Hysteretic Properties Research Articles

Accounting for hysteretic characteristics in P‐delta analysis of structures

AbstractStudies in the literature have shown that P‐delta () effects are highly influenced by the hysteretic characteristics of a structural system. However, international buildings and bridge codes prescribe ‐induced amplification factors, limits for negligible effects and limits for dynamic instability that neglect this influence. As a result, different margins of safety against actions are currently specified for different structural systems, with steel structures, for example, presenting reduced margins of safety with respect to concrete structures. Adopting a sub‐set of the PEER earthquake record database composed of 1964 earthquake records, this paper presents a statistical analysis of displacement amplification ratios for systems with different hysteretic models, fundamental periods and ductility levels. In terms of both elastic and inelastic stability coefficients, limit values of the stability coefficient for negligible effects and dynamic instability are proposed for the most common structural typologies, such as steel, well and poorly detailed reinforced concrete, and self‐centering structures. Analytical estimates of the median, 84th and 98th percentile values of the displacement amplification that take into account the combined effect of stability coefficient, ductility level and hysteretic properties are proposed.

Structural property of stainless steel minor-axis joints of interior columns with box panel

With the component method, a design approach was derived for predicting the structural properties of stainless steel end-plate joints with box panel, where box panel was formed using the skin-plates welded between the column flanges along the minor-axis. Four end-plate minor-axis joints with box panel were tested under static and cyclic loading, involving beam-to-interior column joints made of austenitic and duplex stainless steels. The monotonic and hysteretic properties of the experimental joints were discussed, including the failure characteristics, experimental curves (F-Δ), and degradation and energy dissipation behaviour. Meanwhile, elaborate finite element (FE) models were developed for further analysis of the structural behaviour of the tested joints, and a parametric study was conducted afterwards. The proposed design approach provided reasonable estimations for the experimental and FE results of stainless steel minor-axis joints with box panel, demonstrating the applicability of this proposal.

Properties of inhomogeneous-type magnetorheological elastomer formed in the presence of a magnetic field with tilted angles

Magnetorheological elastomers (MRE) are smart materials whose mechanical properties can be tuned using an applied magnetic field. Many studies have shown that MRE properties are influenced by particle size, particle volume fraction, and matrix material type. The particle-magnetic dipole theory has demonstrated that the angle of the particle chains significantly affects the properties. This study investigated the effects of the alignment angle of the particle chains on the properties of MREs. The inclination angle is a parameter associated with the external magnetic flux density. MRE samples fabricated under a magnetic field with different tilt angles were prepared for the shear tests. The primary properties of MRE, such as viscoelasticity, magnetic-induced properties, and hysteresis, were comprehensively investigated in the samples. The equivalent stiffness and loss of energy changed significantly in the tilted angle domain. The force–displacement loops also showed a clear difference among the samples when the experiments were performed at the same amplitude, frequency, and magnetic flux density. The experimental results show that the magnetic and hysteretic properties strongly depend on the initial tilt angle of the chain.

Research on Hysteretic Behavior of FRP-Confined Concrete Core-Encased Rebar.

FRP-confined concrete core-encased rebar (FCCC-R) is a novel composite structure that has recently been proposed to effectively delay the buckling of ordinary rebar and enhance its mechanical properties by utilizing high-strength mortar or concrete and an FRP strip to confine the core. The purpose of this study was to study the hysteretic behavior of FCCC-R specimens under cyclic loading. Different cyclic loading systems were applied to the specimens and the resulting test data were analyzed and compared, in addition to revealing the mechanism of elongation and mechanical properties of the specimens under the different loading systems. Furthermore, finite-element simulation was performed for different FCCC-Rs using the ABAQUS software. The finite-element model was also used for the expansion parameter studies to analyze the effects of different influencing factors, including the different winding layers, winding angles of the GFRP strips, and the rebar-position eccentricity, on the hysteretic properties of FCCC-R. The test result indicates that FCCC-R exhibits superior hysteretic properties in terms of maximum compressive bearing capacity, maximum strain value, fracture stress, and envelope area of the hysteresis loop when compared to ordinary rebar. The hysteretic performance of FCCC-R increases as the slenderness ratio is increased from 10.9 to 24.5 and the constraint diameter is increased from 30 mm to 50 mm, respectively. Under the two cyclic loading systems, the elongation of the FCCC-R specimens is greater than that of ordinary rebar specimens with the same slenderness ratio. For different slenderness ratios, the range of maximum elongation improvement is about 10% to 25%, though there is still a large discrepancy compared to the elongation of ordinary rebar under monotonic tension. Despite the maximum compressive bearing capacity of FCCC-R is improved under cyclic loading, the internal rebars are more prone to buckling. The results of the finite-element simulation are in good agreement with the experimental results. According to the study of expansion parameters, it is found that the hysteretic properties of FCCC-R increase as the number of winding layers (one, three, and five layers) and winding angles (30°, 45°, and 60°) in the GFRP strips increase, while they decrease as the rebar-position eccentricity (0.15, 0.22, and 0.30) increases.

Cyclic behavior and seismic control performance of SMA friction damper

Using superelastic shape memory alloy (SMA) bars and non-asbestos organic friction material, this study developed an innovative self-centering friction damper (SCFD). This hybrid passive control device consists of the self-centering device using SMA bars and the friction energy dissipation device which can provide excellent self-centering ability and energy-absorbing ability to meet the requirements of civil engineering applications. To explore the feasibility and hysteretic properties of the SCFD, experimental tests under cyclic loading were conducted. According to the experimental results, the proposed SCFD exhibited a stable and repeatable flag-shaped hysteretic response, which can achieve the recovered displacement of 76.07% and dissipated energy of 6.04 kJ at 42 mm. The finite element model of the SCFD using ABAQUS software was established and validated by experimental results. And a series of numerical simulations with different parameters were performed, which enables a more in-depth interpretation of the SCFD. Additionally, a system-level nonlinear time-history analysis was performed on a three-story steel frame equipped with and without SCFDs. The dynamic analysis results indicated that the SCFDs could effectively reduce structural damage and enhance post-earthquake recoverability under rare earthquakes.

Experimental study on hysteretic properties of oscillating column structures

This research aims at the problem of excessive temperature stress in the super-long structural system. In order to release the temperature stress and bending moment, a new type of oscillating column structure is proposed. Rubber pads are set up above and below the column to reduce the transmission of bending moment and make the column suffer more shear and axial force. The mechanical properties and mechanism were studied by seismic test. The experimental structure shows that this system has good deformation and mechanical properties compared with ordinary column structure and can be effectively applied to practical engineering.

Theoretical and Experimental Analysis of a Winding Rope Fluid Viscous Damper

This paper investigated a winding rope fluid viscous damper (WRFVD) that uses the frictional amplification mechanism of a winding rope to obtain the operating characteristics of a viscous damper-like device. The WRFVD combined the advantages of fluid viscous dampers and friction dampers. It not only retained the mechanical characteristics of the fluid viscous damper but also reduced manufacturing costs. First, the construction and working principles of the WRFVD were introduced. A theoretical model that could accurately simulate the hysteretic characteristics of the damper was derived. Then, a series of dynamic tests were performed on six prototypes of the WRFVD. The dynamic performance under different displacement amplitudes and device parameters was analyzed based on the test results. In addition, the theoretical model was validated by experimental results. Finally, a series of parametric analyses of the WRFVD were performed. The experimental results showed that the WRFVD is a type of velocity-dependent damper with smooth and plump hysteretic curves under sinusoidal displacement excitation. Fatigue loading tests showed that the WRFVD had excellent fatigue resistance capacity and stable operational performance. The established theoretical model was reasonable and satisfactorily reproduced the hysteretic properties of the WRFVD. The parametric analyses showed that it was not recommended to improve the performance of the WRFVD by the method of adjusting the damping coefficient and pretightening load. It was reasonable to adjust the performance of the WRFVD by setting a smaller velocity exponent, an appropriate winding turn of winding ropes, and a suitable friction coefficient.

Thermodynamically-Consistent Modeling of Ferromagnetic Hysteresis.

Models of ferromagnetic hysteresis are established by following a thermodynamic approach. The class of constitutive properties is required to obey the second law, expressed by the Clausius-Duhem inequality, and the Euclidean invariance. While the second law states that the entropy production is non-negative for every admissible thermodynamic process, here the entropy production is viewed as a non-negative constitutive function. In a three-dimensional setting, the magnetic field and the magnetization are represented by invariant vectors. Next, hysteretic properties are shown to require that the entropy production is needed in an appropriate form merely to account for different behavior in the loading and the unloading portions of the loops. In the special case of a one-dimensional setting, a detailed model is determined for the magnetization function, in terms of a given susceptibility function. Starting from different initial magnetized states, hysteresis cycles are obtained by solving a nonlinear ordinary differential system. Cyclic processes with large and small amplitudes are established for materials such as soft iron.

Efficiency of shape memory alloy seismic restrainers for several conditions of bridge joints

Movement joints are needed in bridges to accommodate longitudinal expansion and contraction. Enough joint width needs to be available to accommodate not only longitudinal expansion but also expected movements of joints during earthquakes. This may result in excessive joint openings. Devices that can dissipate energy have been suggested to reduce joint displacements. Shape memory alloy (SMA) is one of these energy dissipation devices, which is well known for its ability to return to its natural shape after being deformed. Several cases of bridges and different conditions of seismic events are modeled and tested using developed software programs in MATLAB to show the efficiency of using SMA inside bridge joint openings. These models include the case of two adjacent frames with SMA inside them (2–frames), the case of multi–frames with constant hysteretic SMAs between every two of them (N–frames), the case of multi–frames with constant hysteretic SMAs taking the delay of seismic forces between frames into consideration (delay), and the case of variable masses of bridge frames. Also, parametric studies are performed to show the impacts of all parameters of bridge frames and SMA retrofit devices on seismically joint openings. The results show that the superelastic SMA device plays a huge role in controlling bridge opening and enables limiting the joint width of all models during earthquakes with different values reaching 60% in some cases depending on bridge frame properties, ground motion characteristics, and the hysteretic properties of SMA devices.

The Thiamine-Dependent Hysteretic Behavior of Human Transketolase: Implications for Thiamine Deficiency

We have investigated the hysteretic properties of human transketolase with emphasis on its dependency on thiamine pyrophosphate concentration. As demonstrated previously, the reaction progress curves revealed a slow transition from an initial low velocity to a faster final steady-state velocity, characterized by the rate constant τ-1. The rate of the transition was dependent on the concentration of the thiamine pyrophosphate cofactor, with progressively longer transition times found as the concentration of thiamine pyrophosphate was decreased. At physiological thiamine pyrophosphate concentrations, the inverse rate constant was in the range of 10 to 20 min for fibroblast-derived transketolase and increased dramatically with only small decreases from these levels of thiamine pyrophosphate. Variation in the lag was found when transketolase from different individuals was examined. Moreover, at low levels of thiamine, the rate of the transition was different between fibroblast- and lymphoblast-derived transketolase. The substantial lag in formation of active holoenzyme and the findings of interindividual variation and cell type variation in the lag period suggest mechanisms for the loss of transketolase activity during thiamine deficiency and may explain, at least in part, the differential sensitivity to deficiency demonstrated by tissues and individuals.

Numerical studies on the seismic response of a three-storey low-damage steel framed structure incorporating seismic friction connections

A 9 m high, near full scale three-storey configurable steel frame composite floor building incorporating friction-based connections is to be tested using two linked bi-directional shake tables at the International joint research Laboratory of Earthquake Engineering (ILEE) facilities, Shanghai, China, as part of the RObust BUilding SysTem (ROBUST) project. A total of nine structural configurations are designed and detailed. To have a better understanding of the expected system behaviour, as well as effects of other structural and non-structural elements (NSEs) on the overall system response, experimental testing at component level has been conducted prior to the shake table testing. This paper presents an introduction to the ROBUST project, followed by a numerical study on one of the nine configurations of the structure, having Moment Resisting Steel Frame (MRSF) in the longitudinal direction and Concentrically Braced Frame (CBF) in the transverse direction. Hysteretic properties employed in the numerical models are validated against component test results. The predictions of the building's seismic response under selected base excitations are presented indicating the likely low damage performance of the structure.

Amplification in Mechanical Properties of a Lead Rubber Bearing for Various Exposure Times to Low Temperature

In this paper, new formulations to predict the change in mechanical properties, namely, post-yield stiffness and characteristic strength of lead rubber bearings (LRBs) at low ambient temperatures, are proposed based on test results. Proposed formulations consider not only the effect of low temperature but also the effect of exposure time to low temperature. Accordingly, a full-scale LRB was tested dynamically after being conditioned at temperatures of −20, −10, 0, and 20 °C for 3, 6, and 24 h. During the displacement-controlled cyclic tests, various levels of shear strain were applied to the isolator with loading frequencies of 0.1 Hz and 0.5 Hz. Then, force-displacement curves of LRB were recorded, and the corresponding amplifications in its hysteretic properties were noted. The accuracy of existing equations to estimate the amount of amplification in mechanical properties was evaluated through the experimental results. It was found that the existing formulas do not represent the effect of exposure time on LRB characteristics at low temperatures. On the other hand, the proposed equations result in highly accurate estimations of post-yield stiffness and characteristic strength of LRB at low temperatures for different exposure times.

Hysteresis Performance and Restoring-Force Model of Precast Concrete Ring-Lap Beam-Column Joints

In order to study the restoring-force characteristics of precast concrete ring-lap beam-column joints, three precast concrete ring-lap beam-column joint specimens and one cast-in-place concrete beam-column joint specimen were designed and fabricated, and low-circumferential repeated loading tests were conducted. The results show that the bearing capacity of the ring-lap beam-column joint is higher than that of the cast-in-place beam-column joint, and with the increase in the lap length, the bearing capacity, ductility, and energy dissipation capacity of the ring-lap beam-column joint increase significantly, and the local damage is also mitigated. Based on the test results and the existing restoring-force model theory, a trifold restoring-force model is proposed for precast concrete ring-lap beam-column joints considering the effect of lap length. The proposed restoring-force model is consistent with the hysteresis curve of the assembled column, which indicates that the proposed restoring-force model can better reflect the influence of the lap length on the hysteresis characteristics, and can provide a reference for the structural elastic–plastic analysis and engineering application of the precast concrete ring-lap beam-column joint. The proposed restoring-force model can better reflect the influence of lap length on the hysteretic properties, which can provide a reference for the structural elastoplastic analysis and engineering application of this precast concrete ring-lap beam-column joint.

Manipulation of the electrical and memory properties of MoS2 field-effect transistors by highly charged ion irradiation.

Field-effect transistors based on molybdenum disulfide (MoS2) exhibit a hysteresis in their transfer characteristics, which can be utilized to realize 2D memory devices. This hysteresis has been attributed to charge trapping due to adsorbates, or defects either in the MoS2 lattice or in the underlying substrate. We fabricated MoS2 field-effect transistors on SiO2/Si substrates, irradiated these devices with Xe30+ ions at a kinetic energy of 180 keV to deliberately introduce defects and studied the resulting changes of their electrical and hysteretic properties. We find clear influences of the irradiation: while the charge carrier mobility decreases linearly with increasing ion fluence (up to only 20% of its initial value) the conductivity actually increases again after an initial drop of around two orders of magnitude. We also find a significantly reduced n-doping (≈1012 cm-2) and a well-developed hysteresis after the irradiation. The hysteresis height increases with increasing ion fluence and enables us to characterize the irradiated MoS2 field-effect transistor as a memory device with remarkably longer relaxation times (≈ minutes) compared to previous works.

Numerical study on hysteretic characteristics of transmission tower K-joints

Introduction: The mechanical properties of joints have a significant impact on the dynamic response of transmission tower structures.Methods: Considering bolt slip, the numerical model of the transmission tower K-joint is established. The mechanical properties of K-joints are studied from three aspects: failure mode, load-displacement hysteretic curve, and stiffness degradation by numerical method. The effects of bolt preload, friction coefficient, and member strength on the hysteretic properties of the K-joint are analyzed.Results: The results show that due to the complexity of K-joints, bolt slip will lead to the reduction of ultimate bearing capacity and the change of failure position. In order to accurately obtain the mechanical properties of K-joints, the influence of bolt slip should be considered in the research process; The plumpness of load-displacement hysteretic curve is greatly affected by parameters; The stiffness of K-joints degenerates with the increase of loading times.Discussion: The results provide a reference for the mechanical analysis of the transmission tower.

Hysteretic tests of stud connection subjected to combined shear and tension

The hysteretic behaviour of stud connections in the shear direction under the combined action of shear and tension was studied by the push-out test of eight cyclic loading specimens. To compare the difference between cyclic loading and monotonic loading on the shear capacity and the shear–slip curve, eight monotonic loading specimens were designed as reference specimens. The main variables considered in this study were the diameter of the stud, the strength of the concrete, and the magnitude of the tensile force in the stud. Based on the test results, failure modes, shear–slip curves and characteristic points on the curves of all specimens were evaluated. Hysteretic responses such as ductility, strength degradation and energy dissipation of cyclic loading specimens were analysed. The test results show that the diameter of the stud, the strength of concrete and the tensile force of stud connectors have significant effects on the hysteretic performance of stud connections. The stud connection with larger stud diameter and higher concrete grade has higher shear resistance, higher ductility index and higher energy dissipation capacity. In comparison to stud connections under pure shear loading, the hysteretic properties of stud connections with combined action of shear and tension are degraded. The influence of tensile force on the hysteretic performance of stud connections under the combined action of shear and tension would thus need to be taken into consideration in the design of composite structures.

A statistical study of inelastic displacement ratio spectrum for existing structures

AbstractDisplacement‐based design has gained importance due to the emergence of the performance‐based engineering, and it has now become desirable to estimate maximum (inelastic) displacements of structures for different levels of seismic hazard. Being closely related to damage, displacement (or drift) has become an important parameter necessary to meet various performance goals. It is considered convenient to estimate the inelastic displacement demand in a structure by multiplying the elastic displacement demand of the structure with a ratio called the inelastic displacement ratio. A comprehensive study is conducted for the parametric dependence of the inelastic displacement ratio in single‐degree‐of‐freedom (SDOF) systems with known relative lateral strengths, on strong motion duration, earthquake magnitude, epicentral distance, and geological site conditions. This study is different from the earlier studies of similar types in that other governing parameters are kept fixed while the effects of variations in any particular parameter are studied. This study is based on the generation of ensembles of synthetic accelerograms from a database of 1274 accelerograms recorded in western USA for the pseudospectral acceleration (PSA) spectra of given source and site parameters. It is found that strong motion duration may influence the inelastic displacement ratios, depending on the hysteretic properties of the oscillator, in the case of durations not much longer than 10 s. Earthquake magnitude has a significant influence on these ratios for the SDOF systems of most periods, while site geology appears to be important for the stiff oscillators. A scaling model is also proposed in this study for estimating the inelastic displacement ratio spectrum from a normalized relative velocity spectrum of the ground motion. The proposed model indirectly includes the effects of various governing parameters and is shown to preserve the trends available from the direct study.

Field-Driven Magnetic Phase Diagram and Vortex Stability in Fe Nanometric Square Prisms

In this work, we deal with the zero temperature hysteretic properties of iron (Fe) quadrangular nanoprisms and the size conditions underlying magnetic vortex states formation. Different aspect ratios of a square base prism of thickness t with free boundary conditions were considered in order to summarize our results in a proposal of a field-driven magnetic phase diagram where such vortex states are stable along the hysteresis loops. To do that, a Hamiltonian consisting of exchange, magnetostatic, Zeeman and cubic anisotropy energies was considered. The time dynamics at each magnetic field step was performed by solving the time-dependent Landau-Lifshitz-Gilbert differential equation. The micromagnetic simulations were performed using the Ubermag package based on the Object Oriented Micromagnetic Framework (OOMMF). Circular magnetic textures were also characterized by means of topological charge calculations. The aspect ratio dependencies of the coercive force, nucleation and annihilation fields are also analyzed. Computations agree with related experimental observations and other micromagnetic calculations.

On stress and deformation accumulation of continuously welded rails under cyclic thermal loading in high-speed railways

This paper focuses on the stress and deformation accumulation of continuously welded rails (CWR) in ballastless tracks under cyclic thermal loading, which could pose a potential threat to the stability and service life of CWR but related theoretical studies are yet to be conducted. Firstly, the nonlinear longitudinal resistance of fasteners (LRF) resulting from the CWR-rail pad contact interface is mathematically described by extending the classical Dhal friction model and verified via an in-door experiment. Both the hysteretic and softening properties of the LRF can be captured compared with the traditional ideal elastoplastic model. Most importantly, we originally propose a quasi-dynamic method (QDM) to tackle nonlinear static problems by extending an explicit numerical integration algorithm from the dynamics field to the statics. Afterwards, the quasi-dynamic equilibrium equations of CWR in the tunnel transition zone and on the simply-supported beam bridges subjected to thermal loads and LRF are constructed, and the reliability of QDM to obtain static responses is well-validated by existing analytical methods. Finally, the limitation of the ideal elastoplastic LRF model, distribution characteristics and accumulation process of rail longitudinal deformation and axial additional stress are fully unveiled. The current work is conducive to better recognition of the longitudinal mechanical behavior of CWR under cyclic thermal loads.

Design recommendations for self-centering buckling restrained braces

Self-centering buckling-restrained braces (SC-BRBs) have typical flag-shaped hysteresis. Differing from conventional buckling-restrained braces (BRBs) which can result in significant residual drifts, the SC-BRB incorporates additional prestressing elements, so that it can recenter after earthquakes, which is critical for seismic resilience. Current seismic design procedures can be used to calculate the key properties of conventional braces (e.g. BRB), but they cannot be used to determine the additional hysteretic properties of SC-BRB braces. To achieve a comprehensive understanding of the performances of SC-BRB systems and develop their design recommendations, this paper conducted a parametric study of two typical SC-BRB systems, using a 12-story steel braced frame office building. Then, the overall behavior of the SC-BRB system was compared with those of a BRB system and two self-centering energy dissipative brace systems. The selection of SC-BRB properties appeared to be a tradeoff between demands on component properties and seismic performances. The criteria for proportioning the system were suggested. Numerical results showed that, although the SC-BRB systems had smaller residual drifts than the BRB system, they generated more significant high-mode effect than the other comparable systems.