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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]

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]

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 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]

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]

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]

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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 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 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 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.

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]

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]

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.

Geopolymer is known to have many structural and nonstructural benefits, but the attractive characteristic of this novel material is that it depends essentially on a byproduct from different industries, and the use of Portland cement is absent. This concrete is an environmentally friendly product and is essential as the sustainability issue is considered. Compared with the material properties, the behavior of reinforced concrete members made of geopolymer has gained less importance by past researchers. Therefore, this review paper aims to summarize the evidence of the structural behavior of geopolymer concrete beams to provide a better understanding of the characteristics of reinforced geopolymer beams. A total of sixteen published works on geopolymer beams reinforced with steel rebar have been reviewed, and it found that there are 83 beams tested in flexure and 29 beams tested to highlight the shear behavior. For comparison, some researchers have tested control beams made of Portland cement concrete (PCC). It is noted that geopolymer concrete (GPC) beams have a performance, in general, better than that of PCC beams in terms of strength and ductility. Design proposals for PCC beams could be safely used for GPC beams, and the software based on the finite element method accurately predicts the load-deflection response. However, further study is recommended to provide more detailed and cost-effective design methodologies for the potential use of GPC in large-scale field applications.

Atmospheric instability is one of the necessary conditions for the occurrence of severe convective weather, which is characterized by its intricacies. This paper first briefly reviews the air parcel theory and points out its limitations in application, for example, changes in pressure and vorticity of the environmental atmosphere inevitably caused by the strong upward motion of parcels in convective storms. Then, the concepts of static instability, symmetric instability, and other types of instability are reviewed. A special focus is given to summarizing the conditions for conditional instability, moist absolute instability, and conditional symmetric instability, as well as their relationship with the occurrence and development of convective storms, with some misunderstandings being clarified. The most effective method for determining conditional instability is to make a finite virtual displacement of the parcel and then use convective available potential energy (CAPE) for identification. However, the calculation of CAPE and convective inhibition is sensitive to the temperature and moisture of the parcel, and they should be computed and corrected using virtual temperature. The optimal CAPE value has better representativeness than that of the surface-based CAPE. In strong vertical wind shear and low CAPE environments, the acceleration effect of dynamic disturbance pressure gradient caused by rotation is crucial for the development of severe convective storms. Convective instability does not necessarily correspond to conditional instability. A straightforward method for distinguishing conditional symmetric instability is to use saturated equivalent geostrophic potential vorticity. We further summarize the mesoscale rainband characteristics caused by this type of instability.

Chicken breast as the raw material was fully sheared and then the obtain minced meat was rested at 4 ℃ for different time (0~48 h). The thixotropy and rheological properties of the chicken minced meat was further analyzed, and the effect of resting time on the properties of the chicken minced meat gel was also investigated. The results showed that the chicken minced meat exhibited pseudoplasticity, thixotropy and weak gel properties (G'>G''), and the viscosity, thixotropy, elasticity (G') and viscosity (G'') of the chicken minced meat gradually increased with the increase of resting time. The cooking loss rate of the chicken minced meat gel significantly increased (P

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]

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]

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]

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 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]

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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 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]

This study investigates the response of small-scale, reinforced ultra high performance concrete beams. Seven specimens were cast and experimentally tested. Steel fiber volume fraction, amount of longitudinal and transverse steel reinforcement, and casting direction varied between specimens. High longitudinal reinforcement ratios of 4.1% and 9.5% were expected to drive relatively large shear demands and low steel fiber volume fractions of 0.5% and 1% were expected to decrease the UHPC's ability to resist tension, shear, and compression. Specimens were either cast at one end or mid-span. All specimens failed in shear, as expected. R/UHPC beams with only 0.5% fibers and a stirrup spacing equal to half the beam's depth carried more ultimate load than beams with 1% fibers and twice the stirrup spacing. At a 0.5% fiber volume fraction, UHPC performed well, exhibiting fiber bridging in tension and resisting spalling in compression. As longitudinal reinforcement ratio increased from 4.1% to 9.5%, load carrying capacity generally increased, but not proportional to the increase in steel. Placement method did not influence fiber orientation in the R/UHPC beams when measured in 2D planes transverse or longitudinal to the specimens' major axis. The longitudinal and transverse reinforcement interrupted fiber flow and prevented significant fiber alignment; combined with the short span of the beams, these factors mitigated the influence of placement method. [ABSTRACT FROM AUTHOR]

Fibre-reinforced polymers (FRPs) are widely used in industry due to their impressive strength-to-weight ratio, corrosion resistance and high durability. One of the primary components of FRPs is synthetic resins, specifically epoxy, which has been identified as harmful to the environment. To address this concern, an eco-friendly alternative made from basalt fibres and bio resin has the potential to reduce the environmental impact. This study investigates Basalt Fibre-Reinforced Polymer (BFRP) laminates manufactured using two bio resins, AMPRO™ BIO and Change Climate, comparing them to one conventional epoxy resin, WEST SYSTEM®, in terms of tensile modulus, strength and fracture toughness, as well as shear properties. The results indicate that BFRP laminates made with bio resins exhibit comparable or better mechanical properties to their conventional counterparts with tensile strength being between 6 and 17% more in bio resins compared to the conventional resin, thereby paving the way for further exploration of sustainable FRP laminates in future engineering applications. [ABSTRACT FROM AUTHOR]

It is widely recognized in both research and practice that fibers have great potential to partially, or completely, substitute conventional transverse reinforcement in webs of girders subjected to moderate shear forces. However, despite extensive research in recent years, there is still no consensus in the research community on the mechanically sound modeling of the shear strength of fiber‐reinforced concrete (FRC). Accordingly, current code provisions for the design of FRC to resist shear rely on (semi‐)empirical approaches and are thus justifiably restrictive. This article addresses this knowledge gap by proposing the application of the theory of plasticity to the design of FRC webs. Limit analysis methods for conventionally reinforced concrete are extended to FRC by incorporating the residual crack‐bridging stress offered by the fibers in a consistent manner. This stress, as well as the limits of applicability of the theory of plasticity, are derived through a sensitivity analysis using the recently developed Cracked Membrane Model for FRC considering fixed, interlocking cracks. Based on these investigations, a straightforward and efficient mechanically based shear design model suitable for the design of FRC webs with and without conventional transverse bar reinforcement is proposed. The model is validated against a large database of panel and beam experiments, providing valuable insights into its reliability. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Headed studs are shear connectors in composite structures used at the adjoining face of a steel beam and a concrete slab. In this research, the conventional shape of a headed stud was restructured to resemble the shape of a coconut palm stem (royal palm) without a change in the overall material volume, with the aim of improving the shear strength of the composite connection. Six innovative shear connectors for composite structures, named coconut palm stem royal shaped headed stud shear connectors (CPSR studs), were examined. Abaqus/Explicit was used to model a push-out specimen and the finite-element model was successfully validated using published experimental results. The six different CPSR studs encased in three grades of concrete (C40, C50 and C60) were tested for shear strength, stiffness and load–slip performance. The results for the innovative CPSR studs were compared with those for uniform cross-section headed studs; when embedded in C40, C50 and C60 grade concrete, the results showed, respectively, 35–41%, 37–44% and 41–52% improvements in the ultimate strength of the shear connection. The improved shear strength capacity of the CPSR studs without a change in the overall volume of stud material means that fewer studs are required, leading to economic benefits. [ABSTRACT FROM AUTHOR]

The paper delves into the seismic performance of braced corrugated shear panels, examining the impact of varying thickness and depth of corrugations. Utilizing models with thickness ranging from 6 mm to 10 mm and depths of corrugations spanning 20 mm to 100 mm, nonlinear cyclic analyses are conducted under cyclic loading conditions. The results indicate that increasing thickness demonstrates substantial enhancements, with a 40% surge in energy dissipation capacity, a 20% rise in ultimate load resisting capacity, and a doubling of drift. However, deeper corrugations yield significant energy dissipation, and ultimate load increases up to a depth of 40 mm, beyond which a decline in energy dissipation capacity is noted. The study underscores the importance of optimizing thickness and depth configurations, with the findings revealing that simultaneous increase in both parameters may lead to panel overstiffening and diminished energy dissipation capacity. Overall, these insights provide valuable guidance for enhancing the seismic resilience of braced corrugated shear panels. [ABSTRACT FROM AUTHOR]

This paper presents the outcomes of a comprehensive experimental investigation aimed at characterizing the in-plane shear strength of Unreinforced Masonry (URM) wallettes subjected to diagonal compression. The study focuses on the strengthening of these wallettes using precast Ultra-High Performance Concrete (UHPC) diagonal strips, externally bonded onto the wall substrates through high-strength epoxy mortar. Twenty-three wallettes, each measuring 1000 mm × 1000 mm × 70 mm, were meticulously constructed and subjected to in-plane diagonal compression. Among these, eighteen wallettes underwent strengthening utilizing various configurations of UHPC, with a key emphasis on variables such as UHPC strip width and thickness, substrate nature, and corner confinement with enlarged UHPC rectangular plates. Findings from the experimental program highlighted the significant influence of UHPC retrofit parameters on the wallettes performance. Notably, corner confinement emerged as an effective strategy against premature toe crushing failure, enhancing the wallettes ability to withstand higher in-plane compressive loads. While UHPC strip width exhibited moderate impact, UHPC strip thickness emerged as a dominant factor. Increasing strip width from 100 to 250 mm yielded an approximate 8% shear strength improvement, whereas doubling strip thickness from 10 to 20 mm led to a substantial 27% enhancement. Notably, enhanced strip width demonstrated pronounced benefits in terms of ductility and energy dissipation capacity. Excessive UHPC retrofit thickness induced brittle failure despite escalating shear strength. Conversely, thinner UHPC retrofits achieved a favorable balance between strength, ductility, and energy dissipation. Wallettes retrofitted with 5 mm UHPC exhibited an impressive 2.36-fold shear strength increase compared to reference walls, while those with 10 mm and 20 mm UHPC retrofits experienced 2.14 and 2.78-fold improvements, respectively. Furthermore, the manner of UHPC application significantly influenced the strengthening system's behaviour. For identical strengthening layouts, the direct bonding of UHPC onto masonry substrates resulted in a 25% increase in shear strength compared to UHPC bonding onto plaster overlays. [ABSTRACT FROM AUTHOR]

In order to promote stirrup yielding prior to concrete crushing and avoid over-reinforcement failure modes in reinforced concrete (RC) members, current design codes stipulate limits on the maximum amount of shear and torsional reinforcement. Studies have shown that the shear strength limits introduced based on the plane-truss approach estimate the maximum shear strength and shear failure mode with reasonable accuracy. However, the torsional strength limits derived based on the space-truss analogy and thin-walled tube theory generally overestimate the maximum torsional strength. In this study, the difference between the limiting values introduced in current design codes on the maximum shear and torsional strengths was evaluated by analysing the test results of 406 shear and 153 torsional members. Additionally, experimental tests were conducted on 22 RC beams subjected to torsional moments in order to measure the strain rate of the web concrete directly and investigate the torsional strength limits. The torsional strength limits derived based on the space-truss model overestimated the actual maximum torsional strength. Based on these observations, a lower limit for the maximum torsional strength is proposed in order to avoid over-reinforced torsional failure. [ABSTRACT FROM AUTHOR]

An optoelectronic sensor was developed to measure the in-plane displacement between two parallel surfaces. This sensor used a photodetector, which was placed on one of the parallel surfaces, to measure the intensity of the red (R), green (G), blue (B), and white/clear (C) light spectra of a broad-spectrum light that was reflected off a color grid on the opposing surface. The in-plane displacement between these two surfaces caused a change in the reflected RGB and C light intensity, allowing the prediction of the displacement direction and magnitude by using a polynomial regression prediction algorithm to convert the RGB and C light intensity to in-plane displacement. Results from benchtop experiments showed that the sensor can achieve accurate displacement predictions with a coefficient of determination R2 > 0.97, a root mean squared error (RMSE) < 0.3 mm, and a mean absolute error (MAE) < 0.36 mm. By measuring the in-plane displacement between two surfaces, this sensor can be applied to measure the shear of a flexible layer, such as a shoe's insole or the lining of a limb prosthesis. This sensor would allow slippage detection in wearable devices such as orthotics, prostheses, and footwear to quantify the overfitting or underfitting of these devices. [ABSTRACT FROM AUTHOR]

The integration of textile-reinforced concrete (TRC) and reinforced concrete (RC) has recently emerged as a promising strategy for developing hybrid structures. This study examines the flexural and shear behavior of a hybrid deck combining TRC-integrated formwork and RC through 3-point and 4-point bending tests on eight specimens with aspect ratios (a/d) ranging from 1.6 to 2.9. The test results show that the TRC integrated formwork, with its customizable cross-section and strong load-bearing capacity, is ideal for bridge deck structures. Its cracking load exceeds the required construction strength. Furthermore, the TRC formwork enhances load-carrying capacity, stiffness, and ductility, serving as an effective shear connector between concrete layers. The hybrid deck specimens display minimal, fine cracks, indicating enhanced crack resistance, improved serviceability, and reduced crack occurrence. Shear compressive and diagonal shear failures were noted in specimens, but the TRC formwork successfully averted transverse cracks at the interface, ensuring enhanced interfacial bond strength and structural integrity. [ABSTRACT FROM AUTHOR]

In smooth prismatic open channels, the boundary shear stress is obtained from continuity and momentum equations. The shear stress is a function of gravity, secondary flow and gradient velocity. In this research, semi-analytical equations were developed to estimate the average boundary shear stress in smooth rectangular and trapezoidal open channels with side slopes of 0.5, 1.0, 1.5 and 2.0 using conformal mapping techniques. After dividing the channel cross-section into bed and wall sub-sections, a previously presented method was used to estimate the average shear stress of the bed and the wall in open channels. For the studied case, in the first estimate of shear stress, the secondary current and constant eddy viscosity were neglected. After determining correction factors for secondary currents and eddy viscosity, the second estimation provided a good match with experimental measurements of the average shear stress for all aspect ratios. [ABSTRACT FROM AUTHOR]