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ABSTRACT This paper introduces a novel approach that combines proper orthogonal decomposition (POD) with thermodynamics‐based artificial neural networks (TANNs) to capture the macroscopic behavior of complex inelastic systems and derive macro‐elements in geomechanics. The methodology leverages POD to extract macroscopic internal state variables from microscopic state information, thereby enriching the macroscopic state description used to train an energy potential network within the TANN framework. The thermodynamic consistency provided by TANN, combined with the hierarchical nature of POD, allows to reproduce complex, nonlinear inelastic material behaviors, as well as macroscopic geomechanical systems responses. The approach is validated through applications of increasing complexity, demonstrating its capability to reproduce high‐fidelity simulation data. The applications proposed include the homogenization of continuous inelastic representative unit cells and the derivation of a macro‐element for a geotechnical system involving a monopile in a clay layer subjected to horizontal loading. Eventually, the projection operators directly obtained via POD are exploited to easily reconstruct the microscopic fields. The results indicate that the POD‐TANN approach not only offers accuracy in reproducing the studied constitutive responses, but also reduces computational costs, making it a practical tool for the multiscale modeling of heterogeneous inelastic geomechanical systems. [ABSTRACT FROM AUTHOR]

Pile foundations supporting wind turbines, silos, elevated water tanks or bridge piers are frequently subjected to multi-component loads, which may lead to significant rotations and settlements compromising the safe operation of the structure. The prediction of these displacements is of major concern and can be easily carried out using force-resultants plasticity models, also referred to as 'macro-elements', stemming from the idea of describing the foundation behaviour by a single upscaled constitutive relationship between generalized forces and displacements. When properly formulated, they can reproduce key aspects of the mechanical response of the foundation at low computational cost as compared to numerical analysis. To this end, a new macro-element for pile groups formulated in the classical framework of strain-hardening elasto-plasticity is presented and discussed. The required model parameters can be calibrated by closed-form equations and additional few data of numerical and/or experimental nature. The proposed mathematical framework is finally validated against the results of centrifuge tests and 3D finite element analyses. [ABSTRACT FROM AUTHOR]

Previous plasticity models for predicting anchor kinematics under eccentric loading in clay are mostly rigid plastic. They may produce inaccurate outcomes in some conditions. This paper presents an elastoplastic model to address this issue. Closed-form solutions for anchor velocities are derived considering two types of boundary conditions: the padeye (1) fastened to a mooring chain, with the chain behavior modeled; or (2) hinged to a rigid rod. Compared with previous methods, the proposed method more realistically captures the soil behavior while avoiding complicated iterative procedures for solving anchor velocities, thus enabling anchor trajectories to be accurately and efficiently obtained by simple time integration. A series of 3D large deformation finite element analyses are conducted to study the anchor behaviors under different eccentric loading, and the proposed model is used to reproduce these simulations. Their results are compared for validation, with good agreements achieved. These results indicate that anchors under eccentric loading will ultimately translate along a fixed direction with constant soil reaction forces. Analytical solutions for this ultimate state are given based on the proposed method. Particularly, the ultimate resultant soil reaction force is demonstrated always passing through the anchor center. This is an assumption in a previous literature but is found to be a consequence of the proposed anchor constitutive relations. [ABSTRACT FROM AUTHOR]

This paper presents a new finite element framework for seismic analysis of IABs (and other similar structures) on vertical and batter piles that takes into account nonlinear soil‐structure interaction. A previously developed macro‐element and linear impedance matrix are implemented in a time and modal domain solution, respectively. Detailed pseudo‐codes describing the implementation strategy for the macro‐element are provided. The solutions are validated using rigorous numerical models constructed in OpenSees MP. The software is further demonstrated by performing an extensive set of incremental dynamic analyses, where the effect of linear and nonlinear SSI, batter angle, pile spacing and asymmetric configuration is addressed and discussed. [ABSTRACT FROM AUTHOR]

In this paper, an advanced rheological model for impacts of ellipsoidal blocks on deformable ground surfaces, introducing the effects of block eccentricity and orientation at impact, is presented. This allows us to assess impact penetration and force, restitution coefficients, and block trajectories. A parametric analysis was carried out by considering different block aspect ratios, impact angles and initial block orientations at impact. The results are presented in terms of restitution coefficients, penetration and force time histories, maximum penetration depth, maximum force and rotational/total kinetic ratios. Impacts along the major block axis, versus those along minor axis, are characterized by larger penetrations (ranging from 3.3 to 50%), shorter impact durations (ca 50%) and very slightly larger vertical forces (ranging from 0.3 to 60%) according to the model parameter used. In contrast, the impact angle is shown to strongly affect maximum penetration and force values, and markedly increase rotation at impact. Analogously, normal restitution coefficient is severely dependent on impact angle, with a variation of more than two orders of magnitude. A mathematical expression for computing the energetic restitution coefficient from the normal and tangential apparent restitution coefficients and the ratio between the rotation and total kinetic energy is proposed. This overcomes the drawback of classical restitution coefficients greater than one when a change in block rotation occurs allowing us to bracket the coefficient of restitutions values to support and improve classical rock fall simulations also highlighting their intrinsic limitations. Finally, the effects of block geometry and initial angular velocity on rockfall simulations were analyzed by implementing the approach in the HyStone simulation code. The simulated frequencies of the maximum height during each ballistic trajectory follow an exponential distribution, whereas those for normal and tangential apparent restitution coefficients follow normal distributions. Highlights: A new rheological model for impacts of ellipsoidal blocks is formulated. The model provides impact variables for different impact angles, initial orientations and block shape. Model results are used to compute restitution coefficients. Rockfall numerical simulations with HyStone implementing the extended impact model are performed. Statistical distributions of the normal and tangential apparent restitution coefficients are examined. [ABSTRACT FROM AUTHOR]

In recent years, interest in adhesive bonding has grown as it can be considered an efficient solution in terms of strength‐to‐mass ratio when applied to lightweight structures or an interesting solution to complement conventional technologies. The study of bonded adhered joints is carried out using a technique based on the macro‐element method (ME), the ME shape functions are modeled using Taylor expansion power and Fourier expansion series. The purpose of this work is to compare the stiffness matrix obtained first from the entire Taylor series and then with the entire Fourier series. The method has been developed so far for 1D‐bar and 1D‐beam kinematics frameworks. [ABSTRACT FROM AUTHOR]

This article focuses on the description of material properties of segments of masonry structures in three-dimensional analyses. It mainly considers degraded and damaged multi-leaf masonry walls. In the beginning, the causes of degradation and damage to masonry are described with examples. It was reported that the analysis of such structures is difficult due to the adequate description of the mechanical properties in the individual segments of the structure and the amount of computational cost of large three-dimensional structures. Next, a method of describing large fragments of masonry structures by means of macro-elements was proposed. The formulation of such macro-elements in three-dimensional and two-dimensional problems was given by introducing limits of variation in material parameters and damage of structures expressed by the limits of integration of macro-elements with specified internal structures. Then, it was stated that such macro-elements can be used to build computational models by the finite element method, which allows the analysis of the deformation–stress state, and at the same time, reduce the number of unknowns in such issues. A strategy for performing analyses and examples of practical applications in masonry analyses were proposed. It was reported that the results of the analyses can be used to plan the repairs and strengthening of structures. Finally, the conducted considerations and proposals were summarised, as well as examples of practical applications. [ABSTRACT FROM AUTHOR]

Prior to implementing retrofitting measures for seismic action, it is necessary to evaluate the global capacity of unreinforced masonry (URM) buildings. Even with simplified assumptions, equivalent frame (EF) modeling adequately captures global responses and failure mechanisms in existing buildings, making it a popular modeling strategy among structural engineers. However, macro‐elements employed in the EF modeling of URM walls consider in‐plane (IP) and out‐of‐plane (OP) behaviors separately by decoupling their interaction and require independent verification for OP failure involving limit analysis. Such decoupling of interaction is justifiable if proper wall‐wall/wall‐floor connections and rigid‐diaphragm action of slabs are ensured; however, OP failure is likely a result of inadequate connections. Multiple components of ground motion excitation and plan eccentricity in buildings can activate bidirectional interaction in such circumstances. Due to OP damage, the interaction reduces the full IP strength of a URM wall, resulting in overestimating its lateral capacity. This paper proposes a frame‐like 3D macro‐element incorporating the effect of OP action on the IP shear response of URM piers under static and monotonic lateral loads. Only two parameters modifying IP shear stiffness and capacity are required to account for the interaction. Analytical expressions for the interaction parameters are proposed from a detailed micro‐modeling study. The paper also demonstrates, within the EF modeling, the applicability of the proposed macro‐element for seismic analysis of regular URM shear walls with openings. [ABSTRACT FROM AUTHOR]

This paper presents a novel macro‐element for vertical and batter pile groups. The numerical scheme is based on de‐coupled, single pile response. Each pile consists of two separate load‐displacement formulations (axial and transverse) that take a displacement increment as input and return a diagonal tangent stiffness value. The effect of rotation is implicitly incorporated in the transverse load‐displacement formulation. The presented macro‐element does not require pre‐defined failure surfaces or other parameters, and is therefore not restricted to a specific foundation configuration, soil profile or soil type. The macro‐element may be calibrated using any type of non‐linear pile‐soil model. The developed macro‐element is validated using rigorous numerical models for a variety of configurations. [ABSTRACT FROM AUTHOR]

The depth distribution of soil properties are governed by several interacting factors including land use types (LUT) and agro-climate (AgC) factors. Yet, there is little information on the effects of LUT, AgC and their combination on soil properties along depth, which this study aimed to investigate. We collected a total of 36 composite soil samples using the manual percussion of a steel core tube layer by layer vertically up to 30 cm in sites representing both highland and lowlands, and analyzed for selected soil properties. A significant main effects of LUT on the depth distribution of bulk density (BD), Ca, Na, K and Cu, and AgC on soil texture, pH, EC, Ca, Na, K, P, Mn, Fe and Cu were noted. The two-way ANOVA analysis also revealed the significant effects of both LUT and AgC on the depth distribution of BD, Na, K, Cu and EC, reflecting their influences on the paths associated to bio-geo-recycling processes. Compared to crop and forestlands, the average SOC and Fe were lower while EC, CEC, Ca, Na, K, P, Mn and Zn were higher in homegarden located in highland than lowland, possibly the acid nature of the highland soil may make the extractable cations available. SOC was not significantly influenced by AgC, LUT and their interaction effect. Based on the Elemental Enrichment Ratio (EER), the SOC was concentrated in the upper surface soil in forest and cropland located both in highland (1.79, 1.33) and lowland (1.80, 1.57), respectively. The reverse propagation pattern SOC depth distribution in soils under homegarden with EER of 0.7 (highland) ad 0.8 (lowland) showed that implementing such system can accelerate carbon sinking and safely store it in subsoil. Also, diversified species composition associated with respective root architectures in the homegarden system, make it an efficient soil nutrient management, which should be widely promoted.

An extended formulation of the macro-element (ME) based models, representing for both adherends and adhesive along the entire overlap in only one four-node element, is presented. Compared to earlier modelling, continuum ME (CME) and discrete ME (DME) based models, the adherend parts are also modelled as plane continuum media, for which high order displacement fields are freely supposed. Both extended CME (ECME) and extended DME (EDME) based modelling can have their displacement field orders of each continuum layer be set individually, and can be enriched using springs for interfaces or boundary conditions modelling, allowing the stresses to vanish at the free edges. The methodology and formulation of the stiffness matrix for both the adherend without adhesive and the bonded overlap is presented. The assessment is performed for a single-lap joint geometry by comparison results from a plane strain finite element (FE) model with extended ME-based models. Good agreements are shown for both thin and thick adhesive case studies. • Extended formulation of discrete and continuum macro-element using polynomial series, under plane stress or strain conditions. • Influence of kinematics expansion order on the adhesive and adherends stress distribution for a single lap bonded joint. • Enrichment of models with springs for interfaces or boundary conditions modelling. • Natural behaviour of stresses at free edges, along the x-axis. [ABSTRACT FROM AUTHOR]

Large areas of farmland soil in southern China are deficient in potassium (K) and are contaminated with cadmium (Cd). Previously, we suggested that the K supplementation could reduce Cd accumulation in sweet potatoes (Ipomoea batatas (L.) Lam). In the present study, we investigated the underlying physiological and molecular mechanisms. A hydroponic experiment with different K and Cd treatments was performed to compare the transcriptome profile and the cell wall structure in the roots of sweet potato using RNA sequencing, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The results showed that K supply inhibits the expressions of IRT1 and YSL3, which are responsible for root Cd uptake under Cd exposure. Furthermore, the expressions of COPT5 and Nramp3 were downregulated by K, which increased Cd retention in the root vacuoles. The upregulation of POD, CAD, INT1 and SUS by K contributed to lignin and cellulose biosynthesis and thickening of root xylem cell wall, which further reduced Cd translocation to the shoot. In addition, K affected the expressions of LHT, ACS, TPS and TPP associated with the production of ethylene and trehalose, which involved in plant resistance to Cd toxicity. In general, K application could decrease the uptake and translocation of Cd in sweet potatoes by regulating the expression of genes associated with Cd transporters and root cell wall components.

This manuscript presents a simplified approach to adhesive joints calculation. Aviation and space rocket engineering constructions joints deals with coaxial cylindrical pipes that can be connected by adhesive with advantages in terms of tightness, aerodynamic efficiency, manufacturability, low weight. Glue joints are, therefore, considered and simplified in this article by the analytical calculation of the shape functions for a macro-element applied to the Volkersen's theory. The mathematical solution makes possible to calculate the explicit form of the stiffness matrix of the macro-element. The analysis proposed shows the perfect matching of the solution for a single element under classical mechanical loads. [ABSTRACT FROM AUTHOR]

Masonry infill walls are among the most vulnerable components of reinforced concrete (RC) frame structures. Recently, some techniques for enhancing the performance of the infills have been proposed, aiming at improving both the global and the local behaviour of the infilled frame structure. Among the most promising ones, there are those that aim to decouple or reduce the infill‐frame interaction by means of flexible or sliding joints, relying respectively on rubber or low‐friction materials at the interface between horizontal subpanels or between the panels and the frame. Numerous models have been developed in the last decades for describing the seismic response of masonry‐infilled RC frames, but these have focused mainly on the case of traditional infills. This study aims to fill this gap by proposing a two‐dimensional macro‐element model for describing the in‐plane behaviour of RC infilled frames with flexible or sliding joints. The proposed modelling approach, implemented in OpenSees, is an extension of a discrete macro‐element previously developed for the case of traditional infill panels. It is calibrated and validated in this study against quasi‐static tests from the literature, carried out on masonry‐infilled RC frames with sliding and rubber joints. The study results show the capabilities of the proposed modelling approach to evaluate the benefits of using flexible joints in terms of minimising the negative effects of the interaction between infill and RC frame and limiting the increase of global stiffness of the system with respect to the bare frame condition. [ABSTRACT FROM AUTHOR]

The structural assessment of existing historical structures is a complex task due to the inner main difficulty in making up reliable models for structural analysis, able to include mechanical and geometrical nonlinearities, existing damage, complex configurations and arrangements of materials. This task becomes more difficult in mixed RC-masonry structures, which structural modelling can be particularly tough due to the different connections and interactions between structural members and materials. This paper presents the case study of a multi-storey mixed Reinforced Concrete (RC)-masonry historical structure, namely the former mill "Molino-Pastificio Soresi" building, located in Partinico (Sicily—Italy). It is shown as it is possible to obtain an accurate and detailed representation of the building, as well as a reliable structural model. The assessment of the seismic vulnerability from the global point of view of the considered case study is carried out through a multidisciplinary approach based on four stages: (1) historic analysis and study of the relevance of the building; (2) geometrical survey and photographic documentation; (3) structural identification and materials; (4) BIM implementation and structural modelling. [ABSTRACT FROM AUTHOR]

Typha domingensis is an invasive aquatic weed species dominating floodplains/wetlands, grazing and farmlands in the savannah zones of Nigeria, particularly in states like Jigawa, Kano and Yobe. This affects agricultural activities which threatens socio-economic developments in the region. Plants serve as a major source of food for both human as well as other animals. In this study, the nutritional value of this aquatic weed was assessed for use as an alternative fodder in relation to some common livestock fodder. Seedlings of Typha domingensis were collected from a harvested plot of Typha invaded area. Samples were air dried and then ground for determination of macro-elements and proximate composition using standard procedures. Results on the proximate composition revealed 80.01% moisture content, 11.68% ash content, 2.90% crude protein, 8.30% crude lipid and 6.90% crude fiber. The percentage of macronutrients determined which include Ca, Mg, K, Na, P, S and Cl were 0.93, 0.36, 0.12, 0.02, 0.11, 0.01 and 0.04 respectively. From the values obtained, the proximate composition of T. domingensis was relatively low, although the moisture and ash content were comparable to some fodder species. However, other important criterion such as crude protein; crude fiber and nearly all the macro-nutrients have low concentration. Hence T. domingensis is considered to have low nutritional value and cannot be effectively used as an alternative of fodder/forage in the affected areas. [ABSTRACT FROM AUTHOR]

The effective differentiation between global and local modes plays a fundamental role in the selection and application of the most appropriate seismic analysis procedures. This is particularly relevant in the case of historical heritage structures and ensembles of buildings in old city centres: due to the complexity of the structural scheme, the stratification of interventions, and the irregularity of the structural configuration with the absence of seismic details, several local modes frequently characterize the dynamic response of those structures. Distinguishing local and global modes might be challenging even from the experimental point of view in the presence of few measured degrees of freedom. Nevertheless, an accurate analysis of local modes can support the identification of macro-elements and the selection of the most appropriate analysis procedure. The present paper illustrates an original approach addressing the differentiation between global and local modes through the spatial correlation of modal displacements. The proposed approach can be either automated and integrated into software for structural analysis or applied in the context of an experimental campaign, and its application to simulated case studies is discussed. [ABSTRACT FROM AUTHOR]

Featured Application: The macro–element formulated in the study can be implemented in any FE–based software for the static (quasi–) and dynamic analysis of masonry structures. It assures an attractive computational cost and accuracy level with respect to standard continuous FE models. A Finite Element (FE) based macro–element is described for the mechanical response of masonry structures within different ranges of analysis. The macro–element is composed of discrete rigid quadrilateral FE plates whose adjoining interfaces are connected through FE trusses. It allows representing both elasticity and strength orthotropy, full material nonlinearity and damage through a scalar–based model. The possibility of coupling with a so–called FE2 (multi–scale) strategy is also addressed. Validation of the macro–element is conducted within linear static, vibration, and cyclic (nonlinear) problems, in which both static and dynamic ranges are explored. Results are compared with those retrieved from traditional FE continuous models. Advantages are highlighted, as well as its robustness to cope with convergence issues and suitability to be applied within more general and larger–scale scenarios, such as the analysis of anisotropic materials subjected to static and dynamic loading. Formal details are given for its reproducibility by academics and practitioners—eventually within other FE platforms—as the improved running times may be of utmost importance in dynamic problems or highly nonlinear (material) quasi–static analysis. [ABSTRACT FROM AUTHOR]

The severity of climate causes biochemical and nutritional changes in plants. Our study focuses on the adaptation of the olive tree to the climatic conditions by the improvement of essential oils, polyphenols and macro-elements synthesis in leaves, stems and roots of Meski, growing under various bioclimatic zones of Tunisia (North, Centre and South). The mineral content was determined using a flame photometer and the volatile components were analyzed by GC-FID and GC-MS. Meski cultivar resists to severe climatic conditions, in maintaining its nitrogen content almost constant in leaf and wood for all studied areas. Moreover, leaves showed richness in calcium and sodium than roots for all areas. The GC-MS analysis of Meski leaves allowed the identification of fifty seven components. The main constituents were (E)-β-damascenone, nepetalactone, geranic acid, (E)-β-damascone, (E)-nerolidol, (E)-2-decenal whose levels varied significantly with climate conditions. In fact, to adapt to the severity of climate, southern Meski leaves produced more essential oils and polyphenols than the northern ones. Therefore, the increase of essential oils and polyphenols can be considered as a response of the tree to surround aggressions and to oppose the oxidative stress that results from the severity of climatic conditions, characteristic of the southern area. [ABSTRACT FROM AUTHOR]

Nutrient manipulation is a promising strategy for controlling plant diseases in sustainable agriculture. Although many studies have investigated the relationships between certain elements and plant diseases, few have comprehensively explored how differing mineral nutrition levels might affect plant–fungal pathogen interactions, namely plant susceptibility and resistance. Here, we systematically explored the effects of the seven mineral elements that plants require in the greatest amounts for normal development on the susceptibility of soybean plants (Glycine max) to Fusarium oxysporum infection in controlled greenhouse conditions. Nitrogen (N) negligibly affected plant susceptibility to infection in the range 4 to 24 mM for both tested soybean cultivars. At relatively high concentrations, phosphorus (P) increased plant susceptibility to infection, which led to severely reduced shoot and root dry weights. Potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), and iron (Fe) induced plant resistance to infection as their concentrations were increased. For K and Ca, moderate concentrations had a positive effect on plant resistance to the pathogen, whereas relatively high doses of either element adversely affected plant growth and promoted disease symptoms. Further experiments were conducted, assessing disease suppression by selected combinations of macro-elements and Fe at screened concentrations, i.e., K (9 mM) plus Fe (0.2 mM), and S (4 mM) plus Fe (0.2 mM). The disease index was significantly reduced by the combination of K plus Fe. In conclusion, this systematic investigation of soybean plant responses to F. oxysporum infection provides a solid basis for future environmentally-friendly choices for application in soybean disease control programs.

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Composite stepped repairs can achieve high strength recovery without the addition of bolts or fasteners to the structure. They are therefore a major issue in the field of aerospace composite structure damage repair. However, there is no standardized method to design this type of repairs. Many analytical, semi-analytical and finite element models were proposed throughout the years to predict the strength of stepped repairs, using various hypotheses and simplifications. The aim of this paper is to investigate the influence of modelling hypotheses on stress distribution and strength prediction of composite stepped repairs. Five simplified stepped joint models using macro-element (ME) modelling and finite element method (FE) are compared to a full 3D FE model of a stepped repaired panel. The influence of step length and adhesive fracture toughness was investigated to determine the field of validity of each model. Among FE models, it was shown that modelling the equivalent joint under 2D generalized plain strain gives a very close strength prediction to the 3D stepped repair model while saving computation time. Simplified macro-element models under bar or beam hypotheses are fairly close to the results of FE modelling, but the deviation between those and FE is sensitive to step length and adhesive fracture toughness. [ABSTRACT FROM AUTHOR]

The structural assessment of existing historical structures is a complex task due to the inner main difficulty in making up reliable models for structural analysis, able to include mechanical and geometrical nonlinearities, existing damage, complex configurations and arrangements of materials. This task becomes more difficult in mixed RC-masonry structures, which structural modelling can be particularly tough due to the different connections and interactions between structural members and materials. This paper presents the case study of a multi-storey mixed Reinforced Concrete (RC)-masonry historical structure, namely the former mill “Molino-Pastificio Soresi” building, located in Partinico (Sicily—Italy). It is shown as it is possible to obtain an accurate and detailed representation of the building, as well as a reliable structural model. The assessment of the seismic vulnerability from the global point of view of the considered case study is carried out through a multidisciplinary approach based on four stages: (1) historic analysis and study of the relevance of the building; (2) geometrical survey and photographic documentation; (3) structural identification and materials; (4) BIM implementation and structural modelling.

Summary: This work proposes a mechanical‐probabilistic formulation of the soil–structure interaction, taking into account the variability of the mean velocity of shear wave seismic load. This work aims at studying the sensitivity of the seismic response of a reinforced concrete frame structure by accounting for different seismic scenarios. For this purpose, the simplified model of a two‐story structure system has been developed. This model is based both on a macro‐element approach and on a stochastic collocation method. The sensitivity of the maximum displacement of the structure under different average shear wave velocities is studied. This aim in view, Gaussian or lognormal random variables are arbitrarily chosen to model this velocity. Analysis of the seismic vulnerability of the soil–structure system leads to cumulative distribution functions, which sometimes show significant differences for the same soil class in the sense of the European standard for the design of structures for earthquake resistance. [ABSTRACT FROM AUTHOR]

A Finite Element (FE) based macro–element is described for the mechanical response of masonry structures within different ranges of analysis. The macro–element is composed of discrete rigid quadrilateral FE plates whose adjoining interfaces are connected through FE trusses. It allows representing both elasticity and strength orthotropy, full material nonlinearity and damage through a scalar–based model. The possibility of coupling with a so–called FE2 (multi–scale) strategy is also addressed. Validation of the macro–element is conducted within linear static, vibration, and cyclic (nonlinear) problems, in which both static and dynamic ranges are explored. Results are compared with those retrieved from traditional FE continuous models. Advantages are highlighted, as well as its robustness to cope with convergence issues and suitability to be applied within more general and larger–scale scenarios, such as the analysis of anisotropic materials subjected to static and dynamic loading. Formal details are given for its reproducibility by academics and practitioners—eventually within other FE platforms—as the improved running times may be of utmost importance in dynamic problems or highly nonlinear (material) quasi–static analysis.

Adhesively bonded joints are often addressed through Finite Element (FE). However, analyses based on FE models are computationally expensive, especially when the number of adherends increases. Simplified approaches are suitable for intensive parametric studies. Firstly, a resolution approach for a 1D-beam simplified model of bonded joint stress analysis under linear elastic material is presented. This approach, named the macro-element (ME) technique, is presented and solved through two different methodologies. Secondly, a new methodology for the formulation of ME stiffness matrices is presented. This methodology offers the ability to easily take into account for the modification of simplifying hypotheses while providing the shape of solutions, which reduced then the computational time. It is illustrated with the 1D-beam ME resolution and compared with the previous ones. Perfect agreement is shown. Thirdly, a 1D-beam multi-layered ME formulation involving various local equilibrium equations and constitutive equations is described. It is able to address the stress analysis of multi-layered structures. It is illustrated on a double lap joint (DLJ) with the presented method. [ABSTRACT FROM AUTHOR]

This paper presents the development, implementation, and validation of a macro-element suitable for the linear analysis of innovative 3D plug-and-play joints between tubular columns and lightweight steel truss-girders. The macro-element is based on the component method, accounts for the three-dimensional interaction between the tube faces, and its components have a clear physical meaning. Simplified procedures are developed for the closed-form computation of the stiffness matrix of the macro-element based on the geometric and mechanical properties of the nodal zone. This facilitates practical application in everyday design scenarios. Furthermore, the macro-element's architecture is implemented in the framework of OpenSees as a standalone beam-to-column joint finite element. Validation of the conceptual design is accomplished through parametric studies, comparing its performance with models generated in higher-order finite element commercial software, Abaqus. This research offers a valuable resource for the linear analysis and design of innovative 3D plug-and-play joint connections in structural engineering, enhancing efficiency and reliability in construction practices. • Created a macro-element for linear analysis of innovative plug-and-play steel joints. • Accounted for 3D tube face interactions in component-based macro-element design. • Implemented the macro-element as a stand-alone beam-to-column joint FE in a software. • Validated the beam-to-column joint FE against higher-order FE models. [ABSTRACT FROM AUTHOR]

A methodology for the formulation of the stiffness matrix of an enriched finite element, called continuum macro-element (CME), representing for the full length of a bonded overlap and both the adhesive and the adhesive in only one four-node elements, is presented. Compared to earlier macro-elements modelling the bonded overlap as beams on elastic foundation, the CME supposed the adherends and the adhesive as plane continuum media, for which higher-order displacement fields is supposed for the adhesive. The formulation of the stiffness matrix for the adherend outside of the overlap is presented as well to address the stress analysis of single-lap bonded joint for assessment purpose. The assessment is performed by comparisons with the results from (i) a plane strain finite element and (ii) two recent papers by Nguyen and Le Grognec (2021) and Methfessel and Becker (2022). Good agreements are shown. [ABSTRACT FROM AUTHOR]

Abstract The interest in functionally graded adhesive (FGA) joints has been increasing in recent years. For example, FGAs offer the opportunity to optimize the strength of multi-material bonded joints by locally tailoring the adhesive properties and without modifying the design of the adherends to be joined. The development of dedicated stress analyses to predict the stress distribution is then of the highest interest to control the strength of such joints. The Finite Element (FE) method is able to address the stress analysis of FGA joints but is computationally costly. Simplified stress analyses have then been developed. The objective of this paper is to assess the prediction of simplified stress analyses, solved through the macro-element (ME) technique, with respect to those of FE models. It is shown that the predictions of ME models are in a sufficient agreement with the FE models to be employed at a pre-sizing stage. The influence of the overlap length is then investigated by the means of the simplified stress analyses. A noticeable result is the existence of an overlap length for which the adhesive peak shear stress is minimal, in the 1D-bar kinematics framework. [ABSTRACT FROM AUTHOR]

Abstract The demand for designing lightweight structures without any loss of strength or stiffness has conducted many engineers and researchers to seek for alternative joining methods. In this context, adhesive bonding may appear as an attractive joining method. However the interest of adhesive bonding remains while the structural integrity of the joint is ensured. According to recent literature the cohesive zone model (CZM) appears as a suitable approach able to predict both static and fatigue strength of adhesively bonded joints. This approach of the fracture process of adhesive layers is based on the modeling of the adhesive mechanical behavior through a set of adhesive cohesive properties in either mode I, mode II or mixed-mode I/II. The strength prediction of adhesively bonded joints is then highly dependent on the CZM parameters. The methods used to experimentally characterize them are thus essential. A new methodology, termed direct method, is presented and tested. It is based on the measurement of displacement field of bonded adherends at the crack tip of classical specimens allowing for the loading of the adhesive layer in pure mode I, pure mode II and mixed-mode I/II. The tested adhesive is a methacrylate–based two-component adhesive paste found under the reference SAF30 MIB manufactured by AEC Polymers (ARKEMA group). The adherends are in aluminium 6060. It is shown that it is possible to characterize the cohesive properties of the adhesive layer using the direct method. The numerical tests involve both adherends and adhesive nonlinearities. Nevertheless, the presented experimental implementation passes by the development of a dedicated data pre-processing to interpret the experimental measurements, highlighting the significance of the choice of the measurement means linked to the design of specimen. [ABSTRACT FROM AUTHOR]

Abstract Published foundation models and procedures for calculation of caisson foundation response typically assume a rigid caisson in deformable soil. However, recent published measurement data from a prototype suction bucket jacket has revealed that the lid flexibility of the caisson foundations significantly influences the dynamic foundation stiffness felt by the jacket legs. This paper investigate this soil-structure-interaction problem and presents a modelling approach for including the effect of caisson flexibility in a macro-element. The macro-element, originally developed by assuming a rigid foundation, was modified by included a stiffness correction and a procedure to account for changes in the elastic coupling between horizontal load and moment due to the caisson flexibility. The modified macro-element successfully re-produced the response to general load paths computed by geotechnical finite element analyses, where the foundation was modelled in detail with structural elements and the surrounding soil was represented by continuum elements. The general principles behind the modification is generic in the sense that it can be implemented in other foundation models. Highlights • Caisson flexibility may significantly influence the is foundation stiffness felt by above structure. • Caisson flexibility may significantly influence the coupling between moment and horizontal load. • The caisson flexibility can be implemented as a series coupled three-dimensional spring. • The series coupled extension are implemented in a macro-element in the paper and the approach can be used with other models. • Appropriate sub-modelling can be used for streamlining the computation of caisson flexibility in design. [ABSTRACT FROM AUTHOR]

Abstract Functionally graded adhesive (FGA) joints involve a continuous variation of the adhesive properties along the overlap allowing for the homogenization of the stress distribution and load transfer, in order to increase the joint strength. The use of FGA joints made of dissimilar adherends under combined mechanical and thermal loads could then be an attractive solution. This paper aims at presenting a 1D-bar and a 1D-beam simplified stress analyses of such multimaterial joints, in order to predict the adhesive stress distribution along the overlap, as a function of the adhesive graduation. The graduation of the adhesive properties leads to differential equations which coefficients can vary the overlap length. For the 1D-bar analyses, two different resolution schemes are employed. The first one makes use of Taylor expansion power series (TEPS) as already published under pure mechanical load. The second one is based on the macro-element (ME) technique. For the 1D-beam analysis, the solution is only based on the ME technique. A comparative study against balanced and unbalanced joint configurations under pure mechanical and/or thermal loads involving constant or graduated adhesive properties are provided to assess the presented stress analyses. The mathematical description of the analyses is provided. [ABSTRACT FROM AUTHOR]

This article presents the identification of dynamic properties of a stone masonry building, followed by numerical simulation of its dynamic response accounting for soil-foundation-structure interaction. The first part regards numerical simulations of the earthquake response of a two-story building prototype with timber floors, made of three-leaf stone masonry without laces. This 1:2 scale prototype was tested on a shaking table in its as-built state and after strengthening, at the National Technical University of Athens. Afterward, the building prototype was modeled with flat shell elements and equivalent frames (common frames and macro-elements), for an investigation of its linear and nonlinear seismic response, assuming base fixity. Numerical results were compared to the experimental ones, which yielded conclusions on the considerations of each employed modeling strategy, as well as its efficiency and applicability. The second part considers the effect of soil-structure interaction using appropriately modified foundation stiffness values to account for the foundation soil flexibility. Comparison of the numerical results with and without SSI effects showed how the flexibility of the soil-foundation system and the soil-structure interaction modified the system’s modal characteristics and response within the elastic range, in terms of both seismic loads and deformations, and produced conclusions about its consequences on the overall structural stability. [ABSTRACT FROM AUTHOR]

This paper focuses on the development of a new non-linear macro-element for the modelling of soil-foundation interaction. Material and geometrical nonlinearities (soil yielding and foundation uplift respectively) are taken into account in the present macro-element to examine the response of shallow foundations under monotonic and cyclic loads. Several applications of soil-foundation systems are studied. The results obtained from these applications are in very favourable agreement with those obtained through other numerical models in the literature. [ABSTRACT FROM AUTHOR]

Biochar which is intensively used in the issue of the struggle against global warming in recent years also enhances the physical, chemical and biological properties of the soil when it is added to the soil. With this study; the impact of the biochar applications (0%, 0.5%, 1%, 2%, 3%, 4% and 5% (v/v)) in different doses under the conditions with and without incubation on the yield of the chickpea plant and nutrient concentrations has been examined. The study has been carried out with three repetitions according to the experimental pattern of randomized blocks in the plastic pots with the capacity of 3 kg under the greenhouse conditions. The addition of biochar was made 60 days before the plantation of the herbs to the pots with incubation and watering has been made with pure water for 60 days. The dry matter production and nutrient concentrations have been determined in the plants harvested in the broad bean bonding period. The results of the study have shown that the application that increases the dry matter production of the chickpea plant most is the application of 3% biochar dose under the conditions with incubation (10.02 g pot-1). In addition; the biochar applications have decreased the uptake of other nutrient except for K and Zn under both the conditions with and without incubation. While 3% biochar application under the conditions with incubation and 4% biochar application without incubation have been the applications having the most significant impact on the Zn concentration of the chickpea plant respectively with 67.2 mg Zn kg-1 and 60.5 mg Zn kg-1, 2% biochar application has been the application which has had the most significant impact on the K concentration of the chickpea with respectively 2.81% K and 2.37% K under the conditions both with and without incubation. In addition; when the general averages in the study have been assessed, it has been determined that the biochar applications have more impact on the dry matter production of the chickpea plant and the concentrations of N, P, K, Zn and Mn according to the conditions without incubation. [ABSTRACT FROM AUTHOR]