Cyclic Resistance Research Articles

An experimental study for effectiveness of steel fibre reinforced exterior beam-column joints under cyclic resistance

An ability of the structure to sustain levels of inelastic deformation, implicit in ductility values, is dependent on the material and detailing used. In order to achieve this high percentage of lateral reinforcement in the core of the joint is needed; which lead to reinforcement congestion and construction difficulties. In this paper, the behaviour of beam-column joint was investigated for different variations in spacing of lateral reinforcement in critical region. This increased spacing of lateral hoops reduced the reinforcement conjunction and addition of steel fibre reinforced concrete (SFRC) for same region help to remove deficiency due to removal of lateral reinforcement. The steel fibre volume fraction of 2% was used in critical region. Test results of six one-third scaled beams-column joints of reinforce concrete frame are presented to study the influence of steel fibres for effective reduction of lateral hoops in joint region. The experimental investigations also incorporate the evaluation of parameters such as ultimate strength, energy dissipation, ductility, stiffness, specific damping capacity and crack patterns. An experimental result demonstrated that SFRC beam-column joint perform satisfactorily and showed enhancement in all above properties. The behaviour of beam-column joint also showed that the additions of fibre in critical region provided necessary confinement and ductility after reduction in lateral hoops.

Liquefaction susceptibility of clayey sands under saturated and partially saturated conditions

Experiences from previous earthquake events have indicated that sands containing non-plastic (silt) or plastic (clay) fines are susceptible to liquefaction. These experiences underline the need for improving the fundamental understanding of the seismic behaviour of silty and clayey sands and for developing appropriate methods to evaluate their liquefaction potential. This paper presents an attempt to elucidate the integrated effects of fines (non-plastic silt and plastic clay) inclusion and degree of saturation on the cyclic behaviour and liquefaction resistance of sands based on systematic experiments. One of the notable findings of the study is that, apart from the familiar mode of cyclic mobility, clayey sand can also undergo flow-type failure under either fully or partially saturated conditions. The unified correlation between the cyclic resistance ratio and the state parameter (ψ), established earlier for clean and silty sand in the framework of critical state soil mechanics, is found to work for clayey sand as well. Furthermore, it is shown that the impact of saturation on the cyclic strength of clean and clayey sands can be reasonably characterised using the compression wave velocity normalised by the shear wave velocity.

Effect of steady-state strength of medium to dense sand on the performance of sheet pile wall as identified through centrifuge tests and Type-B and C simulations

This study focuses on five centrifuge experiments of a sheet pile wall performed by three institutions, which cover relative densities ranging from 55 % to 66 %. A strain space multiple mechanism model incorporated in the computer program FLIP is used for the simulation. In the Type-B simulation performed before the centrifuge test data release, the steady-state strength Sus is not considered, i.e., Sus is assumed to be infinity (Sus=∞), and only cyclic resistance is considered. In the Type-C simulation performed after the release of the centrifuge test data, Sus and cyclic resistance are considered. When Sus=∞, the computed displacements of the sheet pile wall are consistent with or unconservative by a factor of one-half of the measured displacements. However, when Sus ranges from 1500 to 7500 kPa evaluated for clean sands, the computed displacements are generally consistent with the measured displacements, or slightly conservative. When Sus ranges from 100 to 400 kPa evaluated for sands with fines content of 5 %, or when Sus ranges from 20 to 50 kPa inferred from cyclic laboratory tests, the computed displacements are conservative by a factor of one and a half or two of the measured displacements. The steady-state strength of medium to dense sand is identified as a significant factor influencing the performance of a sheet pile wall.

A shear history model for capturing the liquefaction resistance of sands at various cyclic stress ratios

Various constitutive formulations have been developed over the years to reproduce the cyclic resistance of sands. A common challenge for existing models is the accurate simulation of the cyclic strength of sands for a wide range of initial conditions and different cyclic stress levels when adopting a single calibration. Many liquefaction models tend to overpredict the resistance of the soil under large-amplitude loading, while underestimating the strength at low-amplitude cyclic shearing. This manifests itself in slopes of simulated cyclic resistance ratio curves (CRR-curves) which are steeper than experimental studies indicate. This paper provides a discussion on the effects of large-amplitude and low-amplitude cyclic shearing on a granular material based on micromechanical and experimental investigations presented in the literature. A constitutive model with a shear-history threshold is proposed, which accounts for a shift of the apparent angle of phase transformation under cyclic loading. In addition, a novel expression for a deviatoric fabric tensor is introduced to describe the evolution of shear-induced fabric anisotropy while a soil is dilating and contracting. Combining these two features in one formulation within the bounding surface plasticity framework enables an accurate prediction of cyclic strength of sands under a wide range of cyclic stress ratios.

Металознавчі аспекти дисперсійного нітридного зміцнення високовуглецевих сталей Повідомлення 1. Вплив параметрів аустенізуючого нагріву та відпуску на фазовий перерозподіл азоту та ванадію в сталях

Systemic fundamental research for several decades at the FTIMS of the National Academy of Sciences of Ukraine and the accumulated experience of industrial application have shown that the technology of dispersion nitride hardening, which is based on the alloying of steels with nitrogen and vanadium, is a method of significantly improving the entire complex of physical, mechanical and operational properties of cast and deformed carbon, low-alloy and alloy steels of various functional purposes. The most significant advantage of the steels developed at the FTIMS of the National Academy of Sciences of Ukraine is a simultaneous significant increase in their static and cyclic strength, fracture toughness, thermal strength and heat resistance, wear resistance, annealing, weldability, reduction or complete elimination of the tendency to natural, deformation and warm embrittlement. Medium- and high-carbon pre-eutectoid and eutectoid steels of high strength and wear resistance are widely used in various fields of mechanical engineering. However, they are most widely used for railway wheels and rails. The reliability and operational resource of wheels and rails, which are in extremely harsh operating conditions, mainly determine the technical and economic performance indicators of railway transport. At the same time, existing relatively cheap non-alloyed and low-alloyed medium- and high-carbon wheel and rail steels no longer meet the modern requirements of increased speeds and load capacity of rolling stock. Keywords: carbon steels, dispersion nitride hardening, austenization, tempering, phase redistribution of nitrogen and vanadium.

Формирование и исследование свойств покрытий из металлического стекла FeWCrMoBC на стали 35

Introduction. To obtain metallic glass coatings it is necessary to achieve high cooling rates of melt. FeWCrMoBC composition has high melt viscosity and sufficient glass-forming ability to fix of the amorphous state at cooling rates implemented by electric discharge alloying with the use of a crystalline electrode. The purpose of the work is one-stage deposition of amorphous coating by electric discharge alloying, using crystalline anode FeWCrMoBC, prepared by casting and studying the properties of modified surface of carbon steel: wettability, high-temperature resistance, tribological properties. Methods and Results. The structure of anode and coatings was investigated by X-ray diffraction analysis in CuKα radiation on a DRON-7 diffractometer. In contrast to the X-ray patterns of the anode material, sharp Bregg reflexes were not observed on the X-ray patterns of the coatings, but a wide halo was present in the range of angles 2Ѳ = 40–50°, which indicates its amorphous structure. The cyclic high-temperature resistance test was carried out at 700 °C for 100 hours. The wear rate and coefficient of friction of the specimens were studied under dry sliding friction at a speed of 0.47 m/s at a load of 25 N with the use of a counterbody made of high-speed steel M45. The influence of the discharge pulse duty cycle on the character of mass transfer (anode erosion, cathode weight gain, mass transfer coefficient) during coating formation was investigated. With a decrease in the duty cycle of the discharge pulses up to 9 times, the erosion of the anode increased up to 5 times, and the cathode mass gain increased up to 2.2 times. The maximum mass-transfer coefficient was achieved at the highest duty cycle. An increase in a number of surface properties of carbon steel after coating was observed: the hardness of the surface of the specimens increased by 2.3–2.6 times; the average thickness of the coatings was in the range of 56–80.6 µm; the wetting angle was in the range of 108.4–121.3°; the coefficient of friction decreased by 1.2–1.4 times; the wear resistance increased by 2–3.3 times; oxidizability in air decreased by 14–18 times. Scope and Conclusions. The achieved higher properties (hardness, wear resistance, high-temperature resistance, and hydrophobicity) of the executive surfaces of parts made of carbon steel after deposition of the proposed coatings can be used in various branches of engineering production. The results of the work confirmed the possibility of deposition of metallic glass coatings by electric discharge alloying with the use of cast anode material FeWCrMoBC on carbon steel.

Electrochemical behavior and surface stability of dental zirconia ceramics in acidic environments

Dental zirconia ceramics, widely employed in dentistry for their biocompatibility and mechanical properties, face challenges in long-term viability within the oral cavity. This study focuses on analyzing the electrochemical behavior of a commercial dental zirconia ceramic type in acidic environments. Through extensive electrochemical investigations, including Electrochemical Impedance Spectroscopy (EIS) and cyclic polarization resistance (Cpol), corrosion resistance was assessed. Despite indications of material dissolution, our results demonstrate significant corrosion resistance, as reflected in low corrosion current density (Icorr) values. Notably, the study reveals the development of a protective oxide layer at the ceramic-electrolyte interface, contributing to material stability. XRD analysis confirms the presence of stable crystallographic phases (t-ZrO2) even after exposure to acidic media. Surface characterizations utilizing scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX) affirm minimal surface damage and maintained elemental composition. These findings illuminate the intricate electrochemical behavior of dental zirconia ceramics in challenging environments, underscoring their potential for durable dental restorations. This interdisciplinary research bridges dentistry and materials science, providing valuable insights for optimizing material properties and advancing dental materials and restorative techniques.

Effect of Overburden Stress and Plasticity on the Cyclic Resistance of Silts

Effect of Overburden Stress and Plasticity on the Cyclic Resistance of Silts

Mechanism of seismic liquefaction for heterogeneous soil

In addition to inducing uncertainty in the predicted response, natural spatial variability of soil properties affects the mechanical response of geotechnical structures. When a failure surface is involved in the response, this surface can deviate from its theoretical location to pass through weaker zones of material. For the case of seismically induced soil liquefaction, it has been found that a larger amount of excess pore water pressure is generated in a soil exhibiting small-scale variability of its properties than in the corresponding uniform soil having geomechanical properties equal to the average properties of the heterogeneous soil. An explanation for this important phenomenon is provided in this paper based on the results of centrifuge experiments and numerical simulations of heterogeneous and homogeneous saturated soil deposits subjected to seismic loads. It is demonstrated, based on a detailed analysis of the results, that partial drainage during the earthquake, consisting of pore water inflow from loose soil zones that liquefy first toward surrounding dense areas, may trigger softening of dilative soils. The water inflow effects in terms of volumetric strains leading to reduced cyclic resistance of dense sands are compared with results of specially designed cyclic triaxial tests reported by other researchers.

Study of the Influence of Surface Treatment with a Flexible Tool on the Cyclic Durability Resistance of Steel Grade 25

Study of the Influence of Surface Treatment with a Flexible Tool on the Cyclic Durability Resistance of Steel Grade 25

Cyclic and Postcyclic Pullout Resistance of Soil Nail

Cyclic and Postcyclic Pullout Resistance of Soil Nail

Cyclic oxidation resistance and self-healing properties of HfB2-doped glass composite coatings at 900 °C

HfB2-doped glass coating exhibits superior cyclic antioxidative performance compared to pure glass coating. The HfB2 particles inhibit the precipitation of crystals with low thermal expansion coefficient, mitigating the risk of fish-scaling failure. In addition, the HfB2-doped glass composite coating, with high contents of amorphous phases, maintains its viscous flow properties even after multiple high temperature cyclic oxidations, which enables it to self-heal. Moreover, the oxidation product (B2O3) of HfB2 enhances network connectivity of the glass system, providing more unsaturated sites for the chemical bonding of the self-healing process.

Cyclic tests and shear resistance design of stiffened corrugated steel plate shear walls

Corrugated steel plate shear walls (CSPSWs) are commonly employed as lateral-load-resisting components in regions with high seismic activity. In order to enhance their shear resistance, stiffeners can be affixed to CSPSWs, forming stiffened CSPSWs (S-CSPSWs). This paper presents experimental and numerical investigations into S-CSPSWs. Firstly, two specimens were tested under cyclic shear loads, one of which was an unstiffened CSPSW specimen, while the other was an S-CSPSW specimen. The typical failure modes observed from the test were global buckling and fracture of the corrugated steel plate (CSP). Both specimens exhibited stable hysteretic loops and excellent energy dissipation. It was observed that the stiffeners could constrain the out-of-plane deformation of the CSP, thus increasing its energy dissipation capacity. However, the fracture during the initial stage reduced the shear-carrying capacity and energy dissipation capacity. Subsequently, a finite element (FE) model is developed to simulate the test results. Additionally, the elastic buckling loads of S-CSPSWs are investigated by employing the validated FE model. The shear buckling coefficient is estimated by introducing a rigidity ratio between the stiffeners and the CSP. Finally, the shear resistance design method is established and is helpful in promoting the application of S-CSPSWs. The design formulas proposed in this paper agree well with the FE analysis results and can be effectively implemented in practice.

Comparison of a tailings material and a natural sand in seismic site response analyses

This article investigates the seismic response of a tailings sand material in the context of site response analysis. The computed response is contrasted with that obtained for an equivalent deposit consisting of a well-characterised natural sand. Initially, the fundamental properties of both materials are used to interpret and compare their behaviour in the framework of Critical State Soil Mechanics (CSSM). Subsequently, both materials' monotonic and cyclic responses are calibrated for an advanced bounding surface plasticity model. Finally, the impact of different calibration approaches is examined through site response analyses under a strong motion. This process identifies fundamental differences between the two geo-materials, impacting the single elements simulations, especially the accuracy of undrained cyclic triaxial tests. The site response analyses examined herein show the impact of the calibrations adopted for both materials in terms of acceleration response spectra, displacements, and excess of pore water pressures (PWP). Although a relatively deep phreatic surface is adopted, the cyclic resistance and permeability of both materials plays a dominant role in the site response characteristics, controlling the excess PWP generation and hence the non-linear behaviour in the soil deposit. Finally, parametric studies are also conducted to explore the impact of permeability of the sands in the site response.

High-temperature cyclic oxidation of micro- and nano-ZrO2–25wt.%CeO2–2.5wt.%Y2O3 thermal barrier coatings at 1300 °C

In this study, the high-temperature cyclic oxidation resistance of micro- and nano-ZrO2–25wt.%CeO2–2.5wt.%Y2O3 (CYSZ) thermal barrier coatings (TBCs) was investigated. The TBCs were applied on IN738LC/CoNiCrAlY using the atmospheric plasma spray (APS) technique and subjected to high-temperature cyclic oxidation through 5-h cycles at 1300 °C. Various characterization techniques, including X-ray diffraction (XRD), Raman spectroscopy, nanoindentation, and field-emission scanning electron microscopy (FESEM), were used to assess the TBCs. Results indicated that annealing tetragonal zirconia at 1300 °C can generate antiphase boundary defects. The Young's modulus and hardness of nano- and micro-CYSZ TBCs decrease with the increase of antiphase boundary density. XRD and Raman results, the phase transformation behavior of tetragonal zirconia can be correlated to antiphase boundary density. Furthermore, the study showed that the nano-CSZ TBC has better oxidation resistance than the micro-CYSZ TBC at 1300 °C.

Dynamic response of a low plasticity silt deposit: comparison of in-situ and laboratory responses

This study compares the in-situ dynamic response of a low plasticity silt deposit subjected to multidirectional loading from vibroseis shaking and controlled blasting to a suite of element-scale, cyclic laboratory test specimens. The agreement between excess pore pressures and simple shear strain relationships over a wide range in strains is remarkable. Slightly larger excess pore pressures observed in-situ are attributed to three-dimensional loading and pore pressure migration/redistribution in the shallower portions of the deposit. Noted differences in shear modulus, G, are attributed to strain rate effects, spatial variability in the in-situ stiffness, and hydraulic boundary conditions. The variation in in-situ G/Gmax follows the trend from torsional shear specimens up to 0.4% shear strain; larger strains in the silt deposit imposed by controlled blasting yielded a stiffer response than that from cyclic torsional shear and direct simple shear specimens due in part to field drainage for deeper portions of the deposit. The in-situ cyclic resistance ratio for the deeper portion of the deposit in which plane body waves could be assumed and for the selected excess pore pressure ratio criterion was larger than that of stress-controlled cyclic direct simple shear (CDSS) test specimens, despite the detrimental effect of multidirectional shaking in the field. The effect of strain history, spatial variability, and drainage boundary conditions to drive differences between the in-situ and laboratory test specimens is identified.

Effect of Solution Heat-Treatment on the Oxidation Resistance of Ni-Base Single-Crystal Superalloy

To clarify the effect of solution heat-treatment on the oxidation resistance of Ni-base single-crystal superalloy TMS-238, the evaluation of dendrite/inter-dendrite segregation of alloying elements in the as-cast and heat-treated samples, and its effect on cyclic oxidation resistance were investigated. Cyclic oxidation test results at 1100 °C for up to 150 cycles clearly showed that the as-cast samples with element segregations had lower oxidation resistance compared to heat-treated samples with homogeneous structure. Further, for the as-cast sample, rapid growth and spallation of oxide consisting of NiO, Cr2O3, and Al2O3 were observed around the dendrite core for 10 cycles of oxidation. Analysis of sub-surface on sample isothermally oxidized at 1100 °C for 10 minutes showed that rapid oxide growth is due to the formation of discontinuous Al2O3 layer at dendrite core with lower Al concentration. Furthermore, in this study, the threshold value of Al concentration and Gibbs energy for the formation of continuous Al2O3 layer were estimated and determined to be around 5.2 wt pct and − 556.6 ± 0.5 kJ/mol, respectively. This indicated that the solution heat-treatment for TMS-238 should be conducted above 1305 °C for exhibiting oxidation resistance at 1100 °C, to meet the threshold value within the whole region between dendrite and inter-dendrite.

Effect of CrMoN addition on the thermal stability and cyclic impact resistance of TiVN coatings

By adding V atoms to TiN, the tribological and mechanical properties of TiVN coatings are improved. Multilayered coatings, rather than monolayered ones, may further enhance the mechanical properties and thermal stabilities of TiVN. Therefore, an approach was employed in this study to synthesize gradient-and-multilayered CrMoN/TiVN coatings through vacuum arc ion plating. During the impact fatigue test that utilized a cyclic loading device, the correlation between cyclic impact resistance and coating structures of the deposited coatings were evaluated. Vacuum annealing and high temperature oxidation at temperatures exceeding 600 °C were used to assess the thermal stability of the coatings. Although the as-deposited TiVN coating achieved the highest hardness of 30.2 ± 2.5 GPa, the CrMoN/TiVN multilayer coating only experienced a slight decrease to 29.1 ± 2.2 GPa, which exceeded the solid solution quaternary CrMoTiVN mixture rule prediction. When compared to the high-hardness monolayered TiVN and the low-hardness CrMoN, the CrMoN/TiVN multilayer coatings demonstrated the best resistance to cyclic impact. The TiVN coating displayed the worst oxidation resistance, as shown by the emergence of elongated vanadium-rich Ti-V oxide slats on the surface after oxidation. The CrMoN coating exhibited higher oxidation resistance than TiVN, and small granular chromium oxides formed on the surface beyond 700 °C. The addition of CrMoN to TiVN to form CrMoN/TiVN resulted in improved oxidation resistance by inhibiting the oxidation of TiVN. A different oxidation behavior was found for the CrMoN/TiVN coatings. The design of gradient-and-multilayered CrMoN/TiVN coatings is proven to be advantageous for applications that aim to enhance the thermal stability and cyclic impact resistance of mechanical tools.

A Study of Liquefaction Potential on Retaining Wall and Embankment in Parangtritis Village

Parangtritis Village located in Bantul Regency, Special Region of Yogyakarta. Previous studies showed that the Opak Active Fault line passes right through the east side of the construction. This study aims to examine the potential for liquefaction in the retaining wall and embankment structures in Parangtritis Village in the event of an earthquake in the area. The subsurface evaluation was based on N-SPT drilling data as well as soil data at 4 drill point. The bedrock acceleration value was determined based on SNI 2833:2016. To obtain a more specific bedrock peak acceleration value, the Indonesian Spectra Design seismic data was used by the Directorate General of Highway, Ministry of Public Works and Housing, where the PGA bedrock acceleration value is 0.558 g. The stages of liquefaction potential analysis are divided into three stages, Cyclic Stress Ratio, Cyclic Resistance Ratio, Factor of Safety. Liquefaction Potential Index analysis as a determinant of potential damage. Data processing results at four drill points indicate that the soil layer at several depths has liquefaction potential with a safety factor value of <1. The results of these calculations show that the LPI value is in the LPI vulnerable > 15, indicating a high liquefaction potential.

Ground Motion and Liquefaction Study at Opak River Estuary Bantul

In Mei 2006, an earthquake occurred, and liquefaction was induced in Bantul Regency in the form of lateral spreading and sand boiling. Based on Indonesia’s liquefaction susceptibility zone map 2019, the Bantul coast was identified as a high liquefaction hazard zone. There is a high risk of liquefaction in that location, and if liquefaction occurs, the effective stresses of the soil will be lost. This study aimed to determine ground motion-induced liquefaction potential in Opak river estuary in Bantul. The peak ground acceleration can be predicted by probabilistic seismic hazard analysis (PSHA) based on Indonesian spectra design application, deterministic seismic hazard analysis (DSHA) based on the mechanism of a recent earthquake in Bantul, and non-linear earthquake site response analysis (NERA) based on the 2004 Parkfield California earthquake, the 1986 Chalfant Valley California earthquake, and the 1987 Superstition Hill California earthquake. The value of acceleration from site-specific responses with DSHA and NERA is 0.558 g. Then, the maximum acceleration, seismic magnitude, N-SPT bore log soil, and other soil parameters are analyzed with a semi-empirical simplified method to estimate the safety factor of liquefaction potential using Settle3. The liquefaction safety factor was calculated by dividing the cyclic resistance ratio by the cyclic stress ratio; liquefaction occurs if the safety factor is less than 1. The result indicates that the Opak river estuary has a liquefaction potential beneath the surface from -1.5 to -16.5 m depth with various thick each boreholes. It implies that the bearing capacity design of the foundation system in this area and the liquefaction effect that will emerge when an earthquake occurs must be appropriately considered.