Calculation Of Shear Strength Research Articles

First-principles study of tensile and shear strength of Fe-Al and [formula omitted]-AlFeSi intermetallic compound interfaces

First-principles virtual tensile and shear strength calculations have been performed on the Fe2Al5// Fe4Al13 and α-AlFeSi// Fe4Al13 interfaces. The Fast Inertial Relaxation Engine (FIRE) algorithm is used for optimizing these complex Intermetallic Compound (IMC) interface structures. To characterize the virtual tensile strength, an extended generalized Universal Binding Energy Relation (UBER) was used to fit the energy-displacement data. The virtual tensile strength was evaluated with the Rigid Grain Shift (RGS) methodology without atomic relaxations during tensile displacement and with RGS+relaxation with atomic relaxations. All calculated values for IMC//IMC interfaces in this study are compared with pure Al//Fe and Al//IMCs [1] interfaces to identify the role of IMCs at aluminum-steel joints.

Semi-empirical method for the calculation of shear stress, stiffness and maximum shear strength of bituminous interfaces under in-service conditions

The structural response of a flexible pavement as a whole depends on the adherence between the bituminous layers, which are rarely found to be fully bonded or completely detached. In order to define the degree of bonding between the layers, the shear stiffness of the interface under in-service conditions is a fundamental property.The aim of this work is to propose a semi-empirical method based on laboratory test results for estimating the relative displacement speed between the sides of the interface, the shear stiffness, the shear stress and the shear strength from results of a direct shear test.

A review of research on the shaft resistance of rock-socketed piles

Shaft resistance generally dominates at the service loads of rock-socketed piles and therefore is always a topic of large research interest. This paper reviews the research progress that has been made in the last four decades in understanding the shear mechanism of the pile–rock interface and in calculating the shaft resistance. First, particular attention is given to notable previous studies of the shear mechanism and the method for calculating the shear strength at the pile–rock interface. Next, some commonly used design methods and many empirical correlations between the ultimate shaft resistance fsu and the unconfined compressive strength σc of the intact rock are summarized, and the factors considered in these design methods (e.g., roughness, joints, discontinuities, smear, construction, and disturbance) are compared. Also, the factors that influence the shaft resistance of rock-socketed piles are summarized. Then, by evaluating briefly the existing theoretical methods, the limitations of elastic normal stiffness and the two-dimensional shear model are discussed. Finally, combined with a comparison between the elastic and elastoplastic solutions of the normal stress increment with the radial displacement increases and an analysis of paths of radial and tangential stress and possible crack formation of the bore wall during expansion, three modification methods using the elastoplastic solution to calculating the increment of normal stress are proposed to calculate shear strength at the pile–rock interface and some suggestions are also made for future research to optimize the calculation of shaft resistance.

Shear transfer behavior between substrate recycled aggregate concrete and new natural aggregate concrete

AbstractThis paper investigated the shear transfer behavior between substrate recycled aggregate concrete and new natural aggregate concrete. A total of 72 push‐off tests with substrate‐to‐new concrete specimens were performed considering the effects of concrete strength grade, replacement ratios of recycled coarse aggregate, and lateral constraints ratios. Existing design codes and empirical models for calculating shear strength were reviewed and verified. Results show that concrete cracks occurred and developed along the shear transfer plane. Increasing the concrete grade and lateral constraints can both improve the crack stress and shear strength, while the incorporation of recycled coarse aggregate has a slight adverse effect on them. The model in fib Model Code 2010 based on shear‐friction theory gave the most accurate but still conservative values compared with experimental results and can be used to predict the shear transfer behavior between substrate recycled aggregate concrete and new natural aggregate concrete.

Influence of the Micro-deformation Characteristics of Binary Media on the Shear Behavior of Structural Plane

Binary media structural planes exist widely in natural rock mass and rock mass engineering, which are weak points of engineering and important factors that affect engineering stability. Thus, the mechanical behavior analysis of binary media has important engineering significance. The influence of the parallel bonding modulus ratio of binary media on the shear mechanical behavior of structural planes was investigated from the perspective of microscopic parameters on the basis of the numerical calculation method of discrete elements. A binary media model, including a flat structural plane, was established using the particle flow code. By changing the microscopic parameters, direct shear tests under different constant normal loads were conducted on the models with different parallel bond modulus ratios. The changes in shear stress, number of cracks, and normal displacement with shear displacement were recorded to investigate the influence of the parallel bond modulus ratio on the failure mode and failure development rule of the binary media. Two main results were obtained. First, the difference in modulus between two sides of the structural plane of the binary media greatly influences the peak strength, failure area, crack development, and location of the failure plane in the shear behavior of the binary media. Second, an increase in normal load will reduce the influence of the parallel bond modulus ratio on peak shear strength. Empirical formulas for strength parameters and modulus difference were proposed in this study on the basis of the simulation results. The shear strength calculation formula, including the microscopic parameters, was proposed and verified.

Nanoscale Run-In of Silicon Oxide-Doped Hydrogenated Amorphous Carbon: Dependence of Interfacial Shear Strength on Sliding Length and Humidity

We conducted atomic force microscopy (AFM) experiments by sliding hard tetrahedral amorphous carbon (ta-C)-coated and diamond AFM probes against silicon oxide-doped hydrogenated amorphous carbon (a-C:H:Si:O) films. We reproducibly observe a substantial reduction in friction with repeated sliding. This behavior qualitatively resembles the run-in effects generally seen in macroscale frictional sliding on diamond-like carbons (DLCs), including this a-C:H:Si:O film in particular. As the applied normal load is increased with repetitive sliding, the friction reduces in tandem. The lateral stiffness of the nanoscale contact is measured as a function of applied normal load, thus the real contact area and the interfacial shear strength are inferred throughout the sliding experiments. These measurements show that the friction reduction is caused by a reduction in the interfacial shear strength of the contact. We propose that this arises from sliding-induced structural modification of the a-C:H:Si:O film. The calculated shear strengths are more than an order of magnitude higher than estimates from macroscale friction experiments. Additionally, humidity-controlled experiments show no significant humidity dependence of the friction despite a very strong dependence at macroscale. Reasons for these contradictions with macroscale experiments are discussed.

Shear strength calculating model of FRP bar reinforced concrete beams without stirrups

The models in ACI 440.1R-15, AASHTO LRFD-17, CSA S806-12, CSA S6-14, ISIS M03-07, JSCE-97, CNR DT203-06 and BISE-99 did not properly reflect the effects of the reinforcement ratio and modulus of elasticity of the longitudinal fiber reinforced polymer (FRP) bars, shear span-to-depth ratio or size effect on the shear strength of FRP bar reinforced concrete beams without stirrups. A database of 389 FRP bar reinforced concrete beams without stirrups failed in shear was collected lately, and a new model was proposed to calculate the shear strength based on the experimental data of 188 beams in the database, whose variables are reinforcement ratio and modulus of elasticity of the longitudinal FRP bars, shear span-to-depth ratio, or the effective depth of the beams. The efficiency of the proposed model has been evaluated by comparing the calculated shear strength with the experimental data of another 201 beams in the database. It indicated the calculated shear strength values using the proposed model are more consistent with the experimental results compared to those using the models in existing design codes.

Macro–Microscopic Study on the Shear Characteristics of Filled Joints with Different Roughnesses

Rock-like materials and Barton’s standard joint curve were used to make filled joint specimens, and the shear characteristics of the filled joints were studied. Discrete element software was used to analyze the failure mechanism during filled joint shearing. Based on the experimental findings, a new theoretical model of joint shear strength was proposed. It was found that joint roughness has a great effect on filled joint shear failure, which is manifested via three different morphologies. The effects of the filler on the shear stress–strain curve are mainly a higher slope in the elastic phase and a lower slope in the plastic phase. The shear failure of the filled joint starts from local small damage of the filling and then progresses to failure of the bonding surface or the filling itself. Based on the proportion of the joint failure surface area to the joint surface area, a new formula for calculating shear strength is proposed.

Shear Behavior of Bolt-Reinforced Joint Rock Under Varying Stress Environment

Bolt empowers significant efficacy in reinforcing jointed rock mass, which is mainly embodied in the enhancement of shear performance and the restraint to the dislocation between rock blocks. However, the prevailing assumption that the influencing area of bolt covers the whole joint surface contradicts to the experimental evidence of direct shear tests. In this case, by adopting saw-tooth filling joint samples made of rock-like materials, the direct shear tests were conducted under different normal stresses, and the influencing mechanism of bolt on the shear performance was investigated. Then, the similarities and differences in shear strength, deformation, and failure patterns of unbolted and bolted joints with different filling ratios were analyzed. Besides, based on the assumption of elliptical influencing area of bolt, a new shear strength calculation model of bolted joints was established, and theoretical calculation results show an excellent agreement with test results, verifying the rationality and validity of the proposed model.

Optimization of Spot Welding for Peel load on SPCC Steel Sheets

Spot welding is a process of connecting two metal components through one or more connection points by using heat from electrical resistance which is carried by two electrodes to the metal to be connected with a certain welding time. The purpose of this study is to determine the effect of voltage and time of pressure used for spot welding on the shear strength and peel strength on the SPCC plate. The variables used in this study are independent variables of electric current variation of 2.30 V, 2.70 V, 3.20 V and time variation of 3 seconds, 4 seconds, and 5 seconds with 1mm plate thickness. The dependent variable in this study is the calculation of shear strength and peel strength in universal testing machine, and the controlled variable in this study is 1mm plate thickness characteristic of SPCC palate work piece. The research method was carried out using the ANOVA Factorial with the null hypothesis that there was no influence of the spot welding time and voltage on spot welding on the shear strength and strength of the SPCC material's peel. The results of the study are for the shear test seen from the calculation using MINITAB, the time variation of the pressure is no effect, while for the voltage and the combination of time suppression and voltage there is influence. For strength testing, the null hypothesis is rejected for all variations, which means that there is an influence on the strength of the peel test.

Shear Strength Prediction Model of FRP Bar-Reinforced Concrete Beams without Stirrups

The shear strength prediction model for fiber-reinforced polymer (FRP) bar-reinforced concrete beams without stirrups in ACI440.1R-2015 does not consider the “size effect” and the effect of shear span-to-depth ratio and predicts the zero-shear strength for concrete members without longitudinal reinforcement. A modified shear strength prediction model for FRP bar-reinforced concrete beams without stirrups was presented in this paper. The proposed model takes into account the effect of concrete strength, size of the beam, shear span-to-depth ratio, reinforcement ratio, and modulus of elasticity of the longitudinal reinforcement and the “size effect.” The superiority of the proposed model has been evaluated by comparing the calculated shear strength of FRP bar-reinforced concrete beams without stirrups by the proposed model with the experimental results and calculated values by the models in design codes, respectively. It confirmed that the shear strength of FRP bar-reinforced concrete beams without stirrups by the proposed model was in better agreement with the experimental results.

Shear Performance of Reinforced Concrete Beams Affected by Satisfactory Composite-Recycled Aggregates.

This paper is the outcome of experiments on the shear performance of reinforced concrete beams with approved composite-recycled aggregates. The strength grade of composite-recycled aggregate concrete (CRAC) was between 30 MPa and 60 MPa. The shear span-to-depth ratio varied from 1 to 3. The adaptability of HRB400 rebar, with critical yield strength of 400 MPa, used as stirrups was also verified. As the composite technology overcame the shortcomings of recycled coarse aggregate, CRAC had similar mechanical properties with those of conventional concrete. Details on the shear behaviors of test beams under a four-point loading test are presented. The results indicated that the changes of CRAC strain, stirrup strain, and shear-crack width depended on the failure patterns, which are controlled by the shear-span to depth ratio. The stirrups yield at the failure of reinforced CRAC beams. The shear cracking resistance and the shear capacity of reinforced CRAC beams can be predicted by the statistical equations. Based on the design codes GB50010, ACI318-19, Model Code 2010 and DIN-1045-1-2008 for conventional reinforced concrete beams, the shear strengths provided by CRAC and stirrups are statistical analyzed. The rationality of the design equations is examined by the utilization level of shear strength provided by CRAC. The maximum shear-crack widths are extracted from the test data of reinforced CRAC beams at normal service state. Comparatively, by specifying the lower limit of shear strength provided by the CRAC with various shear-span to depth ratios, China code GB50010 gives a rational method for utilizing CRAC. Under the premise that the design of shear capacity would give considerations to meet the normal serviceability, the factored strength of HRB400 rebar should be 360 MPa for the calculation of shear strength provided by stirrups. The design methods in codes of GB50010, ACI318-19 and Model Code 2010 are conservative for the shear capacity of reinforced CRAC beams.

FRICTION ANGLE OF POLISHED SURFACES OF SANDSTONE AND CONGLOMERATE FROM THE SEMANGGOL FORMATION, BERIS DAM, KEDAH DARUL AMAN

The Beris Dam is founded on a sequence of thick bedded to massive conglomerate and gritstone with some sandstone and mudstone, mapped as the Semanggol Formation of Triassic age. Portable shear box tests on polished surfaces of a sandstone, and a conglomerate, core yield friction angles of 18.0o and 20.8o, respectively. These friction angles are comparable with residual friction angles of between 17.5o and 19.0o determined in field and laboratory tests on sheared mudstone surfaces of the Semanggol Formation at the Muda Dam. Apparent cohesion values determined in the portable shear box tests result from the restricted normal displacement test conditions and should not be considered in shear strength calculations.

Effect of polypropylene and steel fibers on web-shear resistance of deep concrete hollow-core slabs

Twelve shear tests were conducted on fiber-reinforced precast/prestressed concrete hollow-core (PCHC) slabs to quantify the effectiveness of polypropylene (pp) and steel fibers (hooked and high-strength/straight types) on shear resistance. Different volume fractions of pp fibers (0.11 and 0.22%) and steel fibers (0.51 and 0.89%) were investigated. The experimental results showed that there were moderate increases in shear strength with the use of pp fibers while substantial increases in shear resistance were observed with the use of steel fibers. In addition, shear strength increased with steel-fiber content. Moreover, with the same steel fiber content of 0.89%, specimens with high-strength/straight fibers exhibited superior performance in shear resistance compared to specimens using hooked steel fibers. In addition, web-shear failure occurred in the majority of specimens. However, as steel fiber content was increased up to 0.89%, in some instances, failure mode shifted from web-shear to flexural-shear failure. In addition, the 2010 fib model code formula for shear strength of steel-fiber-reinforced-concrete (SFRC) members was used to estimate shear capacity of the tested slabs using steel fibers. The calculations showed that the fib model code was overly conservative for shear-strength predictions of SFRC hollow-core slabs reported in this investigation. A semi-empirical formula to calculate shear strength of hollow-core slabs with steel fibers was proposed. It was verified using a database including the 6 shear-test results from this study and another 39 shear-tests on SFRC hollow-core slabs compiled from literature. The formula had a mean value of 1.12 for the ratio of experimental shear strength to calculated shear strength with a coefficient of variation of 0.21.

A Study of Size Effect in Shear Resistance of Reinforced Concrete Beams Based on Machine Learning

Size effect is common in structural engineering where a large component fails at lower stress level than a tiny one made of the same material. As a result, the calculation of the loading capacity of a structural component need to be revised when size effect is considered, especially for the reinforced concrete (RC) beam under shear loading. However, due to inadequate theoretical analysis of the size effect in shear failure, the calculation of shear strength in codes all over the world is far from accurate. In this research, the machine learning method, which can efficiently analyse and process data, is applied to study the size effect in shear strength of beams via exploring the experimental data collected worldwide on shear failure of RC beams. The back propagation (BP) neural network model of shear strength of RC beams is built and trained by the data exist, and then give a prediction of shear strength. The values predicted are compared with the values calculated from codes and Bažant size effect formulas and the experimental data, which indicates the feasibility and superiority of machine learning method in dealing with size effect in shear failure.

To the Shear Strength of Concrete

Interpretations of the “pure shear” phenomenon were presented. The incompatibility of “pure shear” for concrete as a special case of stress state and destruction form was indicated. Due to the variety of cases of concrete and reinforced concrete elements destruction by shearing, it is impossible to establish a concrete shear strength single characteristic, and all its empirical values are particular for individual cases. As an alternative to calculating shear strength, a sufficiently strength calculating general theory of concrete and reinforced concrete elements under complex inhomogeneous stress-strain states, developed on the basis of the ideal concrete plasticity premise on the destruction surface and variational method, was proposed. The developed methodology has been comprehensively tested. An example of using the theoretical results of concrete elements strength solving the problem of the with a two-way strip load application by the variational method in the plasticity theory to determine the concrete strength characteristics was given.

Strength Design and Analysis of the Grouting while Drilling Equipment’s Sleeve

According to structure and working-condition of the grouting while drilling equipment, sleeve’s compressive strength and torsion strength are calculated with elastic theory, which are simulated and verified with FEA Software. The results indicate that its maximum internal stress exceeds the elastic yield limit at 30 MPa external pressures, and that the sleeve is working with risk in 3000 m underground soft coal.With Prandtl stress function method, the calculated shear strength in the sleeve’s small end is far more than the material’s shear strength due to 1500 N·m torque, the small end is stress concentration area and it can’t meet the requirement. Finally, sleeve’s theoretical work external pressure is calculated as 29.8 MPa and its axial deformation is about 0.2 mm, with radial deformation level at 0.03 mm, which can be referenced to tolerance design in the assembly.

Relationship between the Shear Strength and the Depth of Cone Penetration in Fall Cone Tests

The determination of liquid limit is of great significance in the engineering classification of soil and the selection of the control standard of highway subgrade packing and compactness. Based on the research achievements of many scholars on the relationship between the shear strength and the depth of cone penetration in fall cone tests in the liquid limit tests, the process of penetration was analyzed according to the Law of Conservation of Energy, and the expression of K was derived. Then, the expression was verified by the experimental data of different scholars and the existing data of various countries and institutions. And, the results were also compared with those obtained by the previous scholars using limit equilibrium theory. The results indicate that the new expression is in good agreement with the experimental results. K can be predicted well. And so, the shear strength can be calculated based on the depth of cone penetration, and then, the experimental value of the shear strength can be compared with the calculated value through laboratory tests. The influence of cone weight and cone angle on the shear strength calculation was analyzed. In addition, the liquid limit index of different standards was discussed based on the expression of K, and suggestions on how to achieve relative combination of different codes and standards were raised, which was very helpful for international communication.

A Shear Strength Model for a Subsidence Backfill Body Based on Adhesion Friction Theory

Proper determination of the shear strength of the backfill body used to fill the subsidence is the basis for subsidence restoration and the stability analysis of materials. This study developed a shear strength calculation model for the backfill body by introducing adhesive friction theory into the shear strength analysis. A direct shear test was performed in the laboratory to verify the proposed method. Test results suggested that the shear strength calculation method based on adhesive friction theory can calculate the variation in the actual contact area between grains in the tested samples undergoing shearing and estimate the peak shear strength. The actual contact area was divided into two components, namely, adhesive contact area Arm and contact area reduction caused by shear displacement, which exhibited a maximum at Armax. The shear strength values calculated by this method were smaller than laboratory values, and their differences increased with the rock proportion in the backfill body. The differences between the theoretical and experimental values of shear strength increased with the rock grain size. The results of theoretical calculation, combined with the results of laboratory experiments, can provide support for the proper determination of shear strength of the backfill body.

Slope Stability from a Hydrological Perspective: Taking Typical Soil Slope as an Example

In the traditional research of slope stability, it is difficult to continuously obtain the moisture content of soil in long time sequences. In combination with the precipitation, temperature, and vegetation cover data in the study area, the variable infiltration capacity hydrological model is used to estimate the daily variation of soil moisture content, which is used as a calculation condition for the analysis of slope stability. The results show that, from 1970 to 2010, the spatial‐temporal distribution of soil moisture content in the Weihe River Basin showed an increasing trend. Moreover, the shear strength of soil decreased, but the range was stable at approximately 2%. The strength reduction method based on the M‐C inscribed circle criterion (DP3) shows that the slope stability factor k had an increasing trend for over 40 y. The portion of the period with a k value higher than 1.2 is more than 85% of the entire period, that with a k value between 1 and 1.2 is approximately 9%, and that with a k value less than 1 is approximately 5.5%. The R/S analysis results show that the Hurst coefficients of the τ‐t curve and the k‐t curve are 0.5568 and 0.5888, respectively, and that the slope is in a state of no variation. Based on these factors, the present and future of the slope is in a stable state. This scheme is a method of studying slope stability based on hydrology, and it provides a modern alternative for soil shear strength calculation and geological hazard assessment.