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In the design and assessment of thick concrete shell structures subjected to out‐of‐plane loads, there is often a need to evaluate the response of shear critical components or to evaluate the influence of combined loading on shear response. This paper first presents the results from three shear‐critical large‐scale shell strip experiments subjected to combinations of shear, moment, and axial load. The experiments were monitored with digital image correlation equipment to capture the full deformation field response throughout loading. The paper then presents a simplified three‐dimensional model to predict the shear response of shear critical shell elements. The model called the 3D SEM, is compared to the shell strip experiments presented in this paper and is used to predict the interaction of in‐plane versus out‐of‐plane shear for several series of shear critical shell tests in the literature. [ABSTRACT FROM AUTHOR]

Reinforcing bars in structural concrete are typically designed to carry axial forces. Nevertheless, due to their bending stiffness, the bars can also carry transverse forces, that are associated with the localized bending mechanism (dowel action) resulting from the relative displacements (or slip) wherever a crack interface or a discontinuity interface (between two concrete parts cast at different times) intercept the bar. Such localized bending induces stress concentrations in both the bars and the concrete. The relative displacement can occur at interfaces either perpendicular to the bar or inclined with respect to its axis. Thanks to steel ductility, the bending stresses in the bars due to dowel action do not impair the sectional capacity at the ultimate limit state. Fatigue verifications, however, require an accurate evaluation of these stresses under imposed transverse displacements or shear forces. As well known, dowel action can be described by means of the traditional unidimensional Winkler's model (beam on an elastic foundation), where the bearing stiffness of the concrete embedment is typically introduced through a couple of parameters, namely the bar diameter and the concrete strength in compression. The actual behavior of a dowel, however, is definitely more complex and for such a reason, improvements are needed for the Winkler's model to introduce other parameters typical of actual structures. Hence, a new formulation is introduced in this study for the bearing stiffness, that is calibrated based on mechanical considerations and measurements with optical fibers. The proposed formulation also accounts for the following parameters: angle between the crack and the bar, concrete‐cover thickness, number of load cycles and the softening effect caused by the local secondary cracks radiating from bar ribs during the pull‐out process. The predictions of the model—implemented with the proposed bearing stiffness—fit fairly well the test results under both monotonic and cyclic loads, in terms of shear force–transverse displacement response and peak stress in the reinforcing bars. [ABSTRACT FROM AUTHOR]

More and more often, semi‐precast reinforced concrete slabs with lattice girders are employed for industrial buildings or bridges, where they are exposed to high cycle fatigue loading. Despite research in recent years that has led to the formulation of an S–N curve for lattice girders, the effects of cyclic loading on semi‐precast slabs have not yet been sufficiently clarified. Moreover, research has so far been limited to single‐span slabs. The effects of continuous slab systems, which are mainly realized in buildings and bridges, cannot be considered in the calculation of fatigue resistance yet. To improve the fatigue design concept for shear and interface shear, theoretical and experimental investigations were conducted at the Institute of Structural Concrete, RWTH Aachen University. In addition to the fatigue behavior of 16 tests under cyclic loading, particular attention is paid to the increase in shear and interface shear resistance at the inner support of continuous slabs. Furthermore, the influences of the support detailing were investigated. The findings illustrate further potential for optimization of the design under cyclic loading. [ABSTRACT FROM AUTHOR]

Biofilms are subjected to many environmental pressures that can influence community structure and physiology. In the oral cavity, and many other environments, biofilms are exposed to forces generated by fluid flow; however, our understanding of how oral biofilms respond to these forces remains limited. In this study, we developed a linear rocker model of fluid flow to study the impact of shear forces on Streptococcus gordonii and dental plaque‐derived multispecies biofilms. We observed that as shear forces increased, S. gordonii biofilm biomass decreased. Reduced biomass was largely independent of overall bacterial growth. Transcriptome analysis of S. gordonii biofilms exposed to moderate levels of shear stress uncovered numerous genes with differential expression under shear. We also evaluated an ex vivo plaque biofilm exposed to fluid shear forces. Like S. gordonii, the plaque biofilm displayed decreased biomass as shear forces increased. Examination of plaque community composition revealed decreased diversity and compositional changes in the plaque biofilm exposed to shear. These studies help to elucidate the impact of fluid shear on oral bacteria and may be extended to other bacterial biofilm systems. [ABSTRACT FROM AUTHOR]

Evaluation of treatment outcomes in patients supported by temporary mechanical circulatory support (tMCS) currently relies mainly on mortality, which may not sufficiently address other patient benefits or harms. Bleeding and thrombosis are major contributors to mortality. Still, current bleeding scores are not designed for critically ill patients undergoing tMCS, only consider selected populations, and do not account for the high heterogeneity among bleeding and thrombotic adverse events. To improve clinical management, a group of European experts has proposed a revised scoring system based on the MOMENTUM 3 Hemocompatibility Score and the Society of Cardiac Angiography and Interventions (SCAI)classification of cardiogenic shock. The new system termed the Scoring Haemostasis Events and Assessment for Risk (SHEAR) score, is divided into a baseline characterization stage and four escalating scoring stages encompassing all aspects of clinical relevance. This report summarizes the literature on hemocompatibility-related adverse events associated with tMCS, including bleeding, stroke, vascular access complications, hemolysis, thrombosis, and device failure. The SHEAR score provides a simple and rapid bedside scoring system aiming to provide a univocal tool to increase physician awareness of hemocompatibility complications at baseline and beyond, improve clinical research, and enable the capture of device-related complications that will inform relevant outcomes beyond mortality. [Display omitted] [ABSTRACT FROM AUTHOR]

Bridges situated in northern climate regions, which face severe environmental conditions and daily fatigue loading, are prone to accelerated deterioration and corrosion of their components. The application of carbon fiber–reinforced polymer (CFRP) sheets bonding to the surface of bridge elements has emerged as an attractive solution for enhancing bridge strength. Past studies and field implementations have effectively showcased the viability of this approach in strengthening bridges. An exceptional opportunity arises with the deconstruction of a bridge in Canada, providing a unique chance to assess and study the condition of reinforced concrete elements strengthened with CFRP. These elements have endured real service conditions, including fatigue loads and exposure to aggressive environmental factors. This paper presents the experimental results of a research program that aimed to investigate the residual fatigue life and capacity of 60-year-old reinforced concrete bridge girders, which were strengthened using CFRP sheets. The study focuses on assessing the performance of these girders under different test conditions, providing valuable insights into their remaining fatigue life and load-carrying capabilities. The two 60-year-old girders have been strengthened with CFRP for the last 10 years of the service life of the bridge. The two full-scale girders were tested under 2 million fatigue load cycles and then tested monotonically until failure at the structural lab of the University of Sherbrooke. The test results revealed that the CFRP-strengthening technique can extend the service life of the bridge element and enhance its shear capacity. The CFRP–concrete interface and CFRP sheets showed excellent bonding behavior, as no damage-debonding failure or tensile rupture occurred until the formation of the diagonal shear crack. [ABSTRACT FROM AUTHOR]

Recent experiments revealed a new amorphous ice phase, medium-density amorphous ice (MDA), formed by ball-milling ice Ih at 77 K [Rosu-Finsen et al., Science 379, 474–478 (2023)]. MDA has density between that of low-density amorphous (LDA) and high-density amorphous (HDA) ices, adding to the complexity of water’s phase diagram, known for its glass polyamorphism and two-state thermodynamics. The nature of MDA and its relation to other amorphous ices and liquid water remain unsolved. Here, we use molecular simulations under controlled pressure and shear rate at 77 K to produce and investigate MDA. We find that MDA formed at constant shear rate is a steady-state nonequilibrium shear-driven amorphous ice (SDA), that can be produced by shearing ice Ih, LDA, or HDA. Our results suggest that MDA could be obtained by ball-milling water glasses without crystallization interference. Increasing the shear rate at ambient pressure produces SDAs with densities ranging from LDA to HDA, revealing shear rate as a new thermodynamic variable in the nonequilibrium phase diagram of water. Indeed, shearing provides access to amorphous states inaccessible by controlling pressure and temperature alone. SDAs produced with shearing rates as high as 106 s−1 sample the same region of the potential energy landscape than hyperquenched glasses with identical density, pressure, and temperature. Intriguingly, SDAs obtained by shearing at ~108 s−1 have density, enthalpy, and structure indistinguishable from those of water “instantaneously” quenched from room temperature to 77 K over 10 ps, making them good approximants for the “true glass” of ambient liquid water. [ABSTRACT FROM AUTHOR]

Ventral furrow (VF) formation in Drosophila melanogaster is an important model of epithelial folding. Previous models of VF formation require cell volume conservation to convert apically localized constriction forces into lateral cell elongation and tissue folding. Here, we have investigated embryonic morphogenesis in anillin knockdown (scra RNAi) embryos, where basal cell membranes fail to form and therefore cells can lose cytoplasmic volume through their basal side. Surprisingly, the mesoderm elongation and subsequent folding that comprise VF formation occurred essentially normally. We hypothesized that the effects of viscous shear may be sufficient to drive membrane elongation, providing effective volume conservation, and thus driving tissue folding. Since this hypothesis may not be possible to test experimentally, we turned to a computational approach. To test whether viscous shear is a dominant force for morphogenesis in vivo, we developed a 3D computational model incorporating both accurate cell and tissue geometry, and experimentally measured material parameters. Results from this model demonstrate that viscous shear generates sufficient force to drive cell elongation and tissue folding in vivo. [ABSTRACT FROM AUTHOR]

The utilization of 20CrNiMo/Incoloy 825 composite materials as high-pressure pipe manifold steel can not only improve the strength and hardness of the steel, but also improve its corrosion resistance. However, research on the heat treatment of 20CrNiMo/Incoloy 825 composite materials is still scarce. Thus, the aim of this study was to investigate the influence of solid solution treatment on the microstructure and properties of 20CrNiMo/Incoloy 825 composite materials. Firstly, the composite materials were subjected to solid solution treatment at temperatures ranging from 850 to 1100 °C with varied holding times of 1 h, 4 h, and 6 h. Microstructural analysis revealed that the solid solution treatment temperature had a more pronounced effect than the treatment time on the interface decarburization layer, carburization layer, and grain size. It was observed that the carburized layer thickness decreased while the decarburized layer thickness increased with an increase in the solid solution treatment temperature, oil cooling was found to enhance the hardness of the base layer of the composite materials, and the size of the original austenite grains of 20CrNiMo steel and Incoloy 825 increased with an increase in the solid solution treatment temperature. Secondly, the tensile properties, microhardness, and fracture morphology were evaluated after the composite materials underwent solid solution treatment at temperatures between 950 °C and 1100 °C for 1 h. The results indicated that increasing the solution temperature initially led to an increase in tensile strength and elongation after fracture, followed by a decrease; furthermore, the hardness of Incoloy 825 exhibited a declining trend, while the hardness of 20CrNiMo first decreased then increased. Thirdly, the shear properties and interfacial element diffusion of the composite materials were analyzed following solid solution treatment in a temperature range of 950 °C to 1100 °C for 1 h. The findings demonstrated that higher solid solution treatment temperatures induced full diffusion of Cr, Ni, and Fe atoms at the interface and softened the matrix, leading to an increase in the thickness of the diffusion layer and toughening of the composite interface. Therefore, the shear strength increased with an increase in the solid solution treatment temperature. Finally, the optimal solid solution treatment process for 20CrNiMo/Incoloy 825 composite materials was determined to be 1050 °C/1 h oil cooling, following which the composite materials had good comprehensive mechanical properties. [ABSTRACT FROM AUTHOR]

Protecting coastal regions is crucial due to high population density and significant economic value. While numerous strategies have been proposed to mitigate scouring and protect coastal structures, existing techniques have limitations. This paper introduces a novel approach, SEAHIVE®, which enhances the performance of engineered structures by utilizing hexagonal, hollow, and perforated concrete elements externally reinforced with glass fiber-reinforced polymer (GFRP). Unlike conventional steel bars, GFRP offers superior durability and requires less maintenance, making it a sustainable solution for any riverine and coastal environment. SEAHIVE® aims to provide robust structural capacity, effective energy dissipation, and preservation of natural habitats. Although some research has addressed energy dissipation and performance in riverine and coastal contexts, the structural performance of SEAHIVE® elements has not been extensively studied. This paper evaluates SEAHIVE® elements reinforced with externally bonded GFRP longitudinal strips and pretensioned GFRP transverse wraps. Testing full-size specimens under compression and flexure revealed that failure occurred when the pretensioned GFRP wraps failed in compression tests and when longitudinal GFRP strips slipped in flexure tests. Strength capacity was notably improved by anchoring the GFRP strips at both ends. These findings underscore the potential of the SEAHIVE® system to significantly enhance the durability and performance of coastal and riverine protection structures. FEM simulations provided critical insights into the failure mechanism and validated the experimental findings. In fact, by comparing FEM model results for cases before and after applying GFRP wraps under the same compression load, it was found that maximum stresses at crack locations were significantly reduced due to compression forces resulting from the presence of pretensioned GFRP wraps. Similarly, FEM model analysis on flexure samples showed that the most vulnerable regions corresponded to the locations where cracks started during testing. [ABSTRACT FROM AUTHOR]

This study delves into the efficacy of external strengthening methods in improving the shear behavior of defected reinforced concrete (RC) beams that lack shear stirrups, utilizing both experimental and numerical methodologies. Failure risk of such beams is a potential threat which is mitigated carefully to increase building safety and sustainability to avoid risk of construction failure. Ten RC beams underwent three-point experimental testing to assess the influence of the strengthening scheme and the presence of mechanical anchors. Two beams were designated as control specimens, while eight beams were strengthened with the application of additional strain-hardening cementitious composite (SHCC) layer in various configurations. These configurations encompassed single-sided, two-sided, and strip applications, with the inclusion of mechanical anchors. The study found that employing a single-sided SHCC, incorporating vertically bent bars into the RC beam, is recognized for its efficient alleviation of degradation in shear reinforcement. The incorporation of three SHCC strips to partially reinforce the compromised beams demonstrated a modest impact on the initial stiffness. Nevertheless, noteworthy enhancements of 46% and 42% were observed in both cracking and ultimate loads, respectively. Furthermore, increasing the number of the SHCC strips to four resulted in a more significant improvement in the load–deflection responses. Enhancing the compromised beams by applying four SHCC strips to the beams using bolts offers a feasible alternative to the configuration where SHCC was uniformly attached along the entire defected zone. Moreover, a numerical model was created to simulate the tested beams. The model effectively anticipated the progression of cracks, ultimate capacity, and deflection, indicating excellent agreement with the experimental observations. [ABSTRACT FROM AUTHOR]

Web buckling of steel plate girders creates an undesirable failure mode as it can limit the ultimate load capacity of plate girders. This paper presents details of an experimental investigation aimed at strengthening slender end panels of steel plate girders using three different types of fibre-reinforced polymer (FRP) composite materials (glass-fibre-reinforced polymer (GFRP) pultruded section stiffeners and woven carbon-fibre-reinforced polymer (CFRP) and GFRP fabrics). The plate girders were fabricated using non-rigid end posts and were tested in three-point bending. The test results showed an increase of up to 54% in the ultimate strength of the FRP-strengthened end panels compared with the non-strengthened control panel, which was the result of increased out-of-plane stiffness of the web. A breakdown of the bond between the steel and the FRP fabric occurred in the end panels strengthened with CFRP and GFRP fabrics, while no bond breakdown of the pultruded sections was observed at the ultimate load. Analytical methods proposed by some of the design codes underestimated the critical buckling load and overestimated the ultimate load of the non-strengthened end panel. [ABSTRACT FROM AUTHOR]

AbstractThe granular and natural characteristics of soil introduce size effects to its deformation and strength properties. Therefore, investigating the phenomenon of strain localisation in soil requires a multi-scale characterisation. This study examined the intrinsic scale patterns in samples with different sizes of reinforcing particles through triaxial compression tests. Additionally, the formation mechanism of microscopic shear bands was investigated using numerical simulation methods. Drawing from the soil cell model theory, the average strain energy release coefficient was introduced to validate the transformation of the overall strain energy of the specimen after reaching the peak stress. This reflects the progressive initiation and competitive process of multiple bands. The results indicate that samples with different sizes and types of reinforcing particles exhibit various failure patterns, including single-type, ‘x’-shaped, ‘v’-shaped, parallel and others. The soil exhibits size effects, with the ratio of intrinsic scale to particle size decreasing as the size of reinforcing particles increases. Prior to the stress peak, non-elastic dissipation energy begins to increase, indicating the initiation of plastic deformation in the soil. Localised strain zones are activated, and after the peak, there is a sharp increase in stress within the shear bands, accompanied by rebound outside the band. [ABSTRACT FROM AUTHOR]

The process by which placental trophoblasts fuse to form the syncytiotrophoblast around the chorionic villi is not fully understood. Mechanical features of the in vivo and in vitro culture environments have recently emerged as having the potential to influence fusion efficiency, and considering these mechanical cues may ultimately allow predictive control of trophoblast syncytialization. Here, we review recent studies that suggest that biomechanical factors such as shear stress, tissue stiffness, and dimensionally-related stresses affect villous trophoblast fusion efficiency. We then discuss how these stimuli might arise in vivo and how they can be incorporated in cultures to study and enhance villous trophoblast fusion. We believe that this mechanical paradigm will provide novel insight into manipulating the syncytialization process to better engineer improved models, understand disease progression, and ultimately develop novel therapeutic strategies. • Biomechanical stress has recently been suggested to influence trophoblast fusion. • These stresses may arise from fluid shear, matrix stiffness, and 3D architectures. • Recreating such stresses in culture models may improve in vitro syncytialization. [ABSTRACT FROM AUTHOR]

The accurate and precise prediction of shear and flexural strengths in reinforced concrete (RC) and fiber-reinforced concrete (FRC) beams necessitates advanced computational techniques. This study pioneers the application of an Artificial Neural Network (ANN) to model these strengths and to classify failure modes in beams. Leveraging a dataset of 116 experimental tests on ultimate strengths from extensive literature, the ANN was meticulously trained, tested, and validated, revealing that the optimal neuron count for the modeling task was 15. This configuration achieved a root mean square error (RMSE) of 0.096 MPa and a coefficient of determination (R²) of 0.95, outperforming traditional design models. The study further explored an independent variable importance analysis, revealing that the beam width and effective depth were paramount in predicting strengths, findings that are congruent with established structural engineering principles. The analysis also highlighted the significance of post-cracking resistance parameters, particularly the residual flexural strength at 2.5 mm deflection, in enhancing the predictive model. The ANN classification successfully differentiated between shear and flexural failure modes, achieving an impressive accuracy of 96.5% with 25 neurons. This dual strength to model and classify underscores the ANN's robustness, offering a comprehensive tool that surpasses conventional model codes in both accuracy and precision. The results advocate for the integration of ANN techniques in structural design, promising a future where machine learning not only informs but also transforms engineering practices. [ABSTRACT FROM AUTHOR]

Virtual technologies, such as AI and parametric protocols, can mash‐up infinite architectural forms in infinite configurations. Perhaps it is beneficial for students to concentrate on the real world for a while. Architectural educator Caleb White teaches at the Weitzman School of Design at the University of Pennsylvania and the Rensselaer Polytechnic Institute School of Architecture, where he guides students to examine machines, their vectors, geometries and components, as a means to re‐engage the physicality of reality. Here, he explains his architectural agenda and shows some of the fruits of his students' labours. [ABSTRACT FROM AUTHOR]

Copyright of Materiały Budowlane is the property of Wydawnictwo SIGMA-NOT and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, full-scale loading tests were conducted to investigate web-shear strengths of hollow-core slab (HCS) members strengthened in shear by using practically viable methods. All the HCS units used in the current test program were fabricated by using the individual mold method, not by the extrusion method, and the key experimental variables of the shear test were set as the presence of shear reinforcement, core-filling concrete, topping concrete, and also the magnitude of effective prestress. The shear force-displacement behaviors, crack patterns, and strain response of shear reinforcements were reported in detail. In addition, to identify the shear strength enhancement provided under various strengthening conditions in a quantitative manner, existing shear test results of series specimens, including a naked HCS member and corresponding composite HCS members with cast-in-place (CIP) concrete and/ or shear reinforcements, were collected from literature. On this basis, a practical design expression capable of estimating shear strengths of HCSs strengthened with CIP concrete and stirrups was suggested based on the ACI 318 code equation. The proposed method evaluated the shear strengths of the collected specimens with a good level of accuracy, regardless of the presence of core-filling concrete, topping concrete, and shear reinforcements. [ABSTRACT FROM AUTHOR]

For the past several decades, there has been an ongoing academic challenge to understand the shear-transfer mechanism in reinforced concrete (RC) members, particularly in those with small shear span-depth ratios, also known as deep beams. Analytical uncertainty regarding shear strength inevitably increases when those deep members are strengthened in shear using externally bonded fiber-reinforced polymer (FRP) composites. This study aims to investigate the complex, interrelated effects of short shear span-depth ratios and FRP composites on RC deep beam members. To this end, the fundamental formulations of the dual potential capacity model (DPCM) are extended to RC deep members reinforced with externally bonded FRP composites. The proposed model can consider the various types of FRP composites, fiber bonding configurations, and fiber layouts, and various failure modes of concrete and FRP reinforcements are also reflected. A total of 131 shear test results of RC deep and short members with externally bonded FRP composites are carefully collected, and those are added to the existing database of RC slender members strengthened with FRP composites. On this basis, the proposed approach is verified by comparing test results with analysis results, and a reasonable level of analytical accuracy is achieved. The statistical data distribution of strength ratios between the test and analytical results is consistent across a range of shear span-depth ratios from approximately 0.7 to 4.0. Overall, the proposed DPCM approach provides a useful tool for analyzing the shear strength of RC deep beam members strengthened with externally bonded FRP composites. [ABSTRACT FROM AUTHOR]

In this paper, some recent analytical expressions including those of codes for shear strength calculation of reinforced concrete (RC) beams without and with stirrups are discussed and verified against experimental data available in the literature. An analytical expression proposed by the author is also introduced and discussed. Two different sets of experimental data were analyzed: one for beams without stirrups composed of 719 data and the other one for beams with stirrups composed of 152 data. Comparison between experimental data and analytical results showed that all of the analytical expressions of international codes are conservative in prediction. The proposed equation gives the same grade of accuracy of the other existing analytical expressions for the prediction of experimental data, and it is derived by a mechanical approach. Comparison shows that although most of the analytical expressions give safe and conservative results, more effort is still necessary to reduce the high scatter of prediction of all the expressions used here, especially for beams without stirrups. [ABSTRACT FROM AUTHOR]

This study examined the use of two configurations for capacity restoration of reinforced concrete (RC) one-way ribbed slabs containing openings in shear zones. Four specimens of half-scale comprised three ribs in addition to a top RC slab. The test plan included a control specimen without openings, one with two rib-cutting shear openings, one strengthened using a blend of carbon FRP (CFRP) composites and steel plates, and another retrofitted with a combination of glass FRP (GFRP) composites and steel plates. The two strengthening schemes were found successful at fully restoring the ultimate load of the specimens. The ultimate load of specimen strengthened using the hybrid CFRP/steel system exceeded the control slab without openings by 52%. However, in the other specimen where a mix of steel plates and GFRP sheets was used, the load capacity was only 5% less than the control specimen without openings. While the dissipated energy and stiffness were reinstated and improved for the hybrid CFRP/steel system, they were partially restored for the GFRP/steel system. Additionally, a prediction approach was developed to estimate the maximum load of the slabs. The developed approach considered potential shear and flexural modes of failure, providing close predictions of the ultimate load. [ABSTRACT FROM AUTHOR]

The multifunctional responsive interfaces of liquid crystal (LC) and water are employed in fundamental research (colloidal assembly) and promising applications (sensing, release, and material synthesis). The stagnant LC systems, however, limit their use in continuous, automated applications. A microfluidic platform is reported where stable LC flow is maintained between aqueous interfaces. The LC‐water soft interface is defined by the preferential wetting of the two phases at the chemically heterogeneous microchannel interfaces. It is shown that the LC‐water interfaces are stable up to significant pressure differences across the interfaces and maintain responsive characteristics. The stability is in a range to cover the perpendicular and flow‐aligned regimes at low and high flow velocities, respectively, in co‐current or counter‐current flow configurations. The LC configuration at the vicinity of the aqueous interfaces is influenced by the shear induced by the bulk LC flow and by the contacting aqueous phases allowing modulation of the LC strain at the responsive interfaces. The simplicity of the construction and operation of the soft‐interface LC flow platform shows promise and meets the fundamental requirements for their integration into next‐generation autonomous platforms. [ABSTRACT FROM AUTHOR]

The predictive capability of an anisotropic yield function highly relies upon the number of the model parameters and its calibration type. Conventional calibration of a plane stress anisotropic yield function considers material behavior in uniaxial and equi-biaxial stress states, whereas it violates shear and plane strain loading conditions. In this study, the direction of the plastic flow in both loading regions was corrected by including shear and plane strain constraint terms to the conventional calibration of the Yld2000 function, and its effect on the sheet metal forming simulations, namely cup drawing and hole expansion tests, was investigated. Two highly anisotropic sheet materials (AA2090-T3 and low-carbon steel) were selected for the investigation, and the anisotropy coefficients were determined. Stress anisotropy was accurately predicted by the conventional method, whereas any decrease in the prediction of the deformation anisotropy could not occur by the applying of the constrained methods. Significant increases in the predicted cup height and differences in the number of the ears were observed by shear constraint identification in the cup drawing. The maximum thinning location in the hole expansion test could be accurately predicted by plane strain constraint identification. [ABSTRACT FROM AUTHOR]

Particle morphology is multi-scale in nature. To investigate the effects of particle morphology at a specific length scale on the macro–micro mechanical behaviours of granular soils, morphological gene decay and mutation was incorporated into discrete-element method (DEM) simulations through spherical harmonic-based principal component analysis. All DEM samples were subjected to axial compression and constant confining stress. The macro-scale and grain-scale behaviours of the granular assembly were investigated. It was found that particle morphology shows significant effects on macro-scale behaviours including initial stiffness, peak stress ratio, volumetric contraction and dilation, and shear band formation, as well as grain-scale behaviours including coordination number, particle rotation and granular skeleton sustaining the major contact force chains. Among the different length scales, local roundness contributes the most to stress ratio, volumetric strain and particle coordination number, while general form contributes the most to shear strain, particle rotation and fabric structure. Another interesting finding was that the particle morphological effects are well reflected in the granular skeleton sustaining the major contact force chains, which is featured with a strong variation of the degree of particle shape irregularity among different kinds of gene-mutated samples. [ABSTRACT FROM AUTHOR]

Copyright of GeSec: Revista de Gestao e Secretariado is the property of Sindicato das Secretarias e Secretarios do Estado de Sao Paulo (SINSESP) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract In recent years, fiber reinforced polymer (FRP) reinforcement has garnered significant interest in the construction industry, particularly in concrete beam construction. Determining the shear capacity of FRP-reinforced beams is, however, an intricate task. The shear capacity of FRP-reinforced concrete beams can be estimated using design equations from various international standards of practice. However, these equations are often adaptations of those used for conventional steel reinforcement, resulting in unreliable estimates. This research compares design equation predictions with experimental data, utilizing test results from 48 carbon FRP-reinforced and 73 glass FRP-reinforced concrete beams. The results reveal significant differences in the accuracy and reliability of shear capacity predictions using American (ACI), Canadian (CSA), and Japanese (JSCE) design standards for both types of concrete beams. The ACI standard has high underestimation and inconsistent predictions for carbon and glass FRP beams, making it unsuitable for shear design. The CSA standard provides consistent predictions with moderate underestimation for both types of FRP beams, but it shows overestimation in certain cases. The JSCE standard consistently shows moderate underestimation without any instances of overestimation, making it a reliable tool for engineers and practitioners to estimate the shear capacity of both types of FRP-reinforced beams.

The curvature causes a variation in the deflection of the outer and inner sides. The effect of curvature was investigated by casting and testing two specimens with the same section – one straight and the other horizontally curved continuous box girder. ABAQUS software was used to numerically model the box girder in order to verify the model and investigate additional parameters. Numerical modeling is successful with less effort, cost, and time because good results are obtained. The effect of the span-to-depth ratio, the compressive strength of concrete, and the percentage of stirrup steel reinforcement was studied numerically. Increasing the height, compressive strength, and percentage of stirrup steel led to a significant increase in load capacity and stiffness. The load capacity in the curved specimen decreased by 11% compared to the straight one due to the effect of torsional moments. A mathematical model was proposed based on the theory of strut-and-tie modeling (STM), where the span was divided into several panels, the effect of torsion was added, and then the results were compared with the traditional sectional method according to ACI and CEB-FIB. For the straight specimen, the sectional ACI, CEB-FIB, and STM methods were used, which gave theoretical results less than the experimental by 31, 48 and 13%, respectively. For the curved specimen, to get closer to reality, the sectional and STM methods were modified by adding the effect of torsion, and the results were less than the experimental tests by 43, 61 and 22%, respectively.

Abstract Maize is the most grown feed crop in the United States. Due to wind storms and other factors, 5% of maize falls over annually. The longitudinal shear modulus of maize stalk tissues is currently unreported and may have a significant influence on stalk failure. To better understand the causes of this phenomenon, maize stalk material properties need to be measured so that they can be used as material constants in computational models that provide detailed analysis of maize stalk failure. This study reports longitudinal shear modulus of maize stalk tissue through repeated torsion testing of dry and fully mature maize stalks. Measurements were focused on the two tissues found in maize stalks: the hard outer rind and the soft inner pith. Uncertainty analysis and comparison of multiple methodologies indicated that all measurements are subject to low error and bias. The results of this study will allow researchers to better understand maize stalk failure modes through computational modeling. This will allow researchers to prevent annual maize loss through later studies. This study also provides a methodology that could be used or adapted in the measurement of tissues from other plants such as sorghum, sugarcane, etc.

The ZCuPb15Sn5/1045 bimetallic composites were prepared by the melt-casting composite method. The mechanical and tribological properties of the copper-steel bimetallic composites under different cooling process conditions were studied. The results showed that with the acceleration of the cooling rate, the copper layer of the copper-steel bimetallic composite became harder, the grain became finer, and the distribution of the anti-friction element Pb became more uniform. Underwater cooling conditions, the shear strength increased, and the shear fracture gradually showed the tendency of tough and brittle fracture. The cooling process had a more significant influence on the tribological properties of the material. When the cooling rate was slow, the copper layer of the bimetallic composites had a high friction coefficient and relatively serious adhesive wear and oxidation wear. For the water cooling sample with a very fast cooling rate, the friction coefficient of the copper layer was low and the wear degree was relatively light.

Abstract The current code provisions in ACI 440.11 are based on the flexural theory that applies to slender members and may not represent the actual structural behavior when the shear span-to-reinforcement depth ratio is less than 2.5 (i.e., deep members). The Strut-and-tie method (STM) can be a better approach to design deep members; however, this chapter is not included in the code. Research has shown that STM models used for steel-reinforced concrete (RC) give satisfactory results when applied to glass fiber-reinforced polymer-reinforced (GFRP)-RC members with a/d less than 2.5. Therefore, this study is carried out to provide insights into the use of STM for GFRP-RC deep members based on the available literature and to highlight the necessity for the inclusion of a new chapter addressing the use of STM in the ACI 440.11 Code. It includes a design example to show the implications of ACI 440.11 code provisions when applied to GFRP-RC deep members (i.e., isolated footings) and compares it when designed as per STM provided in ACI 318-19. It was observed that current code provisions in ACI 440.11 required more concrete thickness (i.e., h = 1.12 m) leading to implementation challenges. However, the required dimensions decreased (i.e., h = 0.91 m) when the design was carried out as per STM. Due to the novelty of GFRP reinforcement, current code provisions may limit its extensive use in RC buildings, particularly in footings given the water table issues and excavation costs. Therefore, it is necessary to adopt innovative methods such as STM to design GFRP-RC deep members if allowed by the code.

AbstractThis paper showcases shear testing conducted on seven reinforced concrete deep beams featuring square openings, aimed at demonstrating the efficacy of a shear strengthening approach utilizing textile-reinforced concrete (TRC). This experimental program researches two types of openings of 150 × 150 mm and 200 × 200 mm at the centre of the shear spans. The solid beam undergoes testing for comparison with both the unstrengthened and strengthened beams containing openings. The study evaluates the effectiveness of TRC through a comparison of load-displacement curves, cracking patterns, and strains in reinforcements between the strengthened and un-strengthened beams. The experimental results indicate that the TRC strengthening technique effectively boosts the shear-carrying capacity of beams. Examination of the tested beams reveals a significant enhancement in stiffness at the point of maximum force, with improvements ranging from 22% to 86%, depending on the opening size and the number of reinforced textile layers. Rupture in TRC and crushing in the concrete strut are observed in the strengthened beams, whereas the un-strengthened beams show severe crushing in concrete at failure. The test results are compared with calculations based on code provisions, revealing that the prediction model consistently yields values 11 to 44% higher than the experimental results. [ABSTRACT FROM AUTHOR]

This paper shows how the effect of combined normal and shear stresses on the rates of tribochemical reactions can be calculated using Evans-Polanyi (E-P) perturbation theory. The E-P approach is based on transition-state theory, where the rate of reaction is taken to be proportional to the concentration of activated complex. The equilibrium constant depends on the molar Gibbs free energy change between the initial- and transition-states, which, in turn, depends on the stresses. E-P theory has been used previously to successfully calculate the effects of normal stresses on reaction rates. In this case, ln(Rate) varies linearly with stress with a slope given by an activation volume, which broadly corresponds to the volume difference between the reactant and activated complex. An advantage of E-P theory is that it can calculate the influence of several perturbations, for example, the normal stress dependence of the shear stress during sliding. In this paper, E-P theory is used to calculate shear-induced, tribochemical reaction rates. The results depend on four elementary activation volumes for different contributions to the Gibbs free energy: two of them due to normal and shear stresses for sliding over the surface and two more for the surface reaction. The results of the calculations show that there is a linear dependence of ln(Rate) on the normal stress but that the coefficient of proportionality between the ln(Rate) and the normal stress now has contributions from all elementary-step activation volumes. Counterintuitively, the analysis predicts that the ln(Rate)-normal stress evolution tends, at zero normal stress, to an asymptotic rate constant that depends on sliding velocity and differs from the thermal reaction rate. The theoretical prediction is verified for the shear-induced decomposition of ethyl thiolate species adsorbed on a Cu(100) single crystal substrate that decomposes by C‒S bond cleavage. The theoretical analyses show that tribochemical reactions can be influenced by either just normal stresses or by a combination of normal and shear stresses, but that the latter effect is much greater. Finally, it is predicted that there should be a linear relationship between the activation energy and the logarithm of the pre-exponential factor of the asymptotic rate constant. [ABSTRACT FROM AUTHOR]

The results of an experimental program conducted to evaluate the performance of shear-critical post-tensioned I-girders with grouted and ungrouted ducts are presented. The experimental program involved the design, construction, and testing to failure of six fullscale specimens with different duct layouts (straight, parabolic, or hybrid) and using both grouted or ungrouted ducts. All tests resulted in similar failure modes, such as localized web crushing in the vicinity of the duct, regardless of the duct condition or layout. Furthermore, the normalized shear stresses at ultimate were similar for the grouted and ungrouted specimens. The current shear design provisions in the AASHTO LRFD Bridge Design Specifications (AASHTO LRFD) were reviewed, and updated shear-strength reduction factors to account for the presence of the duct in the web and its condition (that is, grouted or ungrouted) were proposed. The data generated from these tests served as the foundation for updated shear-strength reduction factors proposed for implementation in AASHTO LRFD. [ABSTRACT FROM AUTHOR]

The present study reports the effect of laser shock peening (LSP) on stress corrosion cracking (SCC) behavior of the shear cut surfaces of type 304L stainless steel. The LSP is carried out on as shear cut surface of SS 304L steel at a fixed laser power density of 3.53 GW cm−2 with multiple passes, i.e., double and triple. The preliminary investigation showed that as shear cut surfaces of SS 304L possess a very high tensile residual stresses of the order of 450-700 MPa and hardness 400 HK0.1. The LSP treatment with double and triple pass led to the generation of high compressive residual stress of the order of − 200, and − 250 MPa as compared to as cut shear surfaces. Microscopic analysis revealed that the shear cut surfaces, after double and triple LSP treatment exhibited significantly reduced susceptibility to the SCC in chloride environment after 8-hour test. The results of the present study recommend that LSP treatment can acts as protector of the product and components of austenitic stainless steel with sheared cut surfaces stored for long time in susceptible corrosive environment. This way a huge loss to the nuclear and process industries can be minimized. [ABSTRACT FROM AUTHOR]

The study was to improve the crushing quality of silage sugarcane tail stem crushing machinery, study the shear and compression characteristics of silage sugarcane tail stem. In this study, Guitang 42, which was widely cultivated in Guangxi, was used as the research object to shear and compress the tail stems of silage sugarcane by WDW-T100 universal testing machine. Based on the central combination design test (CCD), the effects of loading speed, moisture content and sampling position on the shear strength of silage sugarcane tail stems were studied. Based on the single factor test, the effects of compression velocity, presence or absence of stem nodes and compression direction on compression characteristics were studied. The results showed that the shear strength of the silage sugarcane tail stem was 0.66~ 0.95 MPa, and the shearing process could be divided into three stages, and the maximum shear force appeared in the first stage. The Design-Expert 12.0 software analysis determined that the moisture content and sampling position had significant effects on the shear strength (P<0.05), but the loading speed had no significant effect on the shear strength (P>0.05). The maximum compressive force decreased with increasing loading speed. The maximum compressive force of the part with stem joints was greater than that of the part without stem joints. The axial maximum compressive force was greater than the transverse maximum compressive force. The study indicates that the study can provide a reference for the design and optimization of silage sugarcane tail stem crushing machinery and equipment. [ABSTRACT FROM AUTHOR]

The adhesive bonding approach is widely used in assembling of spars, stringers, ailerons, flaps, and rudders in aircraft. The present research investigated the impact of silicon carbide (SiC) nanoparticle inclusion on the shear and free vibrational behaviour of adhesively bonded single lap joints (SLJ). The shear test results showed that the inclusion of 1.5 wt.% SiC in the epoxy resin enhanced the shear behaviour of adhesively bonded SLJ. Furthermore, the failure surfaces of adhesively bonded SiC-reinforced SLJ were examined using a field emission scanning electron microscope (FESEM). The microstructural investigation of the failure surface demonstrated that the development of rougher surfaces, plastic void enlargement, and formation of shear bands in the joint region had improved adhesion among GFRP adherends. Thus, the SiC-incorporated adhesively bonded SLJ had predominant cohesive failures. Meanwhile, the SiC-free lap joint had an adhesive failure due to lower adhesion. The vibrational results avowed that 1.5 wt.% SiC-incorporated adhesively bonded SLJ has higher natural frequencies. Results also affirmed that higher wt.% SiC-incorporated joint had better modal damping values due to nanoparticle accumulation, which increased the interaction between glass fiber reinforced polymer (GFRP) adherends. [ABSTRACT FROM AUTHOR]

Wax/paraffin deposition in production wells and oil pipelines is a major challenge for oil production. Extensive research has been conducted to improve understanding of this process. This paper presents a review of experimental work carried out with flow loops. Previous research investigated paraffin deposition process under the influences of temperature, flow rate/velocity, shear stress, water fraction, gas phase, pipe material, asphaltene concentration, and chemical inhibitors. Test results reveal that temperature and shear stress have significant impacts on wax deposition. Limited research has been conducted on wax deposition under multiphase flow. Even though more than 20 years of efforts have been spent on wax deposition studies, unfortunately we have not fully understood this phenomenon. [ABSTRACT FROM AUTHOR]

In typical reinforced concrete design, reinforcement is designed to carry axial forces, but it can also resist transversal forces by dowel action. This is usually neglected for simplicity's sake in the design phase, but it can be accounted for either explicitly in mechanical models or implicitly in empirical relationships. Furthermore, there are cases where the connection between various concrete elements explicitly depends on dowel action, as for example, in connections between precast elements or between two concrete parts cast at different times. On the other side, dowel action can have a negative impact on the fatigue resistance of reinforcing bars subjected to cyclic loading, because of the local stress concentrations near interfaces due to relative movements, either in sliding or in opening of cracks not perpendicular to the bar. For the assessment of the remaining capacity of existing structures, improved models of the behavior are needed, including realistic models of the behavior of concrete, steel and their interfaces. The aim of the present paper is to provide a contribution to a better understanding of dowel action by two test series. The first series focused on the behavior of the dowel: the concrete specimens with the embedded bars were placed in a custom‐made test setup and subjected to monotonic or low stress‐level cyclic actions with a longitudinal and a transversal crack opening component, up to developing the full plastic capacity of the dowel and rupture at the peak of catenary action. The measurement system included tracking the displacement field at the surface of the concrete and the strains in the dowel by optical fibers glued on its surface. The latter measurements allow to derive the internal forces in the reinforcing bar and deformed shape of the bar as well as the contact pressure between the bar and the surrounding concrete. The results show a strong dependency on the test variables: diameter of the bar, imposed crack kinematics and angle between the bar and the crack. The second test series looked more closely at the behavior of concrete underneath the bar, in the presence of a point load introduced at various locations into concrete through a reinforcing bar. A comparison of the test results with existing models shows a general good agreement and some aspects that deserve to be improved. [ABSTRACT FROM AUTHOR]

Summary: The impact of three food pasteurisation technologies, namely thermal, high‐pressure and ultra‐shear processing, on the metabolites of beetroot juice was evaluated using a processomics approach with nuclear mass resonance (NMR) as an analytical technique. Two batches of beetroots acquired from different local grocery stores were used for this study. Beetroot juice obtained from these batches was subjected to high‐pressure processing (HPP) at 600 MPa and 25 °C for 5 min, ultra‐shear technology processing (UST) at 400 MPa and 30 °C and thermal processing (TP) at 96 °C for 12 min. Principal component analysis (PCA) for the two batches indicated that both extrinsic factors such as processing parameters (temperature, pressure, shear and holding time) and intrinsic factors such as the origin of the beetroot influenced the PCA plot. When the influence of intrinsic parameters was minimised by studying a single batch processed by TP, HPP and UST, distinct clusters for different processing methods were formed, indicating that processing influenced the metabolites. While processing is not the main factor determining the final composition, as indicated by PCA with different batches, supervised techniques like orthogonal partial least‐squares discriminant analysis (OPLS‐DA) and random forest (RF) demonstrated that processing does impact the beetroot juice metabolome. Seven metabolites (leucine, alanine, valine, glutamine, gamma‐aminobutyric acid, fructose and glucose) were identified as potential process‐induced biomarkers. [ABSTRACT FROM AUTHOR]

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Axial compressive strength is a key design parameter for CFRP structures. One of its limiting factors is the non-linear shear behaviour of the unidirectional ply. We investigate the estimation of this behaviour from those of its constituents by computational homogenisation with an hexagonal unit cell and different random microstructures with smooth and clustered fibre distributions. A random microstructure without clusterings predicts the shear modulus most closely. However, the modelled shear responses converge at higher loadings so that an hexagonal model is sufficient to estimate the non-linear shear behaviour and in turn give accurate estimations of measured compressive strength. [ABSTRACT FROM AUTHOR]

The industry's pursuit for higher antibody production has led to increased cell density cultures that impact the performance of subsequent product recovery steps. This increase in cell concentration has highlighted the critical role of solids concentration in centrifugation yield, while recent product degradation cases have shed light on the impact of cell lysis on product quality. Current methods for measuring solids concentration and cell lysis are not suited for early‐stage high‐throughput experimentation, which means that these cell culture outputs are not well characterized in early process development. This article describes a novel approach that leveraged the data from a widely‐used automated cell counter (Vi‐CELL™ XR) to accurately predict solids concentration and a common cell lysis indicator represented as lactate dehydrogenase (LDH) release. For this purpose, partial least squares (PLS) models were derived with k‐fold cross‐validation from the particle size distribution data generated by the cell counter. The PLS models showed good predictive potential for both LDH release and solids concentration. This novel approach reduced the time required for evaluating the solids concentration and LDH for a typical high‐throughput cell culture system (with 48 bioreactors in parallel) from around 7 h down to a few minutes. [ABSTRACT FROM AUTHOR]

The hydrotransport of settling particles using laminar flow as opposed to the more energy‐ and water‐intensive turbulent flow has remained a tentative option for industries due to the complexity in characterizing particle settling dynamics in opaque non‐Newtonian fluids under sheared conditions. To provide insight into this unknown physics, this study focused on viscoelastic shear‐thinning fluids and developed a semi‐empirical model to characterize the batch‐settling dynamics of dilute suspensions (<5 vol% solids concentration) experiencing a shear field. These suspensions consisted of spherical glass microparticles in aqueous xanthan gum solutions. Settling profiles were measured with Electrical Resistance Tomography (ERT) while a motorized belt generated a cross‐shear field. The data acquired by the ERT showed that introducing cross‐shear fields into such suspensions increased settling rates when compared with static settling contexts. Then, a semi‐empirical model describing the "acceleration phase" of the settling process was developed and validated at accuracies between 81% and 97%. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the nonlinear structural behavior of concrete deep beams internally reinforced with glass fiber-reinforced polymer (GFRP) reinforcing bars and containing a web opening of various sizes and locations within the shear span. Three-dimensional (3D) numerical simulation models were developed for large-scale GFRP-reinforced concrete deep beams (300 mm × 1200 mm × 5000 mm) with a shear span-to-depth ratio (a/h) of 1.04. Predictions of the numerical models were validated against published experimental data. A parametric study was conducted to examine the effect of varying the opening size and location on the shear response. Results of the numerical analysis indicated that the strength of the deep beam models with an opening in the middle of the shear span decreased with an increase in either the opening width or height. The rate of the strength reduction caused by increasing the opening height was, however, more significant than that produced by increasing the opening width. Placing a web opening in the compression zone close to the load plate was very detrimental to the beam strength. Conversely, a negligible strength reduction was recorded when the web opening was placed in the tension side above the flexural reinforcement and away from the natural load path. Data of the parametric study were utilized to introduce simplified analytical formulas capable of predicting the shear capacity of GFRP-reinforced concrete deep beams with a web opening in the shear span. [ABSTRACT FROM AUTHOR]

The II–I phase transition of isotactic poly(1‐butene) (iPBu) leads to improved mechanical performance. However, this will take several weeks and increase storage and processing costs. In this work, shear forces are introduced into the supercooled iPBu melt, and the effects of isothermal crystallization temperature (Tc) and shear temperature (Tshear) on crystallization and phase transition are explored. Shear‐induced transcrystalline morphology of Form II with a significantly shortened crystallization induction period can be observed at relatively high Tc (105 °C). Besides, the shear‐induced Form II can transit to Form I faster than the unsheared one. In addition, the phase transition rate increases as the Tshear decreases, with the fastest rate occurring at Tshear of 120 °C. The half transition time (t1/2) is measured as 6.3 h when Tc = 105 °C, Tshear = 120 °C, which is much shorter than the 20.7 h required for unsheared samples. The accelerated phase transition of iPBu can be attributed to the stretching of molecular chains, resulting from shear treatment. This study provides a quantitative analysis of the influence of the shear treatment and the Tshear on the II–I phase transition rate. It also presents a cost‐effective and straightforward approach for expediting the phase transition process. [ABSTRACT FROM AUTHOR]