Shear Force Research Articles

3D Printable Polymeric Composite Material with Enhanced Conductivity Achieved by Affinity Matching.

Polymer-based conductive composites are lightweight, low-cost, and easily processable materials with important applications in various fields. However, achieving highly conductive and 3D printable polymer-based conductive composites remains challenging. In this study, we successfully developed a highly conductive composite suitable for direct ink writing 3D printing using unsaturated polyester resin as the polymer matrix and graphene nanosheets as conductive fillers and rheological modifiers. Due to the well-matched affinity between graphene nanosheets and unsaturated polyester, the graphene nanosheets aggregate within the unsaturated polyester, forming a 3D conductive network. Moreover, the shearing force during direct ink writing 3D printing induces the orientation of the 2D graphene nanosheets, significantly enhancing their conductivity along the printing direction. At room temperature, the unsaturated polyester resin/graphene composite shows a high conductivity of 69.9 S m-1 while maintaining excellent 3D printability. Structures printed using this material exhibit improved heat dissipation and electromagnetic shielding performance. The reported unsaturated polyester resin/graphene nanosheet composites demonstrate outstanding electrical and heat conductivity and excellent processability, making them promising candidates for applications in electromagnetic shielding, printed electronics, and other fields.

Effect of Mixing Methods and Black Conductive Fillers on Properties of Natural Rubber Composites

Carbon black, graphite, carbon nanofibers, carbon nanotubes, and metal fillers increase composite conductivity in natural rubber, which is electrically insulating. Depending on dispersion, conductive filler lowers insulating material resistivity. These materials are frequently used for electromagnetic/radio frequency interference (EMI/RFI) shielding, conductive flexible seals gaskets, and conductive mats used to prevent electrostatic damage to electronic devices. These elastomers could be used to make flexible solar cells or mechanical-to-electricity devices. Temperature, mixing time, shear rate, and cross-linking during vulcanization affect rubber electrical conductivity of composite. To study shear rate effects, vulcanizate of Natural Rubber-based composites filled with carbon black, millable carbon fiber powder, and synthetic graphite powder was prepared by open mixing (two roll mill) and close mixing (internal mixer). We compared how shear rate affects cure, stress-strain, and volume resistivity of conductive filler-based Natural Rubber composites. Increment in clearance of two roll mill during addition of rubber additives along with rubber of reduced the shearing force resulted in less dispersive and distributive mixing and stagnant points due to band formation on roll surface compared to intermix where compound movement had no stagnation point and long wings pushed material axially and two nogs pushed material in other chamber. Compared to two roll mill samples, the compound reached every point of the mixing chamber for best homogeneity, reducing cure time and improving stress-strain and volume resistivity.

Transport behavior of Polymeric Methyl Methacrylate nanoplastics in saturated and unsaturated porous media: Combined influence of electrolyte and organic acids

The migration behavior of Polymeric Methyl Methacrylate (PMMA) nanoplastics in saturated porous media and unsaturated porous media is investigated under conditions of electrolytes in combination with organic acids. In the saturated porous media, the mass recovery rate of PMMA decreases with ionic strength. The inhibition effect of Ca2+ on PMMA transport is stronger than that of Na+. Under the conditions of the coexistence of electrolytes with humic acid (HA), increasing the concentration of HA does not consistently enhance PMMA migration in porous media. However, citric acid (CA) exerts solely an inhibitory effect on PMMA transport. The orthogonal analysis suggests that Ca2+ concentration is the major factor affecting PMMA transport. Extended Darjaguin-Landau-Verwe-Overbeek (XDLVO) interaction energy considering the heterogeneity of HA adsorption on PMMA is calculated to quantify the interactions of PMMA-PMMA and PMMA-quartz sand under different physiochemical conditions. In unsaturated porous media, gravity leads to the creation of dominant channels, and the shear force of water flow in porous media leads to the rapid passage of PMMA through the dominant channels. However, as the water content decreases, the recovery rate of PMMA decreases from 0.99 to 0.71. Significantly, the capillary energy of a colloid retained in a thin film or at the air-water-solid (AWS) interface is several orders of magnitude larger than the XDLVO interaction energy. Findings obtained by this study may improve the current understanding of the environmental fate of nanoplastics in subsurface environments and can provide scientific methods to assess the associated risk of nanoplastics.

A 3-D modelling of monopile behaviour under laterally applied loading

Deploying higher-capacity offshore wind turbines to meet the growing energy demand poses a significant challenge in designing their foundations. Monopiles currently constitute 80% of the foundation installations for these turbines. This study utilizes a nonlinear three-dimensional (3D) finite element model to explore the behavior of monopiles underpinning a five megawatt wind turbine under horizontal loads. The findings reveal that the performance of monopiles is influenced by the strength of the soil and the ratio of pile depth of embedment to diameter (L/D). Examination of flexural bending profiles at/close to failure loads demonstrates the flexible behavior of monopiles, even with a low L/D ratio. The L/D ratio exhibits varying degrees of impact on the normalized ultimate lateral capacity of monopiles, with a notable effect observed in soft clays, resulting in an increase of up to five times for L/D ratios ranging from 3.33 to 13.33. Stiff clays show comparatively lesser effects. Under serviceability loading, an increase in the L/D ratio leads to a 3–6% rise in the maximum flexural moment of monopiles, while the maximum shear force experiences a decrease of 20–30%. Furthermore, a significant reduction, up to five-fold, in the maximum tower tip displacements and rotations at the mudline is observed with an increasing L/D ratio. However, this reduction is more pronounced for higher foundation rigidity.

Hierarchically‐Interlocked, Three‐Axis soft Iontronic Sensor for Omnidirectional Shear and Normal Forces

AbstractArtificial tactile sensing capable of measuring shear and normal forces is crucial for the diverse human‐machine interactions and dexterous robotic manipulations. However, existing soft multi‐axis force sensors usually suffer from limited detectable directions and complex coupling mechanisms, limiting their applications in realistic wearable and robotic systems. Here, a hierarchically‐interlocked, three‐axis soft iontronic sensor is presented with an asymmetrical electrode pattern that leverages the mortise‐and‐tenon structure and ultracapacitive principle to detect omnidirectional shear and normal forces. The designed sensor facilitates the decoupling process and achieves enhanced sensing performances including high accuracy, fast response ability, and mechanical robustness. Prototypical integration and application of the sensor are demonstrated to perform wearable telecontrol of virtual platforms and assist robot gripper through closed‐loop force feedback. A sensing array is further developed to construct a touch panel and identify handwriting based on the continuously measured directions of applied forces. This work may offer a potentially promising solution for the next‐generation intelligent electronic skins requiring multimodal tactile sensing information.

Effect of Different Salinities on the Biochemical Properties and Meat Quality of Adult Freshwater Drum (Aplodinotus grunniens) During Temporary Rearing.

Salinity is a significant environmental component that affects the physiological state of aquatic species. This study aimed to investigate whether water salinity had an impact on the biochemical properties and meat quality of adult Aplodinotus grunniens during temporary rearing of 7 days. Salinity caused increased osmotic pressure and antioxidant enzyme activities of Aplodinotus grunniens, which were attributed to the increase in the content of alanine and glutamate. It raised the hardness and shear force with an increase in salinity, leading to an increase in water-holding capacity. Salinity enhanced the DHA ratio with a decrease in the atherosclerotic index and thrombosis index. Combined with the increase in flavor amino acids and nucleotides, salinity enhanced the umami taste of Aplodinotus grunniens. These findings suggest that temporary rearing in salinity might be a practical approach to improving the meat quality of adult Aplodinotus grunniens.

Seismic response control of shear frame structure using a novel tuned-mass type composite column

Concrete filled steel tube (CFST) column is widely applied in shear frame structure in seismic-prone area owing to its superior earthquake resistant performance. However, CFST column might still suffer damage under a severe earthquake. This paper proposes a novel tuned-mass type column-in-column (CIC) system to improve the seismic behavior of the CFST column and hence protect the structure. The CIC system is formed by splitting the CFST column into a primary column and a secondary column, while the overall cross section area and hence the load-bearing capacity is not changed. By optimally selecting the springs and dashpots to interconnect the two columns, the CIC can act as a non-conventional tuned mass damper (TMD) to reduce seismic vibrations of structures. To demonstrate the proposed CIC concept, a single-story and a five-story frame structure with and without control are designed. Nonlinear time history analyses are performed to study the seismic responses of these structures considering different seismic design levels, earthquake ground motions and CIC control schemes. Numerical results show that the CIC system can effectively reduce the seismic induced story acceleration, displacement and drift ratio of frame structures with the reduction ratios approximately between 21 % and 30 %, and the ratios on reducing the base shear force and bending moment are between 27 % and 31 %, and between 34 % and 49 %, respectively. The proposed CIC control concept is a new solution for mitigations of seismic responses of CFST frame structures.

A review on rheological approaches as a perfect tool to monitor thermal degradation of biodegradable polymers

AbstractThis review provides an in-depth analysis of the thermal degradation of biodegradable polymers through rheological methods. Focusing on key techniques such as time sweep tests, frequency sweep tests, and nonlinear rheological analyses gained at higher shear tests, the review highlights how these approaches offer critical insights into polymer stability and degradation kinetics. It entails an understanding of how molecular weight reduction, a common degradation mechanism, significantly impacts the performance of biodegradable polymers, and how the use of appropriate fillers can enhance thermal stability by mitigating chain scission. The review also discusses the application of the Arrhenius equation in modelling thermal degradation, helping predict degradation rates and optimize processing conditions. Time sweep tests are particularly emphasized for their ability to monitor polymer stability under various environmental conditions, while frequency sweep tests provide insights into the effects of processing/thermal history on material degradation. Tests at higher shear rates, which simulate real-world processing conditions such as extrusion and injection moulding, are explored for their role in understanding how processing-induced shear forces accelerate polymer degradation. Various biodegradable polymers are considered in this review, with polylactic acid (PLA) being the dominant polymer studied across most research, providing a clear picture of its degradation behaviour and strategies for enhancing its thermal stability. Therefore, it is expected that this review will be a comprehensive guide for researchers and engineers looking to optimize the thermal stability and performance of biodegradable polymers in various industrial applications. Graphical abstract

Dietary Tributyrin Improves Growth Performance, Meat Quality, Muscle Oxidative Status, and Gut Microbiota in Taihe Silky Fowls under Cyclic Heat Stress.

Heat stress adversely affects poultry production and meat quality, leading to economic losses. This study aimed to investigate the effects of adding tributyrin on growth performance, meat quality, muscle oxidative status, and gut microbiota of Taihe silky fowls under cyclic heat stress (CHS) conditions. In this study, 120-day-old Taihe silky fowls (male) were randomly divided into six dietary treatments. These treatments included a normal control treatment (NC, fed a basal diet), a heat stress control treatment (HS, fed a basal diet), and HS control treatments supplemented with 0.04%, 0.08%, 0.16%, and 0.32% tributyrin, respectively. The NC treatment group was kept at 24 ± 1 °C, while the HS treatment birds were exposed to 34 ± 1 °C for 8 h/d for 4 weeks. Results showed that CHS decreased growth performance and compromised the meat quality of broilers (p < 0.05). However, tributyrin supplementation improved ADG and FCR in broilers exposed to CHS (p < 0.05). Additionally, tributyrin supplementation resulted in increased shear force value and GSH-Px activity, as well as a decrease in drip loss, ether extract content, and MDA content of the breast muscle in broilers under CHS (p < 0.05). Furthermore, tributyrin supplementation up-regulated the mRNA expressions of Nrf2, NQO1, HO-1, SOD, and GSH-Px of the breast muscle in broilers exposed to CHS (p < 0.05). Based on these positive effects, the study delved deeper to investigate the impact of 0.16% tributyrin supplementation (HS + 0.16%T) on the cecum microbiota. The HS + 0.16%T treatment showed an increase in the relative abundance of Rikenellaceae_RC9_gut_group (p < 0.05) and a trend towards an increase in Lactobacillus (p = 0.096) compared to the HS treatment. The results indicate that supplementation successfully improved the growth performance and meat quality of Taihe silky fowls. Furthermore, tributyrin supplementation, particularly at levels of 0.16%, improved meat quality by enhancing muscle antioxidant capacity, which is believed to be associated with activation of the Nrf2 signaling pathway.

Biomechanical Analysis of Rectus Femoris Kinesio Taping Effects on Post-Muscle Fatigue Stop-Jump Task Performance

Objectives: This study aims to compare the effects of kinesio tape (KT) on the rectus femoris muscle in athletes and novices under pre- and post-fatigue conditions. Methods: Nineteen male volunteers took part, and fatigue was assessed using the Borg CR10 Scale. Kinematic and kinetic data were collected using Vicon MX13+ infrared cameras (250 Hz) and Kistler force platforms (1500 Hz), respectively. Visual 3D v5.0 software analyzed the data, focusing on parameters like angular displacement, ground reaction forces (GRFs), impulse, and joint moments during a stop-jump task. A two-way mixed-design ANOVA was used to assess group, fatigue, and KT effects. Results: There was a significant effect after applying KT. The results showed significant differences in knee flexion range of motion (ROM), hip flexion moment, vertical impulse, and peak vertical GRFs between pre- and post-fatigue conditions (all p &lt; 0.05). The trained group exhibited less knee valgus ROM, higher hip flexion velocity at initial contact, and prolonged time to peak proximal tibia anterior shear force. Conclusions: KT application was found to reduce lower limb loading, improve force acceptance and joint stability, and alleviate fatigue-induced disparities. These findings highlight the potential of KT in enhancing lower limb strength and performance, particularly under fatigue.

Friction-Induced Near-Infrared Emission and Its Mechanism.

Triboluminescence (TL) is an optical phenomenon in which light is emitted from the surface of a material when subjected to pressure or shear forces. Due to its potential applications in non-destructive testing, radiation sources, and spectroscopic probes, TL has garnered increasing attention over the past two decades. However, experimental observations in the infrared spectrum remain limited, and its emission mechanism has not yet been fully understood. In this study, significant emission in the near-infrared spectrum was experimentally observed from the tribo-pairs of Cr/YSZ and quartz/YSZ. The results indicate that the Tribo-Induced Near-Infrared Light Emission consists of three peaks, in which the 780 nm peak is related to the electronic transition between the 3d5/2 and 3d3/2 orbitals of Y3+ ions, while the 880 nm and 990 nm peaks can be attributed to hole centers and T-type centers in the intrinsic defects of YSZ, respectively. Additionally, experiments reveal that the Cr/YSZ tribo-pair exhibits a redshift of 11-18 nm at the 780 nm peak compared to the quartz/YSZ tribo-pair. To explain the cause of the redshift phenomenon, X-ray photoelectron spectroscopy and UV-Vis absorption spectroscopy were used to measure the energy level spacing between the 3d5/2 and 3d3/2 orbitals of Y3+ and the bandgap width of YSZ before and after friction, respectively. We found that the bandgap width of the doped YSZ decreases after friction, which is often accompanied by a reduction in the energy level spacing between the 3d5/2 and 3d3/2 orbitals of Y3+. The extent of the reduction in energy level spacing varies with different dopants, leading to the redshift phenomenon.

Investigation of Churn and Annular Flow Transition Boundaries in Vertical Upward Gas-Water Two-Phase Flow

ABSTRACT Flow patterns in two-phase flow in vertical upward pipes are crucial for predicting phase distribution, flow transitions, and stability. Existing studies on churn to annular flow transitions primarily focus on flow rates, physical parameters, pressure, and temperature, often overlooking pipe diameter. This study addresses this gap using a multiphase pipe flow experimental setup to examine transitions under varying pipe diameters, gas flow rates, and liquid flow rates. Results show that with a constant liquid flow rate, increasing pipe diameter requires a higher gas flow rate to form annular flow, leading to greater pressure gradients and smoother fluctuations. Conversely, with a constant gas flow rate, larger pipe diameters decrease the liquid flow rate needed for annular flow, resulting in smaller pressure gradients and smoother fluctuations. Smaller pipe diameters make annular flow formation easier, with smaller pressure gradients but larger fluctuations. A novel churn-annular flow transition boundary model was developed, considering factors like gas shear force, surface tension, gravity, viscous force, and pressure gradient. Evaluated with 804 experimental data sets, the new model’s prediction accuracy exceeds 98.19%, outperforming traditional models with 53.92%-86.27% accuracy, enhancing applicability across varying diameters.

Performance-based seismic design of controlled rocking reinforced concrete frame with beam-end hinge

This study investigates the seismic performance of the Controlled Rocking Reinforced Concrete Frame with Beam-end Hinge (CR-RCFB) system. The novelty of our research lies in the development and validation of a finite element model that accurately predicts the dynamic response of CR-RCFB structures under various seismic conditions, specifically focusing on the innovative use of joint stiffness ratios and the integration of dampers. A finite element model was developed and validated through shaking table tests. The research examined the dynamic responses of the CR-RCFB under ten ground motion records, varying the node relative stiffness ratios. The interstory displacement amplification coefficient (α) was found to range between 1.08 and 1.20, while the earthquake-reduction coefficient (β) varied from 0.8 to 0.3 depending on the stiffness ratio. Results indicate that node stiffness ratios between 0.01 and 0.25 optimize performance, minimizing peak interstory displacement and base shear response. Additionally, integrating dampers increased the damping ratio from 14.48% to 30.51%, enhancing energy dissipation by shifting absorption from plastic deformation to damper yield. Pushover analysis was used to recalculate and validate the parameters α and β, demonstrating that the integration of dampers effectively controls displacement response. These findings suggest that the CR-RCFB system with integrated dampers offers enhanced seismic resilience by reducing displacement and base shear forces compared to traditional reinforced concrete frames.

Heterochain entanglements forced by shear forces and their influence on the properties of polylactic acid/hydrogenated styrene‐ethylene‐butylene‐styrene tri‐block copolymers blends

AbstractA forced entanglement between polylactic acid (PLA) chains and hydrogenated styrene‐ethylene‐butylene‐styrene (SEBS) tri‐block copolymers chains is designed based on the inertia of PLA to shear force and the sensitivity of SEBS to shear force. The melt blending of PLA with SEBS prepared through a twin‐screw extruder is a strategic method to form interchain entanglements. The influence of star‐shaped SEBS (s‐SEBS) and linear SEBS (l‐SEBS) on the compatibility, crystallization behavior, tensile properties, and rheological characteristics is systematically investigated. The incompatible interfaces between PLA and s‐SEBS or l‐SEBS are confirmed by their interfacial tension and micrographs of their cryo‐fractured surfaces. Although the interfacial incompatibility in PLA/s‐SEBS blends and PLA/l‐SEBS blends, s‐SEBS, or l‐SEBS could effectively enhance their crystallization behavior, tensile ductility and dynamic rheological properties. Relative to the Newtonian behavior of PLA, PLA/SEBS blends exhibit obvious shear‐thinning behavior under frequency‐dependent conditions, which clarifies the physical entanglements of PLA/SEBS blends. PLA/s‐SEBS blends possess stronger heterogeneous entanglements than PLA/l‐SEBS blends, which is verified by the micrographs of cryo‐fractured surfaces, crystallization characteristics, and rheological behavior. This designed concept based on the chain dynamics in the processing provides clues for polymer blends with significantly different sensitivity of chains to shear force to improve their properties.Highlights The melt blending of PLA with SEBS prepared through a twin‐screw extruder. The forced entanglement between PLA chain and SEBS chain is designed. PLA/s‐SEBS blends have stronger heterogeneous entanglement. The addition of SEBS can enhance its crystallization behavior and toughness. PLA/SEBS blends exhibit show shear‐thinning behavior in frequency dependence.

A preliminary biomechanical assessment and user perceptions of a motorized lifter for patient transfer

ABSTRACT A “no-lift” policy in healthcare discourages manual patient lifting to reduce worker injuries. This study explores modifications to a floor lift (NEAR-1) to align with this policy. NEAR-1 features a shorter lower lifting arm and a redesigned sling, enabling patients to (a) transfer in a sitting position, unlike a floor lift’s semi-reclining position, and (b) feel more in control by removing the sling’s rotational degree of freedom and letting the patient’s feet rest on the lifter base. The device also reduced patient weight-bearing, compared to sit-to-stand lifts. Biomechanical analysis was done to map the risk to the nurses and capture the patient’s experience with the modified lift (NEAR-1). Thirteen subjects carried out patient transfer tasks using both the NEAR-1 and the manual transfer approach, and this comparison will provide the baseline data for future systematic reviews. From the results, NEAR-1 significantly reduced the L5-S1 compression, the mediolateral shear forces, and the anteroposterior shear forces, with the exception of the muscle activities in the lower back, the shoulder, and the biceps. Moreover, patients felt safer and more comfortable with the device. Overall, the NEAR-1 lifter presents a biomechanically beneficial and user-friendly option for patients with limited weight-bearing capability.

Preservation of chicken breast meat by ginger extract and ginger essential oil

The study aims to extend the shelf-life of chicken breast meat by different treatments, including: (i) ratio of ginger: water = 60:40, 70:30 and 80:20; (ii) ginger essential oil 6%, 10% and 14%; (iii) edible coatings formula (sodium alginate combined with ginger extract or ginger essential oil). The research evaluated the effect of these treatments on the physicochemical parameters (pH, color, shear force, drip loss) and microbiological indicators (E. coli and aerobic plate count) of chicken breast meat during the cooling storage. The results showed that the physicochemical parameters of chicken breast meat were not affected by different treatments, these parameters were well maintained during cooling storage (4 &amp;plusmn; 1&amp;deg;C). Moreover, the ginger extract 70%, ginger essential oil 10% and the combination of ginger with an edible coating positively inhibit the growth of microorganisms. The total aerobic and E. coli plate count of samples, which were treated by these treatments, decreased within 7-10 days of cooling storage. Moreover, the chicken breast meat was treated with sodium alginate-ginger essential oil 10% had E. coli and the aerobic microbial plate count was within Vietnamese National Standards (TCVN 12429- 3:2021) during ten days of cooling storage.

Seismic isolation design of high-rise shear wall structures in high-intensity areas

Taking a shear wall structure in a high-intensity area of 20 floors as an example, the seismic reduction scheme of the structure was determined, and the Etabs software was used to conduct time history analysis on the seismic and non-seismic structures. The floor shear force, overturning moment, and short-term surface pressure of the isolation support were obtained. The results showed that under frequent earthquake action, the average maximum floor shear force in the X direction of the isolated upper structure was only about 28 % of that of the non-isolated structure. The maximum inter story shear ratio was 0.34, and the maximum floor shear force in the Y direction was only about 25 % of that of the non-isolated structure. The maximum inter story shear ratio was 0.31. The average maximum overturning moment of the upper structure in the X direction after isolation is about 30 % of that of the non-isolated structure. The maximum overturning moment ratio is 0.36, and the average overturning moment of the maximum floor in the Y direction is about 22 % of that of the non-isolated structure. The maximum overturning moment ratio is 0.26. Under rare earthquake action, the maximum inter story displacement angles in the X and Y directions of each floor of the seismic isolation structure are 1/302 and 1/446, respectively. The maximum surface pressure value of the isolation bearing under rare earthquake is 28.9 MPa, the minimum surface pressure value is 5.58 MPa, and the maximum displacement is 579 mm, which meets the requirements of the specifications. Overall, the seismic performance of the seismic isolation structure is good, and the isolation scheme is feasible.

New four-point bending test protocol for the strength grading of timber: relationship between local and global modulus of elasticity (MOE) of maritime pine

ABSTRACT This study focuses on the characterisation of maritime pine according to standards EN408 and EN384 required for timber grading. A comparison of the EN408 bending test setup is performed with a new four-point bending protocol, reducing as much as possible, the effects of the shear force in the span where the deflection is measured. The study highlights difficulties to estimate accurately, the elasticity modulus of wood by using EN408 bending test setup. This is probably due to inaccuracies in the measurements of small curvatures and due to the local heterogeneities of wood. An original four-point bending test is proposed with 75% of the span of the wood beams in pure bending. This configuration clearly exhibits the convergence of measurements, in comparison to EN408 setup. The deformations generated by this new loading protocol allow a better evaluation of the bending modulus E 0. Moreover, the study reveals that the proposed setup supplies an increase of elasticity modulus close to 20%. In addition, dynamic tests are also performed to characterise the Young’s modulus. The experimental results reveal a better agreement between static test, using the new four-point bending configuration and dynamic method, than considering EN408 as a reference.

Impacts of Waste Rubber Products on the Structure and Properties of Modified Asphalt Binder: Part II-Rubber Reclaim.

The issue of forming a reliable and stable structure of a crumb-rubber-modified binder is an important scientific and technical task. The authors supplemented existing concepts of the mechanism of effective interaction with rubber crumb by introducing a preliminary first stage: controlled partial physical destruction of rubber crumb-producing rubber reclaim. Proposed physical methods of rubber crumb destruction include high shear force (roll mills), high temperature, and a plasticizing medium. The controllability and degree of devulcanization of rubber were determined by acetone-chloroform extraction in different time intervals. The degree of devulcanization of rubber in the rubber reclaim was found to be 22 ± 0.24%, with stability over 14 days. It was found that the size of the particles of the rubber reclaim in the bitumen is less than 2 µm. The properties of the structure of the binder modified with rubber reclaim, characterizing the stability and sustainability, have been studied and established. The developed modified binders are stable in storage. Rheological parameters of the structure characterizing intermolecular interaction, such as shear stability for original and RTFOT-aged, modified bitumen, meet requirements of the state standard at test temperature 64 °C. The elastic structural component of the crumb-rubber-modified binder, as indicated by the relative irreversible deformation parameter J3,2, does not exceed 2.6 kPa (<4.5 kPa) at 64 °C. Additionally, it was determined that the rheological structural parameter for fatigue resistance, which characterizes the durability of road pavement under intensive operational conditions, does not exceed 4699 kPa (<5000 kPa) at 16 °C. The use of 10% rubber reclaim combined with waste frying oil provided the opportunity to obtain a modified binder with a stable and sustainable structure without the introduction of additional stabilizers and agents. Test results showed that the overall performance characteristics of the modified binder meet the 64(S)-40 grade standards.

Numerical analysis of FRP retrofitting in RC beam-column exterior joints at high temperatures and predictive modeling using artificial neural networks

PurposeThe purpose of this study is to perform a numerical analysis of fiber-reinforced polymer (FRP) retrofitting in reinforced concrete (RC) joints at high temperatures and predict models using artificial neural networks (ANN). The aim was to gain insights into their structural behavior across a range of loading conditions from room temperature to 800°C. Additionally, the research assessed the efficiency of carbon fiber-reinforced polymer (CFRP), glass fiber reinforced polymer (GFRP) and aramid fiber reinforced polymer (AFRP) strengthening in enhancing the structural performance of the critical sections.Design/methodology/approachThe linear numerical simulations were conducted to evaluate the performance of RC beam-column joints using finite element modelling (FEM) analysis. The ANN model demonstrated exceptional effectiveness in predicting the stiffness of frames with openings, establishing itself as the premier machine learning algorithm for frame stiffness estimation. In the conventional model, 300°C was proven to be an effective temperature approach. Subsequently, maintaining a constant temperature of 300°C, an in-depth analysis of nearly 30 models of three retrofitting techniques was conducted under thermomechanical loading.FindingsThe CFRP retrofits yielded 15% less deflection and 30% more stress than the remaining FRPs, and the ANN models predicted the deflection, main stresses, bending moment and shear force. The ANN model results were compared with those of other frequently used models. The R thresholds (R = 0.954, 0.981, 0.986, 0.968, 0.978 and 0.936) for training, testing and validation indicated that the ANN model achieved data variability. The findings indicate that the ANN model is more accurate because of the strong connection between the numerical model and the prediction.Originality/valueTo identify the pinpoint of critical segments within the rehabilitation section and determine the most effective wrapping method among the three laminates.