisher's site
View description>>

In order to better understand the failure mechanism of recycled aggregate concrete (RAC), a numerical study on modelled recycled aggregate concrete (MRAC) was conducted to investigate the plastic–damage response and crack propagation under uniaxial loading. In the numerical model, the nanoscale mechanical properties and the thickness of the interfacial transition zones (ITZs) were obtained based on advanced nanoindentation. The constitutive relationships of new and old cement mortars and corresponding ITZs were developed using plastic–damage constitutive relationships. The effects of the relative mechanical properties between new and old cement mortars on the failure pattern and stress–strain response of MRAC were investigated. After calibration and verification with the uniaxial compression test, the numerical model was found to be able to reveal the failure pattern and stress–strain curves of MRAC under uniaxial tension. The results showed that microcracks usually first appear around the weak new and old ITZs, and then propagate into the new and old cement mortars. With an increase in the relative strength between new and old cement mortars, the microcrack initiation locations gradually shifted from the new ITZs to the old ITZs. Therefore, the numerical results can provide insight into the modification of RAC using mix design optimisation and ITZ enhancement.

Li, W, Luo, Z, Wu, C & Duan, WH 2018, 'Impact performances of steel tube-confined recycled aggregate concrete (STCRAC) after exposure to elevated temperatures', Cement and Concrete Composites, vol. 86, pp. 87-97.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd The impact behaviours of steel tube-confined recycled aggregate concrete (STCRAC) following exposure to elevated temperatures of 20 °C, 200 °C, 500 °C and 700 °C were experimentally investigated using a 100 mm-diameter split Hopkinson pressure bar (SHPB). The recycled coarse aggregate (RCA) replacement ratios were set as 0, 50% and 100%. The effect of RCA replacement ratio and exposure temperature on the impact properties of STCRAC were analysed in terms of failure modes, stress-strain time history curve and dynamic increase factor (DIF). The results show that the fire-damaged STCRAC can maintain its integrity during impact load. However, there were evident degradations in the dynamic behaviour of STCRAC after exposure to high temperatures of 500 °C and 700 °C. The ultimate impact strength, impact secant modulus and residual impact strength of STCRAC obviously decreased because of the damage due to high temperature exposure. But the degradations of both the ultimate impact strength and impact secant modulus of STCRAC under impact loading were less severe than those under quasi-static loading. The remaining strength factor and the DIF tended to increase with the raise of the elevated temperatures. Overall, during the impact loading, the fire-deteriorated STCRAC exhibited excellent impact behaviour.

Li, X, Liu, YM, Li, WG, Li, CY, Sanjayan, JG, Duan, WH & Li, Z 2018, 'Corrigendum to “Effects of graphene oxide agglomerates on workability, hydration, microstructure and compressive strength of cement paste” [Constr. Build. Mater. 145 (2017) 402–410]', Construction and Building Materials, vol. 179, pp. 537-538.
View/Download from: Publisher's site

Li, X, Wang, L, Liu, Y, Li, W, Dong, B & Duan, WH 2018, 'Dispersion of graphene oxide agglomerates in cement paste and its effects on electrical resistivity and flexural strength', Cement and Concrete Composites, vol. 92, pp. 145-154.
View/Download from: Publisher's site
View description>>

© 2018 Elsevier Ltd Actual dispersion of graphene oxide (GO) in cement paste was investigated by using both X-ray computed tomography and X-ray photoelectron spectroscopy. It was found that GO nanosheets are mainly agglomerated, as an individual phase, with platelet-like morphology and little GO being absorbed onto surfaces of cement particles and hydration products. By performing an electrical resistivity test, GO agglomerates are found to be more electrically insulative than cement paste. Therefore, it is not possible to develop self-sensing cement composites by incorporating GO directly without resolving its dispersion issue. However, GO agglomerates enhance the flexural strength of cement paste because of their special morphology and intrinsic strength. Results showed that the flexural strength of cement paste was increased by 83% with incorporation of 0.04% GO by weight of cement.

Li, Y, Li, W, Deng, D, Wang, K & Duan, WH 2018, 'Reinforcement effects of polyvinyl alcohol and polypropylene fibers on flexural behaviors of sulfoaluminate cement matrices', Cement and Concrete Composites, vol. 88, pp. 139-149.
View/Download from: Publisher's site
View description>>

© 2018 Elsevier Ltd The fracture behavior of unoiled/uncoated polyvinyl alcohol (PVA) fiber reinforced sulphoaluminate cement (SAC) matrices was experimentally investigated and compared with those of polypropylene (PP) fiber reinforced SAC and PVA fiber reinforced Portland cement (PC) matrices in this study. In the experimental investigation, three-point bending tests were carried out for notched fiber reinforced cement beams. Special attentions were paid on their deflection-hardening and multiple crack patterns. The different flexural behaviors between the plain SAC and PC matrices were evaluated using the double-K fracture model. The results indicate that the PVA fiber reinforced SAC matrices exhibited better flexural behaviors when compared with the PVA fiber reinforced PC matrix having comparable matrix strength. The bond strength between SAC matrix and PVA fiber are relatively better than that between the counterpart PC matrix and PVA fiber, while the bond strength between SAC matrix and PVA fiber is obviously stronger than that between the SAC and PP fibers.

Liang, X & Wu, C 2018, 'Investigation on Thermal Conductivity of Steel Fiber Reinforced Concrete Using Mesoscale Modeling', International Journal of Thermophysics, vol. 39, no. 12.
View/Download from: Publisher's site
View description>>

© 2018, Springer Science+Business Media, LLC, part of Springer Nature. A mesoscale model was developed to investigate the effect of steel fiber on the thermal conductivity of steel fiber-reinforced concrete (SFRC). Delaunay triangulation was employed to generate the unstructured mesh for SFRC materials. The model was validated using the existing experimental data. Then, it was used to study how model thickness affected simulation outcomes of thermal conductivity of models with different fiber lengths, by which an appropriate thickness was determined for the later analyses. The validated and optimized model was applied to the study of relationships between thermal conductivity and factors such as fiber content, fiber aspect ratio and different parts of an SFRC block by conducting steady-state heat analyses with the finite element analysis software ANSYS. The simulation results reveal that adding steel fiber increases thermal conductivity considerably, while fiber aspect ratio only has an insignificant effect. Besides, the presence of steel fibers has an obvious impact on the distribution of temperature and heat flux vector of the SFRC blocks.

Liang, X & Wu, C 2018, 'Meso-scale modelling of steel fibre reinforced concrete with high strength', Construction and Building Materials, vol. 165, pp. 187-198.
View/Download from: Publisher's site
View description>>

© 2018 Based on Delaunay triangulation, a 3D meso-scale model is successfully developed and verified. This approach modelling fibre and concrete separately and linking them with slide line contact has the capability to truly reflect the interfacial behaviour of fibre and mortar, and thus achieve high fidelity of numerical simulations. However, meso-scale modelling usually means tremendous complexity and long computational time. This paper proposes a model to achieve relatively high computation efficiency, as well as accuracy. Besides, the model has the potential to deal with small specimens cut from steel fibre reinforced concrete (SFRC) blocks.

Liang, X, Wu, C, Su, Y, Chen, Z & Li, Z 2018, 'Development of ultra-high performance concrete with high fire resistance', Construction and Building Materials, vol. 179, pp. 400-412.
View/Download from: Publisher's site
View description>>

© 2018 Elsevier Ltd Fire or high temperature is a big challenge to ultra-high performance concrete (UHPC). Strength loss of UHPCs can reach up to 80% after exposure to 800 °C. In this study, a total of six UHPC mixtures were designed and tested after subjected to elevated temperatures up to 1000 °C. The effects of aggregate type, fibre type and heating rate were investigated. Residual compressive strengths and stress-strain relationships were studied. Besides, attention was paid to explosive spalling since UHPCs are usually of compact structure and thus more vulnerable to explosive spalling than other concretes. Scanning electron microscope (SEM) analysis was conducted to help understand the mechanism of variation of internal structure under different temperatures. It was found the mixture containing steel slag and hybrid fibre had excellent fire resistance. After being subjected to 1000 °C, this mixture retained a residual compressive strength of 112.8 MPa or a relative value of 69%.

Liu, J, Wu, C, Li, J, Su, Y & Chen, X 2018, 'Numerical investigation of reactive powder concrete reinforced with steel wire mesh against high-velocity projectile penetration', Construction and Building Materials, vol. 166, pp. 855-872.
View/Download from: Publisher's site
View description>>

© 2018 Elsevier Ltd This paper numerically investigates the effects of steel wire mesh reinforcement on reactive powder concrete (RPC) targets subjected to high-velocity projectile penetration. A numerical model based on a computer program called LS-DYNA was validated with experimental data concerning the depth of penetration (DOP) and crater diameter of reinforced RPC targets. With the validated numerical model, a series of parametric studies are conducted to investigate how the variables of steel wire mesh reinforcement such as the configuration of steel wire meshes, number of layers, space between layers, space between steel wires per layer, as well as the diameter and tensile strength of steel wires affect DOP and crater diameter of reinforced RPC targets. Moreover, the energy evolution of projectile and steel wire meshes during the projectile penetration is discussed. Based on the results of parametric studies, an empirical equation derived from the simulation data is proposed to predict DOP of reinforced RPC targets.

Liu, J, Wu, C, Su, Y, Li, J, Shao, R, Chen, G & Liu, Z 2018, 'Experimental and numerical studies of ultra-high performance concrete targets against high-velocity projectile impacts', Engineering Structures, vol. 173, pp. 166-179.
View/Download from: Publisher's site
View description>>

© 2018 Elsevier Ltd Ultra-high performance concrete (UHPC) which is known for high strength, high toughness, excellent ductility and good energy absorption capacity can be adopted as an ideal material in the impact resistant design of structures. In the present study, impact responses of UHPC targets with 3 vol-% ultra-high molecular weight polyethylene (UHMWPE) fibres and UHPC targets with 3 vol-% steel fibres are experimentally investigated subjected to high-velocity projectile penetration, and plain concrete targets under the same loading scenarios are also tested as control specimens for comparative purpose. In addition, numerical studies are conducted to simulate the projectile penetration process into UHPC targets with the assistance of a computer program LS-DYNA. The numerical results in terms of the depth of penetration (DOP) and crater diameter as well as projectile abrasions and damages are compared with the experimental results. Moreover, DOPs of these two types of UHPC targets obtained from tests are compared with the previously proposed empirical model.

Liu, K, Li, Q, Wu, C, Li, X & Li, J 2018, 'A study of cut blasting for one-step raise excavation based on numerical simulation and field blast tests', International Journal of Rock Mechanics and Mining Sciences, vol. 109, pp. 91-104.
View/Download from: Publisher's site
View description>>

© 2018 Elsevier Ltd Over the past several decades, raise excavation has been widely employed in underground mining, civil engineering and military engineering. One-step raise excavation with burn cuts, where all the boreholes are pre-drilled and detonated at one time and no workers need to be underneath the freshly blasted and dangerous ground, is an important and promising method in raise excavation. Cut parameters, especially the parameters of prime cut which used empty hole as a free surface and swelling space, have significant influence on the effect of raise formed. In this study, two small-scale experimental methods, spiral hole spacing method and observation hole method, are designed to determine the prime cut parameters such as hole spacing (L), stemming length (Ls1, Ls2) and air deck length (La) which are normally determined by empirical formula. In order to study the feasibility of the two methods, numerical analysis and experimental tests are conducted in V zone of Sandaozhuang molybdenum mine (SMM), in which there are large numbers of underground goafs need to be controlled by filled raise. The Riedel–Hiermaier–Thoma (RHT) material model, which considers compression damage and tension damage effect under blasting loading, is employed in the LS-DYNA software to study the rock damage zone. Meanwhile, the field tests are carried out according to the two small-scale experimental methods. The comparison results show that the damage zone of numerical simulation has a good agreement with the experimental data. Further, the optimal prime cut parameters obtained from experimental tests are applied in one-step filled-raise excavation, and a 23 m raise that meets the design requirements is formed through the proposed technology. The results indicate that these cut parameters determined by the small-scale experiments are suited for one-step raise excavation. This study can provide two simple field experiments to determine the important prime cut paramet...

Liu, Q, Gao, R, Tam, VWY, Li, W & Xiao, J 2018, 'Strain monitoring for a bending concrete beam by using piezoresistive cement-based sensors', Construction and Building Materials, vol. 167, pp. 338-347.
View/Download from: Publisher's site
View description>>

© 2018 Elsevier Ltd Graphite nanoplatelets (GNPs), promising in improving electrical properties of cement-based materials and its smartness, were used to prepare piezoresistive cement-based strain sensors (PCSSs) in this study. Their piezoresistive responses along vertical, horizontal and inclined directions were measured during applying a vertical cyclic compression. After calibrating free PCSSs by analyzing their gauge factors, three PCSSs are embedded in a four-point bending beam at different stress zones, i.e. uniaxial compression, uniaxial tension and combined shear and compression. In addition to investigating piezoresistive responses of PCSSs embedded in the beam, traditional strain gauges and finite element method (FEM) were also used to grasp the strains at relevant positions for comparison. For free PCSSs, It was found that the electrical resistances along vertical, horizontal and diagonal directions drop by amplitudes of 5.5%, 1.8% and 6.7% respectively, as the increasing of vertical compression. The gauge factor along loading direction was calculated to be −160.8, which illustrated a better sensitivity. In the four-point bending beam, the PCSSs in compressive zone and tensile zone can be used to presume the strain variation by considering the gauge factor obtained from the free PCSS. The reaction of the PCSS in shear zone can illustrate its strain features because a slight volume variation happened in this area, which can also be testified to be only 0.012‰with FEM analysis.

Liu, Z, Wang, D, Liang, J, Wu, F & Wu, C 2018, 'The fast multi-pole indirect BEM for solving high-frequency seismic wave scattering by three-dimensional superficial irregularities', Engineering Analysis with Boundary Elements, vol. 90, pp. 86-99.
View/Download from: Publisher's site
View description>>

© 2018 Elsevier Ltd Taking full advantage of the indirect boundary element method (IBEM) and fast multi-pole expansion algorithm, this paper proposes a fast multi-pole indirect boundary element method (FM-IBEM) to solve the scattering of high-frequency seismic waves by three-dimensional (3-D) superficial irregularities or heterogeneity in a solid half-space. First, IBEM utilizes an exact dynamic Green's function for a full-space to construct the scattered wave field. Subsequently, by employing plane waves expansion of 3-D potential functions of compressional and shear waves, the multi-pole expansion and local expansion coefficients were derived. Implementation of FM-IBEM is presented in detail for wave-scattering problems. Numerical examples illustrate that the proposed FM-IBEM can reduce the memory required by more than an order of magnitude and also greatly improve the computing efficiency, retaining excellent accuracy as well. Ultimately, several high-frequency plane wave scattering problems of 3-D superficial irregularities in a solid half-space are illustrated, and several important scattering characteristics are described based on the high-precision numerical results.

Long, G, Liu, H, Ma, K, Xie, Y & Li, W 2018, 'Development of High-Performance Self-Compacting Concrete Applied as the Filling Layer of High-Speed Railway', Journal of Materials in Civil Engineering, vol. 30, no. 2, pp. 04017268-04017268.
View/Download from: Publisher's site
View description>>

© 2017 American Society of Civil Engineers. The filling layer of a China rail track system III (CRTS III) type ballastless track structure of a high-speed railway is a complicated structure typically constructed from self-compacting concrete (SCC). Excellent properties of SCC are of great importance to ensure the quality of construction technology and long-term service performance of the filling layer. In this study, preparation methodologies and properties of SCC applied as a filling layer are systematically investigated by series of experiments. The results indicate that high-performance SCC with high stability in a fresh state and low deformation in a hardened state was successfully achieved by optimizing aggregates and binder components. Use of viscosity-enhancing compounds can not only effectively improve the workability of fresh SCC, but also significantly enhance mechanical properties and decrease drying shrinkage and creep of hardened concrete.

Lu, Z-H, Li, H, Li, W, Zhao, Y-G & Dong, W 2018, 'An empirical model for the shear strength of corroded reinforced concrete beam', Construction and Building Materials, vol. 188, pp. 1234-1248.
View/Download from: Publisher's site
View description>>

© 2018 Elsevier Ltd A total of 158 experimental tests of shear behavior of corroded reinforced concrete (CRC) beams under action of concentrated load, published in the literature were collected and compiled into a shear strength database. This database was firstly used to discuss important parameters which affect the shear strength of CRC beams. The results show that the effect of stirrups’ corrosion on shear capacity of CRC beams is greater than that of longitudinal reinforcement corrosion. The shear span-to-depth ratio is also an important factor on shear strength of CRC beams. Total 9 available empirical models for predicting the residual shear strength are evaluated and compared based on the test database. It is found that eight of the nine models underestimate the shear strength of CRC beams while the other model gives the overestimated results. It is in this regard that a new empirical model for predicting the residual shear strength of CRC beams is proposed, in which a reduction coefficient is incorporated with the consideration of the effect of stirrups’ corrosion as well as shear span-to-depth ratio. The comparison studies demonstrate that the new proposal can provide an effective and accurate prediction of the shear capacity of CRC beams with a wide range of reinforcement corrosion damages.

Luo, Z, Li, W, Wang, K & Shah, SP 2018, 'Research progress in advanced nanomechanical characterization of cement-based materials', Cement and Concrete Composites, vol. 94, pp. 277-295.
View/Download from: Publisher's site
View description>>

© 2018 Elsevier Ltd Advanced characterization techniques have provided powerful tools for characterizations of materials at micro- and nano-scales worldwide. Although some overviews on nanomechanical characterizations of cement-based materials have been published, they have often focused on nanoindentation. Very limited reviews have been reported on the applications of modulus mapping, PeakForce quantitative nanomechanical mapping, and nanoscratch for researches on the micro and nanoscale compositions, structures and mechanical properties of modern cement-based materials. This paper is aimed at filling this blank. Based on an extensive literature review and authors’ own experience, the basic knowledge (e.g., general concepts, developments, and progresses) involved in the state-of-the-art nanomechanical characterization techniques have been systematically summarized in this paper. The critical issues (e.g., sample preparation procedures and requirements, measurements, and data analysis methods) of these techniques have been discussed in details. The applications of these techniques, especially their suitability for critical characterization of different scales of interfaces of cement-based materials are compared. Finally, the future perspectives of these nanomechanical characterization techniques are highlighted. It is expected that the outlook of this paper can help future researchers make scientific justification on selection of nanomechanical characterization methods and steer inquisitive readers into substantial details that may lead them to successful applications of these advanced techniques.

Ma, J, Fan, F, Zhang, L, Wu, C & Zhi, X 2018, 'Failure modes and failure mechanisms of single-layer reticulated domes subjected to interior blasts', Thin-Walled Structures, vol. 132, pp. 208-216.
View/Download from: Publisher's site
View description>>

© 2018 Single-layer reticulated domes are very common spatial structures. As landmarks, these types of structures can more easily be the targets of terrorist attacks than other buildings. However, blast resistance is not taken into consideration in the design of most civil structures. Therefore, it is important to know the damage level that may be imparted to single-layer reticulated domes after a blast attack. In this study, the dynamic response of reticulated domes subjected to an interior blast was investigated with numerical simulations, and five typical failure modes were identified from the results. In addition, the effects of some important parameters were investigated with a case study. Relationships between failure modes and interior blast impulses were summarised. Finally, the failure mechanisms were analysed, which could provide some design suggestions to decrease the probability of severe damage in spatial structures subjected to extreme dynamic loads.

Metia, S, Ha, QP, Duc, HN & Azzi, M 2018, 'Estimation of Power Plant Emissions With Unscented Kalman Filter', IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, vol. 11, no. 8, pp. 2763-2772.
View/Download from: Publisher's site
View description>>

© 2008-2012 IEEE. Emissions from power plants constitute a major part of air pollution and should be adequately estimated. In this paper, we consider the problem of estimating nitrogen dioxide (NO-X ) emission of power plants by developing an inverse method to integrate satellite observations of atmospheric pollutant column concentrations with species concentrations and direct sensitivities predicted by a regional air quality model, in order to discern biases in the emissions of the pollutant precursors. Using this method, the emission fields are analyzed using a 'bottom-up' approach, with an inversion performed by an unscented Kalman filter (UKF) to improve estimation profiles from emissions inventories data for the Sydney metropolitan area. The idea is to integrate information from the original inventories with tropospheric nitrogen dioxide (NO-2) emissions estimated during one month from the air pollution model-chemical transport model, and then, for validation, to compare the resulting model with satellite retrievals from the ozone monitoring instrument (OMI) above the region. The UKF-based estimation of NO-2 emissions shows better agreement with OMI observations, implying a significant improvement in accuracy as compared with the original inventories. Therefore, the proposed method is a promising tool for estimation of air emissions in urban areas.

Mirzababaei, M, Arulrajah, A, Haque, A, Nimbalkar, S & Mohajerani, A 2018, 'Effect of fiber reinforcement on shear strength and void ratio of soft clay', Geosynthetics International, vol. 25, no. 4, pp. 471-480.
View/Download from: Publisher's site
View description>>

In this study, a series of multi-stage drained reverse direct shear tests were carried out on soft clay samples reinforced with 0.25% and 0.50% polypropylene fibers of 6 mm, 10 mm and 19 mm in length. Tests were carried out at different normal effective stresses and cumulative horizontal shear displacement of 1.17 times of the sample width. Results showed an increase of the shear strength with the increase of fiber content and length. However, the rate of improvement was capped with the normal effective stress applied during the shearing stage. At a high normal effective stress, the shear strength of the fiber-reinforced soft clay approached that of the unreinforced clay regardless of the amount of fiber inclusion. The rate of shear strength improvement decayed with the number of shear cycles. Fiber reinforcement also resulted in a reduction of the compressibility of the soft clay at consecutive consolidation and shear stages. Although the effective internal friction angle of the soft clay was not altered significantly with the fiber reinforcement, the effective cohesion of the soft clay improved significantly as much as 6.4 and 8.5 times with the inclusion of 0.25% and 0.50% of 10 mm long fibers, respectively.

Nguyen, VV, Li, J, Erkmen, E, Alamdari, MM & Dackermann, U 2018, 'FRF Sensitivity-Based Damage Identification Using Linkage Modeling for Limited Sensor Arrays', International Journal of Structural Stability and Dynamics, vol. 18, no. 08, pp. 1840002-1840002.
View/Download from: Publisher's site
View description>>

This paper presents a novel method to localize and quantify damage in a jack arch structure by introducing a linkage modeling technique to overcome issues caused by having limited sensors. The main strategy in the proposed Frequency Response Function (FRF)-based sensitivity model updating approach is to divide the specimen into partitions. The Young’s modulus of each partition is then updated to detect stiffness reduction caused by damage. System Equivalent Reduction Expansion Process (SEREP) is used to reduce the full finite element (FE) model to a linkage model. The number of measured degrees of freedom (DOFs) is then expanded to the linkage model using the mass and stiffness matrices of the linkage model for the synthesis of interpolated FRFs. The FRF sensitivities are then formulated using the linkage model along with the interpolated FRFs to iteratively calculate the values of the updating parameters until convergence is achieved. The methodology and theory behind this procedure are discussed and verified using a numerical and experimental study. The successful implementation of this method has the potential to detect the location and severity of damage where sensor placement is limited.

Nimbalkar, S, Annapareddy, VSR & Pain, A 2018, 'A simplified approach to assess seismic stability of tailings dams', Journal of Rock Mechanics and Geotechnical Engineering, vol. 10, no. 6, pp. 1082-1090.
View/Download from: Publisher's site
View description>>

© 2018 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences In the zones of high seismic activity, tailings dam should be assessed for the stability against earthquake forces. In the present paper, a simplified method is proposed to compute the factor of safety of tailings dams. The strain-dependent dynamic properties are used to assess the stability of tailings dams under seismic conditions. The effect of foundation soil properties on the seismic stability of tailings dams is studied using the proposed method. For the given input parameters, the factor of safety for low-frequency input motions is nearly 26% lower than that for high-frequency input excitations. The impedance ratio and the depth of foundation have significant effect on the seismic factor of safety of tailings dams. The results from the proposed method are well compared with the existing pseudo-static method of analysis. Tailings dams are vulnerable to damage for low-frequency input motions.

Nimbalkar, S, Dash, SK & Indraratna, B 2018, 'Performance of ballasted track under impact loading and applications of recycled rubber inclusion', Geotechnical Engineering, vol. 49, no. 4, pp. 79-91.
View description>>

In this paper a review of the sources of impact loads and their effect on the performance of ballasted track is presented. The typical characteristics and implications of impact loading on track deterioration, particularly ballast degradation, are discussed. None of the procedures so far developed to design rail track incorporate the impact that dynamic loading has on the breakage of ballast and therefore it can be said to be incomplete. An intensive study on the impact of induced ballast breakage is needed in order to understand this phenomenon and then use the knowledge gained to further advance the design methodology. A stiff track structure can create severe dynamic loading under operating conditions which causes large scale component failure and increases maintenance requirements. Installing resilient mats such as rubber pads (ballast mat, soffit pad) in rail tracks can attenuate the dynamic force and improve overall performance. The efficacy of ballast mats to reduce structural noise and ground vibration has been studied extensively, but a few recent studies has reported how ballast mats and soffit pads reduce ballast degradation, thus obviating the necessity of a comprehensive study in this direction.

Pace, B, Munroe, P, Marjo, CE, Thomas, P, Gong, B, Shepherd, J, Buss, W & Joseph, S 2018, 'The mechanisms and consequences of inorganic reactions during the production of ferrous sulphate enriched bamboo biochars', Journal of Analytical and Applied Pyrolysis, vol. 131, pp. 101-112.
View/Download from: Publisher's site

Pain, A, Ramakrishna Annapareddy, VS & Nimbalkar, S 2018, 'Seismic Active Thrust on Rigid Retaining Wall Using Strain Dependent Dynamic Properties', International Journal of Geomechanics, vol. 18, no. 12, pp. 06018034-06018034.
View/Download from: Publisher's site

Qin, L, Gao, X, Li, W & Ye, H 2018, 'Modification of Magnesium Oxysulfate Cement by Incorporating Weak Acids', Journal of Materials in Civil Engineering, vol. 30, no. 9, pp. 04018209-04018209.
View/Download from: Publisher's site
View description>>

© 2018 American Society of Civil Engineers. This paper investigates the effects of weak acids (citric acid, boric acid, and trisodium citrate) with dosages of 0.5, 1.5, and 2.5% of MgO weight on compressive strength, water resistance, and drying shrinkage of magnesium oxysulfate (MOS) cement. Hydration products and microstructure of typical samples are studied by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential thermal analysis-thermogravimetry (DTA-TG), and scanning electron microscope (SEM) facilities. The results show that compressive strength of MOS cement increases with an increasing MgO/MgSO4 molar ratio and decreasing H2O/MgSO4 molar ratio. The addition of citric acid, boric acid, or trisodium citrate significantly enhances compressive strength and water resistance and alleviates drying shrinkage of MOS cement paste. With the incorporation of weak acid, 5 · 1 · 7 [5Mg(OH)2 · MgSO4 · 7H2O] phase, which is a new magnesium subsulfate crystalline product with a needlelike crystal whisker shape, forms in cement paste. This substance behaves in a criss-crossing manner and fills in pores and microcracks, inducing the improved performance of MOS cement paste. With optimum dosages of 0.5, 2.5, and 0.5%, respectively, citric acid, trisodium citrate, and boric acid exhibit decreasing improvement effect.

Rajput, A, Iqbal, MA & Wu, C 2018, 'Prestressed concrete targets under high rate of loading', International Journal of Protective Structures, vol. 9, no. 3, pp. 362-376.
View/Download from: Publisher's site
View description>>

Prestressed concrete is highly being preferred as material for construction in the case of strategic and relevant structures such as, for instance, nuclear containments, armor deposits, shelters, bridges, and military bunkers. It is highly durable, fire and corrosion resistant, and non-porous. In order to study the influence of prestressing on the mechanics of deformation, energy absorption capacity, and failure modes of concrete targets, finite element simulations have been carried out using hard steel bullets and compared with the experiments carried out by the authors earlier. Prestressed concrete targets of plan size 450 mm × 450 mm and thickness of 80 mm were impacted by 0.5-kg hard steel projectiles. The concrete was designed to obtain an unconfined compressive strength of 48 MPa. An initial stress of 10% magnitude of compressive strength was induced by 4-mm-diameter high-tensile-strength (1700 MPa) steel wires in prestressed concrete targets. A grid of 8-mm-diameter steel bars was inserted in the reinforced and prestressed concrete targets to enable the straight comparison between these concretes. The prestressing in concrete has been found to be effective in reducing the volume of scabbed material as well as the ballistic resistance of prestressed concrete targets. The ballistic limit of prestressed concrete with 10% induced stress was found to be, respectively, 14% higher than that of the plain concrete target and 10.2% higher than the reinforced concrete. Failure modes predicted through finite element simulations were found in agreement with that of the actual results.

Rao, P, Chen, Q, Nimbalkar, S & Liu, Y 2018, 'Effect of water and salinity on soil behaviour under lightning', Environmental Geotechnics, vol. 5, no. 1, pp. 56-62.
View/Download from: Publisher's site
View description>>

The east coast of China, in particular Shanghai, is frequently exposed to lightning, and the resulting annual loss approaches US$30 million. All kinds of protection devices transfer the lightning current and the energy into the ground. In this study, the characteristics of the typical soft soil in Shanghai with different values of water content and salinity under the action of lightning shock have been analysed by an impulse current generator and a self-designed test equipment. The test results show that the current waveform from the impact of lightning in soils has a steep rise and a slow fall. At the same lightning intensity, higher water content or salinity leads to (a) shorter peak time, (b) larger peak current waveform, (c) quicker release speed and (d) larger lightning impulse response. The test results are valuable in guiding the design and the reformation of lightning protection and grounding systems.

Salari, Z, Vakhshouri, B & Nejadi, S 2018, 'Analytical review of the mix design of fiber reinforced high strength self-compacting concrete', Journal of Building Engineering, vol. 20, pp. 264-276.
View/Download from: Publisher's site
View description>>

© 2018 Elsevier Ltd Despite application of fiber reinforced concrete, high strength concrete and self-compacting concrete in the construction industry in the last decades, the investigations about combination of these types of concrete in Fiber Reinforced High-Strength Self-Compacting Concrete (FRHSSCC) is very rare in the literature. This study reviews a wide range of experimental data of the mix design in terms of the components and their proportions and the compressive strength of FRHSSCC in the last 12 years. The applied coarse and fine aggregates, chemical and mineral admixtures, fibers, cement, water, powder components and the ratios of water to cement and water to binder are broadly analyzed and evaluated. In addition, the compressive strength of the FRHSSCC mixtures are evaluated. The relationship between the compressive strength with water to cement and water to binder ratios in the mixture, water content, fine and coarse aggregates and the powder content is also discussed and compared in the case studies. Considerable variety of the mix designs with different components and proportions to achieve FRHSSCC without the mixing problems is evident in the collected case studies.

Saleh, A, Far, H & Mok, L 2018, 'Effects of different support conditions on experimental bending strength of thin walled cold formed steel storage upright frames', Journal of Constructional Steel Research, vol. 150, pp. 1-6.
View/Download from: Publisher's site
View description>>

© 2018 Elsevier Ltd Design computations of industrial storage racks in accordance with current industry standards rely in part on laboratory testing. One of these tests is for determining the bending strength of upright sections. When testing the bending strength about the axis of symmetry of the upright, a four-point bending test of the assembled upright frame is mandated. The test arrangement prescribed by the standard must permit free twisting of the section at the supports, while the applied loads and their reactions for each upright may be applied in the plane of the section's shear centre. A test arrangement that provides free twisting of the upright section at the supports is more complex and difficult to set up compared with a simple support. This paper examines if the condition of free twisting at supports is necessary in the case of shear centre loading, especially that relaxing this particular code requirement would lead to a simpler test arrangement. Laboratory testing of two sets of upright frames, loaded through the upright's shear centre but with each set having a different support condition indicated that free twisting at the supports had no effect on the bending capacity of the upright members tested. The paper outlines the test setup and reports the results in form of characteristic load deformation curves of the tested specimen.

Shao, R, Wu, C, Liu, Z, Su, Y, Liu, J, Chen, G & Xu, S 2018, 'Penetration resistance of ultra-high-strength concrete protected with layers of high-toughness and lightweight energy absorption materials', Composite Structures, vol. 185, pp. 807-820.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd Aluminium foam has advantages of excellent shock absorption, cyclic utilization, and lightweight. Ultra-high-molecular-weight polyethylene (UHMWPE) fibre has a low density, a high specific strength, a high modulus and a great capability in energy absorption. Steel wire mesh has high toughness and elongation properties and a good effect on energy absorption. In the present study, UHMWPE fibre, steel wire mesh and aluminium foam were used to protect ultra-high-strength concrete (UHSC) targets to resist DT300 high-strength alloy-steel projectile penetration with striking velocities from 550 m/s to 800 m/s. High-speed impact tests on normal-strength concrete (NSC) targets were also conducted for comparison. Testing results including the failure mode, depth of penetration (DOP), crater dimensions and damage area of protected concrete targets, indicate that the new composite material protective cover has an outstanding performance in the shock wave absorption, especially in reducing the crack propagation and debris spatter of protected UHSC targets, as well as increasing the deviation angles of projectile terminal ballistic trajectories. It is a successful demonstration of anti-penetration properties research for new concrete composite structures.

Sun, Y, Nimbalkar, S & Chen, C 2018, 'Grading and frequency dependence of the resilient modulus of ballast', Géotechnique Letters, vol. 8, no. 4, pp. 305-309.
View/Download from: Publisher's site
View description>>

The stress–strain and degradation response of railway ballast to imparted train loading is often largely dominated by intrinsic properties, including particle size and particle-size distribution (PSD). To investigate these aspects, a series of large-scale triaxial cyclic tests were conducted on railway ballast. To investigate the influence of grading and frequency on the resilient modulus of railroad ballast, laboratory data from previous work were analysed and discussed. It was observed that the resilient modulus of ballast decreased with an increase in the coefficient of uniformity and cyclic loading frequency. However, for samples with the constant coefficient of uniformity, the resilient modulus appeared to decrease as the particle size and the associated broadness increased. It was also found that the resilient modulus underwent substantial reduction with the evolution of particle breakage by shifting the initial PSD to a broader range.

Tapas, M, Brenner, J, Vessalas, K, Thomas, P & Sirivivatnanon, V 2018, 'Effect of Limestone Content in Cement on Alkali-Silica Reaction Using Accelerated Mortar Bar Test', Concrete in Australia, vol. 44, no. 2, pp. 41-47.
View description>>

This paper reports the effect of interground limestone content on Alkali Silica Reaction (ASR) in binder systems with and without supplementary cementitious materials (SCMs) using commercial Portland cement (Type GP) with no limestone addition and a masonry cement with 17% limestone. The results show that increasing cement limestone content up to 17% has no adverse effect on expansion of mortar bars containing reactive greywacke aggregate tested using Australian Standard AS 1141.60.1. The high limestone content of 17% also appears to stabilise the Accelerated Mortar Bar Test (AMBT) expansion after 14 days of immersion in 1M NaOH 80 oC. This is possibly because of the formation of monocarboaluminate as detected by X-Ray Diffraction (XRD), resulting from the reaction of limestone with the aluminate phases in the cement, which may lead to reduced porosity in the mortar as well as the reduced amount of portlandite in the hydrated masonry cement as confirmed by Thermogravimetric Analysis (TGA). Moreover, it was found that the limestone content had no detrimental effect on the efficacy of SCMs to suppress ASR as shown in the expansion of the accelerated mortar bar tests.

Thomas, D & Ding, G 2018, 'Comparing the performance of brick and timber in residential buildings – The case of Australia', Energy and Buildings, vol. 159, pp. 136-147.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier B.V. There is currently a limited use of timber products in residential development in Australia due to the dominance of heavy materials such as concrete, steel and brick. This dominant use of heavy materials is a reversal of the traditional material choice that was based predominantly on timber products. Technological advances and efficiencies drove the change to heavy materials to use in residential construction. The emerging issue with this reliance on heavy materials is the impact of their use on the environment. The carbon impact and problem of finite resource depletion associated with concrete, steel and bricks need to be addressed due to the increasing pressure from national and international requirements and legislations. The construction industry needs to reduce its negative impact on the environment and the renewable nature of timber presents a material solution to the problem. Timber from sustainably managed forests and plantations can be utilised as lumber or manufactured into engineered products for residential development. This paper examines the benefits of timber used in building envelopes when compared with conventional high-density materials such as brick and concrete when construction is designed with equivalent thermal performance. Multiple case studies were used to demonstrate the reduced life cycle energy and costs, and the time of construction benefits of timber when used as an alternative to heavy materials. Results revealed that Life cycle energy and time of construction showed noticeable differences between timber construction and heavy materials and cost showing marginal differences.

Tran, T & Ha, QP 2018, 'Perturbed cooperative-state feedback strategy for model predictive networked control of interconnected systems', ISA Transactions, vol. 72, pp. 110-121.
View/Download from: Publisher's site
View description>>

© 2017 ISA A perturbed cooperative-state feedback (PSF) strategy is presented for the control of interconnected systems in this paper. The subsystems of an interconnected system can exchange data via the communication network that has multiple connection topologies. The PSF strategy can resolve both issues, the sensor data losses and the communication network breaks, thanks to the two components of the control including a cooperative-state feedback and a perturbation variable, e.g., ui=Kijxj+wi. The PSF is implemented in a decentralized model predictive control scheme with a stability constraint and a non-monotonic storage function (ΔV(x(k))≥0), derived from the dissipative systems theory. Numerical simulation for the automatic generation control problem in power systems is studied to illustrate the effectiveness of the presented PSF strategy.

Vahedian, A, Shrestha, R & Crews, K 2018, 'Analysis of externally bonded Carbon Fibre Reinforced Polymers sheet to timber interface', Composite Structures, vol. 191, pp. 239-250.
View/Download from: Publisher's site

Vahedian, A, Shrestha, R & Crews, K 2018, 'Bond strength model for externally bonded FRP-to-timber interface', Composite Structures, vol. 200, pp. 328-339.
View/Download from: Publisher's site

Vahedian, A, Shrestha, R & Crews, K 2018, 'Experimental Investigation on the Effect of Bond Thickness on the Interface Behaviour of Fibre Reinforced Polymer Sheet Bonded to Timber', International Journal of Structural and Construction Engineering, vol. 12, no. 12, pp. 1157-1163.

Vakhshouri, B & Nejadi, S 2018, 'Effect of fiber reinforcing on instantaneous deflection of self-compacting concrete one-way slabs under early-age loading', Structural Engineering and Mechanics, vol. 67, no. 2, pp. 155-163.
View/Download from: Publisher's site
View description>>

The Early-age construction loading and changing properties of concrete, especially in the multi-story structures can affect the slab deflection, significantly. Based on previously conducted experiment on eight simply-supported one-way slabs this paper investigates the effect of concrete type, fiber type and content, loading value, cracking moment, ultimate moment and applied moment on the instantaneous deflection of Self-Compacting Concrete (SCC) slabs. Two distinct loading levels equal to 30% and 40% of the ultimate capacity of the slab section were applied on the slabs at the age of 14 days. A wide range of the existing models of the effective moment of inertia which are mainly developed for conventional concrete elements, were investigated. Comparison of the experimental deflection values with predictions of the existing models shows considerable differences between the recorded and estimated instantaneous deflection of SCC slabs. Calculated elastic deflection of slabs at the ages of 14 and 28 days were also compared with the experimental deflection of slabs. Based on sensitivity analysis of the effective parameters, a new model is proposed and verified to predict the effective moment of inertia in SCC slabs with and without fiber reinforcing under two different loading levels at the age of 14 days.

Vakhshouri, B & Nejadi, S 2018, 'Instantaneous deflection of self-compacting and lightweight concrete slabs at early-age', Engineering Solid Mechanics, vol. 6, no. 2, pp. 143-154.
View/Download from: Publisher's site
View description>>

© 2018 Growing Science Ltd. All rights reserved. This paper describes laboratory tests on twelve simply-supported one-way slabs including four lightweight concrete slabs in this study and previously conducted experiments on eight self-compacting reinforced concrete slabs subjected to loading at the age of 14 days. All slab were identical by dimensions of 3.8 m long supported on 3.5 m span, 400 mm wide, and 161 mm deep with 4N12 bars at an effective depth of 136 mm providing a reinforcement ratio of 0.008. After seven days moist-curing, the specimens were removed from the formworks and subjected to different values of the uniformly distributed loading including the self-weight of slabs. The mid-span deflection of slabs was recorded immediately after putting the loading blocks on the slabs. Despite close values of the compressive strength of the mixtures, the obtained results validate the effect of the concrete type on the instantaneous deflection of slabs. A wide range of existing models of the effective stiffness of reinforced concrete section were investigated to predict the instantaneous deflection of slabs. Majority of the models are developed for conventional concrete. Comparing the predicted and experimental results of mid-span deflection confirmed that the existing models are inadequate for lightly reinforced specimens such as slabs. New models are proposed and verified to predict the effective moment of inertia in the slabs with and without fiber reinforcing concretes.

Vakhshouri, B & Nejadi, S 2018, 'Prediction of compressive strength of self-compacting concrete by ANFIS models', Neurocomputing, vol. 280, pp. 13-22.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd. Many studies predict the compressive strength of conventional concrete from hardened characteristics; however, in the case of self-compacting concrete, these investigations are very rare. There is no study to predict the compressive strength of self-compacting concrete from mixture proportions and slump flow. This paper designs ANFIS models to establish relationship between the compressive strength as output, and slump flow and mixture proportions as input in eighteen combinations of input parameters. The applied dada is taken from 55 previously conducted experimental studies. Effect of each parameter on the compressive strength and its importance level in the developed model has been investigated. Based on the error size in each combination analysis, weighting factor and importance level of each parameter is evaluated to apply the correction factors to get the most optimized relationship. Obtained results indicate that the model including all input data (slump flow and mixture proportions) gives the best prediction of the compressive strength. Excluding the slump flow from combinations affects the prediction of compressive strength, considerably. However it's not as much as the effect of the maximum aggregate size and aggregate volume in the mixture design. In addition, different values of powder volume, aggregate volume and paste content in the mixture reveal different ascending and descending effects on the compressive strength.

Vakhshouri, B & Nejadi, S 2018, 'Review on the mixture design and mechanical properties of the lightweight concrete containing expanded polystyrene beads', Australian Journal of Structural Engineering, vol. 19, no. 1, pp. 1-23.
View/Download from: Publisher's site
View description>>

© 2017, © 2017 Engineers Australia. Lightweight concrete containing expanded polystyrene beads (EPS-LWC) is frequently used in different structural and non-structural applications, since it was first developed about 60 years ago. However, effect of new materials and admixtures to improve its performance and strength are not investigated properly. A wide range of investigations about EPS-LWC since 1976, including the experimental data are evaluated. The collected data contain the information of curing methods, type of fine and coarse aggregates, mineral fillers, chemical admixtures and fibres in each experiment. In addition, the mixture proportions including the size and volume of EPS beads, density and compressive strength of the concrete are presented. Mechanical properties of EPS-LWC from 154 mixture design in 55 experimental programmes are also assessed. Utilising the experimental data, new models are developed and verified by the existing models of the mechanical properties of concrete. The existing models of the mechanical properties of LWC are also compared with those of the convention concrete.

Vakhshouri, B & Nejadi, S 2018, 'Sensitivity of concrete properties to compressive strength', Proceedings of the Institution of Civil Engineers - Engineering and Computational Mechanics, vol. 171, no. 1, pp. 29-44.
View/Download from: Publisher's site
View description>>

Concrete is generally classified by compressive strength (CS) grade, which signifies the characteristic strength required. Other mechanical parameters of concrete are expressed in terms of the CS. Depending on design objectives, economic issues and available materials, normal-strength concrete, high-strength concrete (HSC) or ultra-high-strength concrete (UHSC) might be used in design and construction. Due to the non-linear nature of concrete, there is no proportional relation between properties of concrete, even in corresponding characteristics in different types of concrete. Although design codes and experimental investigations define different limits for HSC and UHSC and present relations for properties of various concrete classes, predicted values are sometimes significantly imprecise. This study broadly presents equations to estimate modulus of elasticity, splitting tensile strength and modulus of rupture for different CS classifications and validates them by comparing with empirical relations and international design codes' formulae.

Vakhshouri, B & Nejadi, S 2018, 'Size effect and age factor in mechanical properties of BST Light Weight Concrete', Construction and Building Materials, vol. 177, pp. 63-71.
View/Download from: Publisher's site
View description>>

© 2018 Elsevier Ltd Replacement of whole or part of normal aggregates with Expanded Polystyrene (EPS) beads in the concrete mix is a reliable method to produce Light Weight Concrete (LWC) with considerable advantages. Due to modification effect on mechanical properties of LWC, it is important to examine whether all the assumed hypotheses about conventional concrete also are applicable for LWC structures. Based on an experimental program, this study investigates the effects of specimen size and shape on the compressive and tensile strength of this type of LWC. In this regard, cylinder specimens with 75 × 150, 100 × 200 and 150 × 300 mm dimensions and cube specimens with 100 and 150 mm dimensions were cast and cured in laboratory conditions. Compressive and tensile strengths were tested after 3, 7, 14, 21, 28, 56 and 91 days. The correlation factor between the compressive strength, tensile strength and the shape and size of specimens is evaluated also.

Walsh, P, Saleh, A & Far, H 2018, 'Evaluation of structural systems in slender high-rise buildings', Australian Journal of Structural Engineering, vol. 19, no. 2, pp. 105-117.
View/Download from: Publisher's site
View description>>

With the rapid population growth and scarcity of developable space, especially in large cities, there is a need for increased density in both commercial and residential housing, and hence a strong demand to maximise floor space by constructing not only tall, but also slender buildings. This study considers different structural systems available for constructing slender high-rise buildings and evaluates their feasibility in terms of the lateral deformation being one of the key governing design criteria for very tall buildings. To examine the performance of different structural systems in buildings of varying height and floorplan, this study applies finite element analyses in a parametric study to compare nine different building configurations under static loading with heights varying from 80m to 460m. The study shows that buildings with square footprints can achieve greater heights over rectangular footprints with the same area and that multiple towers when connected structurally at one or more levels can achieve even greater heights.

Wang, D, He, C, Wu, C & Zhang, Y 2018, 'Mechanical behaviors of tension and relaxation of tongue and soft palate: Experimental and analytical modeling', Journal of Theoretical Biology, vol. 459, pp. 142-153.
View/Download from: Publisher's site
View description>>

© 2018 This study is to characterize mechanical properties of uniaxial tension and stress relaxation responses of muscle tissues of tongue and soft palate. Uniaxial tension test and stress relaxation test on 39 fresh tissue samples from four five-month-old boars (65 ± 15 kg) are conducted. Firstly, the rationality of the samples’ dimension design and experimenal data measurement is validated by one-way ANOVA F-type test. Mechanical properties, including stress-strain relationship and stress relaxation characteristic, are then investigated in details to show the nonlinear behaviors of the tissue samples clearly. Finally, a constitutive model of representing the mechanical properties is formulated within the nonlinear integral representation framework proposed by Pinkin and Rogers, and corresponding material parameters are fitted to the experimental data based on the Levenberg-Marquardt minimization algorithm. The results of the fitting comparison prove that the formulated constitutive model can capture the observed nonlinear behaviors of the muscle tissue samples in both the axial tension and stress relaxation experiments.

Wang, W, Wu, C & Li, J 2018, 'Numerical Simulation of Hybrid FRP-Concrete-Steel Double-Skin Tubular Columns under Close-Range Blast Loading', Journal of Composites for Construction, vol. 22, no. 5, pp. 04018036-04018036.
View/Download from: Publisher's site
View description>>

© 2018 American Society of Civil Engineers. Hybrid fiber-reinforced polymer (FRP)-concrete-steel double-skin tubular columns (DSTCs) are a new form of composite columns that consist of an outer FRP tube and an inner steel tube, with the space between them filled with concrete. Although many studies have been conducted on the hybrid DSTCs, no studies have been conducted on their behavior under blast loading. This study presents the results of a numerical study on the behavior of hybrid DSTCs under close-in blast loading. Numerical models of hybrid DSTCs are developed using finite-element code LS-DYNA, and the reliability of the developed models are validated with available testing results. With the validated models, numerical simulations are carried out to investigate the structural responses of hybrid DSTCs under blast loading. The simulation results indicate that the hybrid DSTCs behave in a ductile manner under blast loading. The outer FRP tube can effectively provide confinement to the infilled concrete, and the inner steel tube plays a key role in resisting the blast loading. Detailed parametric analyses are conducted to investigate the influences of different parameters on the blast behavior of hybrid DSTCs. The blast resistance capacities of the hybrid DSTCs, concrete-filled steel tubes (CFSTs), and concrete-filled double-skin steel tubes (CFDSTs) are compared and discussed based on the simulation results.

Wang, W, Wu, C, Liu, Z & Si, H 2018, 'Compressive behavior of ultra-high performance fiber-reinforced concrete (UHPFRC) confined with FRP', Composite Structures, vol. 204, pp. 419-437.
View/Download from: Publisher's site
View description>>

© 2018 Elsevier Ltd This study presents the results of an experimental program on the compressive behavior of fiber reinforced polymer (FRP) confined ultra-high performance fiber-reinforced concrete (UHPFRC). A total of 38 specimens were prepared and tested under axial compression. In addition to FRP confined UHPFRC, FRP confined ultra-high performance concrete without fiber addition (UHPC), high strength concrete (HSC), and normal strength concrete (NSC) were also tested to investigate their comparative performances. The test results indicate that the FRP confined UHPFRC can exhibit ductile behavior if sufficient FRP confinement is provided. However, due to their ultra-high strength as well as the unique microstructure, FRP confined UHPFRC is likely to exhibit more brittle behavior than FRP confined NSC and HSC. Compared to FRP confined NSC and HSC, the confinement efficiency is less for FRP confined UHPFRC. Sudden stress reduction or stress fluctuations are observed shortly after the initial peak stress (axial stress at the first peak point) for FRP confined UHPFRC. Based on the confinement level, the stress-strain behavior of FRP confined UHPFRC may experience a second ascending branch or a continuous descending branch after the sudden stress reduction or stress fluctuations. The influences of FRP layers, FRP types, and fiber addition on the compressive behavior of FRP confined UHPFRC are observed to be significant. Moreover, existing stress-strain models available for FRP confined UHPFRC are evaluated by using a database collected in this study.

Wu, W-H, Thomas, P, Hume, P & Jin, J 2018, 'Effective Conversion of Amide to Carboxylic Acid on Polymers of Intrinsic Microporosity (PIM-1) with Nitrous Acid', Membranes, vol. 8, no. 2, pp. 20-20.
View/Download from: Publisher's site
View description>>

Carboxylate-functionalised polymers of intrinsic microporosity (C-PIMs) are highly desirable materials for membrane separation applications. The recently reported method to afford C-PIMs was via an extensive base hydrolysis process requiring 360 h. Herein, a novel and effective method to convert PIM-CONH₂ to C-PIM using nitrous acid was studied. The chemical structure of C-PIM was characterised by ¹H NMR, 13C NMR, FTIR, elemental analysis, UV-Vis, TGA and TGA-MS. Complete conversion from amide to carboxylic acid groups was confirmed. Decarboxylation of C-PIM was also successfully studied by TGA-MS for the first time, with a loss of m/z 44 amu (CO₂) observed at the first degradation stage. TGA also revealed decreased thermal stability of C-PIM relative to PIM-CONH₂ under both N₂ and air atmosphere. Gel permeation chromatography (GPC) analysis showed continuous molecular weight degradation of C-PIM with extended reaction time. Aromatic nitration was also observed as a side reaction in some cases.

Xu, R & Fatahi, B 2018, 'Geosynthetic-reinforced cushioned piles with controlled rocking for seismic safeguarding', Geosynthetics International, vol. 25, no. 6, pp. 561-581.
View/Download from: Publisher's site
View description>>

In this study, a cushioned pile foundation reinforced with geosynthetics is proposed to protect buildings and foundations from seismic energy. This composite foundation utilises piles to control foundation settlement while the geosynthetic-reinforced cushion modifies the dynamic structural characteristics and the load transfer mechanism. The seismic performance of this proposed foundation system is evaluated numerically using FLAC3D software. A fully coupled nonlinear dynamic analysis was conducted in the time domain. The variation of shear modulus corresponding to shear strains in the soil is used to simulate the dynamic behaviour of the soil, while the influence of the plasticity index is also captured. The soil-geosynthetic interface utilises the Mohr-Coulomb failure criterion to capture possible sliding and pull-out of the reinforcement layers. 3D numerical predictions of the tensile forces mobilised in the geosynthetic layers, the shear forces, the lateral deformations and maximum and residual inter-storey drifts in the building are presented and discussed in this paper, as well as how the shear forces and bending moments develop in the piles, and the lateral pile displacements. The results indicate that the proposed geosynthetic-reinforced cushioned pile foundation can provide design engineers with an alternative solution for safeguarding buildings constructed on soft soils in earthquake-prone regions.

Xu, R & Fatahi, B 2018, 'Influence of geotextile arrangement on seismic performance of mid-rise buildings subjected to MCE shaking', Geotextiles and Geomembranes, vol. 46, no. 4, pp. 511-528.
View/Download from: Publisher's site
View description>>

Geotextile layers make it possible to construct mid-rise buildings sitting on shallow foundations in unfavourablesoil conditions; this study investigates how the arrangement of geotextiles affects the seismic performance ofmid-rise buildings under Maximum Considered Earthquake (MCE) shaking. The geotextile arrangement con-sidered here includes the stiffness (5000 kN/m–12000 kN/m), the length with respect to width of the foun-dation (B) (1B–4B), the number of geotextile layers (1–7 layers), and their spacing (250 mm–1000 mm).FLAC3D is used for the numerical simulation and to carry out nonlinear dynamic analysis in the time domain,and an inelastic constitutive model is used to simulate the behaviour of the structure and the geotextile layersunder seismic loads. Variations in the shear modulus of soil and the corresponding damping ratio with cyclicshear strain are considered using a hysteretic damping algorithm to model the reasonable dissipation of energyin the soil. The interface between the foundation and ground surface, including the material and geometricalnonlinearities, are used to capture any possible slide and uplift in the foundations. The results are presented withregard to the geotextile arrangement considered, and include the tensile force mobilised in the geotextile layers,the response spectra at the bedrock and ground surface, the shear force developed in the structure, the maximumrocking angle of the foundation, permanent foundation settlement, maximum lateral displacement and themaximum and residual inter-storey drifts. The results show that the geotextile layers close to the edges of thefoundation sustained most of the stress induced by foundation rocking, and the geotextile arrangement has asignificant influence on the seismic response of mid-rise buildings. Thus, to satisfy the seismic performance ofbuildings and to optimise the design of foundations reinforced with geotextiles, the stiffness, length, number andspacing of the geotextile layers sh...

Xu, S, Wu, C, Liu, Z & Li, J 2018, 'Numerical study of ultra-high-performance steel fibre–reinforced concrete columns under monotonic push loading', Advances in Structural Engineering, vol. 21, no. 8, pp. 1234-1248.
View/Download from: Publisher's site
View description>>

A finite element model is developed to investigate the behaviour of ultra-high-performance steel fibre–reinforced concrete columns under combined axial compression and horizontal monotonic push loading. The effects of steel fibre content, axial compression ratio, reinforcement ratio (or rebar ratio), stirrup ratio and shear span ratio on the structural behaviour of ultra-high-performance steel fibre–reinforced concrete columns are investigated in detail. The numerical model shows good agreement in bond–slip behaviour of specimens based on CEB model results and numerical results, and such behaviour should be taken into consideration in engineering practice. The results indicate that the developed finite element model could predict the structural behaviour and failure mode of ultra-high-performance steel fibre–reinforced concrete columns effectively. It is found that the reinforcement ratio, axial compression ratio, shear span ratio and volume fraction of steel fibre have a great influence on both the structural behaviour and failure modes of specimens.

Ying, XY, Li, WZ, Kan, Q, Zhang, Z & Ding, G 2018, 'Numerical method for shape optimization of standard floor of the high-rise buildings in hot-summer and cold-winter areas under the low energy consumption target—taking the L-shape as an example', Lowland Technology International, vol. 20, no. 1, pp. 57-64.
View description>>

Shape is an important consideration in building design due to its significant impact on building performance in energy consumption. This paper presents a methodology to program planes using MATLAB language. Three side length factors were proposed as the design variables for L-shaped layouts, and eighteen kinds of L-shaped layouts were generated by changing those variables individually. An energy consumption simulation software (DesignBuilder) was developed to simulate the energy consumption of these layouts of high-rise buildings as experimental models. The correlativity between the width ratio and depth ratio of all experimental models and their energy consumption was examined when deriving the corresponding polynomial function. The main finding of the study suggested that there were certain critical points for both width ratio and depth ratio of the standard floor of high-rise buildings with L-shaped plane, which was 0.4 for width ratio and 0.67 for depth ratio. The energy consumption increased rapidly beyond the critical point, and there was a slight fluctuation at another interval. Further, this paper provided a range of side length ratio in contour plots which showed the variation of energy consumption of L-shape high-rise buildings with width ratio and depth ratio under the weather condition in Hangzhou, China.

Yu, Y, Li, W, Li, J & Nguyen, TN 2018, 'A novel optimised self-learning method for compressive strength prediction of high performance concrete', Construction and Building Materials, vol. 184, pp. 229-247.
View/Download from: Publisher's site
View description>>

© 2018 Elsevier Ltd Concrete strength (CS) is one of the most important performance parameters that are crucial in the design of concrete structure. The reliable prediction of strength can reduce the cost and time in design and avoid the waste of materials caused by a large number of mixture trials. In this study, a novel predictive model is put forward to predict the CS of high performance concrete (HPC) using support vector machine (SVM) approach, which has benefits of nonlinear mapping, high robustness and great generalisation capacity. In the proposed model, the input variables include the contents of water, cement, blast furnace slag, fly ash, super plasticiser, coarse and fine aggregates and curing age, which produces the CS of HPC as the output. In order to improve the model performance, a type of enhanced cat swarm optimisation (ECSO) is adopted to optimise the key parameters of SVM. Finally, the model is trained and evaluated using a total of 1761 data records, which are collected from existing literatures. The results indicate that the proposed SVM-based model exhibits better recognition ability and higher prediction accuracy than other commonly used models, and it can be considered as an effective method to predict the CS property of HPC in infrastructure practice.

Yu, Y, Li, Y, Li, J, Gu, X & Royel, S 2018, 'Nonlinear Characterization of the MRE Isolator Using Binary-Coded Discrete CSO and ELM', International Journal of Structural Stability and Dynamics, vol. 18, no. 08, pp. 1840007-1840007.
View/Download from: Publisher's site
View description>>

Magnetorheological elastomer (MRE) isolator has been proved as a promising semi-active control device for structural vibration control. For its engineering application, developing an accurate and robust model is definitely necessary and also a challenging task. Most of the present models, belonging to parametric models, need to identify various model parameters and sometimes are not capable of perfectly capturing the unique characteristics of the device. In this work, a novel nonparametric model is proposed to characterize the inherent dynamics of the MRE isolator with the features of hysteresis and nonlinearity. Initially, dynamic tests are conducted to evaluate the performance of the isolator under various loading conditions, including harmonic, random, and seismic excitations. Then, on the basis of the captured experimental results, a hybrid learning method is designed to forecast the nonlinear responses of the device with known external inputs. In this method, a type of single hidden layer feed-forward network, called extreme learning machine (ELM), is developed to forecast the nonlinear responses (shear force) of the device with captured velocity, displacement, and current level. To obtain optimal performance of the developed model, an improved binary-coded discrete cat swarm optimization (BCDCSO) method is adopted to select optimal inputs and neuron number in the hidden layer for the network development. The performance of the proposed method is verified through the comparison between experimental results and model predictions. Due to the noise influence in the practical condition, the robustness of the proposed method is also validated via adding noise disturbance into the supplying currents. The results show that the proposed method outperforms the standard ELM in terms of characterization of the MRE isolator, even though the captured responses are polluted with external measurement noises.

Zhang, C-C, Zhu, H-H, Shi, B & Fatahi, B 2018, 'A long term evaluation of circular mat foundations on clay deposits using fractional derivatives', Computers and Geotechnics, vol. 94, pp. 72-82.
View/Download from: Publisher's site
View description>>

© 2017 Elsevier Ltd This study proposes to use fractional derivatives to evaluate the long term performance of circular mat foundations overlying clays and also predict the associated ground settlement. Closed form solutions for the deflection and bending moment of foundations and the subsequent reaction of subgrade are obtained with the Mittag–Leffler function. Numerical examples are used to determine how the fractional order affects the time dependent properties of the foundation and ground settlement, and to simulate the case history of a large standpipe constructed over Tertiary sediments. New insights into design and prediction of shallow foundations and ground settlement are also discussed.

Zhang, L, Chen, Q, Gao, G-Y, Nimbalkar, S & Chiaro, G 2018, 'A New Failure Load Criterion for Large-Diameter Under-Reamed Piles: Practical Perspective', International Journal of Geosynthetics and Ground Engineering, vol. 4, no. 1.
View/Download from: Publisher's site
View description>>

© 2017, Springer International Publishing AG, part of Springer Nature. Sustainable performance of heavy structures such as tanks, storage yards and tall buildings often rely on an efficient transfer of vertical and lateral loads to underlying ground. If the foundation soil does not have sufficient strength, the piles may be belled out (under-reamed) at the base, often termed as large-diameter belled piles (LDBPs). In reality the deformation and failure mechanism of LDBPs are significantly different and are influenced by the nature of foundation soil. However, in the absence of appropriate design guidelines, LDBPs are simply treated as conventional straight piles, often ignoring enlarged base. To access effects of enlarged base on load-deformation behavior, full-scale load tests are conducted on several LDBPs. A novel interpreted failure load criterion is proposed for LDBPs. The general applicability of this criterion is verified using the data from nine independent pile load tests retrieved from four different projects across China. Adopting the proposed method, provision of a much effective and economic design for LDBPs is feasible in comparison with the criteria currently prevalent in practice.

Zheng, J, Li, Y, Hu, M, Wen, J, Wang, J & Kan, J 2018, 'Feasibility study of a miniaturized magnetorhological grease timing trigger as safety and arming device for spinning projectile', Smart Materials and Structures, vol. 27, no. 11, pp. 115030-115030.
View/Download from: Publisher's site
View description>>

Safety and arming (S&A) device is to keep the fuze for projectile unarmed during shipping, handling and storage, while arming the firing section at a proper time via sensing external conditions such as pressure, position, etc. With the increasing need for smaller S&A devices, miniature design with a compact configuration and high reliability is on demand. This paper proposes a miniaturized timing trigger as S&A device for a spinning projectile by utilizing the "locking" and "unlocking" properties of magnetorheological (MR) grease with/without the presence of magnetic field. The design and arming mechanism of the timing trigger are firstly introduced in which the MR grease is locked by a magnetic field generated by two permanent magnets (PMs). Under sufficient firing acceleration, the PMs disengage to unlock the contraction flow of MR grease, which enables its triggering function. A theoretical analysis was conducted to interpolate the delayed time against the geometry of the device, shear/extensional characteristics of MR grease and the spinning rate of a projectile. A series of tests have been conducted to measure the delayed times by tuning the physical parameters, including particle concentration, spinning rate and orifice diameter, etc. The experimental results showed that this theoretical model is capable of well calculating the delayed time of MR grease timing trigger.

Zheng, J, Li, Y, Wang, J, Shiju, E & Li, X 2018, 'Accelerated thermal aging of grease-based magnetorheological fluids and their lifetime prediction', Materials Research Express, vol. 5, no. 8, pp. 085702-085702.
View/Download from: Publisher's site
View description>>

© 2018 IOP Publishing Ltd. In this article, the effect of elevated temperature on the rheological properties of grease-based magnetorheological fluids (G-MRFs) with the focus on long-term storage lifetime has been investigated. These G-MRF samples were subjected to accelerated heat aging process for the estimation of thermal stability and useful lifetime prediction. The well-known Arrhenius-Weibull relationship with a modified Powell-Beal conjugate gradient (CGP) algorithm was employed to model the 'life in service' for the achievement of possible life distribution at different temperature conditions. By defining the failure criteria of G-MRF samples as a maximum reduction of either viscosity or shear stress by more than 10%, the underlying degradation mechanism was revealed through Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analysis. Based on the statistical inference from accelerated life test (ALT), the life expectancy of G-MRF under nominal operating temperature is estimated to be 15.2 years, which outpaces the capability of most industrial applications. Experimental results showed that the performance of shear stress is more likely to degrade under long-term treatment of high temperature in comparison with low temperature. Thus, it is suggested to store the G-MRF at relatively low temperatures for longevity extension and reliability improvement.

Aghayarzadeh, M, Khabbaz, H & Fatahi, B 1970, 'Numerical analysis of concrete piles driving in saturated dense and loose sand deposits', Numerical methods in geotechnical engineering IX, European Conference on Numerical Methods in Geotechnical Engineering, CRC Press, Porto, Portugal, pp. 1031-1038.
View description>>

Many approaches and techniques are used to evaluate pile axial capacity ranging from static methods to dynamic methods, which are based on either the results of pile driving or numerical simulations, which require reliable constitutive models representing the real soil behaviour and the interaction between the pile and soil. In this paper, using PLAXIS software and different constitutive soil models including Mohr-Coulomb, Hardening Soil and Hypoplastic with Intergranular Strain models, the behaviour of concrete piles driven into saturated dense and loose sand deposits under a hammer blow is evaluated. The main objective of this study is to assess the influence of different factors including frequency of loading and Hypoplastic soil model parameters on the recorded velocity and pile head displacement. In addition, the concept of one-dimensional wave propagation induced by pile driving is discussed. It is indicated that using the Intergranular Strain concept, defined in Hypoplastic soil model, small strain behaviour of soil around the pile during driving can directly be captured. The results of this study reveals that considering the Hypoplastic model, incorporating the Intergranular Strain concept, can accumulate much less strains than the corresponding predictions excluding the Intergranular Strain, and hence predict the pile performance during driving more realistically.

Basaglia, B, Shrestha, R, Crews, K & Yokoyama, Y 1970, 'Vibration response of a long-span LVL floor: Comparison between Japanese and Australian assessment measures', WCTE 2018 - World Conference on Timber Engineering, World Conference on Timber Engineering, Seoul, Korea.
View description>>

At present, there is no single conclusive floor vibration assessment standard and different countries follow different procedures and guides. This paper presents a comparison between the Japanese and Australian floor vibration assessment measures and criteria through a case study of a 9-metre span LVL ribbed-deck cassette floor. The assessment measures include the response factor, representative vibration dose value, peak acceleration, vibration level and VLT. The aim of the paper is to identify the reasons behind the differences and to learn about recent research in floor vibration from Japan that may be different from Western practices.

Booth, N, Stuart, B, Thomas, P & Maynard-Casely, H 1970, 'Rheo-ND: Temperature and shear induced crystal transformation of a model triglyceride observed using neutron diffraction', Neutrons and Foods 5, Sydney.

Dadzie, J, Runeson, G & Ding, G 1970, 'Sustainable Technologies as Determinants of Energy Efficient Upgrade of Existing Buildings', 2018 International Conference on Smart Grid and Clean Energy Technologies (ICSGCE), 2018 International Conference on Smart Grid and Clean Energy Technologies (ICSGCE), IEEE, Kajang, Malaysia, pp. 145-149.
View/Download from: Publisher's site
View description>>

© 2018 IEEE. The impact of existing buildings on the environment is increasing. There is the need to realign and focus on achieving true sustainability that considers sustainable upgrade of existing built facilities. Thus a detailed sustainable upgrade (SU) to improve energy efficiency requires critical understanding of all the parameters likely to impact energy savings actions. Sustainable upgrade of existing buildings adopts sustainable technologies (STs) to reduce the impact of high energy consumption and greenhouse gas emissions. The purpose of this paper is to identify the main STs adopted to improve energy performance of existing building. A detailed literature review on the nature and characteristics of SU and the technologies adopted was undertaken as part of the overall methodology. A survey, based on questionnaire with all the STs adopted was administered to professionals in the sustainability industry in Australia. The results from statistical analyses of the survey responses show a total of 21 technologies which are mostly adopted. A factor analysis shows the main components as: Lighting and automation, HAVC, envelope, renewable energy, HVAC equipment, and Passive technologies.

Dang, LC & Khabbaz, MH 1970, 'Assessment of the geotechnical and microstructural characteristics of lime stabilised expansive soil with bagasse ash', the 71st Canadian Geotechnical Conference and the 13th Joint CGS/IAH-CNC Groundwater Conference, the 71st Canadian Geotechnical Conference and the 13th Joint CGS/IAH-CNC Groundwater Conference, Alberta, Canada.
View description>>

Bagasse ash is a readily available waste by-product of the sugar-cane refining industry; its improper disposal can cause adverse environmental impacts. Therefore, bagasse ash is considered in this assessment to investigate the possibility of utilising it as an additive for stabilisation of expansive soils. This study aims to assess the improvement in geotechnical properties of expansive soil stabilised with various contents of bagasse ash and lime. The geotechnical characteristics of stabilised soil were examined through a series of unconfined compressive strength (UCS) tests of untreated and treated soil specimens for various curing periods of 3, 7, 28, and 56 days. A preliminary study on the microstructure development of untreated and treated soils was also conducted using scanning electron microscopy (SEM) technique. The results of the UCS tests reveal that the additions of hydrated lime alone, and combined hydrated lime-bagasse ash improved the compressive strength and the stiffness of stabilised soil remarkably. The significant strength development of lime treated soils with bagasse ash was observed not only at the initial stage of 28 days of curing but also at the subsequent 28 days irrespective of additive content. However, for soil samples treated with hydrated lime alone, the predominant strength gain was obtained at the initial stage of 28 days of curing. Subsequently, the compressive strength remained almost constant when curing time exceeded 28 days. The outcomes of the SEM analysis indicate the change in microstructure of the stabilised soils and the formation of new cementitious compounds of Calcium-Silicate-Hydrate (C-S-H). The findings of this study reveal that the application of hydrated lime and bagasse ash combination, as reinforcing construction materials, enhances the geotechnical properties of expansive soil. Using bagasse ash combined with lime can address the coming environmental impacts of bagasse ash disposal, while providing c...

Dang, LC, Khabbaz, H & Fatahi, B 1970, 'Evaluation of Swelling Behaviour and Soil Water Characteristic Curve of Bagasse Fibre and Lime Stabilised Expansive Soil', PanAm Unsaturated Soils 2017, Second Pan-American Conference on Unsaturated Soils, American Society of Civil Engineers, Dallas, Texas, pp. 58-70.
View/Download from: Publisher's site
View description>>

© 2018 American Society of Civil Engineers (ASCE). All rights reserved. This paper presents an experimental investigation on the enhancement of swelling behaviour and soil water characteristic curve (SWCC) of bagasse fibre and lime stabilised expansive soil. Lime stabilisation is commonly used to improve the engineering properties of expansive soil. Bagasse fibre, an industrial waste by-product left after crushing of sugarcane for juice extraction, was used in this study as reinforcing component in combination of lime for expansive soil stabilisation. The expansive soil used in this investigation was collected from Queensland, Australia. In order to investigate the influences of combination of bagasse fibres and lime on the engineering behaviour of unsaturated expansive soil, a variety of stabilised soil samples were prepared by changing proportions of randomly distributed bagasse fibres combined with different lime contents. An array of experimental tests was performed including free swell potential, swelling pressure, and one-dimensional consolidation tests. Soil suction tests were conducted using the contact filter paper technique on natural and stabilised expansive soil samples. The results revealed that lime-bagasse fibre treatment of expansive clay has a significant effect on swelling behaviour and SWCC response of treated soils. Combination of hydrated lime and bagasse fibre resulted in more improvement on swelling behaviour of soil samples when compared to that treated with lime only. The air entry value of stabilised expansive soil increased with an increase in the stabiliser content.

Dong, Y, Fatahi, B, Khabbaz, H & Kamruzzaman, AHM 1970, 'Investigating Effects of Particle Scaling for Cavity Expansion Simulation Using Discrete Element Method', PROCEEDINGS OF GEOSHANGHAI 2018 INTERNATIONAL CONFERENCE: FUNDAMENTALS OF SOIL BEHAVIOURS, GeoShanghai International Conference on Fundamentals of Soil Behaviours, Springer Singapore, Tongji Univ, Shanghai, PEOPLES R CHINA, pp. 938-946.
View/Download from: Publisher's site

Hasan, H, Khabbaz, H & Fatahi, B 1970, 'Strength Property of Expansive Soils Treated with Bagasse Ash and Lime', ADVANCES IN CHARACTERIZATION AND ANALYSIS OF EXPANSIVE SOILS AND ROCKS, 1st GeoMEast International Congress and Exhibition on Sustainable Civil Infrastructures, Springer International Publishing, EGYPT, pp. 24-35.
View/Download from: Publisher's site

Hoang, VT, Phung, MD & Ha, QP 1970, 'Adaptive twisting sliding mode control for quadrotor unmanned aerial vehicles', Proceedings of the 2017 Asian Control Conference, ASCC 2017, Asian Control Conference, IEEE, Gold Coast, QLD, Australia, pp. 671-676.
View/Download from: Publisher's site
View description>>

This work addresses the problem of robust attitude control of quadcopters.First, the mathematical model of the quadcopter is derived considering factorssuch as nonlinearity, external disturbances, uncertain dynamics and strongcoupling. An adaptive twisting sliding mode control algorithm is then developedwith the objective of controlling the quadcopter to track desired attitudesunder various conditions. For this, the twisting sliding mode control law ismodified with a proposed gain adaptation scheme to improve the controltransient and tracking performance. Extensive simulation studies andcomparisons with experimental data have been carried out for a Solo quadcopter.The results show that the proposed control scheme can achieve strong robustnessagainst disturbances while is adaptable to parametric variations.

Hoang, VT, Phung, MD, Dinh, TH & Ha, QP 1970, 'Angle-Encoded Swarm Optimization for UAV Formation Path Planning', 2018 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2018 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), IEEE, Madrid, Spain, pp. 5239-5244.
View/Download from: Publisher's site
View description>>

© 2018 IEEE. This paper presents a novel and feasible path planning technique for a group of unmanned aerial vehicles (DAVs) conducting surface inspection of infrastructure. The ultimate goal is to minimise the travel distance of DAVs while simultaneously avoid obstacles, and maintain altitude constraints as well as the shape of the UAV formation. A multiple-objective optimisation algorithm, called the Angle-encoded Particle Swarm Optimization (θ- PSO) algorithm, is proposed to accelerate the swarm convergence with angular velocity and position being used for the location of particles. The whole formation is modelled as a virtual rigid body and controlled to maintain a desired geometric shape among the paths created while the centroid of the group follows a pre-determined trajectory. Based on the testbed of 3DR Solo drones equipped with a proprietary Mission Planner, and the Internet-of- Things (loT) for multi-directional transmission and reception of data between the DAV s, extensive experiments have been conducted for triangular formation maintenance along a monorail bridge. The results obtained confirm the feasibility and effectiveness of the proposed approach.

Indraratna, B, Ngo, NT, Nimbalkar, S & Rujikiatkamjorn, C 1970, 'Two Decades of Advancement in Process Simulation Testing of Ballast Strength, Deformation, and Degradation', ASTM Special Technical Publication, Symposium on Railroad Ballast Testing and Properties, ASTM International100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, New Orleans, LA, pp. 11-38.
View/Download from: Publisher's site
View description>>

This paper describes salient features of a set of large-scale ballast testing equipment developed at the University of Wollongong, Australia, and how the test results and research outcomes have contributed to transforming tracks in the Australian heavy haul and commuter networks, particularly with regards to the strength, deformation, and degradation of ballast. Ideally, ballast assemblies should be tested in prototype scale under actual loading conditions. This is because a reduction in particle sizes for testing in smaller equipment can reduce the internal angle of friction (shearing resistance) of the granular assembly in a macro sense, and the angularity of the particles in a micro sense, and hence the volumetric changes during the shearing process. In response to the worldwide lack of proper test facilities for ballast, the University of Wollongong has, since the early 1990s, designed and built a number of large-scale process simulation triaxial testing rigs. They are all custom made to minimize any boundary effects and also to evaluate the deformation and degradation of ballast, particularly the size, shape, and origin of aggregates used as ballast in Australian tracks. This triaxial process simulation equipment was originally used to characterize the behavior of coarse aggregate used for state railway standards for monotonic loading, but since then it has been fitted with dynamic actuators to simulate actual track conditions involving the true cyclic loading nature while also capturing the wheel-rail dynamics that correspond to high-speed commuter rail and fast heavy-haul operations. These tests invariably demonstrated completely different stress–strain and volumetric characteristics of ballast compared to conventional static or monotonic testing of the same test specimens.

Maynard-Casely, H, Stuart, B, Thomas, P & Booth, N 1970, 'Rheo-ND: Temperature and shear induced crystal transformation of a model triglyceride observed using neutron diffraction', 2018 ANBUG-AINSE Neutron Scattering Symposium, Sydney.

Nguyen, TLH, Shrestha, R & Crews, K 1970, 'How the choice of building materials affects the environmental burdens in non-residential and multistorey residential building construction?', WCTE 2018 - World Conference on Timber Engineering, World Conference on Timber Engineering, WCTE, Seoul, Korea.
View description>>

Concrete and steel are the predominant building materials in non-residential and multi-storey residential building construction. However, with the advances in engineered wood products and environmental benefits of using timber in construction, there is an increased interest of using timber in non-residential and multi-storey residential projects in the last few years. This paper presents detailed case studies of two recently constructed buildings and investigates how the choice of building material in non-residential and multi-storey residential building construction affects the environmental burdens such as embodied energy, operational energy consumption and associated carbon dioxide (CO 2 ) emissions, which in turn can have an influence on the decision-making process for the choice of the building materials.

Nsiah-Baafi, E, Vessalas, K, Thomas, P & Sirivivatnanon, V 1970, 'Mitigating alkali silica reactions in the absence of scms: A review of empirical studies', fib Symposium, The International Federation for Structural Concrete 5th International fib Congress, Melbourne, pp. 3829-3844.
View description>>

The mechanism and severity of alkali-silica reaction (ASR) is subjective to the conditions of the availability of moisture and sufficient alkali content, and the presence of reactive aggregates. Since the 1940s, key focus has been placed on the reduction of alkali content by way of addition of supplementary cementitious materials (SCMs). However, the cost of SCMs and the realization that the availability of these materials could become limited in the untold future has influenced some researchers to investigate the development of protocols for the use of aggregates minimizing the likelihood of potential severe ASR. This paper presents a summary and review of the various strategies that have been adopted in recent years for the mitigation of ASR without utilising the addition of SCMs.

Roboredo, C, Thomas, P, Vessalas, K & Sirivivatnanon, V 1970, 'Alkali limit in cement with supplementary cementing materials - A review', fib Symposium, The International Federation for Structural Concrete 5th International fib Congress, Melbourne, pp. 3702-3708.
View description>>

The alkali silica reaction (ASR) may cause deleterious cracking in concretes as a result of the reactions of reactive aggregates in concrete systems that contain elevated alkali contents. Current strategies applied in the mitigation of ASR are based on limiting the alkali content (Na2Oe) of the cement and concrete and through the screening of aggregates with additional surety provided by the use of supplementary cementitious materials (SCMs) in the partial replacement of cement. These strategies pose significant issues for the construction materials industry through increased manufacturing costs and reduction in volumes of viable raw materials that meet the imposed criteria. The effective mitigation of deleterious ASR using SCMs should change the focus of regulators and standards authorities to risk management through the assessment of the risk profile of a concrete mix in a particular application. Using a risk profile to assess alkali limits has the potential to relax alkali limits in cements. To achieve this aim a deep understanding of ASR in cement-SCM-aggregate concrete mixes is required through laboratory testing correlated with long-term field performance. This paper reviews ASR, reactivity assessment of aggregates and the role of SCMs in ASR mitigation and proposes a change in the focus to a balanced alkali limit based on assessed risk for the occurrence of deleterious ASR.

Royel, S, Ha, QP & Aguilera, RP 1970, 'Frequency-Shaped Second-Order Sliding Mode Control for Smart Suspension Systems', 2018 15th International Conference on Control, Automation, Robotics and Vision (ICARCV), 2018 15th International Conference on Control, Automation, Robotics and Vision (ICARCV), IEEE, Singapore, Singapore, pp. 907-912.
View/Download from: Publisher's site
View description>>

© 2018 IEEE. Design of a frequency-shaped second-order sliding mode (FS2SM) controller is demonstrated by means of exploiting second-order low-pass filter (LPF) to model the dynamic sliding surface to shape the frequency characteristics of the equivalent dynamics. The proposed technique is numerically verified in the simulation of a half-car model (HCM) with inbuilt active hydraulically interconnected suspension (HIS) system. The closed-loop performances confirm that inclusion of an appropriate filter in the control scheme allows not only to reduce the roll angle but also its spectrum can be shaped.

Sanchez Roboredo, C, Thomas, P, Vessalas, K & Sirivivatnanon, V 1970, 'Advantages of Using High Alkali Cements and Industrial Waste Materials in Prevention of Alkali-silica Reaction in Concrete', Advancing Materials and Manufacturing CAMS2018 conference, Advancing Materials and Manufacturing CAMS2018 conference, University of Wollongong.

Shakor, P, Nejadi, S & Paul, G 1970, 'An investigation into the behaviour of cementitious mortar in the construction of 3D printed members by the means of extrusion printing', 1st International Conference on 3D Construction Printing, Melbourne, Australia.

Shakor, P, Nejadi, S, Paul, G & Sanjayan, J 1970, 'A Novel Methodology of Powder-based Cementitious Materials in 3D Inkjet Printing for Construction Applications', 6th International Conference on Durability of Concrete Structures, ICDCS 2018, Sixth International Conference on Durability of Concrete Structures, Whittles Publishing, University of Leeds, Leeds, West Yorkshire, LS2 9JT, United Kingdom, pp. 685-695.
View description>>

Recently, additive manufacturing techniques such as 3D printing are becoming increasingly popular and widely used in a variety of applications. Inkjet 3D printing (i.e. powder-based printing) is one of the most reliable frequently-implemented techniques in 3D printers. This paper discusses a novel methodology to replace the currently used typical powders in 3D printing to make it possible to use the printed specimens in construction applications. The printed cubic (20?20?20mm) and prism (60?5?5mm) specimens with different saturation levels are printed to investigate the relative strength of the 3D printed specimens. Curing in different saturation environments can increase their strength and durability. In general, the experimental results show that the highest compressive strength was recorded (14.68MPa) for the samples that are first cured in water then dried in an oven for one hour at 40°C, comparing to the samples that are cured without drying at 40°C (4.81MPa). Accordingly, it has been discovered that the post-processing technique has an effective and significant impact on the strength of the printed specimens. Furthermore, samples which are cast using manual mixing have been also been compared in detail.

Singh, AM, Phung, MD & Ha, QP 1970, 'Modelling and Fast Terminal Sliding Mode Control for Mirror-based Pointing Systems', 2018 15th International Conference on Control, Automation, Robotics and Vision (ICARCV), 2018 15th International Conference on Control, Automation, Robotics and Vision (ICARCV), IEEE, Singapore, pp. 1158-1163.
View/Download from: Publisher's site
View description>>

© 2018 IEEE. In this paper, we present a new discrete-time Fast Terminal Sliding Mode (FTSM) controller for mirror-based pointing systems. We first derive the decoupled model of those systems and then estimate the parameters using a nonlinear least-square identification method. Based on the derived model, we design a FTSM sliding manifold in the continuous domain. We then exploit the Euler discretization on the designed FTSM sliding surfaces to synthesize a discrete-time controller. Furthermore, we improve the transient dynamics of the sliding surface by adding a linear term. Finally, we prove the stability of the proposed controller based on the Sarpturk reaching condition. Extensive simulations, followed by comparisons with the Terminal Sliding Mode (TSM) and Model Predictive Control (MPC) have been carried out to evaluate the effectiveness of the proposed approach. A comparative study with data obtained from a real-time experiment was also conducted. The results indicate the advantage of the proposed method over the other techniques.

Stuart, B, Thomas, P, Barrett, M & Head, K 1970, 'A spectroscopic investigation of sculptural modelling clay materials for conservation purposes', 13th Infrared and Raman Users Group Conference, Sydney.

Thomas, P 1970, 'Water in Opal', 9th National Opal Symposium, Lightning Ridge, NSW, Australia.
View description>>

Precious opal is a hydrous silica (SiO2.nH2O) and contains anywhere between 2 and 18% by mass water. Australian opal – AG contains circa 5.5 to 8.5% water with an average of 6.9% water while the water content of opal – CT derived from a range of sources from Australia and internationally is more variable and depends on the porosity of the opal.The water contained in opal is of two general types; silanol or bound water (Si–OH) and molecular water (H2O). The silanol water can be found internally in the opal as well as on the surface. Internal silanol water is related to Si-O-Si linkages breaks, but they may also be associated with internal surfaces of capillary pores in the opal structure. The molecular water can be found trapped in the 3D superstructure of the silica network (hence the designation – AG or amorphous-gel like), in cavities or voids present between the spheres and in capillary pores. In Australian opal – AG, the molecular water is present trapped in the silica superstructure and in the voids between contacting silica spheres, although there is also some evidence of large capillary pore water. For opal – CT the picture is more complex and depends on the origin of the opal. Mexican, Ethiopian and Australian Tintenbar opal are all of the CT type and contain capillary pores in the smaller end of the scale. These pores contain much of the molecular water although there remains significant portion of the water trapped in the silica superstructure. In opal – CT, the capillary pores are often interconnected and are exposed to the surface as is demonstrated by the absorbent Ethiopian hydrophane opals where water is easily lost or absorbed. Given the variety of water types in opal, this presentation discusses the states of water with in opal – AG and – CT and then speculates on the role that water and microstructure has on the physical properties of opal.

Vahedian, A, Shrestha, R & Crews, K 1970, 'Timber type effect on bond strength of frp externally bonded timber', WCTE 2018 - World Conference on Timber Engineering, World Conference on Timber Engineering, Seoul, Korea.
View description>>

The performance of FRP composite bonded externally to timber is complex and limited attempts have been made to-date to investigate the bond behaviour of the FRP to timber interface. Furthermore, analytical solutions to determine the interface behaviour of FRP to timber have not been fully investigated and are not covered in current standards. This study investigates the influence of timber type and timber mechanical properties on the bond strength of FRP-to-timber joints. Two different types of timber (LVL and hardwood) have been used and results of experimental tests showed that with the increase of timber tensile strength and modulus of elasticity, the interfacial bond strength increases; however, the failure mode can be brittle. Specimens made from LVL exhibited more ductile behaviour failing gradually; while joints made from hardwood failed suddenly in a brittle manner. It was also observed that the local slip between FRP and timber was higher for joints fabricated from LVL compared to hardwood. Therefore, to achieve a satisfactory bonded joint, the effectiveness of timber mechanical properties is required to be accurately considered.

Vahedian, A, Shrestha, R & Crews, K 1970, 'Width effect of FRP externally bonded to timber', 9th International Conference on Fibre-Reinforced Polymer (FRP) Composites in Civil Engineering, CICE 2018, 9th International Conference on Fibre-Reinforced Polymer (FRP) Composites in Civil Engineering (CICE 2018), Paris, pp. 558-565.
View description>>

Bond mechanism between timber and fibre reinforced polymer (FRP) composites is affected by a number of variables. However, effect of parameters such as bond width, bond length, material properties and geometries on the bond strength is not fully understood. This study investigates the influence of bond width on the bond strength and failure mode of externally bonded FRP-to-timber interface. Pull-out tests on 136 FRP-to-timber joints with different FRP widths were conducted. Results of experimental tests showed that the bond width has significant effect on the bond strength; with the increase of FRP width, the interfacial bond strength increases. In addition, it was observed that the maximum shear stress decreases with the increase of FRP-to-timber width ratio. Furthermore, FRP-to-timber width ratio impacts on the local bond-slip in which slip of the bond reduces when this ratio is increased.

Xu, R & Fatahi, B 1970, 'Effects of Pile Group Configuration on the Seismic Response of Buildings Considering Soil-Pile-Structure Interaction', PROCEEDINGS OF GEOSHANGHAI 2018 INTERNATIONAL CONFERENCE: ADVANCES IN SOIL DYNAMICS AND FOUNDATION ENGINEERING, International Conference: Advances in Soil Dynamics and Foundation Engineering, Springer Singapore, Tongji Univ, Shanghai, PEOPLES R CHINA, pp. 279-287.
View/Download from: Publisher's site
View description>>

Mid-rise buildings supported by different configurations of end-bearing pile foundations can fulfil the design requirements addressed in the modern building codes and selecting the most efficient configuration is a challenging task. In this study, the influence of group configuration (but keep the area replacement ratio constant) on the seismic response of mid-rise buildings resting on end-bearing pile foundations considering seismic soil-pile-structure interaction (SSPSI) is investigated. A soil-pile-structure system is simulated in FLAC3D to carry out the fully nonlinear seismic analysis in the time domain. The elastic-perfectly plastic structural behaviour is considered while the variation of soil shear modulus due to cyclic shear strain and the corresponding damping ratio is simulated adopting hysteretic damping algorithm, and the soil plastic behaviour is modelled using Mohr-Coulomb criterion. The results of the seismic pile responses, namely the envelopes of shear forces and bending moments along the piles and the lateral pile displacements, and the building responses including the base shear, and the lateral building displacements are reported and discussed. It is observed that for the cases analysed, the pile group configuration influences the seismic response of the system. Provided that the same volume of concrete (i.e. constant area replacement ratio) is used for all cases, by increasing the number of piles but with smaller diameters, more seismic loads may be attracted to the system due to the kinematic interaction between the piles and the surrounding soil and consequently causing the increase in the base shear and lateral displacements of the building.

Xu, ZM, Thomas, P, Jones-Amin, H & Stuart, B 1970, 'A spectroscopic investigation of Paraloid blends for use as archaeological adhesives', 13th Infrared and Raman Users Group Conference, Sydney.

Yeganeh, N & Fatahi, B 1970, 'Seasonal Effects on Seismic Performance of High Rise Buildings Considering Soil-Structure Interaction', 16th European Conference on Earthquake Engineering, 16th European Conference on Earthquake Engineering, Thessaloniki, Greece.
View description>>

The Seismic Soil-Structure Interaction (SSSI), which is a tangled phenomenon, is concerned with the shear waves in preference to the longitudinal waves on account of a prevalent greater energy content in the former. The need for the high rise buildings in the megalopolises results in the paramountcy of the seismic soil-foundation-building interaction analysis in order to achieve the reliable predictions and mayhap curtail the severe damage and probable partial or total collapse of the superstructures. The seasonal effects could influence the soil moisture content particularly in the vadose zone near the surface, exacerbated by the climate change effects, inducing more frequent floods and drought. Wherefore, a soil-structure model was evaluated in this study, subjected to the soil moisture variations in the vadose zone, by utilizing the 3D finite difference modeling technique through the fully nonlinear dynamic analysis in the time domain considering SSSI during the 1994 Northridge earthquake. In particular, the objective was probing the possible effects of the selected degree of saturation (Sr) values, i.e., 5%, 17.5%, 60%, and 100%, for the noncohesive soil, named “Glacier Way Silt”, in conjunction with the small-strain shear moduli on the seismic performance and its corresponding damage of a 20-story reinforced concrete moment-resisting building frame. It is of note that the said values of Sr were employed for the common 4-m zone of influence in Australia, being a sequel of the natural and artificial wetting-drying cycles. Get to the point, it was concluded that the season, in which an earthquake befalls, is stark prominent insomuch as it is potent to impact the extend of the damage in a superstructure.

Zhang, X, Fatahi, B & Khabbaz, H 1970, 'Investigating Effects of Fracture Aperture and Orientation on the Behaviour of Weak Rock Using Discrete Element Method', Proceedings of GeoShanghai 2018 International Conference: Rock Mechanics and Rock Engineering, GeoShanghai International Conferences, Springer Singapore, Shanghai, pp. 74-81.
View/Download from: Publisher's site
View description>>

The effects of the fracture aperture and orientation on the behaviour of weak rock were numerically investigated using discrete element method (DEM). In this study, the mechanical behaviour of the intact and fractured rock specimens was simulated by adopting the discontinuum based software PFC3D. The rock specimens with various fracture apertures and orientations were replicated, and the effects of these two fracture characteristics were studied through triaxial tests. The flat-joint model was employed for simulating the stress-strain behaviour of intact rock and had the ability to reproduce the cementation effect. The smooth-joint contact model was utilised to simulate the sliding effect of the fractures. The effects of five different fracture orientations were investigated in the combination of three different fracture aperture categories, namely very tight, open, and moderately wide. It can be concluded that the strength of the fractured weak rock specimens reduces as the fracture aperture width increases. The amount of alternation in strength and deformability that were contributed by fracture apertures differed with the orientations of the fracture. With the fracture orientation that was parallel to the deviatoric loading, the effect of fracture aperture on the strength and deformability of the specimens was less evident.

Zhu, Q, Dinh, TH, Hoang, VT, Phung, MD & Ha, QP 1970, 'Crack detection using enhanced thresholding on UAV based collected images', Australasian Conference on Robotics and Automation, ACRA.
View description>>

This paper proposes a thresholding approach for crack detection in an unmanned aerial vehicle (UAV) based infrastructure inspection system. The proposed algorithm performs recursively on the intensity histogram of UAV-taken images to exploit their crack-pixels appearing at the low intensity interval. A quantified criterion of interclass contrast is proposed and employed as an object cost and stop condition for the recursive process. Experiments on different datasets show that our algorithm outperforms different segmentation approaches to accurately extract crack features of some commercial buildings.

Fatahi, B 2018, 'Sustainable Design and Construction for Geomaterials and Geostructures', Springer.
View/Download from: Publisher's site
View description>>

"This book presents recent research findings and critically reviews the existing literature related to assessment of geotechnical structures under complex and extreme loading conditions such as cyclic, seismic and blast loads.