Relative Slip Research Articles

Analysis of Bonding Properties of Corroded Reinforcement Concrete

In order to investigate the degradation of bonding properties between corroded steel bars and concrete, this study employs the half-beam method to conduct bond-slip tests between corroded steel bars and concrete after impressed-current accelerated corrosion of the steel bars in concrete. The effects of steel corrosion rate, steel bar diameter, steel bar strength grade, and concrete strength grade on the bonding properties between concrete and corroded steel bars were analyzed. The influence of different corrosion rates on specimens’ bonding strength and bond-slip curves was determined, and a constitutive relationship for bond-slip between corroded steel bars and concrete was proposed. The results indicate that the ultimate bonding strength of corroded reinforced concrete specimens decreases with increasing corrosion rate. Additionally, an increase in corrosive crack width leads to a linear decrease in bonding strength. Evaluating the decline in adhesive properties through rust expansion crack width in engineering applications is feasible. Furthermore, a bond-slip constitutive relationship between corroded steel bars and concrete was established using relative bond stress and relative slip values, which aligned well with the experimental findings.

Prefabricated bolted PEC beam-to-CFST column joints: Development and its seismic behavior

This paper developed a novel bolted connection of prefabricated partially encased composite (PEC) beam to concrete-filled steel tubular (CFST) column by end-plates or π-connectors, and two joints with varying design details were tested subjected to cyclic loading. The seismic performance of the developed connections was investigated by experimental and finite element (FE) analysis. It was observed that both the two type connections exhibited concrete crushing within the PEC beam, accompanied by localized buckling and eventual fracture of the flanges in the main steel component of the beam. At the same time, other components were essentially in the elastic phase, such as end-plates, π-connectors, high-strength bolts, and column steel tubes. The bolted end-plate connections demonstrated excellent hysteretic performance, exhibiting high ductility factors. The stiffness, ductility, and energy dissipation capacity of the bolted π-connector connections were significantly diminished due to the influence of relative slippage between the π-connectors and the beams, in stark contrast to the bolted end-plate connection. According to Eurocode 3, the suggested connection configurations exhibited semi-rigid behavior and full-strength characteristics for non-sway frames.

The Cyclic Performance and Macro-Simplified Analytical Model of Internal Joints in RC-Assembled Frame Structures Connected by Unbonded Prestressed Strands and Mortise-Tenon Based on Numerical Studies

This paper introduces a novel type of connection that integrates unbonded prestressed strands (UPS) and mortise-tenon in an assembly frame structure (UPS-MTF). First, the damage process and failure modes of the joints under reciprocating horizontal loads were systematically analyzed using refined numerical models. The recommended values of the design parameters of the joints were derived from the parametric analysis results. Refined numerical modeling results reveal the diagonal compression strut mechanism within the core region of the joint. The diagonal compression struts model assists in establishing the theoretical calculation formula for the skeleton curve of shear stress–strain in the core region. Second, a genetic algorithm (GA) parameter was identified for the restoring force model of the core region to determine the parameters of the hysteresis rules. Finally, a macro-simplified analytical model of the joint was created based on the restoring force model of the core region, and parameter analysis was conducted to verify the applicability of this macro-simplified analytical model. The research results prove that the damaged form of the joint proposed in this paper originates from the shear and relative slip damage between the components in the core region. The axial compression ratio significantly affects the hysteretic performance of the joints, and the upper and lower limit values were identified for the axial compression ratio of the joints. The area and initial effective stress of the UPS exert a minimal effect on the hysteretic performance of the joint. Based on the method proposed in this paper for determining the restoring force model in the core region of the joints, the hysteresis curves obtained from the macro-simplified analytical model closely match the refined numerical analysis model results. This correspondence verifies the applicability of the macro-simplified analytical model.

Surface effect on the partial-slip contact of a nano-sized flat indenter

The partial-slip contact at nano-scale is always influenced by a surface effect. A new model based on the Gurtin-Murdoch (G-M) surface elasticity theory is proposed in this paper to study the partial-slip contact behavior of a rigid flat nano-indenter on an elastic half-space. The surface effect in the partial-slip contact is characterized via a non-classical boundary condition involving a surface-induced normal traction related to the residual surface stress and a surface-induced tangential traction related to the surface elasticity, the influences of which on stress and displacement fields and the stick-slip state at the contact surface are investigated. It is found that, with the increase of residual surface stress, both the normal pressure and vertical and horizontal displacements in the contact zone decrease, the relative slip between indenter and substrate reduces and the stick region is enlarged. Such effects are basically attributed to the action of the surface-induced normal traction opposite to the externally applied compression. However, the increase of surface elastic constants is conductive to the relative slip and results in a shrinkage of the stick region, which is attributed to the action of the surface-induced tangential traction opposite to the frictional stress. An interesting phenomenon is further unveiled that, when the frictional coefficient increases, the dominant role in affecting the stick-slip state changes from the surface-induced tangential traction to the normal one, thus inspiring a feasible route to manipulate the surface effect by tuning the frictional coefficient of substrate. The present research enables one to better understand the partial-slip contact behavior of nano-indenters, which is of guiding value for anti-wear designs in nano-mechanical devices.

Ab initio investigation of electronic structure and magnetic transformation during the bcc to hcp transition in Fe induced by pressure

The pressure-induced structural transition from a body-centered cubic (bcc) to a hexagonal close-packed (hcp) crystal in Fe is studied through ab initio electronic structure calculations, combining with the thermodynamic and kinetic phase-transition methods. According to the energy-volume relationship and thermodynamic criterion, the reasonable phase transition pressure is calculated to be about 13.88 GPa. The SSNEB method is employed to examine kinetic structural and barrier changes along bcc-hcp transition under various pressures. The transformation path involves the deformation of (110)bcc into the tightly packed (0001)hcp, accompanied by the relative slip of (110)bcc along the [1̅10]bcc direction, leading to the formation of the hcp structure. Our results indicate a reduction in the transition barrier of bcc-hcp with increasing pressure. Under the thermodynamic phase transition pressure, the bcc-hcp phase transition barrier is still as high as 140 meV, implying that pure hydrostatic pressure is not a sufficient condition to drive the phase transition. In addition, different from the continuous change of volume, the magnetism of the structure undergoes a magnetic mutation at the transition state, and the phase transition process involves complex magnetic transitions.

Finite Element Analysis of Relative Slip Between Tight Tops and the Human Body

To investigate the fabric performance of tight tops and the influence of clothing pressure on the relative slip between clothing and the human body, a simulation model based on finite element analysis is proposed. This model simulates the relative slip distance under dynamic conditions. Initially, a three-dimensional model for numerical simulation was established through reverse engineering. Subsequently, material properties and boundary conditions were defined. Finally, the model was analyzed using ANSYS Workbench, and the obtained results were compared with the stretch ratio of the skin on the human back. The results indicate that, under constant conditions, the Young’s modulus of the fabric has a greater influence on the slip and shows a significant positive correlation, with correlation coefficients ( R) all exceeding 0.99. The impact of clothing pressure on sliding is relatively small, and the sliding distance decreases with an increase in clothing pressure. In addition, it has been demonstrated that there is a significant correlation ( p < 0.05) between the relative sliding distance of clothing and the stretch ratio of the skin. The study could provide a helpful guideline for the design of smart clothing, and it can provide valuable insights for various applications, such as sportswear and medical apparel.

Experimental investigation on flexural performance of steel-UHPC composite beams with steel shear keys

Test results of steel-ultra high performance concrete (UHPC) composite beams with welded steel shear keys (SSKs) under four-point bending are presented in this paper. The objective of the investigation is to reduce the self-weight and manufacturing cost of large-span structures. The study investigates the effects of strength of concrete slab, type, spacing and size of SSK, and concrete slab height and width on flexural behavior of composite beams. The experimental results demonstrate that enhancing concrete strength, reducing SSK spacing, increasing concrete slab size, and using large-size SSK can all significantly enhance the flexural performance. The composite beams with welded SSK exhibit a maximum relative slip of less than 4 mm, while the counterpart with welded bolts has a maximum relative slip greater than 4 mm. The study shows that the welded SSK is more effective than welded bolts in improving the interface shear performance of composite beams and improving the stiffness and load capacity. Additionally, the study defines four failure modes of steel-UHPC composite beams, and the formulae for flexural capacity is developed based on the reasonable basic assumptions. The calculated results fit well with the tested results. The research findings can be provided as a technical support for the design and application of steel-UHPC composite beams.

Experimental studying the effect of transverse reinforcement passing through perfobond holes on the structural behavior of perfobond shear connection

The push-out test program was carried out on three groups of nine small specimens to investigate the effect of the transverse reinforcement passing through the perfobond holes on the structural behavior of perfobond shear connector. The number of transverse reinforcements passing through the perfobond holes was changed in each group. One of the groups had no transverse reinforcement, and the other groups had one and two transverse reinforcements passing through the perfobond holes. The quantities observed in this program were the load capacity, the relative slip between the hot-rolled steel and the concrete slab, and the failure mode of specimens. The results showed that the transverse reinforcement passing through the perfobond holes enhanced the load capacity and significantly reduced the relative slip between the hot-rolled steel and the concrete slab.

The damage and response of some underground structures by the 2023 February 6 Great Turkish Earthquakes and some considerations

Two successive disastrous earthquakes occurred on February 6, 2023 in the province of Kahramanmaraş of Türkiye. These earthquakes resulted in loss of more than 50.000 lives and several cases of serious damage to various engineering structures. Some roadways and railway and underpass tunnels were also damaged by the earthquakes as a result of heavy shaking as well as faulting. In addition, many rockfalls occurred at the portals of railway and roadway tunnels. The faulting caused quite severe damage at the railway tunnel near Ozan village. The concrete lining of the new Erkenek tunnels ruptured at several places. The damage in the new Erkenek twin tunnels may be related to mass movements caused by heavy ground shaking as well as an inclined geological structure together with low overburden next to a valley. Sinkholes of man-made and natural cavities occurred in several locations including urbanized areas. In this study, the authors describe the damage to underground structures by the doublet Kahramanmaraş earthquakes with some detailed analyses of Erkenek tunnels. Furthermore, the causes of the damages are described and their implications on the seismic design of underground structures are discussed. The observations indicated that underground openings crossing by faults and fracture zones may be enlarged to accommodate relative slips along faults and fracture zones. Furthermore, the ductility of support should be high in such zones in order to prevent brittle failure, which may have very disastrous effects. In addition to man-made underground structures, natural underground rock structures may be damaged or sinkholes may be caused by earthquakes as observed in the 2023 Kahramanmaraş earthquakes. The computational results clearly explain why the valley-side of one of the tunnels was more damaged compared to that of the mountain-side tunnel. It is also noted that some of the sinkholes in the earthquake region can be explained using some techniques available in literature.

Three-dimensional elastoplastic analysis of strain-softening surrounding rock based on the non-linear bond-slip relationship considering hydraulic-mechanical coupling

After the anchor is installed, relative slip between the anchor and the surrounding rock will occur in the actual engineering. Based on the proposed nonlinear bond-slip model, a three-dimensional elastoplastic analysis of the strain-softened surrounding rock is performed in this study while considering hydraulic-mechanical coupling. A numerical iterative method of surrounding rock analysis is proposed, which considers the relative slip between the anchor and the surrounding rock. These stresses and displacements of the surrounding rock, as well as the anchor shear stress distribution, can be obtained using the proposed method. Furthermore, the calculation results of the program are compared with the existing field test results and with the calculation results of other methods to verify the accuracy of the proposed method. The results indicate that the calculation results of the proposed method are generally in line with the test results, and the largest slips occurring at the two ends of the anchors. Meanwhile, the proposed method is applied to an actual engineering, and the results agree well with the field data. Finally, the effects of seepage and strain softening of the surrounding rock on the interaction between the surrounding rock and the anchors are investigated by parametric analysis.

Material characteristic-controlled particle segregation in rock-ice avalanche

Rock-ice avalanches exhibit significant particle segregation driven by density and friction differences between ice and rock. This study meticulously uncovers intricate segregation dynamics in rock-ice avalanches, focusing on density variations, friction disparities, and ice volume fractions through physical flume experiments and numerical simulations. Results reveal clear patterns: ice particles cluster at front regions in flow, while rocks move to the rear. Ice occupies upper flow-depth areas, while rocks settle lower. In density-controlled segregation, low-density ice segregates upward and forward due to diminished inertia, whereas in friction-controlled scenarios, low-friction ice displays heightened flowability, causing forward and downward segregation. Density-controlled and friction-controlled segregation both result in forward segregation in the flow direction, exhibiting competitive dynamics in flow-depth. Lower ice volume fractions increase the relative slip of ice particles along shear planes, and decrease the relative slip of high-density rock particles in the flow-depth direction, accentuating forward segregation and reducing it in flow-depth.

Numerical Investigation on the Seismic Behavior of Novel Precast Beam–Column Joints with Mechanical Connections

Traditional cast-in-place beam–column joints have the defects of high complexity and high construction difficulty, which seriously affect the efficiency and safety of the building construction line, and precast beam–column joints (PBCJs) can greatly improve the construction efficiency and quality. At present, the investigations on the seismic behavior of precast reinforced concrete structures are still mainly focused on experiments, while the numerical simulations for their own characteristics are still relatively lacking. In the present study, the seismic behavior of novel precast beam–column joints with mechanical connections (PBCJs-MCs) is investigated numerically. Based on the available experimental data, fiber models for four PBCJs-MCs are developed. Then, the simulated and experimental seismic behaviors of the prefabricated BCJs are compared and discussed. Finally, the factors influencing the seismic behavior of the PBCJs-MCs are further investigated numerically. The numerical results indicate that the fiber models can consider the effect of the bond–slip relationship of concrete and reinforcement under reciprocating loads. The relative errors of the simulated seismic behavior indexes are about 15%. The bearing capacity and displacement ductility coefficients of the PBCJs-MCs decrease rapidly as the shear-to-span ratio (λ) increases. It is recommended that the optimum λ for PBCJs-MCs is 2.0–2.5. The effect of the axial load ratio on the seismic behavior of PBCJs-MCs can be negligible in the case of the PBCJs-MCs with a moderate value of λ.

Influence of elevated temperatures on the bond performance of CFRP-steel lap joints bonded by nanosilica-modified adhesive with mixed curing agents

Elevated temperatures may influence greatly the mechanical properties of adhesives, and it is difficult for adhesives with a single curing agent to meet the requirements of adequate heat resistance and toughness simultaneously. First, this paper proposes a nano-SiO2-modified epoxy adhesive (GY34) using mixed curing agents to improve the bond performance of CFRP-steel joints at a high temperature. Then, studies are taken to examine the impact of elevated temperatures on the mechanical performance of GY34 with mixed curing agents and the interfacial properties of CFRP-steel double-lap joints bonded by GY34. After that, models are developed to predict the bearing capacity and bond-slip of CFRP-steel double-lap joints at different temperatures using the test data. The results indicate the toughness is optimal at 70 °C when the curing agents C105 and D230 are mixed with a mass ratio of 1:2. The bearing capacity of the CFRP-steel lap joint bonded with GY34 is much higher than the cases only bonded with a single C105 or D230, respectively. Moreover, the load-displacement curve has a significant ductile development stage as the temperature rises below the glass transition temperature (Tg, S), beyond which, the bearing capacity declines. In addition, the length of shear stress transmission and the effective bonding length increase significantly at high temperatures. The bond-slip curve bonded with GY34 has a trilinear trapezoid shape at different temperatures, and the peak shear stress and stiffness decline at various elevated temperatures. Finally, the relative slip and interfacial fracture energies increase first and then decrease with the rise of temperature.

Study on shear behavior and acoustic emission characteristics of precast concrete segmental cover beams with large key teeth

AbstractThe mechanical characteristics of segmental joints are pivotal in defining the comprehensive stress behavior of prefabricated assembled cover beams. In this research, direct shear tests were conducted on dry key‐tooth joints, and acoustic emission technology was employed for monitoring purposes. The shear failure mechanism was explored under a range of influential parameters. Building upon these observations, the study delved into the mechanical response of joints within segmental cover girders subjected to concurrent bending and shear forces. Specimen K‐3‐3 exhibited a higher shear carrying capacity compared to other specimens, indicating that the shear resistance of dry joints proportionally increases with the height of the specimen and the strength of the concrete. The carrying capacity of Specimen K‐4 was marginally lower than that of Specimens K‐3‐1 and K‐3‐2, suggesting that increasing the number of keys does not significantly impact the shear resistance of dry joints. Notably, Specimen K‐3 demonstrated exceptional shear carrying capacity, exhibiting minimal relative slip during failure, and streamlined the casting process. Consequently, these dry joints featuring large key teeth are deemed more appropriate for use as shear connectors in precast concrete segmental cover beams. Crack patterns in large key tooth precast concrete segmental cover beams propagate along the joints. A damage evolution model for the specimens, based on spatial b‐values and T‐values, visually depicts the damage extent in large key tooth precast concrete segmental cover beams. This model demonstrates excellent agreement with experimental results and provides a solid foundation for theoretical research and practical applications of large key tooth precast concrete segmental cover beams.

The relationship between paraspinal muscle atrophy and degenerative lumbar spondylolisthesis at the L4/5 level

BACKGROUND/CONTEXTDegenerative lumbar spondylolisthesis (DLS) is a prevalent spinal condition that can result in significant disability. DLS is thought to result from a combination of disc and facet joint degeneration, as well as various biological, biomechanical, and behavioral factors. One hypothesis is the progressive degeneration of segmental stabilizers, notably the paraspinal muscles, contributes to a vicious cycle of increasing slippage. PURPOSETo examine the correlation between paraspinal muscle status on MRI and severity of slippage in patients with symptomatic DLS. STUDY DESIGN/SETTINGRetrospective cross-sectional study at an academic tertiary care center. PATIENT SAMPLEPatients who underwent surgery for DLS at the L4/5 level between 2016–2018 were included. Those with multilevel DLS or insufficient imaging were excluded. OUTCOME MEASURESThe percentage of relative slippage (RS) at the L4/5 level evaluated on standing lateral radiographs. Muscle morphology measurements including functional cross-sectional area (fCSA), body height normalized functional cross-sectional area (HI) of Psoas, erector spinae (ES) and multifidus muscle (MF) and fatty infiltration (FI) of ES and MF were measured on axial MR. Disc degeneration and facet joint arthritis were classified according to Pfirrmann and Weishaupt, respectively. METHODSDescriptive and comparative statistics, univariable and multivariable linear regression models were utilized to examine the associations between RS and muscle parameters, adjusting for confounders sex, age, BMI, segmental degeneration, and back pain severity and symptom duration. RESULTSThe study analyzed 138 out of 183 patients screened for eligibility. The median age of all patients was 69.5 years (IQR 62 to 73), average BMI was 29.1 (SD±5.1) and average preoperative ODI was 46.4 (SD±16.3). Patients with Meyerding-Grade 2 (M2, N=25) exhibited higher Pfirrmann scores, lower MFfCSA and MFHI, and lower BMI, but significantly more fatty infiltration in the MF and ES muscles compared to those with Meyerding Grade 1 (M1). Univariable linear regression showed that each cm2 decrease in MFfCSA was associated with a 0.9%-point increase in RS (95% CI -1.4 to - 0.4, p<.001), and each cm2/m2 decrease in MFHI was associated with an increase in slippage by 2.2%-points (95% CI -3.7 to -0.7, p=.004). Each 1%-point rise in ESFI and MFFI corresponded to 0.17%- (95% CI 0.05–0.3, p=.01) and 0.20%-point (95% CI 0.1–0.3 p<.001) increases in relative slippage, respectively. Notably, after adjusting for confounders, each cm2 increase in PsoasfCSA and cm2/m2 in PsoasHI was associated with an increase in relative slippage by 0.3% (95% CI 0.1–0.6, p=.004) and 1.1%-points (95% CI 0.4–1.7, p=.001). While MFfCSA tended to be negatively associated with slippage, this did not reach statistical significance (p=.105). However, each 1%-point increase in MFFI and ESFI corresponded to increases of 0.15% points (95% CI 0.05–0.24, p=.002) and 0.14% points (95% CI 0.01–0.27, p=.03) in relative slippage, respectively. CONCLUSIONThis study found a significant association between paraspinal muscle status and severity of slippage in DLS. Whereas higher degeneration of the ES and MF correlate with a higher degree of slippage, the opposite was found for the psoas. These findings suggest that progressive muscular imbalance between posterior and anterior paraspinal muscles could contribute to the progression of slippage in DLS.

Mechanism characterization and sensitivity analysis of parameters of track corrugation in the metro small curve

ABSTRACT For investigating corrugation mechanisms and characterizing sensitive parameters in the metro small curve, a numerical model was established, and the transient dynamics analysis was performed employing the numerical model. Meantime, probability calculations were carried out using Direct Monte Carlo Simulation and Latin Hypercube Sampling, and the sensitivities of random input parameters were analyzed. The results show that the outside wheel-rail contact is in the gauge angle position, while the inside one is in the top-of-rail position. The outside stick-slip distribution is always in the slip state and exhibits multi-point contact; the inside stick-slip distribution exhibits alternating stick-slip and slip states and is all in single-point contact. The formation mechanism of inner rail corrugation can be summarized as the generation of corrugation due to the contact state variation induced by the system instability. The friction coefficient, longitudinal relative slip and modulus of elasticity of the baseplate have greater influence, while the remaining parameters have less effect. Appropriately reducing the friction coefficient, longitudinal relative slip, primary suspension vertical and transverse forces, wheelset transverse displacement and wheel-rail contact angle, increasing the moduli of elasticity and densities of rail pad, baseplate and baseplate pad can make a proactive difference in the corrugation control.

Texture formation under control of S phase characteristic and tensile property of hot-rolling 2A12 aluminum alloy improved by Brass texture

In this paper, 2A12-T3 aluminum alloy is first solution-treated and then experienced an artificial aging for different time to induce different S phase characteristics. By using this method, the texture formation behavior solely contributed from S phase characteristic could be determined during hot rolling. It is found that the increase of S phase in size and density has a positive effect on Brass texture formation, which is attributive to the increased Dislocation Shear Slipping (DSS) near S/Al interface. The relative slip tendency factor (Msx) is proposed to quantitatively evaluate the impact of S phase characteristic on Brass formation. It is revealed that Brass volume fraction (VBrass) has a better positively linear relationship with Msx than texture intensity. Then, the effect of Brass texture on tensile property is analyzed in details. Crystal plasticity simulation shows that Brass texture can improve the yield stress and tensile strength and simultaneously keep the elongation. Comparatively, the rolling sheet aged for 3 h obtains an excellent combination of strength and ductility.

Characterization of multiphase flow through Venturi nozzle using gamma-ray tomography

Venturi-based differential pressure flow meters have proven to be robust and well suited to measure the flowrate of multiphase flow in combination with other measurement techniques. However, important challenges remain in order to reduce the effect of flow regime dependent measurement uncertainties from non-homogeneous flow.Understanding the complexities of multiphase flow through a Venturi is critical, not only for the Venturi flow measurement but also for the potential implications it might have on adjacent measurements affected by the constriction-induced flow perturbations.In this study, we examine the evolution of multiphase flow through a vertically oriented Venturi situated downstream of a T-bend, with a particular emphasis on the effects this might have on associated measurements within a multiphase metering context. Using Gamma-ray tomography, we conducted measurements at the inlet, throat, outlet, and downstream of the Venturi across a wide range of flow rates and Gas Volume Fractions (GVFs). We evaluated gas fraction (GF), slip, and cross-sectional distribution, quantified using measures of asymmetry and annularity.Our findings suggest that deviations between GF and GVF, relative slip velocity, annularity, and asymmetry are generally less at the outlet and downstream of the Venturi compared to the inlet and throat. Notably, annularity exhibits a greater impact than asymmetry on the estimation of bulk fractions from cord measurements.Overall, the study suggests that there may be more favorable conditions for measurements that require a homogeneous mix and less difference between GF and GVF at the outlet or a short distance downstream of the Venturi. However, despite the inlet results showing larger deviations due to inhomogeneous flow compared to the outlet and downstream, these results demonstrate a more predictable pattern in line with predictive models, offering potential benefits for the application of corrective models.

Understanding the role of head size and neck length in micromotion generation at the taper junction in total hip arthroplasty

Modular hip implants allow intra-operative adjustments for patient-specific customization and targeted replacement of damaged elements without full implant extraction. However, challenges arise from relative micromotions between components, potentially leading to implant failure due to cytotoxic metal debris. In this study magnitude and directions of micromotions at the taper junction were estimated, aiming to understand the effect of variations in head size and neck length. Starting from a reference configuration adhering to the 12/14 taper standard, six additional implant configurations were generated by varying the head size and/or neck length. A musculoskeletal multibody model of a prothesized lower limb was developed to estimate hip contact force and location during a normal walking task. Following the implant assembly, the multibody-derived loads were imposed as boundary conditions in a finite element analysis to compute the taper junction micromotions as the relative slip between the contacting surfaces. Results highlighted the L-size head as the most critical configuration, indicating a 2.81 μm relative slip at the mid-stance phase. The proposed approach enables the investigation of geometric variations in implants under accurate load conditions, providing valuable insights for designing less risky prostheses and informing clinical decision-making processes.

Evaluation of residual bond behaviour between rebar and recycled aggregate concrete after high-temperature exposure followed by water spray cooling

This paper presents an evaluation of the residual bond behaviour between rebar and recycled aggregate concrete (RAC) using granite natural coarse aggregates and different recycled coarse aggregate (RCA) replacement levels (δ = 0%, 30%, 50%, and 100%) for both pull-out and cubic specimens. After high-temperature exposure (T = 200, 400, and 600 ℃) followed by water spray cooling, the results revealed a consistent decline in bond strength and compression strength with increasing temperature. Compared to ambient conditions, bond strength and compression strength decreased by 65.2% ∼ 77.8% and 53.2% ∼ 58.4%, respectively, after exposure to 600 ℃. The reduction rate of residual bond strength changed significantly at about 400 ℃. There was a linear relationship between RAC compression strength and rebar–RAC bond strength after high temperature exposure followed by water spray cooling. With increasing RCA replacement levels, the relative bond strength gradually improved at the same temperature. Based on the regression analysis, empirical formula for the rebar–RAC bond strength and bond–slip relationship models were proposed, all taking into account RCA replacement levels and temperature.