Search

Soil reinforcement using geosynthetics is an efficient and cost-effective solution for a variety of geotechnical structures. Along with the increasing use of geosynthetics, there is a need to expand and enhance the design methodologies for these elements, which are still frequently based on conservative limit equilibrium approaches. In this paper, a bibliometric analysis was conducted on geosynthetic-reinforced soil structures (GRS), identifying the state of the art, research trends, and other indicators. The data were obtained from the Scopus platform and processed by VOSViewer v1.6 software. The initial search comprised 552 papers and the screening process selected 516 relevant papers from 1992 to October 2023. The study analyzed the occurrence of publications by year, keyword trends, authors, citations/co-citations, and bibliographic coupling. Then, a focus was given to 3D modeling research on geosynthetics, highlighting the dominant modeling techniques, material properties, and design challenges in GRS. The bibliometric analysis provided a crucial guideline in the identification of relevant papers and research trends, and a series of conclusions were presented regarding the 3D modeling techniques, choice of material properties, and boundary conditions. [ABSTRACT FROM AUTHOR]

This paper introduces a literature review of the accomplished research to calculate the strain concentration factor which shall be considered during the concrete coated subsea pipelines design. The strain concentration results from the discontinuity of the concrete coating which is applied to pipe joints to enhance the pipeline stability on the seabed. The paper introduces a definition of the strain concentration factor and a conclusive explanation of the work performed to calculate the strain concentration factor using the following three methods: full-scale tests, analytical models, and numerical models. The paper also introduces other works addressing the contribution of concrete coating to pipe stiffness. Literature indicates that while full-scale tests produce the most accurate values for the strain concentration factor, due to cost implications, the method is limited to a small range of pipe sizes and coating properties. Although the analytical method produces acceptable results, prediction of strain concentration factor due to concrete coating sliding and beyond steel yield stress and concrete crushing limit is unpredictable. The numerical method using finite element (FE) analysis indicates acceptable strain concentration factor values, however, careful consideration shall be taken due to possible modelling inaccuracies. The review shows that the strain concentration factor is mainly influenced by the thickness and strength of the concrete coating as well as the shear capacity of the external corrosion coating, whilst due to its low impact, the effect of the concrete coating reinforcement is not considered for most of the analysis due to low significance. [ABSTRACT FROM AUTHOR]

This paper pertains to the reliability analysis of transmission tower foundations under variable wind loads. The reliability analysis of the anchor foundation, frequently employed for transmission towers due to their huge uplift capacity at shallow depth, is presented using a systematic probabilistic approach. The paper presents the design of an anchor foundation for a typical transmission tower based on loads obtained by applying lateral wind velocity on the tower. The Multivariate Adaptive Regression Splines (MARS) surrogate model is first developed to construct a deterministic prediction model for the anchor uplift capacity. The developed model is further used in the reliability analysis of the anchor foundation considering variabilities in the soil properties and the uplift load, and the results of the probabilistic analysis are reported in the paper. The results indicate the importance of incorporating variability in design variables for the proper safety of the structure. Soil cohesion is found to be the most sensitive parameter in the uplift capacity of the tower foundation. The comparison of the deterministic factor of safety and failure probability of the foundation brings out the importance of the reliability-based design methodology. [ABSTRACT FROM AUTHOR]

Large seabed trenches have recently been found adjacent to suction caissons with taut and semi-taut moorings. Seabed trenching leads to loss of soil support and additional caisson rotation, and can therefore significantly decrease geotechnical capacity. In this paper, upper-bound solutions are presented that enable calculation of the reduction in ultimate load-carrying capacity of a suction caisson in a trenched seabed compared to optimal capacity in an intact seabed. Failure mechanisms for caissons embedded in an intact seabed are augmented to incorporate a kinematically admissible mechanism for a trench extending from the mudline. The rate of work dissipation is calculated to determine the optimised solution of the inclined capacity of suction caissons. Comparisons of the results of the upper-bound solutions with finite-element analyses show that the failure mechanisms and the calculated load-carrying capacities derived from the two methods agree well. Therefore, the analytical upper-bound method presented in this paper can be employed for efficient routine calculations of suction caisson capacity under inclined load considering seabed trenches, which are increasingly encountered in engineering practice. [ABSTRACT FROM AUTHOR]

This paper investigates the robustness of a single 3D volumetric corner-supported module made of square hollow-section (SHS) columns. Typically, the moment–rotation (M-θ) behaviour of connections within the module (intra-module) is assumed to be fully rigid rather than semi-rigid, resulting in inaccurate assessment (i.e., overestimated vertical stiffness) during extreme loading events, such as progressive collapse. The intra-module connections are not capable of rigidly transferring the moment from the beams to the SHS columns. In this paper, a computationally intensive shell element model (SEM) of the module frame is created. The M-θ relationship of the intra-module connections in the SEM is firstly validated against test results by others and then replicated in a new simplified phenomenological beam element model (BEM), using nonlinear spring elements to capture the M-θ relationship. Comparing the structural behaviour of the SEM and BEM, under notional support removal, shows that the proposed BEM with semi-rigid connections (SR-BEM) agrees well with the validated SEM and requires substantially lower modelling time (98.7% lower) and computational effort (97.4% less RAM). When compared to a BEM with the typically modelled fully rigid intra-module connections (FR-BEM), the vertical displacement in the SR-BEM is at least 16% higher. The results demonstrate the importance of an accurate assessment of framing rotational stiffness and the benefits of a computationally efficient model. [ABSTRACT FROM AUTHOR]

Assessment of mining impact on groundwater is one of critical considerations for longwall extension and sustainability, however usually constrained by limited data availability, hydrogeological variation, and the complex coupled hydro-mechanical behaviour. This paper aims to determine the factors and mechanism of groundwater depressurisation and identify knowledge gaps and methodological limitations for improving groundwater impact assessment. Analysis of dewatering cases in Australian, Chinese, and US coalfields demonstrates that piezometric drawdown can further lead to surface hydrology degradation, while the hydraulic responses vary with longwall parameters and geological conditions. Statistical interpretation of 422 height of fracturing datasets indicates that the groundwater impact positively correlates to panel geometry and depth of cover, and more pronounced in panel interaction and top coal caving cases. In situ stress, rock competency, clay mineral infillings, fault, valley topography, and surface–subsurface water interaction are geological and hydrogeological factors influencing groundwater hydraulics and long-term recovery. The dewatering mechanism involves permeability enhancement and extensive flow through fracture networks, where interconnected fractures provide steep hydraulic gradients and smooth flow pathways draining the overlying water to goaf of lower heads. Future research should improve fracture network identification and interconnectivity quantification, accompanied by description of fluid flow dynamics in the high fracture frequency and large fracture aperture context. The paper recommends a research framework to address the knowledge gaps with continuous data collection and field-scale numerical modelling as key technical support. The paper consolidates the understanding of longwall mining impacting mine hydrology and provides viewpoints that facilitate an improved assessment of groundwater depressurisation. [ABSTRACT FROM AUTHOR]

Fracture structures are important natural gas transport spaces in shale gas reservoirs, and their storage state in shale gas reservoirs seriously affects gas production and extraction efficiency. This work uses numerical modeling techniques to investigate the logging response law of the thermal and epithermal neutrons in the gas-containing fracture environment at various angles, applying neutron logging as a technical method. To increase the precision of the evaluation of the natural gas storage condition in shale gas reservoirs, the angle of the fractures' neutron logging data is analyzed. It is found that even in an environment with the same porosity of the fractures, there are significant differences in the logging results due to the different angles of the fracture alignment: 1. the neutron counts in the high-angle (70–90°) fracture environment are 2.25 times higher than in the low-angle (0–20°), but the diffusion area of the neutrons is only 10.58% of that in the low-angle (0–20°); 2. in the neutron energy spectrum, neutron counts are spreading to the high-energy region (7–13 MeV) along with the increase in the angle of the fracture, and the feature is especially prominent in the approximately vertical (60–90°) fracture environment, which is an increase of 528.12% in comparison with the counts in the approximately horizontal angle (0–30°) environment. The main reason for these differences is the variation in the volume of the fracture within the source radiation. This volumetric difference results from the variation in fracture angles (even though the fracture porosity is the same). In view of the above phenomenon, this paper proposes the concept of "effective fracture volume", which can intuitively reflect the degree of influence of fracture angle on neutron logging results. Further, based on the unique characteristics of shale gas reservoirs and neutrons, this paper provides important theoretical support for the modification of the porosity of the field operation, the evaluation of the physical characteristics of the gas endowment space, and the assessment. [ABSTRACT FROM AUTHOR]

Gas conditioning towers (GCTs) or cooling towers have broad industrial applicability, especially in the cement industry. Most cement factories deal with the same problems faced by other factories. However, the solutions to these problems are barely internationally published and have not received much attention, meaning a lot of time and money is spent on researching previous solutions. Iran is among the top ten cement manufacturing countries in the world. Therefore, many of these problems have occurred in Iranian cement factories. The purpose of this paper is to provide a review of studies in this field over the last couple of decades, with a particular focus on advances in Iran. The most important findings in the literature are summarised in order to suggest the best possible solutions for improving the performance and lifetime of GCTs and decreasing common problems such as dust build-up and wet bottom. Numerical methods for modelling different aspects of GCTs are reviewed. The results can be used to reduce water and energy consumption, air pollution and the repair and maintenance costs of cement factories. [ABSTRACT FROM AUTHOR]

This paper examines a flowslide involving a glacial deposit of low-plasticity silty sand triggered by a karstic spring after a rainfall period. The work aims at explaining the triggering, propagation and kinematics of flow-like landslides in a unique framework. In particular, a material point method open-source code, able to solve coupled hydro-mechanical problems for saturated/unsaturated soils, was developed. Laboratory and field experiments revealed a liquefaction potential of the mobilised material. To simulate such potential, a recent liquefaction model (Ta-Ger), validated so far at a laboratory scale, was selected, extended to unsaturated conditions, implemented and calibrated. The analysis indicates a complex behaviour of the moving mass and explains the mechanisms developing sequentially in the flowslide. The impact of the upper unstable soil mass against the soil at lower elevations is a key phenomenon to generalise soil liquefaction in the entire slope. Patterns of soil velocity and displacements are far from being a uniform flow of liquefied material. The model developed is a powerful tool to interpret flowslides involving a saturated and unsaturated soil profile. The paper includes sensitivity analyses and discusses the discrepancies observed in the run-up of the flowslide climbing on the opposite slope of the valley. [ABSTRACT FROM AUTHOR]

Inclined anchors are used in civil engineering structures where the foundations are expected to resist pullout forces during their operational period. This paper presents a three-dimensional numerical analysis of inclined anchors placed in unreinforced and reinforced sand. The influence of several parameters on the response of inclined anchor plates has been investigated in this study. Results indicate that geogrid reinforcement placed on top of the anchor plate significantly influences the anchor plate's performance. The ultimate pullout capacity is found to increase with the inclination angle (varied from 30° to 60°) of the anchor plate both in unreinforced and reinforced sand. The anchor capacity is also affected by other parameters such as friction angle of sand (varied from 35° to 45°), embedment depth of the anchor plate (varied from 2 to 10) and tensile stiffness of the geogrid. Besides, the comparison between piles and anchors has been presented with the help of an illustrative example of a transmission tower foundation. The design calculations indicate that inclined anchors placed in reinforced sand can lead to economical design at shallow depth as compared to piles. [ABSTRACT FROM AUTHOR]

Hydro-pneumatic energy storage is a form of compressed-air energy storage that can provide the long-duration storage required for integrating intermittent renewable energies into electrical power grids. This paper presents results based on numerical modelling and laboratory tests for a kilowatt-scale HPES system tested at the University of Malta. This paper presents measurements of the discharge cycle, in which energy stored in compressed air within a pressure vessel is hydro-pneumatically converted back into electricity via a Pelton turbine and fed into the national electricity grid. The tests were conducted using a hydraulic turbine operated under different fixed-turbine rotational speed settings, with the pressure being allowed to decrease gradually during the HPES system's discharge cycle. The system's overall efficiency accounted for flow losses, turbine inefficiencies, and electrical losses. The tests showed that this efficiency was practically independent of the compressed-air pressure of specific water turbine runner speeds, despite the water turbine operating at fixed speeds. A numerical model developed in MATLAB Simulink (R2022a) was also presented for use simulating the hydraulic performance of the system during the discharge cycle. The model used secondary loss coefficients for the hydraulic circuit and derived velocity coefficients from computational fluid dynamics (CFD) for the Pelton turbine nozzle. We achieved very good agreement between the predictions based on numerical modelling and the measurements taken during laboratory testing. [ABSTRACT FROM AUTHOR]

Monopile mounted offshore wind turbines (OWTs) are expected to experience a very large number of cyclic loads throughout their operational lifetime, and the existing p–y method of foundation modelling does not fully account for the effects of dynamic cyclic loading, such as pile–soil gapping. In this paper a dynamic model based on the beam on non-linear Winkler foundation scheme with a novel algorithm capable of capturing the effects of pile–soil gapping is presented. It can account for gap cave-in, and the resulting gap size can react dynamically to changing loading amplitudes, using only two calibration parameters. Static and dynamic cyclic loaded model validations are presented, and give very good agreement with experimental results, performing better than existing p–y curves for dynamic loading. The model is also applied to an OWT case study and predictions of natural frequency reduction due to soil erosion agree well with measured results. It is shown that the inclusion of gapping may result in a significant decrease to the natural frequency prediction of OWTs relative to the value predicted without gapping. As such, not to consider gapping could lead to unconservative predictions, and any additional soil degradation throughout the serviceable lifetime could therefore result in unwanted resonance. The method provided in this paper provides a simple and accurate model to predict this behaviour which is crucial to ascertain during the design phase. [ABSTRACT FROM AUTHOR]

A comparative analysis of three advanced architectures for tandem solar cells (SCs) is discussed, respectively: metal oxide, thin film, and perovskite. Plasmonic solar cells could further increase solar cell efficiency. Using this development, an innovative PV technology (an SHTSC based on metal oxides) represented by a four-terminal Cu2O/c-Si tandem heterojunction solar cell is investigated. The experimental and numerical modelling study defines the main aim of this paper. The experimental approach to SHTSCs is analysed: (1) a Cu2O layer is deposited using a magnetron sputtering system; (2) the morphological and optical characterization of Cu2O thin films is studied. The electrical modelling of silicon heterojunction tandem solar cells (SHTSCs) is discussed based on five simulation tools for the optimized performance evaluation of solar devices. The main novelty of this paper is represented by the following results: (1) the analysis suggests that the incorporation of a buffer layer can improve the performance of a tandem heterojunction solar cell; (2) the effect of interface defects on the electrical characteristics of the AZO/Cu2O heterojunction is discussed; (3) the stability of SHTSCs based on metal oxides is studied to highlight the degradation rate in order to define a reliable solar device. Perspectives on SHTSCs based on metal oxides, as well as Si perovskite tandem solar cells with metal oxides as carrier-selective contacts, are commented on. [ABSTRACT FROM AUTHOR]

Mat foundations have been widely used as foundations of mobile offshore platforms such as jack-up rigs and installation platforms. Throughout the service period, the mat bears coupled multi-dimensional loads transferred from the superstructure and directly from the environment. Evaluating the bearing capacity of the mat is the premise of offshore platform design. However, there are few studies on the bearing capacity of commonly used irregularly shaped mats under multi-dimensional load conditions. Looking at two types of A-shaped mats on cohesive soil, uniaxial bearing capacities are calculated using the finite element method (FEM) in this study. The centrifuge test was performed to verify the FEM results. Effects of the length-to-width aspect ratio of the foundation on bearing capacities are discussed. The V-H, V-M, and V-H-M failure envelopes of mats with unlimited and zero tension interfaces are obtained. Studies have shown that the uniaxial bearing capacities change monotonously with aspect ratio increases, and that the bearing capacity of a rectangular A-shaped mat is higher than that of a trapezoidal A-shaped mat. The V-H-M envelope with unlimited tension interface condition is ellipsoid-shaped, while that with zero tension interface is scallop-shaped. With the capacity expressions established in the paper, it is possible to quickly check the bearing state of the mat under a given V-H-M load condition, and then assess the safety of the engineering operation. [ABSTRACT FROM AUTHOR]

Concepts and evolution of multi-scale modelling from the perspective of wave–structure interaction have been discussed. In this regard, both domain and functional decomposition approaches have come into being. In domain decomposition, the computational domain is spatially segregated to handle the far-field using potential flow models and the near field using Navier–Stokes equations. In functional decomposition, the velocity field is separated into irrotational and rotational parts to facilitate identification of the free surface. These two approaches have been implemented alongside partitioned or monolithic schemes for modelling the structure. The applicability of multi-scale modelling approaches has been established using both mesh-based and meshless schemes. Owing to said diversity in numerical techniques, massively collaborative research has emerged, wherein comparative numerical studies are being carried out to identify shortcomings of developed codes and establish best-practices in numerical modelling. Machine learning is also being applied to handle large-scale ocean engineering problems. This paper reports on the past, present and future research consolidating the contributions made over the past 20 years. Some of these past as well as future research contributions have and shall be actualized through funding from the Newton International Fellowship as the next generation of researchers inherits the present-day expertise in multi-scale modelling. This article is part of the theme issue 'Celebrating the 15th anniversary of the Royal Society Newton International Fellowship'. [ABSTRACT FROM AUTHOR]

This paper presents a procedure for determining the elastoplastic parameters of phase-field fracture of sintered material. The material considered was sintered steel Astaloy™ Mo+0.2C of three densities: 6.5, 6.8 and 7.1 g/ cm 3 . The stress–strain curve and Wöhler curve, which are experimentally obtained, are utilized for validation of the numerical simulations. For modelling of damage evolution, a CCPF (Convergence check phase-field) algorithm was used as a numerical framework. During calibration of the numerical parameters, two-dimensional as well as three-dimensional modelling was used. A comparison of different fatigue degradation functions known from the literature is also made. To improve the efficiency of numerical simulations of fatigue behaviour, the cycle skip technique is also employed. [ABSTRACT FROM AUTHOR]

In the last few decades, the problem of pollution resulting from human activities has pushed research toward zero or net-zero carbon solutions for transportation. The main objective of this paper is to perform a preliminary performance assessment of the use of hydrogen in conventional turbine engines for aeronautical applications. A 0-D dynamic model of the Allison 250 C-18 turboshaft engine was designed and validated using conventional aviation fuel (kerosene Jet A-1). A dedicated, experimental campaign covering the whole engine operating range was conducted to obtain the thermodynamic data for the main engine components: the compressor, lateral ducts, combustion chamber, high- and low-pressure turbines, and exhaust nozzle. A theoretical chemical combustion model based on the NASA-CEA database was used to account for the energy conversion process in the combustor and to obtain quantitative feedback from the model in terms of fuel consumption. Once the engine and the turbomachinery of the engine were characterized, the work focused on designing a 0-D dynamic engine model based on the engine's characteristics and the experimental data using the MATLAB/Simulink environment, which is capable of replicating the real engine behavior. Then, the 0-D dynamic model was validated by the acquired data and used to predict the engine's performance with a different throttle profile (close to realistic request profiles during flight). Finally, the 0-D dynamic engine model was used to predict the performance of the engine using hydrogen as the input of the theoretical combustion model. The outputs of simulations running conventional kerosene Jet A-1 and hydrogen using different throttle profiles were compared, showing up to a 64% reduction in fuel mass flow rate and a 3% increase in thermal efficiency using hydrogen in flight-like conditions. The results confirm the potential of hydrogen as a suitable alternative fuel for small turbine engines and aircraft. [ABSTRACT FROM AUTHOR]

The columnar-flow approximation allows the development of computationally efficient numerical models tailored to the study of the rapidly rotating dynamics of Earth's fluid outer core. In this paper, we extend a novel columnar-flow formulation, called Plesio-Geostrophy (PG) by including thermal effects and viscous boundary conditions. The effect of both no-slip and stress-free boundaries, the latter being a novelty for columnar-flow models, are included. We obtain a set of fully 2-D evolution equations for fluid flows and temperature where no assumption is made regarding the geometry of the latter, except in the derivation of an approximate thermal diffusion operator. To test the new PG implementation, we calculated the critical parameters for onset of thermal convection in a spherical domain. We found that the PG model prediction is in better agreement with unapproximated, 3-D calculations in rapidly rotating regimes, compared to another state-of-the-art columnar-flow model. [ABSTRACT FROM AUTHOR]

Gridpoint discretization of the model has a significant impact on the accuracy of finite-difference seismic waveform simulations. Discretizing the discontinuous velocity model using local point medium parameters can lead to artefact diffraction caused by the stair-step representation and inaccuracies in calculated waveforms due to interface errors, particularly evident when employing coarse grids. To accurately represent model interfaces and reduce interface errors in finite-difference calculations, various equivalent medium parametrization methods have been developed in recent years. Most of these methods require volume-integrated averaging calculations of the medium parameter values within grid cells. The simplest way to achieve this volume averaging is to apply numerical integration averaging to all grid cells. However, this approach demands considerable computational time. To address this computational challenge, we propose employing a set of auxiliary grids to identify which grid cells intersected by the welded interface and perform volume averaging only on these specific cells, thereby reducing unnecessary computational overhead. Additionally, we present a 3-D tilted transversely isotropic equivalent medium parametrization method, which effectively suppresses interface errors and artefact diffraction under the application of coarse grids. We also provide an approach for computing the normal direction of the interface, which is essential for the tilted transversely isotropic equivalent medium parametrization. Numerical tests validate the accuracy of the tilted transversely isotropic equivalent medium parametrization method and demonstrate the practicality of the implementation proposed in this paper for complex models. [ABSTRACT FROM AUTHOR]

As a typical feature of traditional Chinese timber structures, columns with floating foot joints are prone to rocking under horizontal force. The column rocking behavior plays an important role in resisting lateral loads. This paper proposes modelling strategies for the rocking behavior of traditional timber columns. The proposed model can capture the contact state of the column foot via a series of distributed axial springs and the possible sliding via a horizontal spring. It has a lower computational cost than refined finite element (FE) models and is independent of numerical calibration compared to rotational spring models. The modelling strategies were validated against refined FE models and experimental data available in the literature. The principle behavior of the approach was carefully investigated including contact stiffness, distribution modes, spring numbers, column bending effects, and computational efficiency. Results show that the effective compression height of the column foot can take the value of the column radius to determine spring stiffness. Column bending needs to be considered in the mechanical analysis of column foot joints for slender columns. The case study on the lateral stiffness of traditional timber frames confirms the applicability of the proposed model in the structural analysis of ancient timber buildings. [ABSTRACT FROM AUTHOR]

This numerical modelling has enabled the prediction of wear rates in different materials and for different sliding conditions. It has also enabled the development of more efficient and reliable wear-resistant materials. Additionally, this modelling has been applied to improve the performance of existing components and to design new ones. The WC-Co coatings are used for wear resistance applications. The paper discusses the numerical modelling approach used for the development of coatings. The different governing equations have been discussed for the development of coatings with respect to process parameters. In this article, discuss the effects of Plasma spraying (PS), cold spraying, HVOF, and DS produce particles with the maximum temperature. WC, WC-12Co, WC-CoCr, WC-(W,Cr), Cr3C2–NiCr, and TiC feedstock powders cover surfaces in thermal spray coating. HVOF deposition coats a variety of substrates efficiently and economically. HVOF deposits homogeneous coatings with low porosity and great wear and corrosion resistance. Heat treatment can improve thermal spray coatings after processing. As a final point, advances in numerical modelling of sliding wear rate are discussed in this article. [ABSTRACT FROM AUTHOR]

This paper deals with numerical modelling of wave and current patterns in the coastal city of Genaveh port (Bushehr province, Persian Gulf) with a sloping breakwater. Three breakwater arm patterns were defined based on the studied area's marine currents. Meteorological model wind statistics (ECMWF) and wave statistics (ISWM) and data from monitoring and simulation projects of the northern coasts of the Persian Gulf were used to model the hydrodynamics of the study area after the breakwater construction. In this numerical modelling, mike 21-SW and HD modules were employed to simulate the wave patterns near the three proposed breakwater arms. Based on observations of the hydrodynamic condition and with consideration of the design wave exhibiting a 100-year return period, it is indicated that an optimal pattern would yield significant wave heights and wave speeds of 0.2 m and 0.25 m/s, respectively, within both the existing and newly constructed harbour basins. [ABSTRACT FROM AUTHOR]

The mechanical behaviour of Fibre-reinforced sands (FRS) has been extensively studied, presenting improved mechanical properties compared to unreinforced soils. Many models have been developed to predict its general stress-strain behaviour. However, the use of double-phase models in FRS is still incipient. Double-phase models are advantageous because they can simulate the whole FRS and the behaviour of its individual components, soil skeleton and reinforcement. This paper uses a modified model for Municipal Solid Waste to reproduce the FRS mechanical response. Introducing a new hardening parameter and a dilatant zone allowed the model to reproduce FRS dilatancy. The model's variables are easily understood, allowing the reproduction of the mechanical behaviour of FRS formed by sands with void ratios ranging from 0.610 to 0.917 and mean grain size from 0.29 to 0.83 mm. The fibres' lengths varied from 12.5 to 51 mm. The results of triaxial and hollow cylinder torsional tests under different stress paths had their main characteristics (peak strength, post-peak behaviour, dilatancy and reinforcement effectiveness) well captured by the model. Predicted and experimental FRS's deviator stress usually differ by less than 15% and the model performance is equivalent or superior to other available models, even requiring fewer input parameters. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of innovative cross-sectional configurations on Low-Cost Bamboo Composite (LCBC) structural members. The study employs both experimental and numerical methods with different resin matrices and bamboo species. In this study, LCBC short columns are designed with different innovative cross-sectional configurations in an attempt to overcome the costly production processes of engineered bamboo. This approach uses bundles of bamboo, both in culm and strip forms. A compatible, environmentally responsible, and economically justifiable resin matrix is used to fabricate an LCBC member. The production of LCBC members does not necessitate highly advanced technology. This capability enables the production of LCBC members in custom-designed cross-sectional shapes and lengths. This study introduces the Russian doll (RD), Big Russian doll (BRD), Hawser (HAW), and Scrimber (SCR) cross-sectional configurations. Extra-large, large, medium, and small sizes of bamboo are employed. Synthetic Epoxy (EXP), a Bio-based Experimental soft filler (BE1), Bio-Epoxy (BE2), Furan-based (PF1) matrices are applied. Furthermore, Moso, Guadua, Madake, and Tali bamboo species are incorporated. The results of this study reveal that the most efficient cross-sectional configuration for compressive strength is the HAW configuration, closely followed by the SCR configuration. LCBC members with bio-resins have shown excellent promise in competing in strength with those made with their synthetic counterparts. The maximum compressive strengths (MPa) were achieved by two specimens with synthetic epoxy closely followed by a specimen with bio-epoxy, namely HAW-EPX-M, RD-EPX-M, and RD-BE2-G specimens with 78 MPa, 75 MPa, and 72 MPa, respectively. In terms of the modulus of elasticity of LCBC with different resin matrices, the stiffest specimens were HAW-BE2-M1, HAW-EPX-M, and HAW-BE2-M2 with 3.89 GPa, 3.08 GPa, and 2.54 GPa, respectively. The theoretical and numerical modelling of the LCBC members showed excellent correlation with the experimental results, which provides the capacity to design LCBC for engineering projects. The LCBC design can be further developed with more bamboo and less resin content. [ABSTRACT FROM AUTHOR]

Columns in traditional timber structures are commonly seen resting on stone bases and are very important in resisting lateral loads. This paper numerically modeled the lateral resistance of the columns combined with experimental investigation. Different numerical models were developed, based on which sensitivity analyses were performed. A practical numerical modelling strategy was further proposed and verified. The analysis results indicated that instead of material properties and contact area, the columns' lateral performance was much more sensitive to the variation of surface curvature at bottom surface. Without consideration of the surface curvature, the modeling error in the initial stiffness and peak load of a column was more than 607% and 8%, respectively. By best matching the load–displacement curves of tested column specimens, the optimal surface curvature was identified as 1/20306.5 mm−1. Then, a practical finite numerical model, characterized by the optimal curvature at the bottom surface, was proposed. This modelling method was validated by use of existing test results of traditional timber columns with different diameters and vertical compression loads. The modelling load–displacement curves agreed well with experimental curves both in terms of the initial lateral stiffness and peak load. Detailed simulation results based on the practical modelling strategy were presented and discussed. [ABSTRACT FROM AUTHOR]

The first and fully validated smoothed particle hydrodynamics (SPH) model is presented to tackle coupled flow–deformation problems in unsaturated porous media that undergo large deformation and post-failure behaviour. Unlike the commonly adopted double-layer SPH framework for saturated soils, this paper presents a three-phase single-layer SPH model capable of predicting anisotropic seepage flows through porous media and their complete time-dependent transition from unsaturated to saturated states, as well as their influence on the mechanical behaviour of the porous media and vice versa. The mathematical framework is developed based on Biot's mixture theory and discretised using the authors' recently developed novel SPH approximation scheme for the second derivatives of a field quantity. The soil is modelled using a suction-dependent elastoplastic constitutive model, expressed in terms of effective stress and suction. In addition, an adaptive two-timescale scheme is proposed for the first time to address existing challenges in solving coupled-flow large-deformation problems that involve a significant difference in the timescale required for the solid and fluid phases. The capability of the proposed SPH model was demonstrated through fundamental consolidation tests and a large-scale rainfall-induced slope failure experiment. Very good agreements with theoretical solutions and experimental results are achieved, suggesting that the proposed SPH model can be readily extended to solve a wide range of large-scale geotechnical applications involving coupled unsaturated seepage–deformation problems. [ABSTRACT FROM AUTHOR]

The paper assesses the effect on the air flow regime underneath a simplified high-speed train of changing the ballast depth and the sleeper shape, with regard to its potential for causing ballast flight or pickup. The study was carried out numerically using the commercial Computational Fluid Dynamics (CFD) software AnSys Fluent. The flow profile beneath the underbody of the train was generated by means of a moving wall above the track. The Delayed Detached Eddy Simulation (DDES) with the SST k - ω turbulence model was used to simulate turbulent flow, and the ballast bed roughness was applied parametrically using the wall roughness feature when resolving the boundary layer. CFD simulations were validated for flow over a cube, showing good agreement with experimental results. Up to three different depths to the ballast surface and three different sleeper profiles were investigated. Velocity profiles and aerodynamic forces on cubes placed between or on top of the sleeper blocks were used to assess the propensity of individual ballast grains for movement. For a standard G44 sleeper, increasing the ballast depth and/or the ballast bed roughness was found to reduce aerodynamic loads on an individual ballast grain. A ballast grain on top of the sleeper is more prone to uplift than a grain on the surface of the ballast bed in the crib. A curved upper surface to the sleeper is beneficial in that it prevents ballast from settling on top, the most vulnerable position. However, the reduced flow separation associated with the curved top may increase the likelihood of ballast pickup from the crib. Hence new sleeper shapes intended to reduce the potential for ballast flight should not only prevent ballast from settling on top, but also increase flow separation through the provision of a sharp surface. A prismatic sleeper shape that achieves both is suggested. [ABSTRACT FROM AUTHOR]

The electric vehicle (EV) industry challenges battery joining technologies by requiring higher energy density both by mass and volume. Improving the energy density via new battery chemistry would be the holy grail but is seriously hindered and progresses slowly. In the meantime, alternative ways, such as implementing more efficient cell packaging by minimising the electrical resistance of joints, are of primary focus. In this paper, we discuss the challenges associated with the electrical characterisation of laser-soldered joints in general, and the minimisation of their resistive losses, in particular. In order to assess the impact of joint resistance on the overall resistance of the sample, the alteration in resistance was monitored as a function of voltage probe distance and modelled by finite element simulation. The experimental measurements showed two different regimes: one far from the joint area and another in its vicinity and within the joint cross-section. The presented results confirm the importance of the thickness of the filler material, the effective and total soldered area, and the area and position of the voids within the total soldered area in determining the electrical resistance of joints. [ABSTRACT FROM AUTHOR]

The goal of this paper is to use the finite element method and computer simulation to prove the effectiveness in assessing the fire resistance of building construction elements, specifically on the example of the fire resistance of fire doors. For that purpose, data from the building where fire doors with defined characteristics were installed were used. For simulation purposes, numerical modelling with thermal and structural analysis will be used. In this way, the parameters of the temperature distribution on the fire door and the contact material due to fire will be obtained, as well as the distribution of strain and stresses, which will indicate the fire resistance of the used structure. Computer simulation with numerical modelling offers a number of advantages both in the speed of providing results of a larger number of variants of the simulation model and in the accuracy of the results obtained once the model is calibrated. Also, the mentioned type of predicting the effect of fire can be applied to other elements of the structure of the construction object, which can significantly influence the decision-making that will prevent the negative consequences of the occurrence of a possible fire. [ABSTRACT FROM AUTHOR]

This paper proposed a new method for modelling joints, using anisotropic plate elements and elastic bar elements to address the issue that joints between panels are usually disregarded in numerical modelling. For small-scale deep excavations, which are frequently performed in the construction of various working shafts but have not been sufficiently studied, two numerical models were developed, using the No.1 Shaft of Tongtu Road Utility Tunnel in Ningbo, China, as a research object. One model considered the joints between the panels as proposed, while the other disregarded the joints as conventional. In comparison to the conventional method, the proposed method was validated due to yielding wall displacements that closely matched the results of the field monitoring, with a notable reduction in the error observed in the calculated displacements for the short side of the excavation. Furthermore, 34 numerical models were developed in order to investigate the influence of excavation length, depth, and diaphragm wall thickness on the relative differences between the calculated displacements obtained by the two models. The results of this study can provide references for the development of finite element models for designing small-scale deep excavation. [ABSTRACT FROM AUTHOR]

Integral abutment bridges (IAB), especially the short to medium-span IABs, have become more popular throughout the years in Australia as well as globally. IABs have advantages over traditional bridges in terms of their construction and maintenance costs due to the elimination of expansion joints. However, the thermal expansion can develop significantly larger earth pressure behind the abutment, thus leading to excessive forces (i.e. moment and shear force) to the foundation, which are not considered during the design process and can cause cracking and failures, eventually. It is observed from the field monitoring of IABs that the earth pressure model used to estimate the pressure distribution is not adequate to capture possible variations. Further, the performance of IABs highly depends on the complex interaction of abutment-backfill and soil-foundation and the time-dependent and cyclic behaviour of backfill and foundation soils. In this paper, nonlinear finite element model of an IAB considering the time-dependent effects of materials is presented to simulate long-term responses due to thermal loading. The developed IAB model results are validated using field monitoring data and parametric study is performed including the geometry of IAB, thermal loading, and soil properties. The results are used to investigate the functional relationship between input parameters and long-term responses which are further utilised to develop a new earth pressure distribution model for the design and performance assessment of IABs. [ABSTRACT FROM AUTHOR]

This paper demonstrates the latest developments in particle-scale modelling of a clay. It shows that by creating an initial sample of platelets featuring aggregated stacks, excellent macroscopic behaviour is achieved. This approach is justified by examining SEM images of clay slurries, and is consistent with the behaviour of real clays. The use of aggregated stacks allows a wider range of platelet interactions and micro properties to be simulated and investigated, and significantly, enables interactions to be modelled that are based on a range of real measurements obtained from surface force experiments. [ABSTRACT FROM AUTHOR]

Currently, fiber-reinforced polymer composites (FRPs) used for demanding structural applications predominantly utilize carbon, glass, and aramid fibers embedded in epoxy resin, albeit occasionally polyester and vinyl ester resins are also used. This study investigates the feasibility of employing recyclable and sustainable materials to formulate a composite suitable for load-bearing structural applications, particularly in scenarios involving low-velocity and high-velocity impacts (LVIs and HVIs, respectively). The paper presents a comparative analysis of the performance of basalt–Elium, a fully recyclable, sustainable, and environmentally friendly composite, with an epoxy-based counterpart. Moreover, an accurate and reliable numerical model has been developed and introduced through which the response of these composites can be examined efficiently and accurately under various loading states. The results of this investigation demonstrate the viability of the basalt–elium composite as a fully recyclable and sustainable material for crafting efficient and lightweight composites. Additionally, the accurately developed finite element model presented here can be used to assess the influence of several parameters on the composite, thereby optimizing it for a given situation. [ABSTRACT FROM AUTHOR]

Rainfall-induced shallow landslides often turn into flows. These phenomena occur worldwide and pose severe hazard to infrastructure and human lives on mountainous areas. Risk assessment, and the design of mitigation measures, can both be informed by back-analysis of previous events. However, shallow instabilities are frequently spread over a large area, with the generated flows occurring in sequences, or surges. Conventionally, back-analysis exercises tackle the problem by simulating runout as a single event, with all surges happening simultaneously. This simplification has repercussions that have not been explored in the literature so far, and whose impact in hazard assessment practice is unclear. Therefore, a novel time-resolving procedure is proposed in this paper, which can for the first time be applied to resolve instability sequences of arbitrary duration. The methodology discretizes the event, detecting instabilities at equally spaced time intervals as a function of rainfall. Thanks to this, the post-failure behaviour of each surge can be tracked by a runout model, with a separate simulation performed every time a new instability is detected. The methodology robustness is tested on two documented case studies. The results reveal that, under some conditions, the time-resolving procedure can lead to significantly different results in terms of runout path, flooded area, and flow heights. This leads to criticism on how back-analysis is conventionally applied, prompting for a review of historical cases. [ABSTRACT FROM AUTHOR]

This paper analyzes the bearing capacity of two-layered soil medium using finite element (FE) software ABAQUS/CAE 2023. Although geotechnical engineers design foundations for layered soil, majorly current geotechnical studies emphasize single homogenous soil. So, this research has significant novelty as it focuses on layered soil and adds to the current literature. A nonlinear FE model was prepared and analyzed to determine the ultimate bearing capacity of two-layered soil (sandy soil over clayey soil). The Drucker–Prager and Mohr–Coulomb models were used to represent sandy soil and clayey soil layers, respectively. Strip footing material properties were considered isotropic and linearly elastic. This study performed parametric studies to understand the effects of thickness, unit weight, and the modulus of the elasticity of sandy soil on the ultimate soil bearing capacity. Additionally, it also analyzed the effect of the cohesive strength of clayey soil on layered soil bearing capacity. Results showed that an increase in sandy soil layer thickness strengthens the layered soil, and thus, improves the bearing capacity of soil. Increasing the sandy soil layer thickness over footing width (h1/B) ratio from 0.15 to 2.0 improved the ultimate bearing capacities with elastic settlements of 350 mm and 250 mm by 145.62% and 101.66%, respectively. Additionally, for a thicker sandy soil layer, an increase in the unit weight and modulus of the elasticity of sandy soil led to higher ultimate bearing capacity. Furthermore, it was concluded that an increase in clayey soil's cohesive strength from 20 kPa to 30 kPa resulted in a 24.31% and 3.47% increase in soil bearing capacity for h1/B = 0.15 and h1/B = 2.0, respectively. So, the effect of cohesion is prevalent in the case of a thicker clayey soil layer. [ABSTRACT FROM AUTHOR]

This paper presents a computational model for determining the axial responses of short circular steel–reinforced concrete-filled steel tubular (SRCFST) columns. A novel confinement model is formulated for the concrete core, which is effectively confined by the external circular steel tube and the embedded steel section. The modelling scheme of the confinement is programmed using a mathematical model that utilises fibre-element discretisation of column cross-sections. The numerical predictions are verified by experimental measurements and results obtained from finite-element analysis, demonstrating the accuracy of the modelling technology. In addition, existing concrete confinement models for concrete in circular concrete-filled steel tubular columns are assessed. The new confinement model is shown to be superior in replicating the responses of SRCFST columns. The influences of the design parameters on the column's performance are numerically investigated and ranked in order of importance through a sensitivity analysis. In this study, not only is the validity of current design standards in determining the axial load capacity of SRCFST columns examined but a new design formula is also proposed. The proposed confinement model can be employed in numerical procedures for the inelastic simulation of SRCFST columns; the design formula is suitable for use in practical design. [ABSTRACT FROM AUTHOR]

Flooding in urban areas is expected to increase its magnitude and frequency in the future. Therefore, there is a strong need to better model sewer–surface flow interactions. Existing numerical methods are commonly based on simplified representations of sewer/surface mass exchange, and mainly validated in steady flow conditions. Current methodologies describing the propagation of transient conditions/waves through interaction nodes are simplified, rely on empirical coefficients and/or lack detailed validation. In this paper, an integrated numerical approach for modelling the propagation of water waves through interaction nodes (e.g., manholes) is presented. In this solution, the shallow water equations are used to simulate the free‐surface propagation inside the sewer network, and an ordinary differential equation is employed for modelling flow regimes through pipes and manholes. The model proposed is validated against the well‐known STAR‐CD modelling software for a number of test cases. Finally, further validation is performed against experimental data describing the evolution of water depth around a manhole in unsteady surcharging conditions. [ABSTRACT FROM AUTHOR]

To enhance the prediction accuracy of forming simulations of carbon fiber unidirectional (UD) thermoset prepregs, particularly the wrinkle predictions, bending behavior of UD prepregs in the forming process needs to be accurately characterized and modelled. In this paper, an improved bending test system was proposed to characterize the bending behavior of UD prepregs at different forming temperatures and loading rates. It is found that both the temperature and the loading rate have significant impact on the bending stiffness of UD prepregs. An obvious nonlinear bending behavior can be noted in the fiber direction. The loading rate sensitivity of bending stiffness in the fiber direction decreases with temperature increasing. To simulate the bending deformation, a superimposed membrane-shell element model was employed to achieve the decoupling of tensile-bending deformation. Membrane element simulated the in-plane tensile and in-plane shear deformations of UD prepregs, while shell element primarily accounted for the bending deformation. Fiber orientation dependent nonlinear bending stiffness was accounted in the model. Deformation simulations were conducted for vertical cantilever bending, horizontal cantilever bending, and compression wrinkling of UD prepregs. Good agreement is noted between simulation and experiment, demonstrating efficiency of the model and validity of measured bending stiffness. [ABSTRACT FROM AUTHOR]

This paper focuses on the vibration serviceability assessment and numerical modelling of an existing steel truss footbridge located in the outskirts of Castellón, Spain. The footbridge is rather slender and composed by a main span and two access ramps supported on three 4-arm piers of different heights. Due to the connection between the main span and the ramps at the top of the tall piers, longitudinal and lateral bending/torsion natural coupled modes of vibration coexist at low frequencies, with a relevant contribution of the piers and access ramps deformation. This leads to a significant three-dimensional and rather complex dynamic response under service conditions. With the aim of characterising the structural dynamic properties and assessing the level of vibrations induced by crossing pedestrians, two in-situ experimental test programmes are conducted. On the one hand, the structural response is measured during several hammer tests and the modal properties are identified and used to update a detailed 3D numerical model by means of a Genetic Algorithm. Due to the lack of information regarding the detailing of the piers foundations, two alternative models are analysed. The relevance of the pier-foundation system rotational stiffness is highlighted for the particular configuration. On the other hand, the footbridge main span response is recorded under different pedestrian activities: walking, running and vandal simulated actions. Finally, the vibration serviceability of the structure is assessed based on current codes and regulations. [ABSTRACT FROM AUTHOR]

Uneven road surfaces are the primary source of excitation in the dynamic interaction between a bridge and a vehicle and can lead to errors in bridge weigh-in-motion (B-WIM) systems. In order to correctly reproduce this interaction in a numerical model of a bridge, it is essential to know the magnitude and location of the various roadway irregularities. This paper presents a methodology for measuring the 3D road surface using static terrestrial laser scanning and a numerical model for simulating vehicle passage over a bridge with a measured road surface. This model allows the evaluation of strain responses in the time domain at any bridge location considering different parameters such as vehicle type, lateral position and speed, road surface unevenness, bridge type, etc. Since the time domain strains are crucial for B-WIM algorithms, the proposed approach facilitates the analysis of the different factors affecting the B-WIM results. The first validation of the proposed methodology was carried out on a real bridge, where extensive measurements were performed using different sensors, including measurements of the road surface, the response of the bridge when crossed by a test vehicle and the dynamic properties of the bridge and vehicle. The comparison between the simulated and measured bridge response marks a promising step towards investigating the influence of unevenness on the results of B-WIM. [ABSTRACT FROM AUTHOR]

It is a well-accepted hypothesis that deep-mantle primary plumes originate from a buoyant source layer at the core–mantle boundary (CMB), where Rayleigh–Taylor instabilities (RTIs) play a key role in the plume initiation process. Previous studies have characterized their growth rates mainly in terms of the density, viscosity and layer-thickness ratios between the denser overburden and the source layer. The RTIs, however, develop in the presence of global flows in the overlying mantle, which can act as an additional factor in the plume mechanics. Combining 2-D computational fluid dynamic (CFD) model simulations and a linear stability analysis, this paper explores the influence of a horizontal global mantle flow in the instability dynamics. Both the CFD simulation results and analytical solutions reveal that the global flow is a dampening factor in reducing the instability growth rate. At a threshold value of the normalized global flow velocity, short- as well as long-wavelength instabilities are completely suppressed, allowing the entire system to advect in the horizontal direction. Using a series of real-scale numerical simulations, this paper also investigates the growth rate  as a function of the density contrast, expressed in Atwood number |${A}_T = ({{{\rho }_1 - {\rho }_2}})/({{{\rho }_1 + {\rho }_2}})$|⁠ , and the viscosity ratio |$\ {\mu }^* = \ {\mu }_1/{\mu }_2$|⁠ , where |${\rho }_1,\ {\mu }_{1\ }$| and |${\rho }_{2,}\ {\mu }_{2\ }$| are densities and viscosities of the overburden mantle and source layer, respectively. It is found that increase in either |${A}_T$| or |${\mu }^*$| promotes the growth rate of a plume. In addition, the stability analysis predicts a nonlinearly increasing RTI wavelength with increasing global flow velocity, implying that the resulting plumes widen their spacing preferentially in the flow direction of kinematically active mantle regions. The theory accounts for additional physical parameters: source-layer viscosity and thickness in the analysis of the dominant wavelengths and their corresponding growth rates. The paper finally discusses the problem of unusually large inter-hotspot spacing, providing a new conceptual framework for the origin of sporadically distributed hotspots of deep-mantle sources. [ABSTRACT FROM AUTHOR]

The review paper analyses and compares numerical modelling techniques for Ultra High Performance Concrete (UHPC) and Textile Reinforced Concrete (TRC). The paper evaluates various approaches used for structural analysis and design, including element analysis, discrete element Modelling (DEM), and computational fluid dynamics (CFD). FEA, demonstrated in fracture analysis, dynamic response, bond-slip analysis, and blast resistance, shows remarkable accuracy, reaching up to 24%. DEM contributes significantly, with improvements in predicting packing density, abrasion resistance, and strain hardening ranging from 15% to 30%. CFD proves vital for UHPC and TRC analysis, achieving accuracies of up to 30% in flow behaviour, blast response, and fluid-structure interaction. Multi-scale Modelling emerges as a crucial tool, with achievements like a 25% improvement in predicting macroscopic deformation. However, challenges persist in Modelling fiber-reinforced and high-strength concrete materials due to their complex behaviour and heterogeneity. The review paper identifies opportunities for future research in advanced multi-scale Modelling approaches, integrating machine learning algorithms, fractal geometry, and advanced numerical models to address these challenges and enhance accuracy in predicting material properties and behaviour. [ABSTRACT FROM AUTHOR]

The 2014 San Leo landslide is a very peculiar landslide, being controlled by a large number of factors that interacted with each other; each one was in turn critical in driving, promoting, or allowing the slope failure. In the ten years after the landslide event, numerous studies were presented in the form of national and international journal articles, conference proceedings, as well as unpublished technical reports. These projects allowed different aspects and mechanisms to be investigated, progressively enhancing our understanding of the landslide. In this paper, we summarize, review, and discuss the various numerical modelling analyses that have been conducted, in order to outline the foundations on which future investigations may be designed. Considering the in depth understanding that has been gained on the geological, lithological, environmental, and engineering aspects of this site, we suggest that the San Leo plateau may be an ideal engineering geological field laboratory useful in investigating the evolution and instability phenomena that affect sites with similar characteristics within the Marecchia Valley region and beyond. [ABSTRACT FROM AUTHOR]

Copyright of Buletinul AGIR is the property of Asociatia Generala a Inginerilor din Romania and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)