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AbstractTo predict the cyclic response of concrete strengthened with FRP, this paper presents a new analytical solution, which uses the cohesive zone model (CZM). Based on the CZM, for intermediate crack-induced debonding, with intermediate flexural cracking of concrete beams repaired with FRP plate, the deteriorative effect of cyclic loading on the adhesive joints (interface) is investigated. To accomplish this aim, a cyclic damage process is coupled with a CZM to predict the cumulative damage evolution along the FRP-to-concrete interface as a function of the number of cycles. Comparing the results from the present model with those found in the literature shows that the constitutive model is able to accurately predict the overall cyclic loading response of concrete strengthened with FRP composites. The main advantage of the proposed model is that it gives the variation of the mid-span deflection, damage development, and interfacial stress distribution with increasing load cycles, and number of loading cycles. We conclude that cyclic degradation of the component materials significantly reduces the resistance and lifespan of the repaired structures. [ABSTRACT FROM AUTHOR]

Based on the shear flow theory for thin‐walled sections, a method for calculating the shear stress nonuniformity coefficient (µ) of a thin‐walled section is proposed according to the energy principle, and the formulas for calculating the µ values of several common sections are derived. The obtained µ value of a box section increases as the aspect ratio increases. Compared with commonly used calculation methods, the proposed method gives more reasonable results and shows that the effect of shear stress in the flange of the flat box section should not be ignored. The effects of the web and flange thicknesses on µ are analyzed and discussed. Based on these effects, a simplified method for calculating the µ value of complex box sections is presented, and this method is demonstrated to considerably reduce the calculation error and meet engineering needs. [ABSTRACT FROM AUTHOR]

Climate change can have a profound impact on river flooding, leading to increased frequency and severity of floods. To mitigate these effects, it is crucial to focus on enhancing early warning systems and bolstering infrastructure resilience through improved forecasting. This proactive approach enables communities to better plan for and respond to flood events, thereby minimizing the adverse consequences of climate change on river floods. During river flooding, the channels often take on a compound nature, with varying geometries along the flow length. This complexity arises from construction and agricultural activities along the floodplains, resulting in converging, diverging, or skewed compound channels. Modelling the flow in these channels requires consideration of additional momentum transfer factors. In this study, machine learning techniques, including Gene Expression Programming (GEP), Artificial Neural Networks (ANN), and Support Vector Machines (SVM), were employed. The focus was on a compound channel with converging floodplains, predicting the shear force carried by the floodplains in terms of non-dimensional flow and hydraulic parameters. The findings indicate that the proposed ANN model outperformed GEP, SVM, and other established approaches in accurately predicting floodplain shear force. This research underscores the efficacy of utilizing machine learning techniques in the examination of river hydraulics.

Introduction. Published studies on the rigidity of consoles under load focus on the issues of their deformation and destruction. Calculations of the inertia moment, fundamentally important characteristic of the strength of the rod, are described. However, the problem of significant time consumption for such calculations has not been solved. The presented study meets the lack. The objective of the work is to describe a new rapid method for analytical calculation of the shear stress distribution in the section of the console corresponding to the action of an external applied force. For the first time, tangential stresses are considered, and examples of calculating the inertia moment for two non-standard sections of the console are given in this context.Materials and Methods. To develop a new method, the console was presented as a pack of plates oriented parallel to the vector of external force. The source calculations were based on the scheme of a console beam with a dedicated plate. The deformation of the rod elements was modeled taking into account the effect of a uniform shear stress field in the plate section. To validate the simplified calculation of the inertia moment of the sections, schemes of a square, ellipse, triangle, hexagon, six-pointed star, and a figured cross were used. Analytical and mathematical research methods were applied, specifically, the Huygens–Steiner theorem.Results. A rapid valid method for calculating the inertia moment of the cross section of the console under loading has been developed. Its difference is the rejection of calculations for each section, taking into account the shape and other features. For any shape of the section, the beam is represented as a bundle of infinitely thin plates, their inertia moments are integrated, and a well-known solution for deflection of a thin plate is used. The method allows us to unambiguously show the distribution of tangential stresses at the end of the console, providing a given deflection, and tangential stresses are used for such solutions for the first time. Their profiles are obtained depending on the direction of the external applied force. Formulas for the inertia moments of complex sections — a six-pointed star and a figured cross — are derived for the first time. Each section is correlated with the stress distribution curve and its maximum value. This data is visualized in the form of diagrams. It is found that the inertia moment and the rigidity of the console do not change when the external applied force is rotated by 30° for a star-shaped section and by 45° for a square and a figured cross. In general, the tangent field depends on the geometry and on the orientation of the section relative to the external applied force.Discussion and Conclusion. The proposed simplified approach to calculating the inertia moment of the cross sections of the consoles makes it possible to uniquely determine the field of tangential stresses at the end, which provides the appropriate value of the external applied force for the given deflection. Engineers and mechanics can use the results of the presented work in the calculations and modeling of deformation of rod structural elements.

Background and Objectives: Today, due to the reduction of water resources and the issue of excessive water consumption in the agricultural sector, for the purpose of distribution, delivery, and flow regulation to waterways, and to prevent water losses, novel structures with better efficiency and easier operation have been introduced by researchers. Lopac gates are one of the hydraulic structures for flow control and regulation, which have features such as the possibility of automation, open-channel flow, and easier installation and placement compared to other structures. In this study, a rectangular multi-lopac gate, which is one of the novel types of lopac gates, has been used. Considering the easier operation of smaller gates compared to larger gates, in this study, has been investigated the effect of two smaller gates instead of a single gate on the hydraulic characteristics in the submerged condition with 70%, 80%, and 90% submergence levels and with the aim of increasing efficiency and ease in design and construction. Materials and Methods: In the present study, several simulations were performed to validate and select the turbulence model. After investigation the performed simulations, a mesh of 800,000 cells, the RNG turbulence model, and a time of 40 seconds for the flow to reach stability were selected. Then, to investigate the hydraulic parameters of maximum shear stress, maximum horizontal force acting on the gate, velocity distribution range, and shear stress in the rectangular lopac gate under submerged flow conditions, and compare it with the single gate case, simulations were performed at three discharges of 25, 35, and 45 liters per second, opening angles of 35, 40, and 45 degrees, and three submergence levels of 70%, 80%, and 90% in two different geometries, with a total of 54 simulations. Results: The results showed that the maximum shear stress has an inverse relationship with submergence and opening angle, and the maximum horizontal force acting on the gate has a direct relationship with submergence and discharge. It was observed that all the investigated parameters in the two-gate case decreased compared to the single-gate case, and the amount of this decrease in the horizontal force acting on the gate was 33.5%, which was the highest decrease at a discharge of 25 liters per second, an opening angle of 45 degrees, and 90% submergence, and the lowest decrease was at a discharge of 25 liters per second, an opening angle of 45 degrees, and 70% submergence. The reduction in the maximum shear stress in the two-gate case compared to the single-gate case was 13.25%, with the highest decrease of 23.29% occurring at a discharge of 45 liters per second, an opening angle of 45 degrees, and 90% submergence, and the lowest decrease of 6.21% occurring at a discharge of 45 liters per second, an opening angle of 35 degrees, and 80% submergence. It was also observed that the distribution range and elongation of velocity and shear stress on the flume bed increased with increasing discharge and opening angle, and in general, the distribution range and elongation of velocity and shear stress on the flume bed decreased in the two-gate case compared to the single-gate case. Conclusion: According to the results, it can be stated that the distribution range of velocity and shear stress has a direct relationship with discharge and opening angle, and the elongation of the velocity and shear stress distribution in the two-gate case decreased compared to the single-gate case. The maximum shear stress has an inverse relationship with the opening angle and submergence, and it decreases by 13.26% compared to the single-gate case. This is due to the reduction of the area of vortices in the two-gate case. Investigating the maximum horizontal force acting on the gate showed that this parameter has a direct relationship with flow rate, opening angle, and submergence, and it decreases by 33.5% in the multigate cases compared to the single-gate case. [ABSTRACT FROM AUTHOR]

This study proposes a practical design approach to estimate the web-shear strength of deep prestressed hollow-core slabs (PHCS). It explores the effects of critical factors such as the shear stress distribution, biaxial tensile strength, and the reduction in effective compressive stress in concrete, quantifying their impact on web-shear strength. A data set of 85 entries is used to undertake a comparative assessment, demonstrating the improved safety and accuracy of the proposed methodology against current design provisions and previous proposals. Moreover, it is shown that neglecting the beneficial effect of the prestressing force in the transfer region leads to a conservative estimation of the web-shear strength. Furthermore, the study introduces three modified design expressions based on ACI 318-19, fib Model Code 2010, and CSA A23.3-14 standards. The proposed methodology has practical implications for enhancing the safe and cost-effective use of deep PHCS in construction practice. [ABSTRACT FROM AUTHOR]

Rock anchors are a common safety measure for stabilising large-scale infrastructure, such as bridge towers, retaining walls, rock slopes and windmills. There are four principal failure modes for rock anchors: (a) tensile failure of the steel anchor, (b) anchor-grout interface failure, (c) grout-rock interface failure, and (d) rock mass uplift. Field tests were performed in a limestone quarry. These tests were designed to test failure modes B and C through pullout. In the tests of failure mode B, the shear stress on the anchor-grout interface is the largest at the top of the grout column and attenuates towards the distal end for small loads. The shear stress becomes uniformly distributed when the applied load is approximately 50% of the ultimate pullout load. The anchors designed to test failure mode C were installed with an endplate and had a higher toughness than the straight bar anchors. The shear stress on the grout-rock interface is the largest at the endplate and attenuates upward before slip starts along the interface. When the ultimate pullout load is reached, and the grout column starts to slip, the shear stress is approximately constant. The bond shear strength on the anchor-grout interface was approximately 20% of the uniaxial compressive strength of the grout, and the bond strength of the grout-rock interface was around 5% for that of the grout. The grout-rock interface is likely determined by whichever is weaker, the grout or the rock.

In order to study the influence of split grouting times on the anchorage performance of prestressed anchor cable, a field test of multisplit grouting was carried out using fiber Bragg grating monitoring technology. The ultimate bearing capacity, displacement, axial force, and shear stress distribution of the anchor cable under different split grouting times were studied. The test results show that (1) compared with conventional grouting methods, multiple split grouting can increase the bearing capacity of the anchor cable by two to three times, and the improvement effect is most obvious in secondary grouting; (2) the number of split grouts has no effect on the axial force of the anchorage section and does not change the shear stress distribution of the anchorage section. The axial and shear stresses of the anchor cable are mainly concentrated at the first 8 m of the anchorage section. With the increasing tension load, debonding and sliding will occur at the front of the anchorage section, and the peak shear stress will move to the depth of the anchorage section. (3) When the anchor cable fails, the total displacement increases with the increase in splitting and grouting times. The conventional grouting anchor cable begins to produce plastic displacement early, while the plastic displacement of the split grouting anchor cable occurs when the external load is close to the failure load. (4) The multiple high-pressure split grouting technology is applicable to the reinforcement of foundation pits or slope engineering and is a valuable support and reinforcement technology. [ABSTRACT FROM AUTHOR]

This study attempted to improve the understanding of the effect of mechanical mismatch on the shear behavior of an interface or discontinuity between different rocks under direct shear. First, general and simplified analytical solutions for the shear stress (τ) distribution on a rock interface or discontinuity were determined. Subsequently, the τ distributions on the rock interface that were acquired from the analytical solutions were demonstrated via numerical simulations. Finally, the effect of mechanical mismatch between the rocks on τ distribution, shear strength, and potential location of crack initiation at the interface was investigated. The results indicated that it was difficult to widely use and promote the developed general solution. This is due to the lengthy expression for the solution and the complexity that was involved in the determination of the integration constants. The simplified solution omits the coupling effect between the interfacial τ and normal stresses (σ). In addition, it could accurately describe τ on a rock interface. The internal moment that was produced by shear forces (P) could significantly affect the τ distribution on a rock interface. Nonuniformly distributed τ is observed on the interface between different rocks and thicknesses. Furthermore, the nonuniformity increased with the increase in the mechanical or thickness mismatch. The τ and its concentration result from the loading of P. The noncoaxial P could produce compression and bending effects. The τ primarily results from the compression effect, and the bending effect affects the τ concentration. Cracks would not initiate simultaneously from both ends of the interface due to the dissimilar τ concentrations. For the sinistral sense of shear, cracks would first initiate from the right interface end if Young's modulus of the upper rock (E1) is smaller than that of the lower one (E2). The results could guide a profound understanding of the shearing behavior of the rock interfaces or discontinuities between different rocks. This study presented general and simplified analytical solutions to calculate the τ distribution on the interface or discontinuity between different rocks that were subjected to direct shear. The accuracy and reliability of the analytical solutions were validated against a series of two-dimensional (2D) finite-element models (FEM) of direct shear. The τ was distributed nonuniformly and concentrated asymmetrically on the interface between different rocks. The τ concentrations were different at both ends of the interface. The difference increased with the increase in the mismatch in Young's modulus (E) between the rocks on either side of the interface. The mechanical mismatch between the rocks could influence the τ distribution, shear strength, and potential crack initiation location at the interface. The results could be important to better understand the shear behavior, strength characteristics, and fracture morphology of the interfaces between different rocks. Furthermore, these could further guide disaster prevention and stability evaluation of rock engineering. [ABSTRACT FROM AUTHOR]

Traditional methods focus on the ultimate bending moment of glulam beams and the fracture failure of materials with defects, which usually depends on empirical parameters. There is no systematic theoretical method to predict the stiffness and shear distribution of glulam beams in elastic-plastic stage, and consequently, the failure of such glulam beams cannot be predicted effectively. To address these issues, an analytical method considering material nonlinearity was proposed for glulam beams, and the calculating equations of deflection and shear stress distribution for different failure modes were established. The proposed method was verified by experiments and numerical models under the corresponding conditions. Results showed that the theoretical calculations were in good agreement with experimental and numerical results, indicating that the equations proposed in this paper were reliable and accurate for such glulam beams with wood material in the elastic-plastic stage ignoring the influence of mechanic properties in radial and tangential directions of wood. Furthermore, the experimental results reported by the previous studies indicated that the method was applicable and could be used as a theoretical reference for predicting the failure of glulam beams. [ABSTRACT FROM AUTHOR]

In this study, a three-dimensional computational fluid dynamics model is established in Ansys Fluent to describe the biodegradation of toluene in an internal loop airlift reactor (IALR). The Euler-Euler approach is used with the standard k-ε method to predict the hydrodynamics of the reactor, and the population balance model is used to describe the bubble size distribution in the reactor. The recently developed concentration variance c 2 ¯ and its dissipation rate ε c formulations are adopted to close the turbulent mass transfer differential equations, so that the turbulent mass diffusivity can be determined without using empirical methods. There is a good agreement between the simulated dissolved oxygen concentrations obtained by the proposed model and the experimental data reported in the literature. As the predicted turbulent mass diffusivity is found to be unevenly distributed and the calculated turbulent Schmidt number Sc t is not a constant but varies, it may not be appropriate to use a constant Sc t or an experimentally determined dispersion coefficient. In addition, the maximal shear stress is found in the top region of the IALR and the liquid flow are very uniform in the riser and downcomer. [ABSTRACT FROM AUTHOR]

• Numerical modelling was conducted to investigate the structural behaviour of CFST K-joints. • Effects of both geometric and material parameters were examined. • A shear stress distribution model for CFST K-joints was proposed. • Analysis-orientated and design-orientated equations for both the plastic and ultimate strengths of CFST K-joints were proposed. This paper presents a comprehensive investigation, numerically and theoretically, into the structural behaviour and design aspects of concrete-filled steel tubular (CFST) gapped K-joints under brace axial loading. Finite element (FE) models were developed and validated against test results from existing experimental programmes. Based on the validated FE models, influences of geometric parameters and steel material properties on the load-deformation curve, plastic strength, ultimate strength and punching shear stress distribution of CFST K-joints were systematically assessed. In general, the chord diameter-to-thickness ratio 2 γ , brace-to-chord diameter ratio β and steel material strength are crucial to the structural behaviour of CFST K-joints, whilst the brace-to-chord thickness ratio τ was found to have minimal influence. A shear stress distribution model was proposed as well to predict the shear stress distribution at ultimate load. To accurately account for the radial support of inner concrete, the classical ring model was modified accordingly. Based on the proposed shear stress distribution model and modified ring model, analysis-orientated and design-orientated equations were formulated to estimate both the plastic and ultimate strengths of CFST K-joints. The calculated plastic and ultimate strengths were compared against the experimental and numerical results, and the comparison demonstrates the ability of the proposed design methods to accurately and reliably determine the plastic and ultimate strengths of CFST K joints. [ABSTRACT FROM AUTHOR]

Many structural analysis problems in civil engineering and mechanical engineering can be treated as plane stress and plane strain problems introduced in the theory of elasticity. One of the popular analytical methods to tackle plane analysis is to determine Airy stress function. In general, the Airy stress function depends on the analyzed domain and the applied loads; however, the number of problems that can be solved by employing this method is limited because of the formidable challenges of guessing trial function. In many cases, the trial Airy stress functions are selected based on the results of a simple beam model or experimental results. This paper introduces a solution of the plane stress subjected to horizontal shear forces by using a polynomial Airy stress function, in which the trail function is predicted from the results of the elementary beam theory of an equivalent model. The numerical investigation on stress distributions was presented, and it showed that although the internal shear force acting on cross-sections have not appeared, shear stress still appeared, and the shear stress diagram had both negative and positive areas.

In order to protect the bank and prevent their erosion spur dike is used. Importance of these structures in the bend is more, because of secondary flows and consequently bank erosion. In this paper the flow pattern around series of vertical spure dikes in the 90° bend is investigated by a 3D RANS solver. In order to simulate the complex behavior of free surface and turbulent flow the volume of fluid method and realizable k-ɛ closure have been used, respectively. Two lengths spure dike (equal to 15 and 25 percent of width), two spacing (3 and 5 three times the length) and two depths (3 and 5cm) in constant discharge 25 lit/s in the mild bend flume with width 0.7m and depth 0.12 m has been examined. Comparison among the results with experimental data shows good agreement among them. Also, the results illustrate spure dike deviations maximum velocity to the inner bank in entrance of bend and then deviations to the middle flume. Increasing the length of the spure dikes increases the velocity but it has no effect on the location of the maximum velocity as in all arrangement occurrence in 71 to 81 degree of bend. In the case of shear stress, the maximum value is in the range of 71 to 81˚.

Abstract The roughness in the floodplains in a compound canal and its impact on hydraulic parameters such as the shear stress and their estimation are one of the problems that have attracted the attention of engineers. In this research, the aim is to investigate the effect of artificial on the floodplain of the compound channel on hydraulic parameters. In experiments, slope of channel bed was 0.0015 and three different discharges have been used. The four types of rigid roughness were used to investigate the effect of these parameters. These roughness elements were arranged with zigzag state with two distances of 4 k and 8 k (k is the height of roughness) in the floodplain. A Preston tube with an external diameter of 3 mm that equipped with dynamic pressure sensors was used to compute the shear stress. The Patel calibration curve was used in order to convert the difference between the static and dynamic pressure measured by the Preston tube to the shear stress values. The results showed that for the zigzag arrangement with the density of 4 k, the shear stress is reduced due to the high roughness density and the greater roughened area. In a rough bed, the shear stress in floodplain was significantly higher than smooth bed, and the stress distribution is such that it has descending trend from the main channel toward the wall of the floodplain. The shear stress increase for roughness with a spacing of 8 k is 22–36% higher than the similar hydraulic condition in a smooth bed and the shear stress for condition with the presence of a cylinder with D = 3 cm and roughness spacing of 8 k was 14–18% higher than the shear stress of bed without a cylinder and the same roughness density. The shear stress for condition of the presence of a cylinder with D = 6 cm and roughness spacing of 4 k is 24–30% more than the roughened plain with distances of 4 k.

To better understand the shear stress distribution in rock-cemented discontinuities, such as bedding planes and mineral-filled natural fractures (NFs), subjected to direct shear, an analytical solution for shear stress was first derived on the basis of the compression and bending theories of materials. The shear stresses obtained using the analytical solution for different conditions were then verified by the numerical simulation method. Finally, the main factors that influence the shear stress distribution in cemented discontinuities were explored using the analytical solution and numerical simulation methods. The results showed that the internal moment generated by shear forces significantly affects the shear stress distribution in a cemented NF. The analytical solution which considers the internal moment can accurately predict the shear stress distribution in most cases. The shear and normal stresses are both concentrated near the ends of cemented NF; however, they are comparatively uniform in the central portion. The shear stress concentration decreases with the increasing width of cemented NF, whereas it increases with Young's modulus of cemented NF. The nonuniformity in shear stress decreases with the specimen height, and only when the specimen height is equal to the specimen length, the error produced by the analytical solution attains a minimum. The tractions on the loading surfaces are significantly nonuniform, and the nonuniform tractions are to balance the bending moment created by shear forces. Moreover, the shear box can dramatically influence the shear stress distribution in cemented NF. Uniform normal and shear displacements which represent the normal and shear forces loaded via a rigid shear box should be used for the boundary conditions. The findings in this study can provide a theoretical foundation for the evaluation of deformation properties and shear strength of intact rocks, rock interfaces, bedding planes, or mineral-filled NFs subjected to direct shear. [ABSTRACT FROM AUTHOR]

This paper presents the computational investigation of air flow over an aircraft at realistic speeds while demonstrating the importance of extending the existing analysis to the complete airplane and how pivotal it is in improving its in-flight performance. The study is done for F16 and F22 aircraft using ANSYS Fluent (19.2) to obtain pressure distribution, shear stress distribution and temperature variation on the complete surface of the aircraft. Since the front section of the aircraft is prone to direct initial impact of surrounding environment, this portion is also examined. Here, as the speed is doubled from Mach 1 to Mach 2, a rise in the value of all the three variables is noticed for the F16 aircraft, whereas the pressure distribution for F22 aircraft shows strange behaviour for the highest speed (Mach 2). On comparing the results over the whole surface, it is seen that F16 experiences smaller pressure (29% lower for Mach 1 and 30% for Mach 2), temperature (9.5% lower for Mach 1 and 30% for Mach 2) and shear stress relative to F22 and the stress shows a huge change (90% lower for Mach 1 and 83% for Mach 2). Results of the present study imply that the design of the aircraft highly influences its performance as the parameters discussed touch their limits. [ABSTRACT FROM AUTHOR]

A multitude of studies have derived one-dimensional velocity distributions, assuming open channels to be rectangular, and have extended their applications to rivers, canals, and other open channels. A cumulative distribution function (CDF) of velocity distribution is proposed based on a channel's cross-sectional geometry. This paper derives a one-dimensional velocity distribution for wide rigid trapezoidal channels using the maximization of Shannon entropy and proposed CDF. Two new parameters, geometric parameter (a), and linear weightage factor (k), are introduced and the dependency of CDF on these two parameters is discussed. These two parameters take into account the cross-sectional geometry of the section and the location of flow velocity measured along the depth, respectively, and, hence, their contributions to velocity distribution, which were not considered when formulating Chiu velocity distribution. The proposed velocity distribution has been found to work significantly well, especially in the middle zone of channel depth, when compared to Chiu's velocity distribution. This has been verified using experimental as well as river field data (assuming the river's cross-section channel to be trapezoidal). The paper also explains the limitation of Chiu's velocity distribution when applied to obtain the average flow velocity in trapezoidal channels. Further, the shear stress distribution (in vertical direction along the depth of channel perpendicular to flow direction) is also derived by entropy maximization based on channel geometry, and the relation of shear stress at the channel bed with bed width and cross-sectional area is established. Finally, the CDF formulation is also proposed for velocity distribution in exponential channels based on channel geometry. [ABSTRACT FROM AUTHOR]

Shear stress distribution prediction in open channels is of utmost importance in hydraulic structural engineering as it directly affects the design of stable channels. In this study, at first, a series of experimental tests were conducted to assess the shear stress distribution in prismatic compound channels. The shear stress values around the whole wetted perimeter were measured in the compound channel with different floodplain widths also in different flow depths in subcritical and supercritical conditions. A set of, data mining and machine learning algorithms including Random Forest (RF), M5P, Random Committee, KStar and Additive Regression implemented on attained data to predict the shear stress distribution in the compound channel. Results indicated among these five models; RF method indicated the most precise results with the highest R2 value of 0.9. Finally, the most powerful data mining method which studied in this research compared with two well-known analytical models of Shiono and Knight method (SKM) and Shannon method to acquire the proposed model functioning in predicting the shear stress distribution. The results showed that the RF model has the best prediction performance compared to SKM and Shannon models. [ABSTRACT FROM AUTHOR]

Epoxy-based isotropic conductive adhesives (ICA) have become the dominant materials in the microelectronic packaging field due to their advantages of low technological temperature, ultrafine line printing, and easy interconnection. During the service of electronic products, the ICA joints are subjected to shear loads induced by mechanical mismatch between packaging chip and substrate. In this work, the joint specimens with different contents of silver flakes (50 wt% and 70 wt%) prepared using pure copper plate adherend in the form of single-lap were used for the tensile–shear tests under different loading rates. The relationship between shear stress and location of the adhesive layer was theoretically derived. The interface fracture energy, shear strength, and fracture displacement of ICA, as well as concentration of shear stress in the adhesive layer, increase with the increase in loading rate. The shear stress concentration is relatively greater for the ICA with higher content of silver flakes. [ABSTRACT FROM AUTHOR]

• An improved model to correlate cone index with Bekker-Wong (B-W) terrain parameters. • Based on the improved model, derivative-free optimization algorithms were developed. • B-W terrain parameters derived from measured cone index using optimization algorithm. • Correlations between the derived and measured B-W terrain parameters are encouraging. To provide terrain data for the development of physics-based vehicle mobility models, such as the Next Generation NATO Reference Mobility Model, there is a desire to make use of the vast amount of cone index (CI) data available. The challenge is whether the terrain parameters for physics-based vehicle mobility models can be predicted from CI data. An improved model for cone-terrain interaction has been developed that takes into account both normal pressure and shear stress distributions on the cone-terrain interface. A methodology based on Derivative-Free Optimization Algorithms (DFOA) has been developed in combination with the improved model to make use of continuously measured CI vs. sinkage data for predicting the three Bekker pressure-sinkage parameters, k c , k ϕ and n, and two cone-terrain shear strength parameters, c c and ϕ c. The methodology has been demonstrated on two types of soil, LETE sand and Keweenaw Research Center (KRC) soils, where continuous CI vs. sinkage measurements and continuous plate pressure vs. sinkage measurements are available. The correlations between the predicted pressure-sinkage relationships based on the parameters derived from continuous CI vs. sinkage measurements using the DFOA-based methodology and that measured were generally encouraging. [ABSTRACT FROM AUTHOR]

The roughness in the floodplains in a compound canal and its impact on hydraulic parameters such as the shear stress and their estimation are one of the problems that have attracted the attention of engineers. In this research, the aim is to investigate the effect of artificial on the floodplain of the compound channel on hydraulic parameters. In experiments, slope of channel bed was 0.0015 and three different discharges have been used. The four types of rigid roughness were used to investigate the effect of these parameters. These roughness elements were arranged with zigzag state with two distances of 4 k and 8 k (k is the height of roughness) in the floodplain. A Preston tube with an external diameter of 3 mm that equipped with dynamic pressure sensors was used to compute the shear stress. The Patel calibration curve was used in order to convert the difference between the static and dynamic pressure measured by the Preston tube to the shear stress values. The results showed that for the zigzag arrangement with the density of 4 k, the shear stress is reduced due to the high roughness density and the greater roughened area. In a rough bed, the shear stress in floodplain was significantly higher than smooth bed, and the stress distribution is such that it has descending trend from the main channel toward the wall of the floodplain. The shear stress increase for roughness with a spacing of 8 k is 22–36% higher than the similar hydraulic condition in a smooth bed and the shear stress for condition with the presence of a cylinder with D = 3 cm and roughness spacing of 8 k was 14–18% higher than the shear stress of bed without a cylinder and the same roughness density. The shear stress for condition of the presence of a cylinder with D = 6 cm and roughness spacing of 4 k is 24–30% more than the roughened plain with distances of 4 k. [ABSTRACT FROM AUTHOR]

This study investigated the structural response of timber-plain concrete panels bonded with epoxy and PUR adhesives under a four-point bending load, both experimentally and numerically. Tests evaluating epoxy- and PUR-bonded glulam-plain concrete panels measured ultimate load (F ult), effective bending stiffness (EI eff), and mid-span deflection (∆ ult). Shear stress within the adhesives was monitored using fiber optic sensors. Numerical simulations estimated F ult and EI eff with errors of 5% and 14%, respectively. These discrepancies may stem from assuming defect-free wood (e.g., no knots), idealized boundary conditions, uniform adhesive thickness assumptions, and unmeasured mechanical and damage properties of wood and concrete (Detailed error source analysis is available in Section 4). Qualitative validation involved comparing sensor-recorded shear stress with simulation results. A parametric study evaluated the effects of adhesive thickness (0.5, 1, and 3 mm), concrete-wood depth ratio (50/85, 85/85, and 150/85 mm/mm), wood type (spruce (Picea), beech (Fagus), and Azobe (Lophira)), concrete strength class (C12/15 and C30/37), and span length (2, 4, and 8 m) on the bending behavior of the panel, and the shear and peel stress distribution within the adhesive bond line. Shear stress prevailed over peel stress in the adhesives, with peel stress approaching shear stress as span length increased (max. τ a / max. σ a ∼ 3.5–7). The ultimate load typically resulted in concrete compression damage and wood fiber damage, influenced by the concrete strength class and wood type. Higher depth ratios led to tension damage in concrete, while adhesive thickness had a minimal impact on stress distribution and failure modes. • Bending behavior of adhesively-bonded timber-concrete composite investigated experimentally and numerically. • Bond behavior of the TCC panels were analyzed with fibre optic sensors. • Parametic studies were considered including adhesive thickness, concrete-wood depth ratio, wood type and concrete strength. [ABSTRACT FROM AUTHOR]

Korean river design standards set general design standards for rivers and river-related projects in Korea, which systematize the technologies and methods involved in river-related projects. This includes measurement methods for parts necessary for river design, but does not include information on shear stress. Shear stress is one of the factors necessary for river design and operation. Shear stress is one of the most important hydraulic factors used in the fields of water, especially for artificial channel design. Shear stress is calculated from the frictional force caused by viscosity and fluctuating fluid velocity. Current methods are based on past calculations, but factors such as boundary shear stress or energy gradient are difficult to actually measure or estimate. The point velocity throughout the entire cross-section is needed to calculate the velocity gradient. In other words, the current Korean river design standards use tractive force and critical tractive force instead of shear stress because it is more difficult to calculate the shear stress in the current method. However, it is difficult to calculate the exact value due to the limitations of the formula to obtain the river factor called the tractive force. In addition, tractive force has limitations that use an empirically identified base value for use in practice. This paper focuses on the modeling of shear-stress distribution in open channel turbulent flow using entropy theory. In addition, this study suggests a shear stress distribution formula, which can easily be used in practice after calculating the river-specific factor T. The tractive force and critical tractive force in the Korean river design standards should be modified by the shear stress obtained by the proposed shear stress distribution method. The present study therefore focuses on the modeling of shear stress distribution in an open channel turbulent flow using entropy theory. The shear stress distribution model is tested using a wide range of forty-two experimental runs collected from the literature. Then, an error analysis is performed to further evaluate the accuracy of the proposed model. The results reveal a correlation coefficient of approximately 0.95–0.99, indicating that the proposed method can estimate shear-stress distribution accurately. Based on this, the results of the distribution of shear stress after calculating the river-specific factors show a correlation coefficient of about 0.86 to 0.98, which suggests that the equation can be applied in practice.

Entropy models have been recently adopted in many studies to evaluate the shear stress distribution in open-channel flows. Although the uncertainty of Shannon and Tsallis entropy models were analyzed separately in previous studies, the uncertainty of other entropy models and comparisons of their reliability remain an open question. In this study, a new method is presented to evaluate the uncertainty of four entropy models, Shannon, Shannon-Power Law (PL), Tsallis, and Renyi, in shear stress prediction of the circular channels. In the previous method, the model with the largest value of the percentage of observed data within the confidence bound (Nin) and the smallest value of Forecasting Range of Error Estimation (FREE) is the most reliable. Based on the new method, using the effect of Optimized Forecasting Range of Error Estimation (FREEopt) and Optimized Confidence Bound (OCB), a new statistic index called FREEopt-based OCB (FOCB) is introduced. The lower the value of FOCB, the more certain the model. Shannon and Shannon PL entropies had close values of the FOCB equal to 8.781 and 9.808, respectively, and had the highest certainty, followed by ρgRs and Tsallis models with close values of 14.491 and 14.895, respectively. However, Renyi entropy, with the value of FOCB equal to 57.726, had less certainty.

This paper proposes a theoretical solution for predicting the pullout properties of a single fiber-reinforced polymer (FRP) rod embedded in a bond type anchorage based on a trilinear bond–slip model. The radial variation of the shear stress and reaction of the steel sleeve are considered in the solution. Pullout procedure with elastic, elastic-softening, elastic-softening-debonding, pure softening, softening-debonding, and debonding stages, as well as the corresponding critical stages, are analyzed. In this theoretical solution, the maximum pullout load, shear stress along the rod–grout interface, axial tensile stress of the FRP rod, and load–slip relationship are derived with explicit formulations. Effective bond length of bond type anchorage is also discussed. The solution is validated against experimental results available in literature. The theoretical solution reveals that the anchorage may attain its maximum pullout load in the elastic-softening, pure softening, or elastic-softening-debonding stage. Moreover, the effects of embedded length, ultimate shear stress, and residual shear stress on maximum pullout load closely related with the stage in which the anchorage attains its maximum pullout load. However, the effect of radius of FRP rod on the maximum pullout load increases with the embedded length, no matter in which stage the anchorage attains its maximum pullout load. [ABSTRACT FROM AUTHOR]

The shear stress distribution at alluvial stream beds and banks is one of the essential parameters in channel stability analysis. In the current paper, a novel uncertainty analysis method based on the framework of a Bayesian Forecasting System (BFS) is presented to evaluate the Shannon entropy model for prediction of the shear stress distribution in both circular rigid-bed and alluvial-bed channels. The Johnson and Box-Cox transformation functions were applied to select the optimum sample size (SS) and corresponding transformation factor for determining a 95% confidence bound (CB) for the Shannon entropy model. The Shapiro-Wilk (SW) test is applied according to the SS used to evaluate the power of transformation functions in the data normalization. The results show that the error distribution between predicted and experimental shear stress values generated using the Box-Cox transformation is closer to a Gaussian distribution than the generated using the Johnson transformation. The indexes of the percentage of the experimental values within the CB (N in) and Forecast Range Error Estimate (FREE) are applied for the uncertainty analyses. The lower values of FREE equal to 1.724 in the circular rigid-bed channel represent the low uncertainty of Shannon entropy in the prediction of shear stress values compared to the uncertainty for the circular alluvial-bed channel with a FREE value equal to 7.647. • A new approach is applied to estimate the uncertainty in the shear stress estimation. • The most influential parameters on the shear stress are studied. • Wide-ranging experiments are used to evaluate the models. • The proposed method can be used as an alternative in practical applications. [ABSTRACT FROM AUTHOR]