Shear Behavior Research Articles

Microstructural Analysis on Shear Behavior of New-fill and Silt Interface in Check Dam

Microstructural Analysis on Shear Behavior of New-fill and Silt Interface in Check Dam

Experimental investigation of flexural and punching behavior for plain PE-ECC slabs with different fiber volume fractions and span-depth ratios

Engineered Cementitious Composite (ECC) exhibits superior tensile ductility, shear capacity, and crack-control ability in comparison to traditional concrete and fiber reinforced concrete. These attributes render ECC a suitable candidate for addressing the brittle punching shear behavior commonly observed in reinforced concrete (RC) flat slabs. To verify the feasibility of using ECC for strengthening the punching shear capacity of concrete slabs, an investigation on the punching behavior of plain ECC slabs was conducted to ascertain their crack patterns, failure mode, strength and energy absorption capacity by means of experiments on twenty-seven 400 mm×400 mm square slabs. The plain ECC slabs were simply supported on a bespoke steel framework with eight supports, centrically loaded with a concentrated load. The fiber volume fraction (FVF) and span-depth ratio (SDR) are the two variables to be examined for their effects on the punching behavior of ECC slabs. Test results revealed that the incorporation of fibers significantly improved the load-bearing capacity, ductility and energy absorption capacity, while it altered the failure mechanism from brittle to ductile. The critical punching shear angles of all tested plain ECC slabs ranged from 40° to 50°. The ECC specimens possessing an FVF of 2 % exhibited markedly superior tensile capabilities compared to those with a 1 % FVF, as evidenced by direct tensile tests. Nevertheless, the ECC slabs with an FVF of 2 % did not demonstrate commensurate improvements in load-bearing capacity relative to their counterparts containing 1 % FVF. The span-depth ratio significantly impacted the failure mode of plain ECC slabs, yielding to punching shear failure at an SDR of 1, and to flexural failure at SDRs of 2 and 3. Moreover, an increase in the SDR value led to a reduction in both the initial cracking load and the ultimate load, concurrently increasing the associated deflection. In addition, a preliminary theoretical analysis was conducted to estimate the bearing capacity of plain ECC slabs. Flexural strength was estimated by yield line theory (YLT) and punching shear resistance was estimated by the model based on theory of plasticity in slab-column systems. The experimental and theoretical investigations could provide insights into the punching and flexural behavior of ECC slabs, laying a groundwork for the design and development of flat systems strengthened with ECC.

Earthquake Performance Analysis of a Masonry School Building's Retrofitted State by the Equivalent Frame Method

Nonlinear analyses of masonry structures are frequently used in both engineering practice and academic studies. Due to the dominant nonlinear behaviour of masonry structures, complex and extensive finite element models are required to obtain accurate analysis results. While masonry walls are usually modelled using fine-meshed shells or solid elements in such structures, high computing power in modelling, analyzing, and post-processing results is necessary for the analyses of large structures. In recent years, the equivalent frame method, as a solution to this problem has been developed and presented in the literature. In this study, the equivalent frame method is used in a masonry structure modelling, and the axial force-bending relationship is represented by force-based fiber elements. The multi-linear load-deformation relationship reflects the shear behaviour of the walls. Within the scope of the study, an existing masonry school building is modelled using the equivalent frame elements with OpenSees software. Seismic performance analyses are done considering the existing and retrofitted states of the structure, and the results are discussed in a comparative manner.

Experimental and numerical study on the shear behavior of hybrid BFRP/steel RC beams without shear reinforcement

Hybrid reinforcement of steel and fiber-reinforced polymer (FRP) bars can provide a balanced performance between strength, ductility, and durability for the concrete structures. Thus, this study evaluates the shear performance of hybrid Basalt-FRP/steel-RC beams without shear reinforcement. A total of twelve RC beams were cast and tested under four-point loading to study the influence of reinforcement type, reinforcement ratio of longitudinal bars and axial stiffness between FRP and steel ratio, [Formula: see text] on the shear performance of the concrete beams. The test results were analyzed in terms of crack patterns, load-midspan deflection, load-crack width relationships, and shear strength of the tested beams. In addition, the experimental results were compared with the theoretical results obtained from various design codes and guidelines. Moreover, a finite element (FE) model was created, and the experimental results were used for validation of the FE model. The test results revealed that the beam specimens designed with similar effective reinforcement ratio exhibits comparable shear strength nevertheless the tensile reinforcement used. Experimental test results demonstrated that using hybrid bars increased the shear capacity of the beams by 11% compared to steel bars. Furthermore, the energy absorption of the hybrid-RC beams was enhanced by 16% compared to FRP-RC beams. By elevating the [Formula: see text] ratio from 1.25 to 2.44, both the shear strength and energy absorption improved by approximately 10%. Notably, there was a significant decrease in the deflection and crack width of the hybrid-RC beams in comparison to the FRP-RC beams. The design codes ACI440.11-22 and CSA S806-12 displayed accurate enough estimates of the shear strength, while JSCE-1997 showed a conservative result.

Experimental and analytical investigation of the shear behavior of steel-bamboo composite I-beams with composite connections

In steel-bamboo composite beams, the debonding failure and slip behavior of steel-bamboo pure bonding interfaces at the flanges often lead to premature failure of beams and underutilization of material strengths. Therefore, a novel steel-bamboo composite I-beam with composite connections was presented in this study, in which the pure bonding interfaces at the beam's flanges were reinforced by self-tapping screws (STSs). 13 beams were designed and fabricated with interface type, shear span-to-depth ratio, height-to-thickness ratios of bamboo and steel at the web, and width-to-thickness ratio of steel at the flange as main parameters. Then, shear tests and theoretical analysis were performed to evaluate the beam's shear behavior. The results indicated that the debonding failure and slip behavior of the beams were effectively limited, and the shear resistance, deformation capacity, and ductility were significantly improved. The shear resistance of beams was improved by reducing the shear span-to-depth ratio, height-to-thickness ratios of the bamboo and steel at the web, and steel flange width-to-thickness ratio. Finally, the developed analytical models can be concluded to be used to accurately predict the interfacial shear stress at the beam flanges in the serviceability limit state (SLS) and ultimate shear capacity of the beams.

A random elastoplastic framework of relationships between CBR and Young’s modulus for coarse-grained soils

The material quality indicator most commonly used for the quality of road materials is the California Bearing Ratio test (CBR). In addition, the CBR test provides a value commonly used to correlate with the resilient modulus (used in the design and analysis of pavement) due to its cost-effectiveness. This test measures soil resistance to penetration by a punch and compares it with the pressure measured in a standard material at the same penetration (2.5 mm or 5 mm). However, this test lacks physical explanations regarding mechanical behavior because the CBR value only compares soil penetration resistance with the pressure measured in a standard material. Another issue arises from the scattered results obtained from both equations and tests, highlighting the need for variability analysis of the CBR test to assess the effect of the different geotechnical variables on the CBR value. For this purpose, simulations using FEM (Finite Element Method) considering random soil parameters were performed for the CBR test. These FEMs included a linear elastic model and two failure criteria (Mohr–Coulomb and Drucker-Prager with a cap) and were prepared for granular soils. The evaluation shows that the increase or decrease in the CBR value is a function of the elastic modulus, yield stress, and friction angle. Moreover, the simulations expand the knowledge of the shearing mechanisms, generated stresses, displacement fields, and load sharing when the CBR test is made. From these results, a physical explanation of test results can be done. FEM simulations showed stress zones in conditions of elastic, compression, and shear behavior. These zones can explain the importance of elastic modulus, yielding stress, and friction angle in the CBR value. From numerical results, a new equation was proposed and compared with practical equations proposed by international standards and other sources to estimate the probability of underestimated values CBR according to the correlations used.

Shear Mechanism of a Novel SFCBs-Reinforced Composite Shear Connector: Experimental, Theoretical Investigations and Numerical Model.

Traditional stud and perfobond leiste (PBL) shear connectors are commonly used as load-transferring components in steel-concrete composite structures. Composite shear connectors fully utilize the advantages of traditional stud and PBL shear connectors. In order to maximize the advantages of composite shear connectors, a novel shear connector for complex environments was proposed. The steel-FRP composite bars (SFCBs) with excellent fatigue resistance and corrosion resistance were introduced to replace the steel bars. This study discussed the failure modes, load-slip curves, and load-strain curves of the composite shear connector. In addition, a finite element analysis (FEA) model was developed to analyze the influence of various factors on its shear behavior. Results showed that compared with traditional composite shear connectors, the introduction of SFCB resulted in a promotion of 7.85% in shear stiffness, and it also led to a significant increase of 63.61% in ductility, further enhancing the mechanical performance. Meanwhile, FEA models were well fitted to the test results, and parametric analysis showed variate effects on shear bearing capacity. In the end, an equation was established to calculate the shear capacity of composite shear connectors, which could provide a reference for further research and engineering applications.

Shear mechanism of UHPC epoxied‐keyed joints in PSUBs: Experimental and numerical investigations

AbstractPrecast segmental ultra‐high‐performance concrete bridge presents broad application prospects. UHPC keyed joints play significant roles in the structural performance of such bridges, which require systematic investigation to comprehend their shear behavior and mechanism thoroughly. This study aimed to explore the shear mechanism of UHPC epoxied‐keyed joints. Experimental and numerical investigations were conducted to investigate the influence of key size, key number, key angle, and reinforcement form on the shear performance. The test results showed that the failure mode was primarily affected by the key number and reinforcement form, which can be divided into three categories: direct shear, segmental shear, and stepwise shear failure. The large‐keyed joints exhibited superior shear performance compared to the three‐keyed joints. The initial shear stiffness, ultimate bearing capacity, and normalized shear stress were 15%, 5.3%, and 5.6% higher, respectively. Furthermore, the mechanism of the two reinforcement forms was clarified. The key rebars mainly improve the ductility of the specimens, while the dowel action of the embedded rebars can enhance the shear efficiency and synergistic force ability of the joints. The numerical simulation results indicated that 2.7% was the best ratio of key rebar, and embedded rebars with larger diameters can strengthen the shear capacity and post‐peak performance of the joints.

Experimental and numerical study of shear behavior of concrete–soft rock interface: with approach of concrete penetration in rock cavities

Experimental and numerical study of shear behavior of concrete–soft rock interface: with approach of concrete penetration in rock cavities

Role of {332} twinning on adiabatic shear behavior during dynamic loading in β-type Ti–15Mo alloy

The microstructural evolution and formation mechanism of the adiabatic shear band (ASB) in {332}<113> twinning-induced plasticity (TWIP) Ti–15Mo alloy were investigated by applying stopper rings in a split Hopkinson pressure bar apparatus. Accompanied by activation of numerous {332}<113> twins, ASB consisting of elongated fine-grains initiated in the dynamically compressed sample with 0.28 true strain. Multiple twins adjacent to the ASB region were severely distorted and refined along the shear direction. Further deformation led to refinement of elongated twins into elongated subgrains, then some of them were subdivided into equiaxed fine-grains. The morphology of the fine-grains within the ASB underwent a complete transition from elongated to equiaxed as the strain increased to 0.33. The equiaxed fine-grains exhibited a random distribution of orientation, which was regarded as the result of dynamic recrystallization. The formation of equiaxed fine-grains was found to obey rotational dynamic recrystallization mechanism through the thermodynamic and kinetic calculations.

Modified calculation on shear stress of girder bridges with corrugated steel webs

The study examines the shear behaviors in girder bridges with corrugated steel webs (CSWs) considering different boundary constraints through theoretical analysis, experimental investigation, and numerical simulation. The accordion effect significantly amplifies shear deformation in CSWs at support locations. The substantial difference in shear stiffness between the CSWs and the concrete slabs constrains the shear deformation of CSWs, resulting in the generation of additional shear force within the CSWs. Therefore, the existing basic shear method is inaccurate for calculating shear stress in CSWs because it neglects this influencing factor. The study proposes an advanced formula for accurately predicting shear stresses near the supports of a cantilever prismatic girder bridge with CSWs by incorporating the additional shear forces induced by the shear deformation of CSWs. Theoretical analysis has revealed that the expression and magnitude of the additional shear force are correlated with the boundary conditions of the girder bridge. The study formulates expressions for the additional shear force induced by shear deformation in girder bridges with CSWs, considering various boundary conditions such as cantilever, simply supported, fixed-end, and continuous spans. It contributes to further enhancing the analytical method for calculating shear stress in prismatic girder bridges with CSWs, accommodating diverse support constraint conditions. The findings have practical implications for guiding the shear design of girder bridges with CSWs under various support systems.

Shear behavior on PBL shear connector with a relatively thin perforated steel plate in steel-UHPC composite bridge deck system

Recently, a new steel-UHPC composite deck system is used for long-span bridges, which uses the perfobond rib (PBL) shear connectors with a thinner steel perforated plate. Because the steel perforated plate is thinner, its failure mode may be different from that of thicker steel perforated plate. To explore the shear behavior of PBL shear connectors in this new composite deck system, five sets of ten specimens are tested in this study. The parameters of the hole diameter, D, the traverse rebar diameter, ds, and the perforated steel plate thickness, ts are considered. The failure modes, strain development versus loading, and some mechanical indexes are discussed. The experiments show that the PBL shear connector with a thinner perforated steel plate causes a shear failure, while the thicker one results in bending or bending-shear failure. According to FE (finite element) analysis, the orthogonal analysis is conducted to investigate the effect of each parameter and their interaction on the mechanical behavior. It is found that the ultimate capacity and stiffness are the most sensitive to the diameter of the traverse rebar, ds, and the perforated steel plate thickness, ts. In addition, a theoretical formula is proposed to predict the bearing capacity of PBL shear connectors. The proposed formula considers the relationship between shear strain and the dilation angle for the first time. The results show a good agreement with the experiments. The study in this paper provides a good reference for the application and optimization of PBLs with a thinner steel perforated plate in new steel-UHPC composite deck system.

The direct shear behavior of the ultra-high performance concrete-filled socket connections between the bridge piers and footings

Ultra-high performance concrete (UHPC)-filled socket connections (UFSCs) provide a novel method for connecting bridge piers and footings, and allow for high matching tolerance and accelerated construction. At present, the lack of related research on the direct shear behavior of UFSCs hindered the promotion of this technology. This paper carried out the push-out test to explore the influences of embedded depths, horizontal confining pressures, and the shear key shapes on the direct shear behavior of the UFSCs. Monolithic specimens were also tested as a reference. The experimental results showed that increasing the socket depth and horizontal confining pressure has a positive impact on the direct shear capacity. With the same key width, escalating the key root height could also enhance the direct shear capacity. The experimental results also indicated that the load-bearing capacity of UHPC-connected specimens was generally lower than those of corresponding monolithic specimens. AASHTO and JSCE formulas were used to predict the direct shear capacity of joints, which relatively underestimated the experimental results. The average ratio between the calculated values of the two formulas and experimental results was 0.70 and 0.81, respectively. Based on the strut-and-tie model (STM), the shear capacity formula for UFSC was proposed, exhibiting a high degree of agreement with the test results, with an average ratio between calculated values and experimental results of 0.98.

Shear behavior of seawater sea-sand concrete beams reinforced with BFRP bars after seawater dry-wet cycling

The shear behavior of 27 basalt fiber-reinforced polymer reinforced seawater sea-sand concrete (BFRP-SSC) beams after seawater dry-wet cycling was comprehensively investigated. Parameters considered included stirrup diameter and spacing, shear span-to-depth ratio, stirrup surface treatment, cycling duration, concrete cover thickness, and seawater temperature. Results indicate that seawater dry-wet cycling increases cracking load and decreases bending stiffness in BFRP-SSC beams. Increasing shear span-to-depth ratio from 1.55 to 2.35 led to load reductions of 31.3 % and 49.7 % at 6.5 mm mid-span deflection. Seawater dry-wet cycling, particularly temperature and duration, significantly impacts the mechanical properties of stirrups. This results in diminished shear contribution and reduced efficacy in inhibiting diagonal crack propagation, leading to a shift in beam failure mode from diagonal compression failure to shear compression failure and diagonal tension failure. Increasing cycling duration from 60 to 120 days decreased tensile strength retention by 19.1 % and 33.3 % respectively. Based on experimental data, Arrhenius theory, and the time shift factor (TSF) method, a predictive model was developed for the shear capacity retention of beams subjected to seawater dry-wet cycling. Results indicate that after 100 years in a tidal environment (70 % and 90 % relative humidity), shear capacity damage factors of 0.77 and 0.52, respectively, can be applied to account for the impact of seawater dry-wet cycling on the shear capacity of BFRP-SSC beams.

High-efficient hybrid arc and friction stir additive manufacturing of high-performance Al-Cu-Mg-Ag-Zr alloy: Microstructural evolution and precipitation behaviors with Ω/L12 co-precipitates

Cost-effective and convenient additive manufacturing technologies are recognized as suitable alternatives for achieving lightweight aluminum alloy components with dense and defect-free parts toward high mechanical properties. Herein, a high-efficient hybrid arc and friction stir additive manufacturing (HAFS-AM) technique was employed to fabricate a high-performance Al-Cu-Mg-Ag-Zr alloy part. The AC pulsed tungsten inert gas (TIG) was utilized for the rapid pre-deposition of Al-Cu-Mg-Ag-Zr alloy with high efficiency. Friction stir processing contributed to eliminating pore defects and refining coarse microstructure in the pre-deposited arc layers, accounting for enhancing mechanical properties. During the HAFS-AM, the coarse θ phase with continuous network morphology was completely broken and gradually dissolved into the α-Al matrix. The addition of Zr element promoted the precipitation of coherent L12-Al3Zr inducing dislocation shearing behavior. The Mg and Ag additions accelerated the precipitation of semi-coherent plate-like Ω and σ phases, where a critical size (thickness and diameter) of precipitates existed for deciding the behaviors of dislocation shearing and dislocation looping. The ultimate tensile strength and elongation of the HAFS-AMed steady-state layer reached 262 MPa and 18.8 %, which were increased by 21 % and 96 % compared to that of the arc layer, respectively. The combined effect of arc and friction stir with high efficiency achieved high-performance manufactured components, expediting the future industry application of advanced additive manufacturing technology.

A Study of the Shear Behavior of Concrete Beams with Synthetic Fibers Reinforced with Glass and Basalt Fiber-Reinforced Polymer Bars

A Study of the Shear Behavior of Concrete Beams with Synthetic Fibers Reinforced with Glass and Basalt Fiber-Reinforced Polymer Bars

Shear behavior of precast bridge deck panels with UHPC wet joints

Ultra-high performance concrete (UHPC) has been widely used in wet joints of precast bridge deck panels (PBDPs) due to its remarkable compressive strength, excellent tensile strength, and exceptional durability properties. However, there is a lack of consistent understanding regarding the mechanical properties of PBDPs with UHPC wet joints, especially shear behavior. To investigate the shear performance of PBDPs with UHPC wet joints, a total of seven bridge deck panels (BDPs) were designed and conducted by four-point bending tests. The test parameters included reinforcement types (straight bar and U-bar), lap details (contact lap and non-contact lap), joint widths (150 mm, 200 mm, 250 mm, and 500 mm), and filling materials (NC and UHPC). According to the test results, the shear behavior of seven BDPs was analyzed. The experiment results showed that all specimens exhibited shear failure, with critical shear cracks occurring in the shear span. For PBDPs with U-bars, the shear capacity of 200-mm-wide UHPC wet joints was 1.5 % higher than that of 500-mm-wide NC wet joints. In addition, the failure pattern had a tendency to gradually shift from shear failure to flexural failure when the width of UHPC wet joints was reduced from 250 mm to 150 mm. To establish 3D finite element (FE) models, a cohesion-friction hybrid model was proposed. The FE models had good simulation accuracy, with a maximum deviation of 7.0 %. Furthermore, a parametric analysis was performed to assess the influence of critical parameters on shear performance. The results showed that longitudinal reinforcement has a greater influence on the shear performance of PBDPs. Finally, shear capacity formulas in the design codes were verified in comparison with test results. The deviation of theoretically calculated values from test results was within 10 %.

Seismic behavior of high-rise modular buildings with simplified models of inter-module connections

Inter-module connections serve as crucial components, horizontally and vertically connecting individual modules to form modular buildings. This paper presents a component-based model that divides inter-module connections into vertical and horizontal connection components, facilitating the simplification of shear and axial behaviors for input into the global numerical model. Initially, experimental studies and numerical simulations were conducted to investigate the shear and axial behavior of these connection components, following which simplified connection component models were derived. Subsequently, a component-based model of inter-module connections was established, in which the shear and axial properties of the vertical and horizontal components were represented by nonlinear connector elements. Finally, the proposed component-based model was incorporated directly into the global frame models of high-rise steel modular buildings, and the seismic behavior was evaluated. The accuracy of the proposed component-based model was investigated by comparing the natural vibration characteristics and global building responses of high-rise steel modular buildings with traditional empirical models established based on assumptions of rigid or pinned fixities. The results reveal that traditional empirical models fail to accurately represent the discontinuous properties of inter-module connections, resulting in an overestimation of structural lateral stiffness. In contrast, the component-based model accounts for the actual load-transfer mechanisms of vertical and horizontal components, providing a more accurate understanding of the natural vibration characteristics and seismic response of high-rise steel modular buildings. The proposed component-based model establishes a critical link between isolated connection behavior and structural response assessment for high-rise steel modular buildings, making it well-suited for accurately predicting global building responses.

A 2-D fabric anisotropic hyperelastic constitutive model based on micromechanics analysis

The analysis of the large deformation process of two-dimensional (2-D) fabrics helps to obtain the new distribution of yarns’ orientation and fiber in-plane density, which exert a considerable influence on the mechanical properties of the 2-D fabric composite component. By examining the underlying micromechanics involved in the shearing process, we developed a shear constitutive law within an anisotropic hyperelastic constitutive model framework, which is capable of capturing the large deformation of 2-D fabrics precisely. The constitutive law introduces parameters with specific physical meanings, facilitating their acquisition and modification. The proposed model was implemented in ABAQUS using a dedicated subroutine, UANISOHYPER_INV, for defining anisotropic hyperelastic material behavior through invariant formulation. The shear properties of 2/2 twill fabric were examined, and the parameters of the shear constitutive model were determined via bias-extension tests and corresponding finite element computations. The accuracy and reliability of the proposed model were validated through a hemispherical stamping test on the 2-D fabric and frame shear experiments performed by other researchers. This work contributes to the field by providing a robust method for characterizing and predicting the shear behavior of textile composites, thus enhancing the design and optimization of advanced fabric materials.

Shear thickening behaviour of polyborosiloxane

Polyborosiloxane (PBS) is often referred to as a “shear thickening/stiffening gel” or “dilatant compound”, sometimes actually meaning an increase in modulus with frequency/strain rate rather than the rheological definition of “dilatant compound”, i.e. an increase in viscosity with shear rate. The shear behaviour of bulk PBS and PBS solution has been studied here by steady shear experiments, and it is observed that PBS exhibits shear thickening behaviour only under certain conditions. The shear behaviour of bulk PBS depends on the degree of reaction of the PBS (i.e. the content of B in the PBS). For PBS solution, the shear behaviour is influenced by the concentration of the solution and the type of solvent (with or without oxygen atom in the solvent). The shear behaviour of PBS systems is related to shear induced structural changes, where the formation of new elastically active B:O dynamic dative bonds (interchain cross-linking) contributes to shear thickening.