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Long integral bridges experience an enhanced cyclic soil structure interaction with their granular backfills, especially due to seasonal thermal loading. For numerical modelling of this interaction behaviour under cyclic loading, it is important to employ a suitable constitutive model and calibrate it thoroughly. However, up to the present, experimental data and calibrated soil models for this purpose with focus on typical well-graded coarse-grained bridge backfill materials are rarely available in the literature. Therefore, one aim of this paper is to present results of a comprehensive cyclic laboratory testing programme on highly compacted gravel backfill material. Based on this, a hypoplastic constitutive model with intergranular strain extension for small strain and cyclic behaviour is calibrated and evaluated against the experimental test data. The soil model's abilities and limitations are discussed at element test level. In addition, cyclic FE analyses of an integral bridge are conducted with several hypoplastic parameter sets from the literature and compared to the calibrated gravel backfill material. The investigation highlights that poorly-graded sands show significantly smaller cyclic earth pressures compared to well-graded gravels intended for the backfilling of a bridge. The soil structure interaction behaviour is clearly governed by the general soil model stiffness, including the small strain stiffness. [ABSTRACT FROM AUTHOR]

A bounded version of the Lotka – Volterra model based on logistic differential equations is suggested to emulate cyclic behaviour in complex evolutionary and other systems. The model provides reasonable approximations for the so-called leaping cycles and other oscillational processes when the main state variables are limited by physical constraints. The model represents a basic model-building block that can be used in system dynamics and other frameworks and applications that require fundamental understanding and modelling of principal features of complex cyclic processes. Two application areas – technological progress and industrial safety – are specifically considered here. The model is shown to emulate techno-economic cycles reasonably well and give an appropriate qualitative description of risk and safety variations in the industrial environment. Simulations using the suggested model are quantitatively compared with the results of agent-based simulations. While a simple model cannot match all details of complex agent-based simulations of the risk and benefit dilemma, the bounded Lotka – Volterra model still gives a reasonable approximation of the process. The conceptual implications of the model are, nevertheless, significant, pointing to common cyclic mechanisms taking place in complex evolutionary systems that may belong to different branches of science. [ABSTRACT FROM AUTHOR]

Leaf springs are components of railway rolling stock made of high-strength alloyed steel to resist loading and environmental conditions. Combining the geometric notches with the high surface roughness of its leaves, fatigue models based on local approaches might be more accurate than global ones. In this investigation, the monotonic and fatigue behaviour of 51CrV4 steel for application in leaf springs of railway rolling stock is analysed. Fatigue models based on strain-life and energy-life approaches are considered. Additionally, the transient and stabilised behaviours are analysed to evaluate the cyclic behaviour. Both cyclic elastoplastic and cyclic master curves are considered. Lastly, different fatigue fracture surfaces are analysed using SEM. As a result, the material properties and fatigue models can be applied further in either the design of leaf springs or in the mechanical designs of other components made of 51CrV4 steel. [ABSTRACT FROM AUTHOR]

The fatigue performance of Laser Powder Bed Fusion manufactured 316L stainless steel is critical for cyclic loading applications. Additive manufacturing of 316L produces a characteristic microstructure consisting of grains with a fine cellular structure within. This microstructure shows a comparatively high fatigue strength combined with a high defect tolerance. The purpose of this paper is to numerically analyse the local response of this microstructure to cyclic loading and, in particular, the joint action between lack of fusion defects and the surrounding grain structure. The traditional incremental analysis method for polycrystalline alloys is computationally expensive. Therefore, a direct cyclic analysis combined with a phenomenological crystal plasticity model is used in this work to predict the stable cyclic response of the material, resulting in a much lower computational cost. Three statistically equivalent representative volume elements are generated. The considered crystal plasticity parameters are calibrated using experimental tensile stress–strain curves. The comparison with incremental analysis demonstrates the accuracy and efficiency of the proposed method. The shakedown limit, based on the maximum load that allows the convergent cyclic response, significantly depends on the local grain orientation around lack of fusion defects, revealing a reason for the large scatter in the fatigue strength.

Intra-oral food processing, including chewing, is important for safe swallowing and efficient nutrient assimilation across tetrapods. Gape cycles in tetrapod chewing consist of four phases (fast open and -close, and slow open and -close), with processing mainly occurring during slow close. Basal aquatic-feeding vertebrates also process food intraorally, but whether their chew cycles are partitioned into distinct phases, and how rhythmic their chewing is, remains unknown. Here, we show that chew cycles from sharks to salamanders are as rhythmic as those of mammals, and consist of at least three, and often four phases, with phase distinction occasionally lacking during jaw opening. In fishes and aquatic-feeding salamanders, fast open has the most variable duration, more closely resembling mammals than basal amniotes (lepidosaurs). Across ontogenetically or behaviourally mediated terrestrialization, salamanders show a distinct pattern of the second closing phase (near-contact) being faster than the first, with no clear pattern in partitioning of variability across phases. Our results suggest that distinct fast and slow chew cycle phases are ancestral for jawed vertebrates, followed by a complicated evolutionary history of cycle phase durations and jaw velocities across fishes, basal tetrapods and mammals. These results raise new questions about the mechanical and sensorimotor underpinnings of vertebrate food processing. This article is part of the theme issue 'Food processing and nutritional assimilation in animals'. [ABSTRACT FROM AUTHOR]

This article presents a novel magnetic pole repulsive damper (MPRD) incorporating neodymium magnetic repulsive blocks and springs. The study explores the mechanical properties of the springs and magnetic blocks through numerical simulations using ANSYS and experimental evaluation. To gain deeper insights into the behaviour of the MPRD, an accurate and high-fidelity finite element model was developed. The evaluation process involved a comprehensive comparison between the numerical simulations and experimental tests, explicitly focusing on cyclic compression-tension forces. The study encompassed the functioning, design implications, fabrication technique, mechanical performance, and numerical simulation for the cyclic compression-tension forces of the MPRD. The cyclic compression-tension tests revealed a gradual increase in force, with the MPRD achieving an ultimate force of 2,877 kN. The MPRD exhibited robust hysteresis behaviour in cyclic loading, showing its capacity to undergo and uphold the stability of the combination of its materials. The cyclic compression-tension results indicated the maximum force carrying capability of the damper. This resilience implies its full reusability in such scenarios. The comparison between cyclic compression-tension tests confirmed the alignment between the numerical simulation and experimental investigation. [ABSTRACT FROM AUTHOR]

This article presents a novel magnetic pole repulsive damper (MPRD) incorporating neodymium magnetic repulsive blocks and springs. The study explores the mechanical properties of the springs and magnetic blocks through numerical simulations using ANSYS and experimental evaluation. To gain deeper insights into the behaviour of the MPRD, an accurate and high-fidelity finite element model was developed. The evaluation process involved a comprehensive comparison between the numerical simulations and experimental tests, explicitly focusing on cyclic compression–tension forces. The study encompassed the functioning, design implications, fabrication technique, mechanical performance, and numerical simulation for the cyclic compression–tension forces of the MPRD. The cyclic compression–tension tests revealed a gradual increase in force, with the MPRD achieving an ultimate force of 2,877 kN. The MPRD exhibited robust hysteresis behaviour in cyclic loading, showing its capacity to undergo and uphold the stability of the combination of its materials. The cyclic compression–tension results indicated the maximum force carrying capability of the damper. This resilience implies its full reusability in such scenarios. The comparison between cyclic compression–tension tests confirmed the alignment between the numerical simulation and experimental investigation.

The paper analyses dynamical growth models predicting the cyclic development of investigated economic factors. The provided research deals with an optimal control problem based on the economic growth model with the production function of Cobb–Douglas type. Following the Pontryagin maximum principle, we derived the Hamiltonian system and conducted its qualitative analysis, which reveals conditions for the cyclic behaviour of the optimal solutions around the isolate steady state. Numerical experiments visually illustrated the obtained results by demonstrating a phase portrait corresponding to a steady state of the focal type. [ABSTRACT FROM AUTHOR]

In this paper, an anisotropic non-associative constitutive model, based on the well-established critical state soil mechanics framework, is developed for the natural and reconstituted clays subjected to monotonic and cyclic loadings. A robust non-elliptical yield surface is implemented in the model which enables it to capture a wide variety of yield stress points. In addition to a realistic soil stiffness simulation, the employed flexible plastic potential surface equips the proposed model to predict a more accurate coefficient of earth pressure at rest. The model uses a combination of conventional volumetric and comprehensive rotational hardening rules to control the evolution of the yield surface caused by plastic strain increments. The adopted rotational hardening rule uses the concept of governing plastic strain increment which not only ensures the existence of the equilibrium state of anisotropy but also takes the effect of plastic strains at different constant stress ratios into account more sensibly. The proposed model is enhanced with a novel double-image stress point bounding surface plasticity type theory to capture nonlinear behaviour inside the yield surface, and also to simulate the cyclic responses. The detailed model formulation is discussed in both triaxial stress space and the e - ln p plane, and the important features of the model are elaborately explored. The capabilities of the model are also demonstrated by an extensive sensitivity analysis. In the end, the model is used to carry out simulations of monotonic and cyclic element tests on different clays and the results are compared with the available experimental data. [ABSTRACT FROM AUTHOR]

The behaviour of seismically damaged steel joints with reduced beam section (RBS) at elevated temperatures has not been widely investigated yet. Therefore, the study summarized in this article aimed to (i) analyse the response of RBS joints at high temperatures and (ii) investigate the influence of plastic damage, due to cyclic loading, on the fire performance of the joints. A set of RBS joints with rib stiffeners on the both lower and upper beam flanges was designed according to European standards and the following parameters were considered: (i) location of the joint (i.e., internal or external joint) and (ii) reduction in the beam flexural resistance (i.e., 65% or 80% of the beam plastic moment). The mechanical response of these joints was simulated by means of finite element models (FEM). The accuracy and effectiveness of the adopted modelling assumptions to mimic the seismic response of the joints were validated against experimental results available from the existing literature. The numerical results highlight that under cyclic loading, all investigated joints exhibit ductile behaviour, allowing the concentration of the plastic deformation within the reduced segment of the beam. The designed reduction in the beam flexural resistance influences the joint fire performance, being impaired in the cases with lower flexural resistance. In contrast, the imposed cyclic pre-damage does not appreciably affect the fire resistance of the investigated joints. [ABSTRACT FROM AUTHOR]

• Structural performance of hollow section concrete-filled GFRP columns under monotonic loads and cyclic loads experimentally assessed. • The influence of concrete strength and FRP tube thickness on the seismic performance of HS-CFGT columns is not independent of each other. • HS-CFGT columns made of high-strength concrete demonstrate commendable ductility. • Design approach for the initial flexural stiffness of the HS-CFGT columns was proposed. The experimental investigation and analytical reporting in this paper focus on the behavior of HS-CFGT members, specifically their response to both monotonic loads and cyclic loads. A total of 8 specimens, divided into two groups, each group with 2 kinds in loading type, including 6 columns under cyclic horizontal loads and 2 columns under monotonic lateral loads, were tested. The details of the experimental setups, procedures, significant observations encompassing failure modes, maximum bearing capacities, displacement corresponding to the peak load, load-displacement hysteretic curves, skeleton curves, stiffness degradation curves, and energy dissipation curves and were truthfully reported. The inspection of the experimental data has yielded several important conclusions regarding the effect of column parameters on the behavior of HS-CFGT columns. The most significant finding is that the influence of concrete strength and FRP tube thickness on the seismic performance of HS-CFGT columns is not independent of each other. Furthermore, the findings additionally suggest that HS-CFGT columns made of high-strength concrete demonstrate commendable ductility. The initial flexural stiffness for the preliminary design of HS-CFGT columns is also provided to facilitate the implementation of this innovative technology. [ABSTRACT FROM AUTHOR]

This work aims to present the first experimental tests investigating the cyclic behaviour of aluminium alloy beams. Box-shaped aluminium members were tested under non-uniform bending. Specifically, four square hollow sections made of 6060 aluminium alloy were subjected to cyclic bending loading. The manuscript presents key experimental results, including load-displacement curves, the number of cycles to failure, failure modes, and ductility properties. Additionally, a finite element model was developed using the ABAQUS software. A combined hardening law was implemented to model the non-linear behaviour of the aluminium material, and the element deletion technique was used to predict the actual fracture of the specimens. Finally, the accuracy of the FE model was assessed by comparing the numerical results with the experimental data. • Experimental tests on box-shaped aluminium beams under cyclic tests. • Material properties, failure modes, resistances, rotations and strain response of specimens have been provided. • Evaluation of local buckling effects on the cyclic behaviour of aluminium beams. • Definition of Finite element model by means of ABAQUS software. • Evaluation of the accuracy of FE model by comparing the experimental and numerical results. [ABSTRACT FROM AUTHOR]

In this study, 16 tests were conducted on seven SMA plate specimens of three different sizes to investigate the effects of size and training on the cyclic tension-release performance of SMA plates. The study focused on the interaction between SMA plate size and key factors such as loading protocols. Key material parameters describing the hysteretic behaviour of SMA plates were derived, and a numerical model accounting for residual strain was developed and calibrated against the test data. Finally, to explore potential structural applications, a gusset plate connection incorporating SMA plates was proposed and analyzed using the calibrated model. The results showed that SMA plates of different sizes exhibited varying residual strains under identical strain conditions. Interestingly, the largest SMA plate did not exhibit the highest residual strain either before or after training, indicating a nonlinear relationship between plate size and residual strain. Additionally, the largest plate stabilized more rapidly during cyclic training, suggesting that larger SMA plates may offer improved stability with repeated use. The close agreement of hysteretic behaviour of the SMA plate specimens between the model predictions and the test data confirmed the model's accuracy. Numerical analyses of the gusset plate connection with SMA plates demonstrated that the SMA plates can enhance connection resilience by reducing residual deformation. • Cyclic tests were conducted to evaluate the hysteresis performance of SMA plates. • Seismic performances of SMA plates of different sizes were compared, especially the self-centring ability both before and after training. • SMA plates with all the dimensions exhibited sufficient energy dissipation within an acceptable deformation range. • Key material parameters were evaluated for numerical modelling of SMA plates. • The potential application of SMA plates in a gusset plate connection was demonstrated. [ABSTRACT FROM AUTHOR]

Leaf springs are components of railway rolling stock made of high-strength alloyed steel to resist loading and environmental conditions. Combining the geometric notches with the high surface roughness of its leaves, fatigue models based on local approaches might be more accurate than global ones. In this investigation, the monotonic and fatigue behaviour of 51CrV4 steel for application in leaf springs of railway rolling stock is analysed. Fatigue models based on strain-life and energy-life approaches are considered. Additionally, the transient and stabilised behaviours are analysed to evaluate the cyclic behaviour. Both cyclic elastoplastic and cyclic master curves are considered. Lastly, different fatigue fracture surfaces are analysed using SEM. As a result, the material properties and fatigue models can be applied further in either the design of leaf springs or in the mechanical designs of other components made of 51CrV4 steel.

This study presents a comparison between triaxial test results and constitutive model simulations for saturated sand subjected to a wide range of stress, relative density and both monotonic and cyclic loadings. This is a preliminary part of a project which is focussed on developing models for the behaviour of unsaturated soils under cyclic loading. There are currently limited experimental data of the cyclic behaviour of unsaturated soils due in part to the difficulty of controlling stress state, degree of initial saturation and uniformity of samples in experiments and their interpretation is challenging due to the mathematical complexity in constitutive models. This study attempts to bridge the abovementioned gap by creating an experimentally validated constitutive model for dynamic loading on saturated sand and then to extend this for unsaturated sands. The paper reports results from a series of monotonic triaxial tests and cyclic triaxial tests on saturated sand. Specimens of 100mm diameter, 200mm height and 54mm diameter, 110mm height have been prepared with different void ratios. These samples have been subjected to a wide range of deviatoric stress in both monotonic and cyclic tests. The results from these tests on saturated Sydney sand are presented and used to demonstrate the ability of the constitutive model. As the constitutive model has been developed for variable saturation demonstration of its success with saturated sand for which considerable data is available is the first stage in simulating the cyclic behaviour of the unsaturated sand.

This study presents the influence of phase change materials (PCMs) on the cyclic behaviour of mortars. A multi-scale analysis comprising mechanical and thermal tests was used to explain the phenomena involved. Mechanical and thermal cyclic tests were performed on four configurations of mortars containing 0%, 5%, 8%, and 10% of PCMs. It was revealed that mechanical cyclic loading did not significantly affect the resistance of mortars contrary to thermal solicitations. Indeed, it was shown that the incorporation of PCMs improved the thermal capacity of the mortars. However, severe degradation of the heat capacity and enthalpy was noticed after the temperature cycles. The physicochemical characterisation tests confirmed a moderate structural degradation, which primarily occurred in the initial cycles. Regarding the thermal cycles, scanning electron microscopy (SEM) and calorimetry characterisations corroborated the leakage of PCMs into the cement matrix, which was responsible for the degradation of latent heat. Finally, it was observed that the PCM–mortars resisted mechanical cyclic solicitations, at least up to 1000 cycles; however, they were still sensitive to repeated variations in temperature. [ABSTRACT FROM AUTHOR]

This study investigated the cyclic behaviour of a severe dilative silica sand from Rudsar, Northern Iran, through simple shear tests. For this purpose, monotonic (constant volume/vertical stress) and cyclic (constant vertical stress) tests were performed on moist sand specimens prepared at initial relative densities of 20–60%, vertical stresses of 100–300 kPa, and cyclic stress ratios of CSR = 0.20, 0.25 and 0.30. These also included bender element tests to determine the small-strain shear modulus Gmax. An increase in initial relative density, vertical stress and number of loading cycles led to a nonlinear increase in the secant shear modulus Gsec, while the opposite was observed for increasing CSR. Moreover, increasing CSR improved the damping ratio, whereas increasing the initial relative density, vertical stress and/or number of loading cycles had negative effects on the damping ratio. Finally, the bender element test results showed that Gmax increased for increasing vertical stress and initial relative density. [ABSTRACT FROM AUTHOR]

This paper presents a constitutive model enabled to simulate monotonic and cyclic behaviour of clay and sand in a unified framework. The bounding surface concept has been utilized to predict a smooth transition from elastic to plastic state of the soil. A new dilatancy relation is proposed to capture the volumetric behaviour of sand and clay in a unified manner. Moreover, closed hysteresis loops and accumulation of the plastic strain during cyclic loading have been regarded appropriately by transmitting the similarity centre of the loading and bounding surfaces in the stress space through a kinematic hardening rule. Furthermore, in order to improve the accuracy and convergence property of the model, an implicit integration scheme is introduced. Finally, the accuracy and performance of the model are verified using several experimental data from the literature. Both drained and undrained behaviours under monotonic and cyclic loading for sand and clay are considered, and the characteristic features of the behaviour are captured. [ABSTRACT FROM AUTHOR]

A building system, promising cost‐efficient residential buildings, is under development. The system uses cold‐formed steel as load‐bearing member and encases it in polystyrene aggregate concrete, a special ultra‐lightweight concrete, which plays building construction roles, and provides increment of load‐bearing capacity, too. Previous research was focusing on individual member design for axial and flexural effects. In order to provide 3D rigidity for buildings horizontal effects (wind load, earthquake, imperfections) should also be considered. The load transfer of the investigated structural system is significantly different for horizontal and vertical (gravitational) actions thus the previously derived design method has to be expanded to describe the resistance against horizontal actions. This paper briefly introduces the building system and deals with some of the components necessary for providing 3D rigidity. Shear panel tests were carried out in order to identify the stiffness, failure mode and load‐bearing capacity of panels. Then two types of panel connection were investigated: (i) slab‐to‐wall, and (ii) wall‐to‐wall. Tests aimed to study the failure mode and load‐bearing capacity of joints. Test‐based design values were determined based on measured data. [ABSTRACT FROM AUTHOR]

This paper presents a study of liquefaction analysis at sand layers of the Izumio site, under ground motion variation during a strong earthquake in Osaka, Japan. Site investigation using standard penetration test and shear wave velocity measurement is conducted. Finite element liquefaction site response analysis integrated with a strain space multiple mechanism model is conducted. Ground motions variation is considered based on the seismic record at surrounding seismic stations. Attenuation analysis is conducted to determine the scaling factor for ground motions. Several results, such as acceleration profiles and cyclic behaviours are presented. The empirical analysis is also conducted to verify the results of the numerical analysis. The results explained that cyclic behaviours of sandy layers in the Izumio site show the liquefaction tendency. The results also showed that sandy layers are indicated as critical layers during the strong earthquake due to the excess pore water pressure reaching the liquefaction threshold. The results of the empirical analysis also present liquefaction indication at sand layers under the variation of ground motion, since the factor of safety against liquefaction is less than 1. The results are generally well-agree with liquefaction evidence and prediction presented in the previous study. The results could bring practical importance in understanding liquefaction potential in the study area.

Describing the nonlinear behaviour of constitutive materials plays an important role in structural analysis. The Giuffrè–Menegotto–Pinto (GMP) model is widely used in the nonlinear modelling of steel structures, with its constituent parameters often calibrated from tests. However, the experimental results obtained require intermediate identification procedures before being used directly, meanwhile, the calibration of model parameters based on experimental data is complicated due to the many interrelated constituent variables. This paper aims to propose a method that calibrates the GMP model parameters optimally based on the experimental data. An available set of test results of high-strength steels subjected to cyclic strain is employed to perform an optimal analysis. The obtained results are then compared to numerical and experimental results to evaluate the effectiveness of the proposed method. An extensive study was carried out to evaluate the applicability of the optimal parameters obtained and those suggested by OpenSees. The findings reveal that the proposed procedure is highly efficient, making it a useful option for developing OpenSees applications that automatically calibrate model parameters. A typical 3D steel frame structure subjected to an earthquake is analyzed to evaluate the applicability of the results obtained. [ABSTRACT FROM AUTHOR]

Crumb rubberised concrete (CRC) is a sustainable material that recycles rubber particles from end-of-life tyres as partial fine aggregates in concrete. To promote the applications of CRC in building structures, this paper presents an experimental study on the cyclic behaviour of beam-column joints from both CRC and traditional concrete (TC) frame structures. CRC with 15% rubber content by sand volume was employed. Three full scale CRC joint samples and one full scale TC sample were tested. Varying axial loads were applied on the top of columns and anti-symmetrical low-frequency cyclic loads were applied at the two beam ends. The failure modes, hysteretic behaviour, stiffness degradation, bearing capacity degradation, shearing capacity, displacement ductility and strain response of CRC and TC joints were investigated and compared. Both CRC and TC joint samples reached their ultimate loads due to shear failure. When CRC and TC were with similar strengths, the first crack loads, yielding loads, ultimate loads and ultimate displacements for TC and CRC joints at the same axial compression ratios were comparable with slight differences within 5%. However, CRC joints exhibited an improved energy dissipation ability by up to 10.4% over TC samples.

This paper presents an experimental study on the behaviour of a braced steel frame with a proposed system: anticompression brace system (ABS) subjected to cyclic lateral loads. The ABS is proposed to deal with common brace buckling problems. In the study, split-K braced steel frames: with ABS and with ordinary brace system (OBS) were used as speciments. Cyclic loading tests were conducted to evaluate the performance of the proposed system in preventing the brace to buckle and to obtain the behaviour of the frame with ABS compared to the frame with OBS under cyclic quasistatic loading. From the cyclic tests, it was observed that the proposed system worked in preventing the braces to buckle, hence, the aimed state, “buckling prevention” was achieved. The results of the study also show that the frame with ABS had a lower initial stiffness compared to the frame with OBS, nevertheless, after exceeding drift ratio of 0.85% based on raw data or 0.64% based on fitted-curves, the frame with ABS exhibited good behaviour through lower degradations in stiffness and cyclic strength relative to the frame with OBS that experienced sudden and greater degradations.

The behaviour of seismically damaged steel joints with reduced beam section (RBS) at elevated temperatures has not been widely investigated yet. Therefore, the study summarized in this article aimed to (i) analyse the response of RBS joints at high temperatures and (ii) investigate the influence of plastic damage, due to cyclic loading, on the fire performance of the joints. A set of RBS joints with rib stiffeners on the both lower and upper beam flanges was designed according to European standards and the following parameters were considered: (i) location of the joint (i.e., internal or external joint) and (ii) reduction in the beam flexural resistance (i.e., 65% or 80% of the beam plastic moment). The mechanical response of these joints was simulated by means of finite element models (FEM). The accuracy and effectiveness of the adopted modelling assumptions to mimic the seismic response of the joints were validated against experimental results available from the existing literature. The numerical results highlight that under cyclic loading, all investigated joints exhibit ductile behaviour, allowing the concentration of the plastic deformation within the reduced segment of the beam. The designed reduction in the beam flexural resistance influences the joint fire performance, being impaired in the cases with lower flexural resistance. In contrast, the imposed cyclic pre-damage does not appreciably affect the fire resistance of the investigated joints.

A rational and efficient seismic design requires a detailed characterization of the members and joints behaviour. The prediction of moment‐rotation response of steel beam‐to‐column joints under cyclic loading is not fully addressed in EN 1993‐1‐8 nor EN 1998‐1. Additionally, EN 1998‐1, requires experimental evidence for the use of dissipative steel beam‐to‐column joints. Therefore, new design tools are required to predict the cyclic behaviour of beam‐to‐column joints. In the scope of the European projects "EQUALJOINTS – European preQUALified steel JOINTS" and "EQUALJOINTS+ ‐ Valorisation of knowledge for European prequalified steel joints" a software that provides analytical predictions of cyclic and monotonic response of prequalified steel beam‐to‐column joints was developed. This software embodies the cyclic component method (CCM), which is an extension for cyclic loading of the component method, coded in EN 1993‐1‐8. The cyclic behaviour of the components, required to feed the CCM, can be gathered from experimental tests using specimens similar to the component to be characterized, e.g. T‐stubs. With this objective an experimental campaign on 14 T‐stubs was conducted at University of Coimbra. Results from tests and assessment of available models are presented in this paper. [ABSTRACT FROM AUTHOR]

• Cyclic tests on T-joints with CHS chord and passing-through plate are presented. • A FE model of the connection is built and validated against the experiments. • Parametric studies examining a wide range of geometrical properties are performed. • A GA tool is used to fit the simulated data with a phenomenological model. • A model predicting cyclic response from connection geometry is validated. This paper focuses on modelling the cyclic response of welded T-joints between Circular-Hollow-Section (CHS) chords and passing-through plates. Recent works have highlighted that, in practical applications, this specific joint typology can be regarded either as a standalone connection or as a component representing one of the main sources of deformability and energy dissipation capacity in more complex beam-to-column joints with CHS columns and passing-through I-beams. Currently, research efforts have primarily focused on predicting the strength and stiffness of this type of connection. However, there is a knowledge gap regarding the characterization of the cyclic response of joints with passing-through members, a crucial aspect for modelling steel structures with these connection types in seismic areas. In light of this, the paper aims to characterize the cyclic response of T-joints with CHS members and passing-through plates using a comprehensive approach that incorporates experimental, numerical, and analytical methods. Initially, the results of an experimental study examining the cyclic behaviour of T-joint specimens with passing-through plates are presented. Subsequently, models of the tested joints are implemented in Finite Element software and validated against the experimental outcomes. The validated models are used to conduct a parametric study, considering 44 different configurations to obtain their force-displacement cyclic responses. These responses are mathematically modelled using the hysteretic uniaxial material from the OpenSees library and a Genetic Algorithm based tool previously developed by the authors (MultiCal). Finally, regression analyses are performed to develop formulations for predicting the mathematical parameters of the hysteretic uniaxial material model starting directly from the geometrical and mechanical properties of the connection. This approach enables designers to model the cyclic response in structural analysis with a straightforward approach, without the need for new calibrations or tests, if the modelled joints fall within the proposed range of calibration. From the point of view of the component modelling, the approach presented aligns with the larger research strand devoted to the extension of the component method codified in Eurocode 3 part 1.8 to cyclic loading conditions. [ABSTRACT FROM AUTHOR]

• The work focused on the cyclic behaviour of Ti-6Al-4V mesostructures by the LPBF. • Realistic 3D mesostructures obtained using microtomographic images were studied. • True local hysteresis loops of cyclically loaded structures were determined. • The influence of defects on the fatigue properties was investigated. • A new approach to fatigue life prediction of lattice structures was proposed. The present work is concerned with the numerical modelling of the cyclic behaviour of Ti-6Al-4V lattice structures. In the study, diamond structures of titanium alloy produced by the additive laser powder bed fusion (LPBF) method with different degrees of relative density were used. Realistic geometric models of the studied mesostructures were generated using computed microtomography, taking into account the imperfections of the material resulting from the manufacturing process. The numerical calculations also took into account the actual material hardening curve in the elastic-plastic strain range. One of the achievements of this work is the numerical modelling of cyclic loading of realistic mesostructures with their imperfections. The areas of the mesostructures most susceptible to fatigue cracking have been identified and analysed. True hysteresis loops and values of local stress and strain amplitude were determined at the locations of highest stress concentration in cyclically loaded diamond structures. The main achievement of the present work was the modelling of the macroscopic fatigue life of the investigated mesostructures based on the true values of stress and strain at the locations most exposed to fatigue cracking. For this purpose, a stress criterion for fatigue cracking of Ti-6Al-4V lattice structures fabricated by the additive LPBF method was proposed. [Display omitted] [ABSTRACT FROM AUTHOR]

Concrete-filled thin-walled galvanized corrugated steel tube (CFCST) is a novel composite member with competitive mechanical behaviour, durability and construction convenience. Several preliminary experimental and numerical works have been conducted on the compressive, flexural, shear, and monotonic torsional performances. However, the unique geometric characteristics of the helical corrugated steel tube (CST) may lead to significant torsional direction-dependent behaviour and complex cyclic torsional working mechanisms, which have not been investigated. This paper therefore presents an experimental investigation of the CFCST under cyclic torsional loads, encompassing the main test variables of member types, diameter-to-thickness ratios, axial compression ratios, and core concrete strengths. The failure modes, hysteretic curves, ductility, energy dissipation capacity, and stiffness degradation are carefully addressed. The cyclic torsional working mechanism of CFCST is discussed through the cyclic test results and strain analysis. The cumulative damage caused by the cyclic torsional loading case is also analysed via the comparisons between the monotonic and cyclic experimental results. The applicability of the existing design methods for the torsional bearing capacity is examined, with specific design suggestions proposed. • Nine specimens tested under cyclic torsional loads. • Torsional hysteretic behaviour addressed carefully and comparatively. • Cyclic torsional working mechanism discussed carefully. • Existing design methods for the cyclic torsional bearing capacity. [ABSTRACT FROM AUTHOR]

The structural effectiveness of textile reinforced mortar (TRM) composites relies on their load transfer capacity to the substrate and the interaction between textile and mortar. The bond plays a crucial role in mechanism of TRM composites. Despite some recent investigations, a deep understanding still needs to be gained on the textile-to-mortar bond to develop suitable analytical and numerical predictive models, improve test methods, and orient design criteria. This work describes a laboratory study in which pull-out tests were carried out to investigate the effect of the slip rate and cyclic loading on the textile-to-mortar bond behaviour. Alkali-resistant glass fabric and sgalvanised ultra-high tensile strength steel cords embedded in two different lime-based mortars were tested. The pull-out response was sensitive to the strain rate at low rates. Cyclic loading produced a strength degradation, which reduced with the number of cycles. [ABSTRACT FROM AUTHOR]

The present paper shows the results of an experimental test campaign on RC base column joints realized using three different typologies of steel reinforcing bars. Traditional TempCore®B450C rebars were adopted in comparison with enhanced ones with Dual-Phase microstructure. The interest in the use of such kind of reinforcing grade comes from its improved performance in terms of durability in presence of aggressive environmental conditions, being able to provide a lower decrease of the deformation capacity, with residual values higher respect to minimum imposed by current standards. Being characterized by the typical undefined yielding stress–strain behaviour, Dual-Phase steel reinforcing bars need an accurate characterization to be used. In the present work experimental tests on RC-DP sub-structures were performed to assess their structural performance in presence of cyclic/seismic loading conditions, comparing results with traditional RC-TempCore® structures' behaviour. [ABSTRACT FROM AUTHOR]

Shape memory filaments have significant implications in smart wearable textiles, biomedical sutures, and additive manufacturing. However, the deterioration of shape memory performance over a range of temperature and strain limits their use in many high-end applications. This investigation reports the shape memory properties of segmented polyurethane filament and its detailed chemical and thermo-mechanical characterization. Shape memory polyurethane (SMPU) based on poly(1,6-hexanediol adipate) (PHA), 4,4′-diphenylmethane diisocyanate (MDI), and 1,4-butanediol (BDO) shows the transition temperature near body temperature. Hard segment and soft segment content in SMPU is 28.5% and 71.5% by weight. SMPU filament exhibited excellent shape recovery (~ 98%) and higher shape fixity (~ 80%) at a strain of 20%, 40%, and 60% and temperature of 30 ℃ and 50 ℃. Results have been supported by thermal and X-ray analysis. The cause of high fixity has been discussed in detail. Experimental results indicated higher crystallization and melting enthalpy. The cyclic test of SMPU filament showed almost complete shape recovery with no change in shape fixity under different thermo-mechanical conditions. [ABSTRACT FROM AUTHOR]

High-Performance Fiber-Reinforced Cementitious Composite (HPFRCC) materials are among the new materials used in recent years and have drawn the attention of structure engineers. High tension resistance in comparison to regular concrete and high ability for energy depreciation are among the advantages of these materials. Passive yielding dampers have also attracted the attention of structure engineers. Steel dampers are among novel dampers which, in spite of simple structure, possess high performance in energy depreciation, plus other advantages, such as being replaceable after the quake, simple structure, possibility of installation in different positions in pipe form in reigning systems, ... etc. The coming survey investigates the effect of strengthening and combining pipe dampers by using HPFRCC materials. The findings show that strengthening pipe dampers by HPFRCC materials could dramatically depreciate the amount of energy entering the system and boost the efficiency of pipe dampers. [ABSTRACT FROM AUTHOR]

A test program was considered to clarify the cyclic characteristics of eight full-scale unstiffened extended end-plates with variable parameters and one SidePlate moment connection. All specimens were subjected to 2010 AISC seismic provision loading protocol where flexural strengths were identified at each interstorey drift angle. The results showed that all unstiffened extended end-plate failed to develop full inelastic capacity of connected beams and plastic hinges mainly appeared in the connection's components. On the other hand, the SidePlate moment connection had the capacity to develop adequate interstorey drift angles up to 0.06 rad, indicating that this type of connection possesses sufficient stiffness and strength to be classified as a rigid and full-strength connection. The results also showed that SidePlate possesses considerably more energy dissipation capacity and an equivalent hysteretic damping ratio compared to unstiffened extended end-plate specimens, especially at higher interstorey drift angles. [ABSTRACT FROM AUTHOR]

Acoustic emissions have been widely used as a means to investigate the damage state of concrete structures. While successful applications have regarded the localisation of cracks, quantification of the damage and safety margin estimation have been elusive because the main approaches are mostly based on empirical observations. In this work, a methodology for the numerical simulation of acoustic emission events in reinforced concrete structures is proposed with the aim of filling this gap. It relies on a numerical model for reinforced concrete structures at the macro-scale which simulates the mechanical cyclic behaviour of the structure. Analysis of the stress and strain states in the numerical model provides the basis for the simulation of the occurrence and quantification of the events. A simple attenuation law is then used to estimate the acoustic event intensity recorded by the sensors. Application to a four-point bending test on a reinforced concrete beam confirms the capability of the model to reproduce the data recorded during the test, including the Felicity effect and the cumulative intensity curve. This could potentially open the path to a more quantitative use of acoustic emission data for structural assessment of reinforced concrete structures, directly linking mechanical models and acoustic observations. [ABSTRACT FROM AUTHOR]

With the aim of reusing assembled steel structures at the end of their service life or after experiencing earthquake damage, a novel demountable and reusable steel beam-to-column joint with bolted-pinned connection has been proposed herein. Its configuration is quite beneficial to the installation and disassembly due to its use of high-strength bolts and pins. The energy-dissipating connection plate (EDCP) is strategically placed in the predetermined energy dissipation area, of which the yield section is wrapped by an external restraining plate, allowing for concentrated damage and deformation of the main structural members within the elastic range under earthquake actions. The EDCP is fabricated from a low-yield-point (LYP) steel material that has excellent ductility and high energy dissipation capacity. To clarify the joint's static and seismic performance, ten joint specimens were designed and prepared, and both monotonic and cyclic loading tests were conducted. The failure mode, load versus displacement response, ductility, and energy dissipation capacity were obtained and analyzed experimentally. Furthermore, the cyclic behaviour of the same tested joints after disassembly and re-assembly were investigated to verify their reusability. The test results indicated that welding stiffening ribs in the unrestrained section of the EDCP can significantly enhance the joint's static loading capacity and seismic performance. Additionally, the damage of all the joints was localized within the EDCP, and no failure was observed in the beam, column components and column seat, which remained within the elastic range based on strain data analysis. It was found that the joint specimens could be disassembled effortlessly and efficiently with nearly no damage to the friction surface and bolt holes within the connection zone. Furthermore, the seismic performance of the re-assembled specimens was essentially identical to that of the original specimens, demonstrating the ability of reuse. • A new demountable and reusable beam-to-column joint is proposed. • Ten steel beam-to-column joints are tested monotonically and cyclically. • Failure modes, static and cyclic behaviour as well as capacities are clarified. • Demountability and reusability performance are evaluated. [ABSTRACT FROM AUTHOR]

Betonarme çerçeve tipi yapıların deprem davranışları, enerji tüketebilen metal elemanlar kullanılarak iyileştirilebilmektedir. Metal elemanlar, yapının çerçeve gözlerine yerleştirildiğinde yapıya giren deprem enerjisini plastik deformasyon yaparak tüketebilmektedir. Yeni nesil yapı tasarımı, plastik şekil değiştirmelerin yapısal elemanlardan çok, deprem sonrasında yenisiyle değiştirilebilen metal elemanlarda yoğunlaşması sağlanarak hasarının azaltılması eğilimindedir. Bu çalışmada enerji tüketme özelliği olan farklı kalınlıklardaki yastık görünümlü metal elemanların çevrimsel davranışı, deneysel ve analitik olarak incelenmiştir. Farklı kalınlıklardaki çelik yastıkların kayma deneyleri İstanbul Teknik Üniversitesi Yapı ve Deprem Mühendisliği Laboratuvarında (STEELAB) gerçekleştirilmiştir. Çelik yastıklar için analitik model geliştirilmiş ve gerçek betonarme yapıdan çıkartılmış bir çerçevenin lineer olmayan analizinde kullanılmıştır. Analiz sonuçları, levha kalınlığına bağlı olarak çelik yastıkların betonarme çerçeve dayanımını %5 ile %20 arasında değişen oranlarda artırdığını göstermektedir. Kalınlığı 18 mm olarak seçilen çelik yastığın kullanıldığı betonarme çerçeve yalın çerçeveden 5 kat daha fazla enerji tüketmiştir. Aynı kalınlıktaki çelik yastık, çerçeve sistemin toplam enerjisinin %55’ini tüketmiştir.