Hysteretic Loops Research Articles

Numerical investigation of existing RC exterior beam-column joints under cyclic loading: case study of 1971 algerian building

Many reinforced concrete (RC) buildings constructed in Algeria before the 1980s may have serious structural deficiencies and are considered substandard according to the Algerian seismic code. Specifically, the failure of the beam-column joints has been the cause of building collapse in many earthquakes in the past: Alasnam October 10, 1980 and Boumerdes May 21, 2003. In this work, the behavior of RC exterior beam-column joints under quasi-static cyclic loading is studied by 3D nonlinear finite element analysis using ANSYS software. To perform the non-linear analysis, the load was applied step by step and the modified Newton-Raphson method was used for the solution. In order to prove that the program successfully captures the necessary response parameters without any modifications to the structure details, some available experimental works were modeled and non-linearly analyzed using ANSYS. Moment-rotation and load-displacement relationships were compared with the experimental data. It was observed that the results are quite similar to each other. Thereafter, a typical RC exterior beam-column joint belonging to a building constructed for residential use in Algeria in 1971 was modeled using ANSYS. The joint was subjected to quasi-static cyclic loading, and its performance was examined in terms of load resistance and failure. The moment-rotation hysteresis curve has been established. The hysteretic loops of the joint, representing the existing structure, showed stiffness degradation and strength deterioration.

Experimental investigation of seismic performance of precast concrete shear walls with overlapping U-bar loop connections

This paper discusses the seismic performance of five reduced-scale shear walls, including one cast-in-place (CIP) concrete shear wall, two precast concrete (PC) shear walls with overlapping U-bar loop connections, and two PC shear walls with modified form-overlapping U-bar loop connections combined with extruded sleeve connections. A quasi-static test was conducted to evaluate the reliability of the overlapping U-bar loop connections and the modified form by comparing the corresponding mechanical parameters of PC specimens with those of the CIP specimen. Moreover, the differences in seismic performance between the CIP specimen and PC specimens with different connection methods were also analyzed in terms of damage process, hysteretic loops and skeleton curves, load carrying capacity, ductility, equivalent stiffness, and energy dissipation. The experimental findings indicated that the mechanical performances of PC specimens with the modified connection form outperformed those of PC specimens with pure overlapping U-bar loop connections, closely resembling the properties of cast-in-place specimens; the failure mode of PC specimens was consistent with that of the CIP specimen; the generation, distribution and development of cracks in PC specimens were also similar to those in the CIP specimen. Furthermore, although the load-bearing capacity and peak displacement of PC specimens were lower than those of the CIP specimen due to the failure of the post-casted concrete strength to meet the requirements, the ductility, equivalent stiffness, and energy dissipation of PC specimens with the modified connection form closely matched that of the CIP specimen.

Blind prediction and post-experimental analysis of RC core wall’s cyclic flexural response using MVLEM-FD

AbstractBlind prediction and post-experimental studies of the flexural cyclic response of a U-shaped core wall, tested at UCLouvain, Belgium, are presented. The tested specimen (referred to as UW1) was modelled using a relatively simple 3D force–displacement-based version of the beam–column multiple-vertical-line-element (MVLEM-FD), developed at the University of Ljubljana (UL), using standard element parameters. The blind prediction accurately identified critical failure points within the specimen. However, the predicted type of failure, attributed to the rupture of longitudinal bars in the boundary region of flanges was somewhat different from that observed in the experiment. These bars were indeed ruptured, but their rupture was preceded by their buckling and the spalling of the surrounding concrete core. Moreover, the predicted force–displacement hysteretic loop exhibited a slight shift compared to experimental observations. Post-experimental studies revealed that this discrepancy was primarily due to the modelling of the loading at the top of the wall rather than the modelling of the wall itself. Specifically, an additional bending moment induced by the eccentricity of the vertical load applied using three actuators, which was overlooked in the blind prediction. Upon correcting the loading, the agreement between the numerical studies and experiment was considerably improved in terms of both the global and local response quantities. Additionally, minor improvements in modelling the boundary regions of the wall’s flanges, considering the relatively large unconfined concrete cover, were introduced, leading to enhanced estimations of near-collapse response.

Study on hysteresis behavior of two kinds of reinforced CHS X-joints

Ultra-low cycle fatigue loading tests were conducted on two reinforced CHS X-joints (external stiffening rings and plates) and an unreinforced joint to analyze their post-yield failure modes, fracture mechanisms, and hysteretic properties. The findings indicate that these three joints exhibit varying failure modes post-yield: the unreinforced joints fail primarily due to chord fracture at the weld; the ring-reinforced joints initially see ring fracture, followed by chord crack at the weld; while the plate-reinforced joints initially fail from chord fracture and subsequently develop cracks at the plate-chord interface. The reinforced joints display plumper hysteretic loops and higher ultimate bearing capacities than the unreinforced joint. Compared to X-1, the tensile and compressive ultimate bearing capacities of RX-1 have increased significantly by 56.9 % and 74.1 %, respectively. In comparison, those of TX-1 have increased moderately by 2.2 % and 67.6 %, respectively, albeit with a slight compromise in ductility. The cumulative energy dissipation of RX-1 and TX-1 has risen by 22.62 % and 131.99 %, respectively, compared to the unreinforced joint. Notably, the dissipated energy before cracking accounts for 16.50 %, 18.16 %, and 22.29 % of the cumulative energy dissipationfor the three joints, respectively, highlighting the substantial contribution of crack propagation to energy dissipation under large deformations. The VUSDFLD subroutine based on Cyclic Void Growth Model (CVGM) is embedded into ABAQUS, this subroutine considers the initiation and propagation of joint cracks. Three finite element models with the same dimensions of the specimens were built to simulate the damage process of the joint. The results show that this method can accurately simulate such joints’ cracking and crack growth behavior under cyclic axial load. The simulated hysteresis curve is in good agreement with the test curve.

An emergent attractor network in a passive resistive switching circuit

Resistive memory devices feature drastic conductance change and fast switching dynamics. Particularly, nonvolatile bipolar switching events (set and reset) can be regarded as a unique nonlinear activation function characteristic of a hysteretic loop. Upon simultaneous activation of multiple rows in a crosspoint array, state change of one device may contribute to the conditional switching of others, suggesting an interactive network existing in the circuit. Here, we prove that a passive resistive switching circuit is essentially an attractor network, where the binary memory devices are artificial neurons while the pairwise voltage differences define an anti-symmetric weight matrix. An energy function is successfully constructed for this network, showing that every switching in the circuit would decrease the energy. Due to the nonvolatile hysteretic function, the energy change for bit flip in this network is thresholded, which is different from the classic Hopfield network. It allows more stable states stored in the circuit, thus representing a highly compact and efficient solution for associative memory. Network dynamics (towards stable states) and their modulations by external voltages have been demonstrated in experiment by 3-neuron and 4-neuron circuits.

Prediction of parameters in the Ibarra–Medina–Krawinkler model for reinforced concrete columns using random forest and active learning

The lumped plasticity model is widely used in the practical modeling of reinforced concrete (RC) columns because of its computational efficiency. However, existing formulations for estimating the backbone curve and cyclic deterioration parameters often fail to accurately predict new data with high variability and necessitate laborious calibrations. To address it, a machine-learning (ML) approach utilizing the random forest (RF) algorithm to predict seven parameters in the Ibarra–Medina–Krawinkler lumped plasticity model for depicting hysteretic response is proposed in this study, where a comprehensive data of 475 RC columns, encompassing diverse material properties, geometric features, and failure modes, is used. In addition, an active-learning framework is integrated to address the limited availability of labeled data in supervised ML tasks, which reduces the exhausted labeling process. The proposed RF surpasses existing research and commonly used ML models regarding coefficient of determination. Additionally, the predicted parameters more accurately simulate the behavior of strength and stiffness degradation in the hysteretic loop of columns than empirical regression formulas. These results will benefit the high-fidelity seismic risk assessments of RC buildings.

Low-Cycle Fatigue Properties of Bimetallic Steel Bar with Buckling: Energy-Based Numerical and Experimental Investigations.

A bimetallic steel bar (BSB) consisting of stainless-steel cladding and carbon steel substrate exhibits excellent corrosion resistance and good mechanical properties. The bimetallic structure of BSBs may affect their low-cycle fatigue performance, and current investigations on the above issue are limited. In this study, the low-cycle fatigue properties of bimetallic steel bars (BSBs) with inelastic buckling were investigated. Experiments and numerical studies were conducted to investigate the low-cycle fatigue capacity for BSBs, considering buckling. The buckling mode of BSBs is discussed. The hysteretic loops and energy properties of BSBs with various slenderness ratios (L/D) and fatigue strain amplitudes (εa) are investigated. With increases in the L/D and εa, the original symmetry for hysteresis loops disappears gradually, which is caused by the buckling. A predictive equation revealing the relation between the εa and fatigue life is suggested, which considers the effects of the L/D. A numerical modelling method is suggested to predict the hysteretic curves of BSBs. The effect of buckling on the stress and energy properties of BSBs is discussed through the numerical analysis of 44 models including the effects of the L/D, εa, and cladding ratios. The numerical analysis results illustrate that the hysteresis loops of BSBs with various εa values exhibit similar shapes. The increase in the cladding ratio reduces the peak stress and the dissipated energy properties of BSBs. The hysteresis loop energy density decreases by about 3% with an increase of 0.1 in the cladding ratio. It is recommended that the proportion of stainless steel inBSBs should be minimized once the corrosion resistance requirements are met.

Seismic behavior of looseness-induced inclined mortise and tenon joints in ancient timber structures: Experimental tests, multi-scale finite element model, and behavior degradation

The inclination damage of mortise and tenon (M-T) joints, caused by the looseness between the mortise and tenon, has an detrimental impact on the overall safety of structures. To investigate the effects of varying inclination rotation on the seismic behavior of ancient M-T joints, four 1/3.2-scaled straight M-T joints with different inclination rotation, one intact joint for comparison and three looseness-induced inclined joints, were cyclically tested. Typical failure modes of the damaged joints were identified. The influence of the tilt deterioration on the joint's hysteretic and rotational behavior was evaluated. The test results showed that with an increase in the inclination rotation, the size of the hysteretic loops of the inclined joints was increasingly smaller, the negative initial slippage and pinching effects were more apparent, the ultimate moment-resisting, initial elastic stiffness, and ductility of the specimens degraded significantly. Furthermore, the multi-scale finite element models of the looseness-induced inclined M-T joints were established using the ABAQUS. Based on the validated numerical model, the parameter analysis was performed. The influence of the frictional coefficient of wood, inclined rotation, and horizontal gap between the tenon and mortise on the joint's hysteretic behavior and energy dissipation mechanism was quantified. It is found that with a friction coefficient of 0.6, the positive and negative ultimate moments-resisting of the joint improved 65.99 % and 35.89 %, respectively; the joint's slip moment and energy dissipation increased by 12.18 and 3.78 times, respectively. With a 0.043 rad inclined rotation, the positive and negative ultimate moments of the joint decreased 23.32 % and 30.46 %, respectively; the joint's positive and negative initial elastic stiffnesses and cumulative energy dissipation reduced 49.12 %, 28.96 %, and 56.33 %, respectively. When the inclined rotation remained at 0.022 rad, the positive and negative ultimate moments of the joint including a 6 mm horizontal gap reduced 26.63 % and 34.20 %, respectively; the joint's positive and negative initial elastic stiffnesses, and accumulative energy dissipation decreased 42.42 %, 59.43 %, and 79.50 %, respectively.

Cyclic Behavior of Partially Prefabricated Steel Shape-Reinforced Concrete Composite Shear Walls: Experiments and Finite Element Analysis

Due to the higher lateral stiffness, load-carrying, and energy dissipation capacities compared with traditional reinforced concrete (R.C.) shear walls, steel shape-reinforced concrete (SRC) shear walls, in which steel profiles are encased in the boundary elements, have been widely applied in high-rise buildings. In order to simplify the on-site construction procedure, this paper proposes a novel partially prefabricated steel shape-reinforced concrete (PPSRC) shear wall using throat connectors. Based on the pseudo-static tests of two large-scale specimens, the effect of construction methods (prefabricated or cast in place) on the cyclic behavior of PPSRC shear walls was investigated by the hysteretic loops, skeleton curves, stiffness degradation, energy dissipation, and deformation decomposition. The test results indicated that PPSRC shear walls could exhibit a comparative cyclic response with the cast-in-place SRC shear walls, and the proposed throat connectors could effectively transfer the stress of the longitudinal reinforcements. Finally, a macro-modeling of PPSRC shear walls based on the multi-layer shell elements in OpenSees 3.3.0 was established and validated by the test results, and the parametric analysis of the axial compression, steel ratio, and concrete strength of prefabricated and cast-in-place parts was then conducted.

Model of Shape Memory Alloy Actuator with the Usage of LSTM Neural Network.

Shape Memory Alloys (SMAs) are used to design actuators, which are one of the most fascinating applications of SMA. Usually, they are on-off actuators because, in the case of continuous actuators, the nonlinearity of their characteristics is the problem. The main problem, especially in control systems in these actuators, is a hysteretic loop. There are many models of hysteresis, but from a control theory point of view, they are not helpful. This study used an artificial neural network (ANN) to model the SMA actuator hysteresis. The ANN structure and training method are presented in the paper. Data were generated from the Preisach model for training. This approach allowed for quick and controllable data generation, making experiments thoroughly planned and repeatable. The advantage and disadvantage of this approach is the lack of disturbances. The paper's main goal is to model an SMA actuator. Additionally, it explores whether and how an ANN can describe and model the hysteresis loop. A literature review shows that ANNs are used to model hysteresis, but to a limited extent; this means that the hysteresis loop was modelled with a hysteretic element.

Vapor Deposition of Bilayer 3R MoS2 with Room-Temperature Ferroelectricity.

Two-dimensional ultrathin ferroelectrics have attracted much interest due to their potential application in high-density integration of non-volatile memory devices. Recently, 2D van der Waals ferroelectric based on interlayer translation has been reported in twisted bilayer h-BN and transition metal dichalcogenides (TMDs). However, sliding ferroelectricity is not well studied in non-twisted homo-bilayer TMD grown directly by chemical vapor deposition (CVD). In this paper, for the first time, experimental observation of a room-temperature out-of-plane ferroelectric switch in semiconducting bilayer 3R MoS2 synthesized by reverse-flow CVD is reported. Piezoelectric force microscopy (PFM) hysteretic loops and first principle calculations demonstrate that the ferroelectric nature and polarization switching processes are based on interlayer sliding. The vertical Au/3R MoS2/Pt device exhibits a switchable diode effect. Polarization modulated Schottky barrier height and polarization coupling of interfacial deep states trapping/detrapping may serve in coordination to determine switchable diode effect. The room-temperature ferroelectricity of CVD-grown MoS2 will proceed with the potential wafer-scale integration of 2D TMDs in the logic circuit.

Test of three-storey confined masonry structure built from clay blocks and PU glue

The paper presents an experimental test of a nearly full-scale three-storey model of a confined masonry structure. The walls were constructed using newly developed clay masonry blocks, with large holes filled with thermal insulation and polyurethane glue instead of mortar. In the construction,relatively thick 38 cm walls and large tie-columns with 25 cm × 25 cm plan dimensions. The test model was built as confined masonry according to Eurocode 8. The innovative materials and construction were developed for thermal efficiency and the test was intended to verify the structural response. The model, test setup, and test procedures are described, and the results of the tests are analysed. The building responded primarily in shear, and ultimately failed in the ground floor in a storey mechanism, but there was also substantial damage on the floor above. Due to the non-standard dimensions of the tie-columns and because masonry was thicker than the tie-columns, the in-plane loaded walls developed an interesting response mechanism in which protruding masonry sheared off. Although this did not significantly impact the overall response, it led to the earlier onset of the significant damage limit state of the structure. The model responded well with wide hysteretic loops and distributed damage, which indicated large energy dissipation capacity, and the response envelopes showed gradual strength deterioration after peak load. The response of the model was quantitatively estimated using the N2 method. Calculations showed that the tested model could withstand a design seismic load corresponding to a 0.21 g peak ground acceleration with significant damage and almost 0.52 g before collapsing. The overstrength was estimated at 1.71.

Structural behavior of steel tube reinforced resilient RAC shear walls under static cyclic loading

This paper proposed a method to enhance the energy dissipation capacity of recycled aggregate concrete (RAC) shear walls reinforced with ultra-high strength bars (UHSB). The proposed method encases circular steel tubes within the boundary elements of walls. With the presence of steel tubes, steel fibers and axial load level as primary research variables, five RAC shear walls were fabricated and tested under reversed cyclic lateral force and constant axial compression to verify the effectiveness of the proposed method. The test results showed that the presence of steel tubes upgraded lateral resistance and enhanced energy dissipation capacity, while causing some subtle splitting cracks. Due to the yielding of the steel tubes, the encasement of the steel tube increased residual drift ratio at large drift, but the measured residual drift ratios of test walls still were kept less than 0.5 % until 2.5 % drift ratio. The addition of steel fibers delayed cracking, constrained the cover concrete and reduced damage to the specimens. Test results also indicated that increasing concrete strength and axial compression level could enhance the lateral resistance of the proposed wall. In addition, a numerical analytical method is presented to analyze the cyclic behavior of the proposed shear walls. Good agreement was observed between the measured and calculated hysteretic loops.

Nonlinear 3D Finite Element Analysis of a Coupled Soil–Structure System by a Deterministic Approach

Fully coupled soil–structure analyses were performed for a building of strategic importance located in the city of Messina (Sicily, Italy). The structure was built after the destructive 1908 earthquake, also known as the ‘Messina and Reggio Calabria earthquake’, which caused severe ground shaking. A parametric study considering three seismograms of this earthquake was performed. Deep in situ and laboratory investigations allowed the definition of the geometric and geotechnical model of the subsoil. Numerical analyses were performed with PLAXIS3D finite element software (Version 21.01.00.479). The Hardening Soil model with small-strain stiffness was accurately calibrated using laboratory and field data. The dynamic response was investigated in terms of accelerations, response spectra, amplification functions, displacements and stress–strain hysteretic loops. The findings show that many aspects must be investigated for the retrofitting of buildings with shallow foundation in areas characterized by a medium to high level of seismic risk: (i) a key role is played by an accurate investigation of the soil; taking into account the specific conditions of the soil, it was possible to investigate its filtering effects; (ii) the dynamic response of the fully-coupled soil–structure system deviates from the free field-site response analysis; (iii) the results reveal the importance of considering the soil nonlinearity in seismic soil–structure interaction problems.

Experimental study of the static and hysteretic performance of grouted steel beam-column inter-connections for modular integrated construction

Modular Integrated Construction (MiC) has gained prominence as a construction method, and the integrity of its structural connections plays a critical role in ensuring the overall stability and safety of buildings. This paper presents an experimental investigation into the static and hysteretic performance of grouted steel beam-column inter-connections designed for MiC. The study examines eight full-scale specimens subjected to both monotonic and cyclic loading conditions, with a focus on failure characteristics, deformation behavior, loading-displacement curves, loading-strain curves, skeleton curves of hysteretic loops, stiffness degradation, and energy dissipation. Key findings of the study include the observation of weld cracking between beam flanges and columns in all specimens, highlighting the necessity of welding quality control to prevent such issues. Grouted connections exhibited superior integrity, with no gap opening or misalignment between upper and lower columns. Additionally, it was found that grouting could enhance the stiffness of certain connections. Removal of diagonal stiffeners significantly decreased peak bearing capacity, emphasizing their importance. The composite action brought about by bolts connecting ceiling and floor beams also proved influential. According to Eurocode 3, all grouted specimens fall under the classification of semi-rigid connections, with a distinction made for partial and full-strength connections. This research contributes valuable insights into the static behavior and hysteretic performance of grouted steel beam-column inter-connections for MiC, providing essential knowledge for the structural design and safety of buildings utilizing this innovative construction method.

Hysteretic Room-Temperature Magnetic Bistability of the Crystalline 4,7-Difluoro-1,3,2-Benzodithiazolyl Radical.

The title radical R⋅, synthesized by reduction of the corresponding cation R+, is thermally stable up to ~380 K in the crystalline state under anaerobic conditions. With SQUID magnetometry, single-crystal and powder XRD, solid-state EPR and TG-DSC, reversible spin-Peierls transition between diamagnetic and paramagnetic states featuring ~10 K hysteretic loop is observed for R⋅ in the temperature range ~310-325 K; ΔH=~2.03 kJ mol-1 and ΔS=~6.23 J mol-1 K-1. The transition is accompanied by mechanical movement of the crystals, i. e., by thermosalient behavior. The low-temperature diamagnetic P-1 polymorph of R⋅ consists of R⋅2 π-dimers arranged in (…R⋅2…)n π-stacks; whereas the high-temperature paramagnetic P21/c polymorph, of uniform (…R⋅…)n π-stacks. With the XRD geometries, CASSCF and broken-symmetry DFT jointly suggest strong antiferromagnetic (AF) interactions within R⋅2 and weak between R⋅2 for the (…R⋅2…)n stacks; and moderate AF interactions between R⋅ for the (…R⋅…)n stacks. The fully hydrocarbon archetype of R⋅ does not reveal the aforementioned properties. Thus, the fluorinated 1,3,2-benzodithiazolyls pave a new pathway in the design and synthesis of metal-less magnetically-bistable materials.

Experimental investigation of self-centering beam-to-column connections with different ribbed top and seat angles

This study experimentally investigated the seismic behavior of a novel self-centering beam-to-column connection with the different ribbed top and seat angles. The connections were composed of square concrete filled steel tubular (CFST) column, H-shaped steel beam, angles with or without stiffening rib, and post-tensioned (PT) high-strength steel tendons. Eight half-scale specimens were designed and tested under cyclic loading. The influences of stiffening rib type including plane rib and multi-wave rib, PT tendon distance, and with or without PT tendons upon the performance of the connection were evaluated experimentally. The results show that the connections installed PT tendons exhibited the double linear hysteretic feature with a slight narrow hysteretic loop due to the friction of the components, the connections assembled the angles or ribbed angles took on the fuller and more stable hysteretic loop, and the connections installed the PT tendons and ribbed angles exhibited the double-flag shaped hysteretic curve. The employment of plane or multi-wave ribbed angles significantly increased the initial rotational stiffness and ultimate moment. For the connection combined the PT tendons and ribbed angles, the average residual rotation angle ratio and the maximum equivalent viscous damping ratio reached about 0.095 and 0.07 at the drift ratio of 2%, respectively. The distance of PT tendons did not affect the hysteretic behavior of the connection. The PT tendons could provide the excellent self-centering behavior of the connection.

The influence of Nd3+ doping on the structural, optical, magnetic, and dielectric characteristics of nanoscale hexagonal wurtzite type ZnO

Nd3+ doped ZnO nanoparticles (NPs) Zn1−xNdxO (x = 0, 0.01, 0.03, and 0.05) were successfully synthesized via simple co-precipitation method. To extract precise crystallite size and lattice strain from the X-Ray Diffraction (XRD) pattern, Halder-Wagner method was employed. High Resolution Transmission Electron Microscopy (HRTEM) analysis clearly substantiates the NPs formation.The band gap variation in the doped samples in comparison with the pristine sample is extracted from UV–Vis diffuse reflection spectroscopy. The decrease in Photo-luminance (PL) intensity is observed to be significant for enhanced photocatalytic applications. At room temperature (RT), all Nd3+doped ZnO samples exhibit a distinct hysteretic loop. The initial magnetization graph and M-T curve fitted by the modified Brillouin function and combination of spin wave and Curie-Weiss law respectively. The well-fittings indicate the co-existence of paramagnetic (PM) and ferromagnetic (FM) phases in the doped sample, and the quantitative contribution to each phase is also extracted. Significantly high dielectric constant and low ac conductivity at a low frequency region support the presence of large dipolar effect-induced frequency-dependent short-range conductivity in these pristine and Nd3+ doped ZnO samples.

Two-dimensional spin-crossover coordination polymers based on the 1,1,2,2-tetra(pyridin-4-yl)ethene ligand.

A series of two-dimensional (2D) spin-crossover coordination polymers (SCO-CPs) [FeII(TPE)(NCX)2]·solv (1: X = BH3, solv = H2O·2CH3OH·DMF; 2: X = Se, solv = H2O·2CH3OH·0.5DMF; 3: X = S, solv = H2O·2CH3OH·0.5DMF) were synthesized by employing 1,1,2,2-tetra(pyridin-4-yl)ethene (TPE) and pseudohalide (NCX-) coligands. Magnetic measurements indicated that complexes 1-3 exhibited SCO behaviors with diminishing thermal hysteresis (7/4/0 K) upon decreasing the ligand-field strength. The critical temperatures (Tc) during spin transition were found to be inversely proportional to the coordination ability parameters (a™) with a linear correlation. The guest effect was also investigated in the solvent-exchanged phases 1-SE/2-SE/3-SE wherein the DMF molecules were replaced by methanol molecules. Compared with 1-3, 1-SE/2-SE/3-SE displayed more abrupt and complete single-step SCO behaviors but narrower thermal hysteretic loops. The results reported here demonstrate that the Tc values of these two families were dominated by the ligand-field strength of the NCX- anions (NCBH3 > NCSe > NCS), whereas the guest effect only modulated the kinetic factor of the SCO nature in this system.

Cyclic loading response of precast concrete beam-column connections with partially bonded draped prestressing tendon

An emulative precast concrete beam-column connection consists of prefabricated columns, T-shaped composite beams with partially bonded post-tensioned (PT) tendon, and cast-in-place (CIP) core region is proposed in this study. Experimental study was carried out to examine the hysteretic behavior of four full-scale beam-column connections under a high axial compression ratio (μ = 0.4). The specimens included a precast interior connection (PC1), a precast exterior connection (PC2), and two corresponding conventional CIP control specimens (RC1 and RC2). Performance assessment of the suggested connection was conducted by evaluating various factors, including failure mode, hysteresis curve, deformation, stiffness, and energy dissipation capacity. Test results revealed that all specimens fulfilled the design objective of strong column-weak beam with flexural failure showed at beams ends. In comparison to RC1, PC1 exhibited a 6.4 % increase in peak load-carrying capacity in the positive loading process and a 7.1 % decrease in the negative loading process. On the other hand, PC2 demonstrated approximately 11.9 % higher load-carrying capacity in the positive loading and a 2.0 % lower capacity in the negative loading when compared to RC2. The ductility coefficients of PC1 and PC2 was 3.39 and 2.64, respectively, which were slightly higher than that of RC1 and RC2 (3.01 and 2.43). All specimens exhibited good deformation restoring capacity and plump hysteretic loops, demonstrating satisfactory energy dissipation capacity. Overall, the proposed connection with partially bonded PT tendon showed comparable seismic performance with their CIP counterparts, indicated its promising potential for use in practical engineering applications.