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Item Open Access Analytical approach to quantify the pull-out behaviour of hooked end steel fibres(Informa UK, 2024) Bashar, I.I.; Sturm, A.B.; Visintin, P.; Sheikh, A.H.An analytical modelling approach is developed in this article to simulate the pull-out behaviour of a single straight/hooked end fibre that is embedded in concrete matrix. The partialinteraction model is used to simulate the interfacial bond between the fibre and matrix along the entire fibre length throughout all stages of loading where additional axial and frictional forces due to straightening a hook is incorporated by simulating it as plastic hinges at the apex of bends. The analytical model is presented in a concise matrix form that helps to minimise the number of solution steps for the involved individual cases and provides a monolithic simplified implementation. A significant advantage of the approach is that it does not require fitting of a smoothing polynomial to show the full-range of fibre load-slip behaviour as it simulates the forces for straightening the fibre as it pulls through a bend and directly couples this to the interfacial bond forces.Item Open Access Python program for spatial reduction and reconstruction method in flood inundation modelling(Elsevier BV, 2021) Zhou, Y.; Wu, W.; Nathan, R.; Wang, Q.J.Fast and accurate modelling of flood inundation has gained increasing attention in recent years. One approach gaining popularity recently is the development of emulation models using data driven methods, such as artificial neural networks. These emulation models are often developed to model flood depth for each grid cell in the modelling domain in order to maintain accurate spatial representation of the flood inundation surface. This leads to redundancy in modelling, as well as difficulties in achieving good model performance across floodplains where there are limited data available. In this paper, a spatial reduction and reconstruction (SRR) method is developed to (1) identify representative locations within the model domain where water levels can be used to represent flood inundation surface using deep learning models; and (2) reconstruct the flood inundation surface based on water levels simulated at these representative locations. The SRR method is part of the SRR-Deep-Learning framework for flood inundation modelling and therefore, it needs to be used together with data driven models. The SRR method is programmed using the Python programming language and is freely available from https: //github.com/yuerongz/SRR-method.Item Open Access Evaluating stochastic rainfall models for hydrological modelling(Elsevier BV, 2023) Nguyen, T.H.T.; Bennett, B.; Leonard, M.Stochastic rainfall models are important tools for evaluating hydrological risks such as flooding and drought because of their ability to randomly generate alternative plausible climatic timeseries. The stochastic generation of climatic timeseries is not an end in itself, since they are typically applied to a catchment to determine the performance of water-related infrastructure systems, such as reservoirs or flood-control measures. This methodology typically involves a train of models to determine the end-of-system impact, yet the evaluation of stochastically generated rainfall timeseries is usually a stand-alone procedure focused on metrics directly related to the stochastic generator. This paper demonstrates discrepancies in this approach by evaluating two, dailytimestep, stochastic rainfall models in terms of rainfall metrics and their subsequently generated flow metrics after rainfall-runoff transformation. The two models are a Markov-based model and a latent-variable model, where each model is calibrated and evaluated showing ‘overall good’ performance. Stochastically generated timeseries, alongside observed rainfall timeseries are inputted to a calibrated catchment model (GR4J) to derive daily flow timeseries. Whereas the rainfall metrics typically showed ‘good’ performance, streamflow-based metrics are not necessarily ‘good’. The procedure is repeated for 277 stations from Australia and 106 stations from the United States of America. Depending on the strictness of the flow-based comparison and region analysed, using the Markov-based model 12–26% of sites were classified as ‘poor’ performing, and 1%-9% of sites were classified as ‘poor’ using the latent-variable model. The results demonstrate that catchment-based performance of flow metrics is more holistic since it magnifies features of the rainfall not otherwise visible to rainfall-based evaluation.Item Metadata only Review of near-surface mounted FRP plates in the strengthening of continuous flexural members and bond behaviour(Taylor & Francis, 2018) Gravina, R.; Aydin, H.; Visintin, P.Bonding carbon fibre-reinforced polymers (FRP) to reinforced concrete (RC) flexural members has become a popular means to enhance load carrying capacity and prolong service life. Considering the type of FRP strengthening system, the near-surface mounting (NSM) technique of embedding FRP strips in saw-cut grooves within the concrete cover of RC members to flexurally strengthen beams and slabs is known to have desirable bond behaviour benefits over external bonded FRP plates. Further the NSM technique has attracted growing attention in strengthening of statically indeterminate RC members. However, little is known about the durability of the critical bond between the embedded FRP and the concrete when installed using this technique. In this paper, experimental results of continuous flexural members strengthened with NSM FRP is collated and reviewed to investigate failure modes, ductility and moment redistribution capability. Ductility and moment redistribution characteristics of strengthened RC members relies on the bond performance of reinforcement to concrete and hence this paper also reviews durability testing of NSM joints. Regression analysis shows that concrete compressive strength and steel reinforcement ratios are paramount to maintaining ductility under all strengthening schemes.Item Metadata only Basic and drying creep of ultra-high performance concrete(Taylor and Francis, 2025) Sun, M.; Visintin, P.; Bennett, T.Experimental observations of the creep behaviour of ultra-high performance concrete (UHPC) are limited, with existing studies all performed on material designs including fibres. This limits the understanding of the underlying behaviour of the cementitious material, including the relative contributions of basic and drying creep. An experimental study of the basic and drying creep was performed on UHPC samples subjected to two different loads for the duration of a year, with two different sample sizes considered. It is demonstrated that there is little difference in magnitude between basic and drying creep, indicating that basic creep is the governing mechanism. The existing creep model in the fib model code 2010 is examined and recalibrated for UHPC.Item Metadata only TALKS: A systematic framework for resolving model-data discrepancies(Elsevier BV, 2023) Vilas, M.P.; Egger, F.; Adams, M.P.; Maier, H.R.; Robson, B.; Mestres, J.F.; Stewart, L.; Maxwell, P.; O'Brien, K.R.Models and data play an important role in informing decision-making in environmental systems, providing different and complementary information. Multiple frameworks have been developed to address model limitations and there is a large body of research focused on improving the quality of data. However, when models and data disagree the focus is usually on fixing the model, rather than the data. In this study, we introduce the framework TALKS (Trigger, Articulate, List, Knowledge elicitation, Solve) as a way of resolving model-data discrepancies. The framework emphasises that a mismatch between data and model outputs could be due to issues in the model, the data or both. Through three case studies, we exemplify how models can be used to identify and improve issues with the data, and hence make the most out of models and data. The framework can be applied more broadly to better integrate models and data in environmental decision making.Item Open Access A robust computational strategy for failure prediction of masonry structures using an improved multi‐surface damage‐plastic based interface model(Wiley, 2023) Nie, Y.; Sheikh, A.; Visintin, P.; Griffith, M.In this study, a new traction-separation based constitutive model for use in finite element simulation of masonry joints under complex loading conditions is developed for cohesive elements. The proposed model is formulated using damage parameters and plastic deformation with mutual couplings, and can accurately simulate the complex nonlinear behaviors of masonry joints considering hardening or softening of strength and stiffness degradation. To enhance the numerical stability of the model, plasticity and damage are separated algorithmically and implemented in two phases. In the first phase, the plastic deformations are treated using a multi-surface plasticity model composed of a smooth hyperbolic yield surface for tension-shear mixed-mode failure and an elliptical cap primarily for the compressive failure. This is implemented in effective stress space and helps restrict the evolution of yield surfaces with no softening, significantly enhancing the efficiency of stress return mapping by the closed point projection method. In addition, an adaptive sub-stepping scheme is adopted to further improve the robustness of the numerical implementation. In the second phase, nominal stresses are computed from the effective stresses using damage parameters. The evolution of these damage parameters is defined in terms of plastic work which is defined by a polynomial form, and is recommended in this study for a better calibration capability. Improvements are made in the formulation of compressive cap including incorporation of hardening of strength and stiffness degradations as these are ignored in existing interface models. This approach helped improve simulation of masonry under cyclic loads with tension-compression transitions. For the structural level applications, the interface model is implemented within a finite element program, which is utilized to simulate failure of a number of masonry specimens under in-plane/out-of-plane monotonic/cyclic loading. The simulated results are rigorously validated with existing experimental data that shows a good potential in modeling masonry structures.Item Metadata only Shear strength of RC beams without web reinforcement(Taylor & Francis, 2016) Zhang, T.; Visintin, P.; Oehlers, D.J.Due to the complexities of the mechanics of shear failure in reinforced concrete (RC) members, most current approaches for predicting shear strength are mainly empirical. Being empirical, these approaches do not physically explain the shear failure mechanism seen in practice and consequently should only be used within the bounds of the testing regimes from which they were derived; this restricts their application to innovative materials such as fibre-reinforced polymer RC beams or those with high-performance concrete. In this paper, a numerical mechanicsbased segmental approach for the shear failure of RC beams with any type of reinforcement and concrete is developed; from the mechanics of the segmental approach, simplifications are made to develop closed form solutions and the resulting design equations are compared to a database of 626 steel-reinforced specimens. Further comparisons to the predictions made by the ACI, AS 3600 and FIB Model Code 2010 approaches show that the proposed approach offers improved accuracy and a reduction in scatter.Item Open Access Meso to macro connections to capture fatigue damage in cemented materials(Elsevier, 2023) Le, V.T.; Bui, H.H.; Nguyen, G.D.; Kodikara, J.; Bodin, D.; Grenfell, J.Fatigue-induced damage is a common issue in cemented materials, involving the progressive formation and complicated propagation of fatigue cracks. These cracks typically localise on weak or fracture planes, leading to inhomogeneous deformation within the material. Thus, accurately predicting the fatigue phenomenon becomes challenging due to the material’s inhomogeneity and the complex evolution of cracks, from initiation to propagation and eventual failure. To address this challenge, this paper presents a constitutive model that accounts for strain discontinuity across fracture planes by employing kinematic enrichment. This enhancement facilitates interaction between the material responses of cracks and the outer bulk, thereby contributing to the overall macro behaviour of the materials. Moreover, the proposed model incorporates a new cohesive-frictional fatigue model that couples damage mechanics and bounding surface plasticity to describe the fatigue behaviour of fracture planes/cracks. Since the proposed model features a characteristic length scale, it exhibits size-dependent behaviour and helps overcome the issue of mesh dependence. The model’s validity is demonstrated through its ability to capture nonlinear fatigue damage under constant/variable cyclic loading and to simulate the propagation of fatigue fracture process zones. Furthermore, the model effectively captures the significant influence of stress amplitudes on the fatigue lives of materials, making it an essential tool for predicting and mitigating fatigue-induced damage in cemented materials.Item Open Access Guided wave-based characterisation of cracks in pipes utilising approximate Bayesian computation(Elsevier, 2023) Zeng, Z.; Gao, M.; Ng, C.T.; Sheikh, A.H.This paper proposed a probabilistic framework of damage characterisation to detect and identify early-state cracks in pipe-like structures using ultrasonic guided waves. The crack location, crack sizes (e.g., depth and width of the crack), and Young’s modulus are considered as unknown parameters in the model updating using a Bayesian approach, by which their values and the associated uncertainties are quantified. The proposed framework is developed based on approximate Bayesian computation (ABC) by subset simulation, which is a likelihood-free Bayesian approach. This algorithm estimates the posterior distributions of unknown parameters by directly accessing the similarity between the measured signals from experiments and the simulated guided wave (GW) signals from the numerical model. In this case, the evaluation of likelihood functions can be smartly circumvented during Bayesian inference. A time-domain spectral finite element (SFE) method with a cracked finite element model is employed to model the pipes to enhance the computational efficiency of the simulation and model updating. Numerical and experimental case studies are carried out to evaluate the performance of the proposed likelihood-free approach. Numerical results show the accuracy and robustness of the proposed approach in identifying unknown parameters under different scenarios. The associated uncertainties of each parameter are also quantified by analysing the statistical properties of the sample set, such as mean and coefficient of variation (COV) values. Experimental results show that the proposed method can accurately identify the unknown parameters, which further verifies the accuracy and practicability of the probabilistic damage characterisation framework.Item Open Access Analysis of crack closure and wake of plasticity with the distributed dislocation technique(Elsevier, 2023) Vidler, J.; Kotousov, A.; Ng, C.T.A new method for the analysis of plasticity-induced closure of finite cracks is developed based on the distributed dislocation technique. The method is applied to analyse closure and opening processes for an embedded fatigue crack propagating under constant amplitude cyclic loading. The obtained solution and presented results can serve as a benchmark for numerical procedures utilising the same yield-strip methodology. Comparison with past numerical studies reveals similar trends, though there are some differences in the crack tip opening values, particularly for low and negative R-ratios. The latter may indicate the need for a better approach to the discretisation of the contact, direct and reverse plasticity zones in the numerical procedures which utilise the same methodology. The developed method is general, and it can be adapted to evaluate the crack tip opening stress for other crack geometries and loading conditions.Item Open Access On how data are partitioned in model development and evaluation: Confronting the elephant in the room to enhance model generalization(Elsevier BV, 2023) Maier, H.R.; Zheng, F.; Gupta, H.; Chen, J.; Mai, J.; Savic, D.; Loritz, R.; Wu, W.; Guo, D.; Bennett, A.; Jakeman, A.; Razavi, S.; Zhao, J.Models play a pivotal role in advancing our understanding of Earth’s physical nature and environmental systems, aiding in their efficient planning and management. The accuracy and reliability of these models heavily rely on data, which are generally partitioned into subsets for model development and evaluation. Surprisingly, how this partitioning is done is often not justified, even though it determines what model we end up with, how we assess its performance and what decisions we make based on the resulting model outputs. In this study, we shed light on the paramount importance of meticulously considering data partitioning in the model development and evaluation process, and its significant impact on model generalization. We identify flaws in existing data-splitting approaches and propose a forward-looking strategy to effectively confront the “elephant in the room”, leading to improved model generalization capabilities.Item Metadata only Water Distribution System Optimization Considering Behind-the-Meter Solar Energy with a Hydraulic Power-Based Search-Space Reduction Method(American Society of Civil Engineers, 2023) Zhao, Q.; Wu, W.; Simpson, A.R.; Willis, A.Abstract not availableItem Metadata only Using Ensemble Streamflow Forecasts to Inform Seasonal Outlooks for Water Allocations in the Murray Darling Basin(American Society of Civil Engineers, 2023) Graham, T.D.J.; Wang, Q.J.; Tang, Y.; Western, A.; Wu, W.; Ortlipp, G.; Bailey, M.; Zhou, S.; Hakala, K.; Yang, Q.Abstract not availableItem Metadata only Dynamic response of delaminated composite and sandwich beams using an efficient sub-lamented based higher order laminate model(Taylor & Francis Group, 2024) Feng, Y.; Sheikh, A.H.; Ng, C.-T.; Smith, S.T.A higher order model having sub-laminate capabilities for dynamic analysis of intact or delaminated composite and sandwich beams are presented. Each sub-laminate considered cubic and quadratic through-thickness variations for axial and transverse displacements respectively. The presence of displacement fields at the external surfaces of the sub-laminates helps to conveniently stack multiple sub-laminates by no additional treatments. The model has the flexibility in choosing the number of sub-laminates that provides the flexibility of controlling accuracy and computational efficiency. Central to the model is the development of a C0 continuous displacement based beam element. A thorough validated of the model is conducted using a wide range of problems having different structural configurations and dynamic loading. The model is then employed to investigate the behavior of new sandwich beam problems with multiple de-laminations under dynamic loads to study the influence of different delamination configurations. New results generated during this process can serve as benchmark data for future research.Item Open Access Beyond engineering: A review of reservoir management through the lens of wickedness, competing objectives and uncertainty(Elsevier, 2023) Wu, W.; Eamen, L.; Dandy, G.; Razavi, S.; Kuczera, G.; Maier, H.R.Traditionally, reservoir management has been synonymous with the operation of engineering infrastructure systems, with the majority of literature on the topic focusing on strategies that optimize their operation and control. This is despite the fact that reservoirs have major impacts on society and the environment, and the mechanics of how to best manage a reservoir are often overshadowed by both environmental changes and higher-order questions associated with societal values, risk appetite and politics, which are highly uncertain and to which there are no “correct” answers. As a result, reservoirs have attracted more controversy than any other type of water infrastructure. In this paper, we address these often-ignored issues by providing a review of reservoir management through the lens of wickedness, competing objectives and uncertainty. We highlight the challenges associated with reservoir management and identify research efforts required to ensure these systems best serve society and the environment into the future.Item Open Access An efficient modelling technique for simulation of guided waves in delaminated composite and sandwich structures(Elsevier, 2023) Feng, Y.; Sheikh, A.H.; Ng, C.-T.; Smith, S.T.The paper presents a higher order laminate model with sub-lamination capability for simulating wave propagation within delaminated composite and sandwich beams. Each sub-laminate adopts cubic and quadratic through-thickness variation for axial and transverse displacement, respectively. This is achieved by taking displacements at external surfaces, which are beneficial for connecting sub-laminates, used to model multilayered structures by stacking them in the thickness direction without additional treatment. The model has the flexibility to achieve the desired level of accuracy and computational efficiency by using a suitable sub-lamination scheme. The delamination can be inserted conveniently between two sub-laminates stacked one over the other. The effect of contact within delamination regions is also incorporated in this model to capture higher harmonics induced by a clapping mechanism produced during delamination closing. The model is implemented within a framework of spectral finite elements in the time-domain. The accuracy and computational efficiency of the model are thoroughly checked by solving numerical examples of wave propagation within intact/delaminated composite/sandwich beams. Detailed finite element (FE) models used to produce results for validation show that the proposed model can save more than 90% of computing time and memory compared to detailed FE modelling to achieve similar level accuracy. The model is finally utilised to investigate the influence of delamination sizes and location on the wave response of sandwich beams.Item Open Access Experimental and theoretical analysis of cracking and tension stiffening in UHPFRC under high-cycle fatigue(Wiley, 2024) Sepulveda, B.D.G.; Visintin, P.; Sturm, A.B.; Oehlers, D.J.Tension-stiffening controls the serviceability behavior of concrete structures as it is responsible for crack formation and, consequently, the deflection of beams. In fiber reinforced concrete, such as ultra-high performance fiber reinforced concrete (UHPFRC), fibers bridge cracks and thereby transfer tensile stresses across the cracked region, allowing for tensile stresses to be carried by the concrete within the cracked region. Due to structures being designed for longer design lives, the consideration of long-term effects such as fatigue is required. Much research has examined tension-stiffening under fatigue when subjected to low cyclic loading, but very little has considered the effects of high-cycle fatigue, especially for UHPFRC. This paper presents the results of nine UHPFRC tension-stiffening tests under high-cycle fatigue in which the crack formation and development under varying cyclic ranges were studied. Specimens were subjected to as many as 5.7 million cycles, and crack readings were taken during each test. The experimental results demonstrate the random nature of cracking on UHPFRC as well as the increase in the crack width under cyclic loads. Finally, this research described the extension of an existing partial-interaction mechanics model to allow for the stress in the fibers and the increase in crack width due to high cycle fatigue.Item Metadata only Development and evaluation of conductive ultra-lightweight cementitious composites for smart and sustainable infrastructure applications(Elsevier, 2023) Ran, H.; Elchalakani, M.; Boussaid, F.; Yehia, S.; Sadakkathulla, M.A.; Yang, B.The stability of electrical conductivity of self-sensing cementitious composites under different environments is the key to the application of structural health monitoring using electrical resistivity/impedance tomography. In addition, the lightweight of concrete is becoming a new requirement for sustainable development. This study aims to develop long carbon fibre (LCF) reinforced ultra-lightweight cementitious composites (ULCC) to address these issues. The mechanical properties and electrical and thermal conductivities of composites were investigated. The conductivity of LCF-reinforced ULCC under different testing methods (AC and DC), frequencies, temperatures, water content in the mixture, and curing ages were examined. The electromechanical properties of LCF-reinforced ULCC under compression (monotonic, cyclic loading under different loading peaks and loading rates) and tension were also tested. Except for the content, the effects of the pre-heating treatment of carbon fibre on the conductivity and electromechanical properties were compared. The experimental results revealed that LCF can remove the polarization effect and maintain the stability of the electrical conductivity of LCF-ULCC under different environments. The LCF can build a complete and continuously 3D conductive pathway, and free electrons can transport stably in the matrix, which can diminish the effect of electrolytic ions on the conductivity. The LCF-reinforced ULCC can show sensitive electromechanical ability where LCF is better used for self-sensing under tension when compared with compression. The conductivity of composites increases with increasing LCF content but initially increases and then decreases with increasing the pretreatment heating temperature of LCF. It is efficient to increase the conductivity and mechanical properties of composites by heating LCF to 300 ◦C. The composites (Oven-dry density: 990–1100 kg/m3 ) are a good thermal insulation material and the thermal conductivity is between 0.35 and 0.45 W/mK. Finally, microstructural analysis was conducted and the mechanisms of the improved electrical conductivity and thermal insulation of the composites were discussed.Item Metadata only Investigation of the shear failure of rock joints using the four-dimensional lattice spring model(Elsevier, 2022) Pratomo, F.Y.; Wei, X.; Zou, C.; Zhao, G.-F.This research adopts the four-dimensional lattice spring model (4D-LSM) to investigate the shear strength and failure mechanism of irregular rock joints and the influence of rock heterogeneity. The 4D-LSM has been used for a wide range of rock engineering applications, however its ability for simulating direct shear tests has not been investigated in detail. The material strength parameters were calibrated using uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS) tests on granite specimens while the joint parameters were calibrated from direct shear tests on saw-cut UCS specimens and rock joints containing a single triangular asperity. From UCS tests, a calibration method is proposed to adjust the excessive machine deformation due to the high brittleness of granite, which is further applied to the direct shear test results. It was found that the strength of rock joints is strongly influenced by the intact rock properties. To investigate the influence of joint geometry and rock heterogeneity, three joint asperity angles and five heterogeneous models were simulated using the calibrated 4DLSM model. Simulation results were able to capture the influence of different joint asperity angles on the shear strength and failure mechanism as reported in previous experimental and numerical studies. With larger asperity angles, higher shear strengths were obtained. Meanwhile, rock heterogeneity represented by particles with lower strength will reduce the shear strength and alter the failure mechanism, especially at a high porosity. This strength reduction was observed to be greater for steep-angle asperities and becomes less significant for flatter asperities. Similar conclusions were also obtained based on the simulations of natural joint profiles. From these findings, it is suggested that the characterisation of rock heterogeneity is crucial to estimate the strength of rock joints. In addition to the roughness parameters, heterogeneity parameters such as porosity are fundamental for rock engineering applications.