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This paper presents a numerical study on the investigation of microscopic mechanism governing the interaction of woven geotextile and angular sand employing the 3D discrete element method (DEM). The surface texture and tensile properties of the geotextile were simulated using overlapping spherical particles, and the angular sand was simulated using rigid blocks. The DEM models were fully calibrated based on previous experimental data. The shear and dilation zones of sand near the interface were quantitatively determined based on particle displacement gradients. Analysis of contact forces was conducted to explain the microscopic mechanism behind the macroscopic strength evolution. The influence of geotextile surface roughness on the shear strength of the geotextile-sand interface is also discussed. The results show that the failure mode of the woven geotextile-sand interface is a combination of particle sliding failure along the geotextile surface and shear failure of the sand within the shear zone above the interface. There is a rapid redistribution of contact forces prior to reaching peak shear resistance, and the average normal contact force within the shear zone remains relatively constant after the peak shear stress is achieved. A completely developed shear zone stabilizes soil deformation, typically after achieving the peak shear resistance. • The thickness of the stabilized shear zone decreases as the normal stresses increase. • The shear zone is completely developed after the peak shear resistance is reached. • Contact forces are rapidly redistributed prior to reaching peak shear resistance. • The evolution of shear strength is caused by interparticle sliding in the shear zone. [ABSTRACT FROM AUTHOR]

• A fully bolted liftable connection (FBLC) for PPVC was proposed. • An experimental study was carried out to reveal shear behavior of the FBLC. • A refined finite element model (FEM) for FBLC was established and verified. • A database on shear behavior of the FBLC was constructed to develop a proxy model. • A multi-objective optimization method on shear behavior of the FBLC was proposed. Prefabricated prefinished volumetric construction (PPVC) has become a research hotspot in recent years. Inter-module connections have a crucial influence on the mechanical behavior of PPVC. However, current studies on shear behavior and optimization design method of the inter-module connection are insufficient. This paper investigated shear behavior and machine learning based optimization method of an innovative fully bolted liftable connection (FBLC) for PPVC. The failure mode, force transferring mechanism, and ultimate load bearing capacity of the FBLC under shear force were revealed by the shear behavior tests. Four specimens were tested and the design parameters included the strength and number of the long stay bolts. Subsequently, a refined finite element model (FEM) of the FBLC was established and validated with the ratios of the shear bearing capacity between the FEA and test results ranging from 0.99 to 1.10. Then, six mainstream machine learning algorithms were utilized to predict shear behavior of the FBLC. The Genetic Algorithm Optimized Neural Network (GANN) provided better prediction accuracy on the shear bearing capacity, with an improvement on R2 by 0.1 % – 3 % compared with other algorithms. Similarly, the Support Vector Regression (SVR) showed higher prediction accuracy on the ultimate displacement, improving R2 by 0.4 % – 12.9 % compared with other algorithms. A stacking algorithm combing the GANN and SVR was developed as the proxy model between the input variables and optimization metrics. In addition, the NSGA-II algorithm was linked to establish a multi-objective optimization method on shear behavior of the FBLC. The yield load, ultimate load and steel consumption were selected as the optimization objectives and the stacking algorithm was used as the proxy model. The Pareto optimal solution sets on the optimization objectives were explored by the NSGA-II algorithm and the optimization design method of the FBLC was established. Compared with the unoptimized specimen, the yield and ultimate shear bearing capacity of the optimized specimen were increased by 113.5 % and 123.6 %, respectively, with the steel consumption reduced by 26.3 %. Finally, a four-story PPVC was established, and the static analysis was carried out under vertical load and wind load. The shear behavior of the FBLC and inter-story drift ratio of the PPVC before and after optimization were compared to verify the reliability of the optimization method. [ABSTRACT FROM AUTHOR]

Vertical prestress loss causes cracking in prestressed box-girder bridge webs. As a new type of prestressed material, iron-based shape-memory alloy (Fe-SMA) rebars can be used as vertically prestressed rebars to compensate for the loss of vertical prestress in box-girder webs. In this study, box-girder webs were simplified into I-shaped beams, and the shear performance of these I-shaped beams with vertical Fe-SMA rebars in the shear span was analyzed to estimate the feasibility of using Fe-SMA rebars. The effects of the activation state, layout spacing, and rebar diameter on the shear performance of the I-beams were explored. The variations in the cracking load, ultimate load, and main tensile strain were systematically investigated. The results indicate a significant transformation from brittle to ductile bending shear failure following Fe-SMA activation. Moreover, the ultimate deflection exhibited a significant increase exceeding a factor of 2. The activation of the Fe-SMA was beneficial for delaying specimen cracking and improving shear strength. Specifically, the shear cracking and ultimate loads increased by 24.21 % and 12.11 %, respectively. Simultaneously, the activation of the Fe-SMA rebar significantly reduced the primary tensile strain within the shear span segment and effectively delayed crack development. The diagonal fracture width of the specimens with the activated Fe-SMA was significantly reduced (67.24 %, 57.14 %, and 52.22 %, respectively) at three different stress settings (400, 450, and 500 kN). Furthermore, a methodology for estimating the shear cracking and bearing capacity of I-beams with vertical Fe-SMA rebars is proposed. The calculated values are in excellent agreement with the experimental data, thereby serving as a valuable reference for future research. • The shear behaviors of I-shaped concrete beams with Fe-SMA rebar were investigated. • A transformation from brittle shear failure to ductile bending shear failure following Fe-SMA activation. • The activation of Fe-SMA exhibited a beneficial effect in delaying shear cracking. • An analytical approach to predict the shear capacity of I-beams reinforced with Fe-SMA rebars was proposed. [ABSTRACT FROM AUTHOR]

This research investigated the shear behavior of concrete beams reinforced with Carbon Fiber Reinforced Polymer (CFRP) bars and grids as longitudinal reinforcements and stirrups, in experiment and finite element (FE) methods. Five concrete beams were tested under a monotonical load and experienced shear failure as expected. The test variables including stirrup ratio and grid dimension were considered to investigate the interaction between grid and concrete, and the influence between the horizontal and vertical fibers of the grid. It found that reducing the grid dimension with the constant stirrup ratio could effectively improve the stress distribution of the grid and the shear capacity of the beam. The grid dimension greatly determined the shear capacity of specimens when the stirrup ratio changed in a small range. The horizontal fibers of the grid had anchoring effects on the vertical fibers and directly carried the tensile stress from concrete at the top and bottom of the beam. In FE analysis, the fiber composite layer was adopted to simulate the CFRP grid. The load-midspan deflection of specimens and strain development of the grid in the FE model showed good agreement with the tests. In parameter analysis, the grid configuration with the horizontal fiber arranged in the middle or upper part of the section was recommended. [ABSTRACT FROM AUTHOR]

• The strengthening technology using eco-friendly UHPFRC-CFRP grid layers incorporating recycled trye fibers was proposed. • The new strengthening technology significantly improves the cracking resistance stiffness and shear capability. • The effects of various types and thicknesses of UHPFRC layers, CFRP grid ratios, and CFRP grid layout angles were analyzed. • Considering corrosion and sustained load, the calculation model for predicting ultimate shear loads was established. Ultra-high performance fiber reinforced concrete (UHPFRC), incorporating recycled tyre fibers, and carbon fiber-reinforced polymer (CFRP) grid were utilized to strengthen the pre-damaged reinforced concrete beams caused by coupling action of sustained loads and marine environment. The failure modes, characteristic loads, deflection features, and strain behavior of the strengthened beams with various types of UHPFRC, thicknesses of UHPFRC layers, CFRP grid ratios, and CFRP grid layout angles were investigated. The results indicated that they exhibited the typical shear failure, and their characteristic loads increased by 102 %–205 % compared to the undamaged beam. By increasing the thickness of the UHPFRC layer and the CFRP grid ratio, and adopting 45° CFRP layout angle, the cracking stiffness, energy absorption capacity, and shear force sharing ability would be further improved, while adopting the UHPFRC incorporating recycled tyre fibers would decrease the ductility. Moreover, analytical models were developed to calculate the ultimate loads, manifesting reasonable accuracy. [ABSTRACT FROM AUTHOR]

In this paper, experimental studies were conducted to examine the shear behavior of reinforced concrete beams, including a combination of crumb rubber (CR) and rice husk ash (RHA). One of the key objectives of the concrete industry is to reduce global emissions and provide environmentally friendly concrete. Twelve RC beams with four replacement levels of CR (0 %, 5 %, 10 %, and 20 %) by fine aggregate (FA) and three substitution ratios of RHA (0 %, 10 %, and 20 %) by cement (one beam from each mix) with dimensions of 120 × 250×2000 mm were cast and tested under four-point loading conditions. The experimental outcomes display that incorporating a combination of CR and RHA reduces workability. The introduction of RHA enhanced both the compressive and tensile strengths. Conversely, the inclusion of CR significantly impacted the loss in concrete strength. The shear capacity, stiffness, and toughness of the tested beams were noticeably enhanced with the addition of RHA up to 10 %, then dropped with the addition of 20 % RHA but remained higher than those of the reference beam. On the contrary, the introduction of CR had a negative effect on the shear capacity and stiffness of tested beams, and incorporating RHA up to 10 % enhanced these effects. To maintain environmental sustainability and preserve natural resources, the ideal substitution ratios for the concrete mix are 10 % CR and 10 % RHA, which produce an acceptable shear capacity with a slight drop of approximately 4.0 %. Additionally, a comparison was conducted between the predicted shear capacity of four design code equations (ACI 318–2019, ECP 203, BS8110, and Euro-2) and the experimental results obtained from all test beams. • Mechanical properties of concrete comprising CR and RHA as FA and cement replacement, respectively, were investigated. • The shear behavior of RC beams comprising RHA as cement replacement was studied. • The introduction of RHA can mitigate the negative effect on concrete strength caused by CR. • The optimum substitution ratios for the concrete mix are 10 % CR and 10 % RHA [ABSTRACT FROM AUTHOR]

• Quasi-static and dynamic single shear tests on CFRP-concrete interface are carried out. • A 3D mesoscale modeling method of concrete with random aggregates is proposed. • Mesoscale concrete model-based FE model for FPR-concrete interface is established. • Failure location transferred from concrete to adhesive layer is numerically reproduced. • Influence of strain rate effect of concrete on interfacial failure mode is discussed. The study on dynamic shear behavior of fiber reinforced polymer (FRP)-concrete interface is of great significance for the performance evaluation and design of FRP externally strengthened concrete structures. Firstly, the quasi-static and dynamic single shear test on the interfacial shear behavior between carbon fiber reinforced polymer (CFRP) sheet and concrete substrate was carried out. The corresponding failure modes of CFRP-concrete interface, CFRP strain-time histories, load-displacement curves, and interfacial shear stress-slip relationships under loading rates of 8.33 × 10−6–10 m·s−1 were obtained. It was indicated that the dynamic interfacial shear behaviors, i.e., interfacial failure mode, debonding load, interfacial shear stress, etc., were sensitive to loading rates. Then, a 3D mesoscale modeling approach of concrete with random shaped, sized, and spatially distributed convex polyhedron aggregates was proposed, in which the volume fraction of aggregates was adjustable within the range of 0–50 % through gravitational drop and size scaling of aggregates. Furthermore, based on the established 3D mesoscale concrete model and the zero-thickness cohesive elements for adhesive layer, numerical simulations for FPR-concrete interfacial shear behavior were conducted and validated by comparing with the present and existing quasit-static and dynamic single shear tests. The experimental phenomenon of the failure location transferring from concrete substrate to adhesive layer at high loading rates was numerically reproduced. Finally, the influences of strain rate enhancing effects of aggregates and mortar on the interfacial failure modes were discussed. It was revealed that the failure location transferring from the concrete substrate to the adhesive layer was significantly affected by the strength enhancement of mortar and aggregates with the loading rate increasing. [ABSTRACT FROM AUTHOR]

Carbon fiber (CF)/epoxy (EP) composites are widely used in structural components. Quasistatic and dynamic shear experiments were designed and conducted to investigate the effect of the loading rate on the shear behavior of the CF/EP interface. Using numerical simulation, the accuracy of the new shear testing methods to test the shear behavior of interface under both quasistatic and dynamic loading conditions was verified. The shear failure stress increases with increasing loading rate, and the failure mode of the CF/EP interface changes from fiber-matrix debonding to almost entirely brittle fracture of the matrix and fiber-matrix debonding. The proposed shear test methods are promising for testing the shear behavior of interface between two kinds of materials or phases, and the shift in the failure mode is a consequence of the effect of the loading rate on the shear behavior of the CF/EP interface. [Display omitted] • New methods tested the quasistatic and dynamic shear behavior of CF/EP interface with the accuracy validated by FEM. • The shear failure stress increases with increasing loading rate. • Dynamic loading was conducted in conjunction with a high-speed camera. • The fracture mode changes from fiber-matrix debonding, to brittle fracture of matrix and fiber-matrix debonding. [ABSTRACT FROM AUTHOR]

The present work reports the results of an experimental program on the mechanical characterization of Reinforced Concrete (RC) beams externally strengthened/repaired by natural sisal Fabric-Reinforced Cementitious Matrix (FRCM) composite. For such, undamaged and pre-cracked RC beams were U-wrapped with a sisal FRCM composite and then tested under bending load. The results showed significant increases in shear strength, up to 25 % for beams with stirrups and 75 % for beams without them. The strengthened/repaired beams also presented stirrups yielding delay during the tests. When compared with other synthetic FRCM strengthening systems from the literature, the enhanced mechanical results of the present work were mechanically equivalent. The cracking pattern and debonding of the sisal FRCM wrap system were measured by the Digital Image Correlation (DIC) technique. The wrap application reduced the crack propagation and debonding behavior was not detected. Finally, the experimental results were confronted with an analytical approach guided by ACI 549.4R-20 and considered sufficiently accurate. • Sisal FRCM composite provided significant shear strengthening for the RC beams. • The sisal FRCM strengthening gains were comparable with the synthetic FRCM. • Experimental results and the analytical approach were sufficiently accurate. [ABSTRACT FROM AUTHOR]

Stress change in rock mass caused by human activities has the potential to cause the sliding and destruction of faults and joints, resulting in induced seismicity. Laboratory experiments are conducted on a simulated fault with various teeth numbers and undulation angles to uncover the mechanism of stress change-induced seismicity. The potential risk of induced seismicity is explained using three methods: the Mohr-Coulomb failure criterion, localization of stress concentration regions, and visualization of maximum shear stress reduction through photoelasticity. Experimental results indicate that the friction coefficient increases with the undulation angle, and the form of stress change has an unignorable impact on frictional instability. The friction coefficient in the vertical unloading process is slightly lower than that in the loading process and larger than that in the shear unloading process. Loading is the stress change caused by shear displacement under constant normal stiffness conditions and unloading is the process of reducing the stress by controlling the position of the boundary constraints in the corresponding direction. Meanwhile, unloading in the shear direction has both seismic and aseismic features. Although the rapid drop of shear stress at the onset of shear unloading may induce fault instability, the reduction of normal stress and the restoration of displacement prove that unloading in the shear direction may also reduce the risk of fault failure in the subsequent process. In addition, the stress concentration region is mainly distributed perpendicular to the contact surface rather than the entire fault. This research is conducive to promoting the application of photoelasticity in studying induced seismicity and provides a practical method for calculating the energy released during such events. Based on the morphological characteristics and stress states of fault surfaces, the findings can be utilized in engineering practice to assess the risk of induced seismicity under different stress change conditions. • A customized direct shear machine coupled with photoelastic is adopted. • The friction coefficient is affected by the form of stress variation. • Unloading in the shear direction has both seismic and aseismic features. • Visualization of stress concentration region and stress drop. [ABSTRACT FROM AUTHOR]

• Lightweight ceramsite concrete (LWCC) was used as a repair material to repair the normal concrete (NC). • The direct shear test was performed to investigate the shear behavior of the LWCC-NC interface under freeze–thaw cycle. • The effects of roughness and freeze–thaw environment on the interfacial shear behavior were studied. • An interfacial damage prediction model based on two-parameter Weibull distribution function was established. In cold regions, the shear resistance of the lightweight ceramsite concrete-normal concrete (LWCC-NC) interface directly affects the safety of the structure. In this paper, the clear water freeze–thaw and chloride-salt freeze–thaw tests were carried out on the interface specimens of LWCC-NC with four roughness types by quick freezing method. Then the shear behavior of the interface under freeze–thaw cycles were studied by direct shear experiments. Finally, an interfacial damage prediction model based on two-parameter Weibull distribution function was established. The results showed that freeze–thaw cycles lead to accelerated interface damage. After 40 freeze–thaw cycles, the shear strength of the interface decreased by 54.92 % −95.88 %. The increase of roughness alleviated the damage of freeze–thaw cycles, and there was the most favorable roughness. With the increase of freeze–thaw cycles and roughness, the interface shear failure mode changed from interface failure to mixed cohesion failure and then to NC failure. The damage of chloride salt freeze–thaw environment was more significant than that of clear water environment, and the shear strength of the specimen decreased by 2 % ∼ 51.89 %. The interfacial damage prediction model and reliability results were in good agreement with the experimental results, which can provide reference for the application of LWCC in reinforcement engineering in cold regions. [ABSTRACT FROM AUTHOR]

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, d s , and the perforated steel plate thickness, t s 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, d s , and the perforated steel plate thickness, t s. 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. • Introducing a new steel-UHPC bridge deck with perforated steel plate as the shear connectors and longitudinal rib. • Shear behavior on PBL shear connector in the new steel-UHPC deck is conducted. • The influence of each parameter of PBL shear connector and its interaction on the structure is obtained. • The formula for the shear capacity of PBL shear connector in the new steel-UHPC bridge deck is presented. [ABSTRACT FROM AUTHOR]

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. • Seawater dry-wet cycling enhances cracking load, reduces bending stiffness of BFRP-SSC beams. • Smaller diameters, thicker covers improve resistance to seawater corrosion. • Seawater dry-wet cycling affects stirrups' contribution, crack propagation, and failure mode. • Shear damage factors should be accounted for the impact of seawater dry-wet cycling. [ABSTRACT FROM AUTHOR]

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 %. • Seven BDPs were designed to investigate the shear behavior of wet joints. • It is feasible to replace 500-mm-width NC wet joints with 200-mm-width UHPC wet joints for PBDPs with U-bars. • As the width of UHPC wet joints decreased, the failure mode shifted from shear failure to bending failure. • The cohesion-friction hybrid model was proposed to simulate the behavior of joint interfaces. [ABSTRACT FROM AUTHOR]

To investigate the shear behavior of externally prestressed precast concrete segmental beams with both positive and negative moment regions (EPCS P&N beams), eight specimens were subjected to failure under various shear span to depth ratios, moment ratios, and joint types. Throughout the testing process, critical crack initiation and development, joint slippage and opening, failure processes and modes, as well as strains in concrete, stirrups, and external prestressing tendons were meticulously recorded. At the point of failure, the concrete in the shear-compression zone near the top surface of the joint section (closest to the loading point in the positive moment region) or near the bottom surface of the joint section (closest to the interior support in the negative moment region) experienced crushing. Subsequently, the external tendons lost support and underwent elastic retraction, causing the two segments on either side of the critical web-shear crack to slide against each other. The elastic strain energy was released significantly as a consequence of the external tendons retracting, leading to the rupture of stirrups intersecting the failure cracks, followed by flange buckling. Based on the test results, a strut-and-tie model was developed to analyze the shear resistance mechanism, and a detailed flowchart for computing the shear resistance of EPCS P&N beams was established. The predictions from the proposed analytical method were compared with the test results, showing good agreement and confirming the rationality of the proposed shear resistance mechanism. • The shear behavior of the EPCS P&N beams with an inflection point was studied by tests. • A novel shear failure mode, exhibiting distinct brittle failure characteristics, was identified in the EPCS P&N beams. • A strut-and-tie model was developed to analyze the shear resistance mechanism of the EPCS P&N beams. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the shear performance of a low-profile perfobond strip (LPBL) connector embedded in a thin ultra-high-performance concrete (UHPC) layer of orthotropic steel–UHPC composite decks (OSUCDs). Push-out tests were performed on 20 specimens to determine the effects of overall dimensions of the strip, strip-end bearing, opening shapes, and perforating rebars. The corresponding shear transfer mechanism was examined through precise finite element (FE) analysis, and prediction methods for load–slip process and shear capacity were proposed through theoretical analysis. The results showed that LPBLs demonstrated satisfactory ductility with an ultimate slip exceeding 6 mm. The strip-end bearing and overall dimensions of the strip, particularly strip length and strip thickness, had significant effects on the shear capacity of LPBLs. As strip length and thickness increased, the weak link in shear capacity of LPBLs transitioned from the fracture of strip to the damage of UHPC dowel and strip-end compressive UHPC, and the contribution of perforating rebars progressively increased as the UHPC dowel's damage intensified. When opening areas were identical and ultimate capacity was controlled by UHPC dowels, circular hole LPBLs and those using wide holes had comparable shear performance, and the notch on the hole also had little effect. The configuration of notched wide holes was more conducive to the construction of LPBLs embedded in a thin UHPC layer. The proposed theoretical model based on LPBL's load transfer path predicted the load–slip curves well, and the accuracy of the proposed simplified equation for the shear capacity of LPBLs was also preliminarily validated by the test results. • Shear performance of low-profile perfobond strip (LPBL) connectors in thin UHPC layer was examined by push-out tests. • Effects of strip dimensions, strip-end bearing, opening shapes, and perforating rebars on shear behavior were identified. • The load transfer mechanism of LPBLs was elaborated through precise finite element (FE) analysis. • Theoretical models based on load transfer path for predicting load–slip curves and shear capacity were proposed and verified. [ABSTRACT FROM AUTHOR]

This study explores the viability of reinforcing multi-openings beams with web steel plates (SPs) as an alternative to conventional shear reinforcement. Eight beams with multi openings and one solid beam were part of the experimental program. Internal reinforcement was provided by different web SP designs for each beam. The existence of transverse apertures and the distribution, thickness, and number of longitudinal and transverse SPs are investigated. It was investigated how important factors affected the tested beams' stiffness, toughness, failure mechanism, load displacement behavior, peak load and accompanying deflection, and cracking load. The results showed that lateral buckling that developed on the steel plates' compression side at the shear span was the reason why all of the tested beams collapsed. In comparison to a single LSP-beam, the peak loads of the beams rose by 59 % and 69 %, respectively, when two and three longitudinal steel longitudinal (LSPs) were executed. Furthermore, compared to performing two thinner LSPs, conducting one thicker LSP, having same thickness of two thinner LSPs, reduced the first crack load, peak load, deflection, stiffness, and toughness of the beams by 17.5 %, 31.39 %, 33.3 %, 1.06 %, and 43.14 %, respectively. Additionally, a finite element approach was used to computationally study the effects of the opening arrangement and the SP-to-beam height ratio. The findings demonstrated a 141 % increase in beam capacity when the SP-to-beam height ratio was raised from 0.4 to 1.0. The beam capacity was increased by 15 % due to the lack of openings near the supports. • This study examined the reinforcing of multi-openings concrete beams using steel plates (SPs). • Applying two or three SPs increased the peak loads of the studied beams by 59 % and 69 %, respectively. • By increasing the SP-to-beam depth ratio from 0.4 to 1.0, the beam capacity was increased by 241 %. [ABSTRACT FROM AUTHOR]

To promote the understanding of the shear behavior of intermittent joints subjected to cyclic shear loads, this paper provides the experimental results of cyclic shear tests in the laboratory. We vary joint configurations and boundary conditions to investigate their effect on the shear behavior and evolution of shear resistance during cyclic shearing. The cyclic shear failure of intermittent joints can be identified as two stages: the cracking of rock bridges (Stage I) and shear slip (Stage II). After ten shear cycles, the shear strength losses generally exceed 50% and reach up to 74.22%. Joint configurations and boundary conditions determine the stress state of intermittent joints during cyclic shearing, thus leading to varied shear zones and evolutions of shear strength. Shear strength is more sensitive to normal stress and joint persistence than joint overlap, spacing, and shear rate. The combination of high joint persistency, moderate joint overlap, small joint spacing, low normal stress level, and high shear rate is most detrimental to the stability of engineering rock masses. Activation of rupture surfaces in different shear directions during cyclic shearing results in a difference in shear strength during positive and negative shearing. Intermittent joints show significant compressibility during cyclic shearing, and the average dilation angle decreases with the cycle number, which also is dependent on joint configurations and boundary conditions. Joint persistence and spacing have a more significant effect on the average dilation angle, while the shear rate is the least significant factor. The combination of high joint persistence, high joint overlap, small joint spacing, high normal stress level, and shear rate during cyclic shearing is the most favorable for compression. • Cyclic behavior of intermittent joints is explored for the first time. • Shear strength evolution differs between positive and negative shearing. • Intermittent joints exhibit considerable compressibility during cyclic shearing. [ABSTRACT FROM AUTHOR]

Shear failure is a brittle type of failures, which should be avoided in any structure as it could cause property loss and human casualties. The shear behavior of thin-walled concrete-filled steel tubular (CFST) columns was hence investigated in this study, involving the tests of 24 thin-walled CFST columns and considering the following parameters: shear span-to-depth ratios = 0.15, 0.3, 0.5, 1, 1.5, and 2; confinement factor = 0.63, 1.27, 1.44, and 1.70; and axial load ratios = 0, 0.2, 0.4, and 0.6. The test results revealed the insights of the initial shear stiffness, failure modes, ultimate bearing capacity, load-deflection curves, load-strain curves, and ductility of the specimens. Based on the failure modes, a method is proposed to evaluate the load resistance, and explain the relationship between the shear span-to-depth ratio and the peak bearing capacity. A compression strut mechanism considering the confinement provided by the steel tube flange is also proposed. The effect of axial load on the shear strength of the concrete core is negligible when the axial load ratio doesn't exceed 0.4. The predicted results from using the proposed simple model agree generally well with the experimental results. • Monotonic tests are conducted to obtain the shear behavior of the thin-walled CFST columns designed with major parameters. • Steel tubes and concrete's contributions to shear capacity are clarified by experimental and analytical results. • The exact effects of some parameters on failure modes and shear capacity are explained based on the experimental data. • The formulas on the shear capacity of the thin-walled CFST columns are proposed based on the compression strut mechanism. [ABSTRACT FROM AUTHOR]

An experimental work on the shear strengthening of reinforced concrete (RC) beams completely wrapped by large rupture strain (LRS) FRP is presented in this paper. A total of 14 three-point bending tests were carried out on simply supported RC beams, with a focus on the impacts of the shear span-to-depth ratio (1.53, 2.25, and 3.01) and FRP reinforcement ratio (0.37 %, 0.75 %, and 1.12 %) on the shear behavior of RC beams strengthened with LRS FRP. For the beams with a median length, the ductility coefficients increased by 81 %, 154 %, and 335 % with the increase in FRP reinforcement ratio. For the long beams, the ductility coefficients increased by 116 %, 286 %, and 470 % as the FRP reinforcement ratio improved. The ductility markedly improved with the increase in shear span-to-depth ratio. PET FRP's fracture was not found at the ultimate state, and the improvement in mid-span deflection after the peak state was mainly contributed by the shear deformation. The strengthened specimens exhibited a ductile shear failure mode. For the short RC beams, the shear capacity was slightly enhanced, and the ductility was not improved after being strengthened. The strengthened short RC beams still showed a brittle diagonal compression failure mode. The experimental shear contribution of PETT FRP was compared with the prediction of the existing design guidelines. Finally, an effective strain model of PET FRP, including the shear span-to-depth ratio effect, was proposed and verified with the experimental results. • Shear performance was studied for shear-critical RC beams completely wrapped by LRS FRP. • Ducile shear failure of LRS FRP-strengthened RC beams was observed. • Effect of shear span to depth ratio on shear behavior was discussed. • Six design guidelines for FRP shear contribution were evaluated. [ABSTRACT FROM AUTHOR]

Asphalt concrete core wall rockfill dam (ACCD) is a type of dam that uses asphalt concrete core wall as the anti-seepage structure and rockfill as the supporting structure. Under action of external loads and modulus differences, interface between the core wall and transition layer is prone to shear deformation, which may lead to excessive shear and tensile stresses in the core wall, and even cause cracks. This paper aims to reveal mechanical behaviors and interaction mechanism of the interface between the asphalt concrete core wall and the coarse-grained soil transition layer. Interface shear tests were conducted under five normal stresses and five shear rates condition using an interface shear test system. The shear stress-displacement behavior and shear strength behavior of the interface were analyzed. Influence of normal stress and shear rate on the shear behavior of the interface was discussed. Nuclear magnetic resonance (NMR) and high-pressure permeameter were used to test internal pores and permeability of the asphalt concrete after shear action. The effect of shear action on apparent damage, pore structure, and permeability of the asphalt concrete was discussed. The results indicated that the interface exhibited strain hardening behavior. The interface undergoes shear compaction deformation. The shear stress, displacement, strength was positively correlated with normal stress and shear rate. Shear action causes damage to the asphalt concrete within a depth range of 43–52 mm from the surface. The damage lead to increase in porosity in the damage influence area. The porosity remains below 3 % after shear action. The shear action did not significantly affect the anti-seepage performance of the asphalt concrete. • Behavior of the asphalt concrete core wall-transition layer interface was revealed. • Normal stress and shear rate has remarkable effect on the interface shear behaviors. • Shear effect did not significantly affect the permeability of asphalt concrete. [ABSTRACT FROM AUTHOR]

Shear failure of structural elements such as beams and columns is considered a brittle failure. Accordingly, the design standards provide conservative equations for determining shear strength to ensure to delay of this abrupt failure. In this regard, the AISC Standard provides equations to determine the shear strength of encased composite members considering the steel contribution, the reinforced concrete contribution, and the strength of the steel section in combination with the transverse reinforcement. The AISC conservatively ignores the combination of the shear strength of steel section and reinforced concrete to determine the shear strength of encased composite members due to insufficient research. This study investigates the shear behavior of encased composite (EC) columns experimentally and numerically. Short EC columns in which their behavior is governed by shear are tested considering several design variables, including the concrete compressive strength, the steel ratio, the shape of the steel core, the ratio of longitudinal reinforcement, the transverse reinforcement spacing, and the level of the composite action. Failure mode, the crack pattern, the load-displacement response, the nominal shear strength of EC columns, the yield condition of steel core, and the effects of key variables on the shear strength of EC columns are presented and discussed. A comprehensive numerical analysis is conducted to investigate the effects of key design variables with a wide range of values on the shear response of encased composite columns. The results of this study show that the exclusion of steel section or reinforced concrete contribution leads to a significant underestimation of the shear strength of encased composite members. Out of the considered design variables, the transverse reinforcement ratio, concrete compressive strength, and steel core ratio are the most influential variables affecting the shear behavior of EC columns. • AISC standard significantly underestimates the shear strength of encased composite columns. • The shear strength of EC columns relies on both steel core and reinforced concrete. • The transverse bars, concrete compressive strength, and steel core ratio significantly contribute to the shear strength. • The level of the composite action affects the shear strength of EC columns. [ABSTRACT FROM AUTHOR]

Recycling construction and demolition (C&D) wastes into useable aggregates in subgrade applications offers significant sustainability benefits. However, the characteristics of recycled aggregates, including particle morphology, crushing strength, and shear behavior, differ substantially from natural aggregates. This paper presented an extensive experimental study on the compaction and mechanics performances of recycled concrete and brick aggregates, with a particular focus on the effects of particle breakage and shape characteristics. The compaction of recycled aggregate specimens comprising three structural types was evaluated using heavy Marshall compaction (HMC) and Superpave gyratory compaction (SGC). The compaction characteristics and particle breakage were examined, enabling a profound understanding of the compaction mechanisms associated with both methods. Furthermore, triaxial shear tests were performed to scrutinize the influences of particle shape, compaction degree, and confining pressure on shear characteristics. Results showed that after 80 gyratory rotations in SGC, the compaction degree of recycled aggregates aligned with the targeted results obtained from HMC. Changes in fractal dimension after compaction exhibited direct correlations with the two-dimensional shape distribution. Axial coefficient, fractal dimension and confining pressure most strongly influenced shear strength. In light of these insights, prediction models for shear strength parameters were proposed using multiple regression analysis. Overall, the study provides valuable insights into the relationships between aggregate morphology, compaction response, breakage behavior, and shear performance. These findings can facilitate optimized design and construction using recycled aggregates to advance sustainable infrastructure development. • Image analysis quantitatively characterized morphology of recycled aggregates. • Significant crushing occurred during compaction, especially for coarser gradations. • Shear testing showed strain-hardening behavior followed expected trends. • Regression models successfully predicted shear strength from shape, density and pressure. [ABSTRACT FROM AUTHOR]

Although fiber-reinforced polymer (FRP) reinforcements have become popular, the post-pultrusion bending leads to significant deficiency in bent portions of FRP hoops and spirals. This study adopts flexible carbon FRP (CFRP) grids as stirrups, and investigates the shear behavior of circular short columns reinforced with GFRP bars and CFRP grid stirrups. Six specimens with different shear reinforcement ratios, axial load ratios and types of stirrups (CFRP grids and steel hoops) were tested to shear failures. The failure modes, crack and strain developments, and shear load-horizontal displacement responses were presented for discussion. All specimens experienced shear-compression failures, and the critical diagonal crack widths increased approximately linearly with shear loads. The typical shear load-horizontal displacement curve consisted of three branches: a linear elastic branch, a cracking branch with progressive slope deteriorations, and an almost flat failure branch. Increasing CFRP grid stirrup ratio could not only enhance strength and ductility performance, but also alleviate the slope degradations, while increasing axial load ratios could enhance the initial cracking loads, restrain crack propagations, and reduce the lateral displacements. In terms of strength performance, steel hoops could be replaced by CFRP grid stirrups even with smaller stirrup ratio. Additionally, analytical investigations suggested that the effective stresses and strains of CFRP grid stirrups at failure may be lower than code limits. [ABSTRACT FROM AUTHOR]

Nanoparticles found in rock avalanches and natural faults were inferred to be the reason for the ultra-low shear resistance of the materials along the shear surface. Nevertheless, this inference has not been physically verified yet. To investigate the role of nanoparticles in the shear behavior of granular materials, we conducted a series of ring shear tests on silicon dioxide nanoparticles (SN), silica sand (S8), and mixtures of the S8 with different contents of SN, under varying normal stresses (σ) and shear velocities (V). Our results showed that the shear strength (μ) of SN is high when σ is small (≤ 215 kPa at our test range), even though the maximum shear velocity is about 210 cm/s, but shows a great decrease under higher σ (≥ 619 kPa). The shear strength of mixtures varied with SN content. For S8 (M0) and the mixture of 10% SN (M10), when sheared under small σ, μ first decreased slightly with increasing V when V is smaller than 1 cm/s, after that it increased slightly with further increase of V. Nevertheless, this kind of shear-rate dependent behavior was not observed in the tests under higher σ. When the content of SN in the mixture was <20%, μ increased with the increase of SN content. However, with further increase of SN content, μ decreased. Under high normal stress conditions, distinctive powder rolls were observed on the shear surface formed on the tests. When the mixtures with lower SN content (≤50%), the powder rolls were not observed. We inferred that powder rolls can be produced under high SN content and high normal stress conditions, and this structure altered the particle movement mode from sliding friction to rolling resistance, resulting in a significant decrease in the shear strength. These findings provide valuable insights into the shear behavior of granular materials with nanoparticles and then provide evidence for a better understanding of the high mobility of rock avalanches. • The shear strength of silica nanomaterial (SN) depends on the applied normal stress. • Shear velocity has no significant impact on the shear strength of SN. • The shear strength of the mixtures of sand with SN depends on the SN content. • Powder roll formation regulates the shear strength of mixtures with high SN content. [ABSTRACT FROM AUTHOR]

Keyed joints play a critical role in ensuring the overall behavior of a precast concrete segmental bridges. However, these joints can exhibit poor shear capacity and durability as well as brittle failure. Polyvinyl alcohol fiber-reinforced engineered cementitious composites (PVA-ECCs) exhibit high shear strength and ductility as well as excellent fracture performance, making them attractive for use in the joints of segmental bridges. This study fabricated 16 Z-shaped specimens with number of keys (one, two, or three), concrete materials (normal concrete or PVA-ECC), and types (monolithic, epoxy, or dry) to investigate their failure modes, cracking loads, shear capacities, residual capacities, and shear stress–vertical displacement curves. The results indicated that the keyed joints exhibited shear failure at the root of a shear key, and an increase in the number of keys increased the residual strengths and ductility of both the dry and epoxy joints, but it had a negative effect on the shear strengths. When PVA-ECC was applied instead of normal concrete, the cracking resistance index for all joints improved significantly and the shear strengths and ductility of the monolithic and keyed epoxy joints increased. Generally, the shear strengths of the epoxy joints were 6.3–29.1% higher than those of the corresponding dry joints; however, the ultimate displacements of the epoxy joints were 46.6–72.4% lower. Finally, a method for calculating method of the shear capacities of keyed PVA-ECC joints was proposed and verified to accurately predict the behaviors of previously tested joint specimens. • The shear performance of PVA-ECC keyed joints was experimentally investigated. • The damage mechanism and failure mode of PVA-ECC keyed joints was analyzed. • The influence of design parameters of keyed joints was discussed. • A calculation method for the shear capacity of PVA-ECC keyed joints was proposed. [ABSTRACT FROM AUTHOR]

Ultra-high performance concrete (UHPC) is a promising alternative for improving the mechanical performance of the steel and reinforced concrete composite bridge deck. Because of the excellent compression and tensile strength as well as the superior durability, the thickness of the UHPC slab can be effectively reduced. Therefore, large diameter short headed stud connector was proposed in this study to match the thin UHPC slab. To investigate the shear behavior of the large diameter headed studs in steel-thin UHPC composite bridges, 6 groups of 12 push-out specimens were designed and tested under the static loading. During the test, the failure mode, load-slip curves, the ductility, shear stiffness and shear strength of the specimens were emphatically focused. Besides, the influences of the aspect ratio of the stud, the thickness of the UHPC slab and the number of the stud in one position on shear behavior of the specimens were evaluated. Furthermore, the ABAQUS software has been used to analyse the large diameter short stud. A proposed modelling strategy used for further parametric analysis was validated with the test results. For the parametric research, different aspect ratio of stud and ultimate strength of stud were evaluated. Test and FEM results showed that the specimens failed in the failure of the root of the stud and the crushing of the concrete. With the increasing of the diameter of the stud, the thickness of the UHPC slab and the ultimate strength of stud, the shear strength and the shear stiffness of the specimens increased. Under the same cross-sectional area of the stud, the shear behavior of a single large diameter short stud connector could be comparable to that of two conventional stud connectors. Finally, after evaluating the results obtained from existing formulas, a predictive equation for the shear bearing capacity of large diameter short studs was proposed, and the accuracy of the calculated results was verified. • We conducted the test on shear behavior of large diameter short stud connectors. • Several influences on the shear behavior of large diameter short stud connectors were explored. • The formula for predicting the shear bearing capacity of large diameter short stud connectors in steel-thin UHPC bridge deck was verified. [ABSTRACT FROM AUTHOR]

Since 3D printed concrete has a promising application in engineering, the combination of 3D printing concrete and other building materials has become a hot research topic.This paper investigates the shear properties of 3DPM-NM specimens which use 3D printed mortar (3DPM) as the precast part and normal mortar(NM) as the cast-in-place part. Four different types of interfacial locking design were analyzed in this paper, including L-shaped, C-shaped, S-shaped and K-shaped. The shear damage law of the specimens was analyzed using digital image correlation (DIC) technology. The results show that L-shaped specimens are basically damaged along the shear surface during the loading process. Most of the initial cracks in the C-shaped, S-shaped and K-shaped specimens appeared along the interfacial bonding surface during the loading process. Then, the cracks in the C, S and K-shaped specimens continued to develop along the interfacial bonding surface or spilt through the specimens directly. The results show the shear properties of the C-shaped specimens are similar to those of L-shaped specimens. And the mechanical properties of S-shaped and K-shaped specimens are better than those of L-shaped specimens which increased by 96% (S-shaped), 78% (K-shaped) respectively. The mean slip is increased by 10% in S-shaped specimens and 28% in K-shaped specimens compared with that of L-shaped specimens. According to the AASHTO GSCB INTERIM-2003 specification, the modified formula for the shear bearing capacity of 3DPM-NM specimens is proposed in this study. The calculated resultsare in good agreement with the test results, which theoretically provide guidance for the application of 3DPM, lay the foundation for its feasibility as a structural body of a building. • Specimens with 3D printed mortar (3DPM) as a precast component and normal mortar(NM) as a cast-in-place part were tested. • Comparison of the shear performance of specimens with different types of interfacial locking design were conducted. • Theoretical analysis and modified calculations of shear strength for 3DPM-NM interfacial locking specimens were carried out. [ABSTRACT FROM AUTHOR]

• A novel perforated steel plate (PSP) shear connector used in modular steel channel–concrete composite floor systems was developed. • Push-out tests were conducted on 15 PSP shear connectors with different parameters. • The failure modes and working mechanisms of PSP shear connectors were studied. • An equation for predicting the shear capacity of PSP shear connectors was proposed. This study aims to investigate the shear behavior of perforated steel plate (PSP) shear connectors used in a novel modular steel channel–concrete composite floor (MSCCF) system, designed to eliminate in-situ wet construction and expedite assembly. Within this context, to understand the efficiency of these PSP connectors, fifteen PSP connectors were experimental evaluated through push-out tests, investigating variables such as PSP thickness, opening diameter, load-bearing area of PSPs, strength of PSPs, concrete strength, and the number of PSPs. Finite element analysis was also performed via ABAQUS to further reveal the working mechanism of PSP connectors. The test results showed that thin PSP connectors failed mainly due to flexural-shear failure or fracture, whereas thicker PSP connectors failed from concrete crushing. Despite the connectors exhibited high shear strength, their characteristic slip varied between 2.32 to 5.35 mm, not meeting the 6 mm ductility requirement for shear connectors in Eurocode 4. An upward trend in shear capacity was observed with increasing PSP thickness, yet a compromise in ductility. Furthermore, opening diameters influenced both shear stiffness and ductility. The spacing between PSPs also played a pivotal role in determining shear capacity. A small spacing induced overlapping concrete stress fields between each PSP layer, resulting in a reduction in shear capacity. An equation to predict the shear capacity of PSP connectors, accounting for PSP-concrete interaction, was developed. The shear capacity values calculated from the equation aligned well with the test results, highlighting the potential and design considerations of PSP connectors in MSCCF systems. [ABSTRACT FROM AUTHOR]

In this study, the coupled FEM-DEM method (FDEM) is adopted to investigate the mechanical response of grouted joint. To realistically capture the post-peak mechanical performance of grouted joint, an improved T-S model is developed by transforming the classical bilinear T-S model into an elastic-brittle T-S model. The validation results show that the improved T-S model can accurately describe the mechanical response of grouted joints under various normal loading conditions. Then, several compressive-shear simulations on grouted joint with different Joint Roughness coefficients (JRC s) and normal loads (F s) were conducted based on the proposed model. Finally, comprehensive analysis was made to study the effects of JRC and F on the deformation characteristics and mechanical behavior of grouted joint. The results indicate that as JRC ranges from 6.57 to 19.1, the cohesion and internal friction angle exponentially increase by 30.8% and 13.4%, respectively. Moreover, JRC has a significant influence on shear displacement corresponding to peak strength, cohesion, and internal friction angle, while F strongly affects with shear displacement corresponding to peak strength and peak shear strength. [ABSTRACT FROM AUTHOR]

Cemented Paste Backfill (CPB) technology has been effective in using the tailings to refill the underground cavities. The wet or dry rock surface can significantly affect the stability of the CPB-Rock interface, and the shear load-bearing capacity of CPB-Rock interface always reflects the overall stability of the filled underground cavities. Therefore, clear understanding on the shear behavior of the CPB-Rock interface with wet or dry rock surface is very important. To investigate the shear behavior of CPB-Rock interface with different rock surfaces (wet and dry), an apparatus for shear tests at CPB-Rock interface was constructed by modifying the servo-controlled GCTS (Geotechnical Consulting & Testing System) loading frame. Over 72 CPB-Rock samples with dry and wet rock surfaces were tested under four confining pressures (0, 50, 100 and 150 kPa) and different curing time (1, 3, 7 days). The findings show that, under the same confining pressure and curing time, the shear strength of the CPB-Rock interface with the dry rock surface is much larger than that of the wet one. Furthermore, with the increase of the curing time under a same confining pressure, the increase of shear strength on the dry rock surface is also larger than that of the wet one due to the presence of water film on the wet rock surface. The shear strength is enhanced with the increase of confining pressure. Further, the testing results were analyzed within the framework of the Mohr-Coulomb criterion, which comply with the corresponding theoretical curve. It is concluded that the dry rock surface is essential to the stability of the filled underground cavities. In case of wet environment for the underground cavities, it is important to find ways to dry the rock surface before carrying out back filling using CPB method. Unlabelled Image • NA testing apparatus was modified to test the shear behaviors of the CPB-Rock interface. • The interactions between different rock surfaces and CPB were analyzed using SEM method. • Dry rock surface is more sensitive to the curing time than wet rock surface. • The changes of shear parameters were given and discussed under different curing time and rock surfaces. [ABSTRACT FROM AUTHOR]

In design, internal stability of EPS lightweight fills are provided either by applying load distributing mechanisms (thick pavements or concrete slabs) or using more strong lightweight material through denser EPS geofoam blocks. However, unit weight of the EPS geofoam is a limited parameter. As an attempt to improve the mechanical properties of EPS geofoam, geocell-geofoam composite (GGC) is introduced in this study. Geocell mattresses were infilled with solidified geofoam beads in the factory to fabricate GGC. The EPS geofoam and GGC samples were tested using a large-scale shear test apparatus of size measuring 1 m3. Results indicate that inclusion of the geocell leads to a considerable increase in the shear strength and a great decline in the compressibility of the geofoam. In comparison with EPS blocks, up to 72% rise in the shear strength and 67% decline in the vertical displacement were observed in GGC samples at the normal stress of 35 kPa. In addition, incorporation of the geocell was found to change the resisting mechanism of the EPS geofoam from cohesive to cohesive-frictional. While there was only 4.5% decline in the cohesion, the internal friction angle of the tested geofoam increased six-fold due to the involvement of the geocell. • Large cubic blocks (99 cm × 99 cm × 99 cm cube) of EPS geofoam were fabricated. • Mattresses of geofoam-geocell composite (GGC), were fabricated in the factory. • Samples of EPS geofoam and GGC blocks were tested using a large-scale (1 m3) direct shear apparatus. • Inclusion of geocell significant rises the shear strength and declines the compressibility of EPS geofoam. • Inclusion of geocell changes the geofoam from a cohesive to a cohesive-frictional material. [ABSTRACT FROM AUTHOR]

The utilization of Fiber-reinforced concrete (FRC) in the construction of Precast segmental concrete bridges (PSCBs) is progressively increasing. The design of joints among precast members can considerably impact the overall integrity and safety of the structure. Consequently, accurately estimating the shear capacities of FRC joints has become critical for evaluating the safety of PSCBs structures. However, the effectiveness and efficiency of formulas or models intended for prediction of the shear capacities of joints with normal concrete are unknown in predicting the shear capacities of FRC joints. In this study, the machine learning (ML) algorithms are employed to predict the ultimate load of FRC joints, utilizing a database of 192 push-off test results. Three individual models (Lasso, SVM, and KNN) and three ensemble models (RF, GBDT, and XGBoost) were developed for estimating the ultimate load. The GridSearchCV technique was utilized for parameter optimization based on the training set, in conjunction with a five-fold cross-validation method. A comparative study revealed that the XGBoost ensemble model surpassed other models, with a predictive performance ranking as follows: XGBoost > GBDT > RF > KNN > SVM > Lasso. The best-performing XGBoost model achieved performance metrics of R 2 = 0.964, MAE = 41.318 kN, RMSE = 56.760 kN, and MAPE = 14.228%. The superior reliability of the XGBoost ensemble model was further validated through comparisons with current design codes and existing models. As ML-based models are typically black-box models, the SHapley Additive exPlanations (SHAP) method was employed to explicitly link the predicted output to the inputs. Based on SHAP results, confining stress (CS), depth of shear key (D), compressive strength of concrete (f cu), total height of joints (H), and height of flat part (H sm) recognized as the crucial parameters affecting ultimate load. • This study applies ML algorithms to predict the ultimate load of Fiber-Reinforced Concrete joints for the first time. • The performance of six ML algorithms, including Lasso, SVM, KNN, RF, GBDT, and XGBoost, was evaluated and compared. • this study compares the performance of machine learning models with design code provisions and other models. • The Shapley Additive Explanations method was used to identify crucial parameters affecting ultimate load. [ABSTRACT FROM AUTHOR]

Conserving the ecosystems of the globe, protecting natural resources, and improving environmental conditions can all be achieved by considering sustainability in the construction industry. Recycling of building and demolition waste is one of the key approaches being investigated to accomplish this target. Twelve reinforced concrete (RC) beams were constructed for the current study in order to analyze the shear behavior of recycled aggregate concrete (RAC) beams externally strengthened with carbon fiber reinforced polymer (CFRP) sheets. The main goal of the experimental matrix was to investigate the effect of the recycled aggregate ratio on the shear response of RAC, where three recycled coarse aggregate ratios of 20%, 60%, and 100% were suggested. Additionally, the effects of incorporating two or four CFRP strengthening layers on the ultimate load, failure pattern, load-deflection responses, and stiffness of RAC beams were also investigated. Results revealed that, when different ratios of recycled aggregate estimated at 20%, 60%, and 100% were substituted for natural aggregates, the compressive strength decreased by 4.3%, 24.2%, and 40.0%, respectively, compared to natural aggregate concrete. Moreover, the RC beam that was cast utilizing 20% recycled aggregates and strengthened with four CFRP sheets exhibited the highest ultimate load among all the tested RAC beams of 84.8 kN, which was 22.9% higher than the un-strengthened specimen totally cast with natural aggregate. Furthermore, a three-dimensional (3D) non-linear finite element model (FEM) was constructed using the ABAQUS program in order to compare the effects of employing continuous CFRP sheets for the whole critical shear span length to intermittent strips that had been experimentally tested. • The compressive and splitting tensile strengths of concrete with 20%, 60%, and 100% RA was studied. • The shear behavior of RAC beams externally strengthened with CFRP sheets was investigated. • Non-linear 3D finite element model (FEM) was constructed using ABAQUS/standard. • The effects of the recycled aggregate ratio and number of strengthening CFRP layers on the load were considered. • Specimen cast utilizing 20% RA and strengthened with four CFRP sheets exhibited the highest ultimate load of 84.8 kN. [ABSTRACT FROM AUTHOR]

The application of externally bonded fiber-reinforced polymers (EB-FRP) is known to improve the shear behavior of reinforced concrete beams. Nevertheless, the studies available in the literature are not sufficient to explain the shear behavior of the beams that have low shear span to effective depth ratios (a v /d) and are strengthened with FRP and the interaction between the horizontal steel shear reinforcement and FRP strips. To fill these gaps in the literature, an experimental study involving twenty-two tests of deep beams with a low a v /d and with different amounts of vertical and horizontal steel shear reinforcement was carried out. Both unstrengthened and strengthened with fully wrapped FRP strips beams were tested where the number of FRP layers, the spacing between them and the type of FRP material were varied. The experimental results showed that the FRP strips improved the shear and ductility capacities of beams with low a v /d. In addition, as the vertical shear steel reinforcement ratio in the beams strengthened with FRP strips increased, the percentage increases in the shear and deflection capacities decreased. Also, as the horizontal shear steel reinforcement ratio in the strengthened beams increased, the percentage increase in the shear capacity increased. Finally, a new equation was proposed to estimate the FRP contribution to the shear capacity. To prove the reliability of the proposed equation, a comparative study was conducted using twenty existing equations. • The effect of the interaction between horizontal or vertical shear reinforcement and fiber-reinforced polymer strips on the experimental results is shown. • The effect of the experimental parameters associated with fiber reinforced polymers on deep beams is determined. • A new equation is proposed that calculates the contribution of fiber-reinforced polymer strips to the shear capacity of the beam. [ABSTRACT FROM AUTHOR]

• Shear behavior of reinforced concrete beams with inclined pre-cracks was studied. • Digital image correlation was used to analyze the crack growth and kinematics. • An explanation for the effect of inclined pre-cracks on shear capacity was given. • The effect of inclined pre-crack to failure mode was studied. Extended growth of existing cracks in reinforced concrete (RC) structures may negatively impact structural performance and cause great risks to structural safety. However, the influence of inclined pre-cracks on shear behavior of RC structures as well as the mechanism behind it are still unclear. In this paper, an experimental investigation is conducted in order to study the correlation between inclined pre-cracks and the shear behavior of RC beams without transverse reinforcement. Eight beams with identical geometric designs and different pre-cracking conditions were categorized into four series and successfully tested: (i) reference beams without pre-cracks, (ii) beams with pre-cracks in the bending span induced via loading, (iii) beams with pre-cracks in the shear span induced via loading, and (iv) beams with artificial pre-cracks in the shear span. The deformation and strain fields were measured by digital image correlation (DIC) technique with a strong focus on the shear-transfer mechanism and cracking propagation. The obtained results reveal that inclined pre-cracks in the bending span may not develop into the critical shear crack (CSC) and exert minor effects on the shear capacity. In contrast, pre-cracks near supports within the shear span tend to develop into the CSC and influence its path and kinematics. This further affects the activation of arch action and aggregate interlock, ultimately resulting in a 3–24% reduction in the load-bearing capacity of this series compared to the reference beams. To summarize, this study reveals the relationship between inclined pre-cracks and shear behavior of RC structures, providing new insight for assessment. [ABSTRACT FROM AUTHOR]

• This study proposed a novel kind of wet joint with UHPC shear keys to connect prefabricated composite beams. • The effects of different parameters for UHPC shear key on strengthening shear performances of wet joints were investigated. • The failure mechanism of novel UHPC shear key joints was clarified in detail. • The calculation formulas considering different factors were established to design and optimize the prefabricated composite beams. Ultra-high-performance concrete (UHPC) has excellent mechanical properties, which could be used in the connecting region between different prefabricated members to improve the continuity and integrity of prefabricated composite structures. In this paper, a novel kind of wet joint with UHPC shear key was proposed to connect different prefabricated components for assembled steel–concrete composite beams, and the effects of different parameters for UHPC shear key on strengthening shear performances of wet joints were evaluated via a series of push-out tests. Results indicated that the specimens with wet joints mainly failed and slipped in the precast and post-cast concrete interface under the longitudinal force. The application of the UHPC shear key could significantly increase the ultimate shear strength of the interface compared to the single layer of extended reinforcements, and the UHPC shear key with embedded short reinforcements could further improve the shear resistance and ductility to ensure the composite action between the precast slab and wet joint. Compared with the dual layers of extended reinforcements, the combination of the UHPC shear key and short straight steel bar presented a better performance in strength under a relatively lower slip level. In addition, the increase in width was helpful for enhancing the shear strength of the UHPC shear key, but the shear keys with the larger width might cause the failure of the precast part between two UHPC shear keys prior to the UHPC shear keys so limiting the strength development of interface, thus the reasonable design size of the shear key should be selected depending on the precast and post-cast concrete strength. Furthermore, an equation for the wet joint with UHPC shear key was proposed, which considered the proportion of effects of different factors such as the interface bonding strength, interface friction, extended reinforcement, negative bending moment, UHPC shear key and embedded short straight steel bar on the longitudinal shear behavior of UHPC wet joints. [ABSTRACT FROM AUTHOR]

The interaction between cemented paste backfill (CPB) and rock at their interface plays a crucial role in the stability of underground backfill structures. Considering the interface roughness could have a significant influence on the shear behavior and mechanical properties of the interface, a series of laboratory direct shear tests were carried out on the CPB-rock interface with various roughnesses. The results indicates that the interface roughness and normal stresses have a remarkable effect on the interfacial shear behavior, with typical stress-shear displacement curves that could be classified into three types depending on the peak and post-peak characteristics. Compared to the smooth interface, the shear strength increases with increasing roughness, owing to the enhancing interlocking effect, which is confirmed by digital image correlation (DIC) in micro views. In addition, the shear contraction observed at the smooth interface changes to shear dilatation at the rough interface, which is caused by wider distribution and higher adhesion of CPB asperities, as observes by using 3D laser scanning technology. Furthermore, a theoretical model for the shear strength, taking into account the influence of interface roughness, is developed to assess its effect on shear strength. The experimental results and the theoretical model presented in this paper will contribute to better understand the interaction mechanism and predict the shear strength of the interface. • The stress evolution could be classified into three types depending on the peak and post-peak characteristics. • The failure process of interface could be analyzed by using the DIC technique. • A theoretical model considering the influence of interface roughness is established to assess its effect on shear strength. [ABSTRACT FROM AUTHOR]

High-strength steel and ultra-high-performance concrete (UHPC) can increase structural resistance and reduce material consumption efficiently. However, current design specifications do not permit the use of them in concrete-filled steel tube members due to the lack of research. To address it, this paper experimentally investigates the shear behavior of square ultra-high performance concrete-filled high-strength steel tube (referred to as C u FT h hereafter) members. A total of 20 C u FT h specimens were tested, considering the effects of the span-to-depth ratio, width-to-thickness ratio of the steel tube, yield stress of steel, and fiber volume content of UHPC. The test results showed that: (i) the failure mode was governed by the shear span-to-depth ratio (a/H), including shear failure (a/H = 0.2 or 0.5) and combined shear-flexural failure (a/H = 0.8 or 1.0); (ii) the shear strength increased with decreasing shear span-to-depth ratio and the width-to-thickness ratio of the steel tube; (iii) increasing the yield stress of steel and fiber volume content of UHPC improved the shear strength. The applicability of current specifications for estimating the shear strength of square C u FT h members was evaluated. It was shown that CECS 28 (CECS 2012) had the most reasonable estimation. • The failure modes of C u FT h members and concrete infill were governed by the shear span-to-depth ratio (a/H). • The C u FT h members included shear failure (a/H = 0.2 or 0.5) and combined shear-flexural failure (a/H = 0.8 or 1.0), while the concrete infill included combined shear-compressive failure (a/H = 0.2 or 0.5) and combined shear-tensile failure (a/H = 0.8 or 1.0). The shear strength increased with decreasing the shear span-to-depth ratio and the width-to-thickness ratio of the steel tube. • Moreover, increasing the yield stress of steel and fiber volume content of UHPC improved the shear strength. [ABSTRACT FROM AUTHOR]

To address the deficiencies in the durability of the bonded connection, an innovative strengthening method combining steel plates with UHPC (ultra-high-performance concrete) is proposed. In this method, the UHPC layer is located between the steel plate and the original damaged RC (reinforced concrete) structures, mainly acting as a binder to enhance the bonding effect. To verify the effectiveness of the proposed method, five RC beams are manufactured and carried out to investigate the shear characteristics and capacity. In this experiment, some factors that may affect the strengthening effect are considered, such as the initial damage degree (represented by different crack widths), steel plate thickness, and strengthening method (two-side or one-side). The experiment results show that the proposed strengthening method can significantly improve the shear capacity (increased by at least 56%) of pre-damaged RC beams without significantly enlarging the cross-section and self-weight. In addition, during the load test, there is no peeling phenomenon for the steel plate-UHPC interface and the UHPC-RC interface. This demonstrates that it is feasible for the UHPC layer to replace epoxy resin glue as a bonding agent to enhance the bonding effect between steel plate and RC. The proposed strengthening method shows promising applications in strengthening old/defective bridges. Moreover, a simple formula for predicting the shear-bearing capacity of strengthened beams is derived. The shear-bearing capacity predicted by the proposed formula is in good agreement with the experimental results. • An innovative SURC strengthening technique for improving the shear behavior of damaged RC/PC bridge is proposed. • SURC strengthening technique can better enhance the shear capacity and inhibit the crack development of damaged RC beams. • UHPC in SURC strengthening technique can be used as a binder to ensure collaborative action at a high level. • Proposed formula for the shear capacity of SURC strengthening technique has an acceptable accuracy. [ABSTRACT FROM AUTHOR]

• Dovetail joints show a 13–51% higher maximum strength performance than straight joints. • The toughness of the dovetail joints was 2–35% higher than straight joints. • Stress analysis of the dovetail joints shows a significant decrease in maximum normal and shear stresses compared to standard joints with tenon height between 15 mm and 30 mm and angles of approximately 70° − 80°. The increase in the size of composite sandwich structures requires the introduction of core splices to join various segments. In this study, a novel core splice joint configuration is studied and proposed for composite sandwich structures of thick aluminum-based honeycomb core and facesheets made from carbon fibers and epoxy matrix. Experimental and numerical efforts investigate the impact of dovetail joints with different tenon angles on the auxiliary behavior of composite sandwich structures. The results are compared to conventional or straight-core splices without dovetail features. The core-splice interaction with the complete mechanical behavior of the system was assessed by subjecting the fabricated specimens to combinations of bending and shear forces. Additionally, 3D-finite element models compared normal and shear stresses in the splice material and the core/splice interface among the dovetail configurations considered. The study shows that depending on the dovetail joint detail, an ultimate strength increase between 13 and 51% is achieved compared to the strength from currently used straight joints. In terms of toughness, the dovetail specimens show a 2% to 35% higher toughness compared to the standard straight joints. [ABSTRACT FROM AUTHOR]

Process design of a waterless single screw extrusion of pasta-filata cheese was established based on the material properties during the major steps plasticization, conveying and texturization. Thermo-rheological properties of model cheese curds (pH 5.8 adjusted by citric acid) were determined by small amplitude oscillatory strain experiments (20 – 80 °C) to narrow a promising range of the process temperature ϑ process. It was shown that ϑ process should be set according to the following relation: ϑ gel-sol (full plasticization) ≤ ϑ product ≤ ϑ tanδmax (peak flowability). Critical shear rates (γ ˙ crit) of plasticized model cheese were analyzed by a capillary rheometer and translated to the screw speeds (SS) by considering the default configuration of the waterless extruder. Upscaling of process conditions was evaluated with regards to product homogeneity and chemical composition, resulting in the most promising parameters, ϑ process = 63 °C and SS = 10 rpm. Experiments using fermented and ripened cheese curd (pH 5.0) corroborated the proposed process design strategy. • New waterless single screw extruder for pasta-filata cheese. • Process design based on major steps: plasticization, conveying and texturization. • Thermo-rheology and shear behavior were analyzed to set process parameters. • Feasibility study on ripened cheese curd (different thermo-rheological properties). [ABSTRACT FROM AUTHOR]

• Considering static test results, optimum amount of GRP fraction is 20%. • As GRP increases, the internal friction angle rises and then decreases, but cohesion decreases. • For either cases of static or repeated loading, compaction barely influences stiffness. • GRP inclusion leads to greater permanent displacement under repeated loading. • Utilizing GRP is not recommended when large amplitudes of repeated loading are expected. The increase of rubber wastes, especially in the form of used tires has become a serious environmental challenge. In this research, the effect of granular rubber particles (GRP) as an additive (up to 50%) was investigated on the behavior of clayey soil under repeated loading using direct shear apparatus. Effect of different parameters were investigated such as GRP percent, unloading/reloading amplitude, number of cycles, normal stress and compaction. With increasing GRP, cohesion constantly decreases but internal friction angle raises at first and slightly decreases after 20% weight fraction of GRP. It was observed that increasing GRP weight percentage leads to higher permanent horizontal displacement and increase of hardening behavior under high normal stresses. The study also revealed that compaction has a negative effect on post-repeated loading shear strength which is an economical point in projects. [ABSTRACT FROM AUTHOR]

• The deflecting shape, bending angle and failure characteristic of the bolts were described and analyzed in detail. • The effect of bolting angles and grout strengths on the bolt contributions was determined quantitatively. • Bolt deflecting behavior near the rock joint was clearly reveal by the strain monitoring. • The founding refines the understanding of the failure mode of sheared bolts in weaker rock. Failures of fully grouted bolts due to the combination of tensile and shear loads are commonly observed, but the bolting mechanism is not clearly revealed. Direct shear tests were conducted on three groups of specimens with different bolting angles or grout strengths, and shear loads, shear displacements and bolt strains were measured. The deflecting shape, the bending angle and the failure characteristic of the bolts were described in detail. The relationship between the shear load and the shear displacement was analyzed, and the internal forces were determined according to the bolt strains or the shear displacement of the joint. The test results show that the bolting angle and grout strength play significant roles in influencing the bolt contribution. With increasing the bolting angle, the bolt contribution rises first and then reduces, and they obey a parabola relationship. Particularly, the contribution of the bolt is less than its ultimate tensile load by a large margin when the bolt steeply intersects the rock joint. A higher shear contribution will be mobilized in a weaker grout. It is also observed that the failure of the bolt occurs at the bolt-joint intersection rather than at the two plastic hinges. [ABSTRACT FROM AUTHOR]

• The shear behavior of three types of RAC was investigated. • The effect of content and type of RCA on shear behavior of RAC were analyzed. • The shear stress-strain constitutive models for three types of RAC were proposed. • Four calculation formulas for shear modulus of RAC were established. This paper studied the shear behavior of three types of recycled aggregate concrete with different replacement levels of recycled coarse aggregate. Sixty cube specimens and thirty beam specimens with uniform depth and varying width were designed to test their mechanical parameters including cube compressive strength, splitting tensile strength, shear strength, peak shear strain, shear stress-strain curves, and shear modulus. We analyzed how these parameters are influenced by the type of recycled coarse aggregate and by recycled coarse aggregate replacement level. We established the strength conversion equations, one-parameter polynomial non-dimensional shear stress-strain equations, and shear modulus calculation formulas of three types of recycled aggregate concrete. It is found that the strength of recycled aggregate concrete I isslightly lower than that of conventional concrete and decrease with the increase of recycled coarse aggregate replacement level. However, the strength of recycled aggregate concrete II and recycled aggregate concrete III is slightly higher than that of conventional concrete when the recycled coarse aggregate replacement ratio is less than 70%. As the recycled coarse aggregate replacement ratio increase, the peak shear strain of three types of recycled aggregate concrete gradually decreases. The shear strength and peak scant shear modulus of three types of recycled aggregate concrete show the rule of recycled aggregate concrete III > recycled aggregate concrete II > recycled aggregate concrete I. Furthermore, the calculated values of several equations established by the authors agree well with the test values. [ABSTRACT FROM AUTHOR]

Most soft interlayers tend to be key factors affecting rock slope stability due to their low strengths. A series of ring shear tests is conducted on reconstituted overconsolidated soft interlayers to investigate the influences of remolded water content and normal stress on shear behavior under drained conditions. The soft interlayer raw samples taken from a potential landslide site in China are first remolded into overconsolidated samples with different water contents but the same dry density and further drained under different normal stresses. The peak strength, residual strength, corresponding shear displacement of the soft interlayers and the loss rate of water content are positively correlated with water content and normal stress. Transformation of strain softening to strain hardening occurs for samples under higher normal stresses. Variations in water contents have notable effects on the shear strengths. Meanwhile, displacements, fragmentations and orientations of samples differ, showing strain softening and hardening behaviors of soft interlayers. • Stress-strain characteristics of soft interlayers are systematically investigated. • Ring shear test is utilized successfully for shear behavior studying. • Variation in compaction moisture content has an obvious effect on shear strength. • Shear behaviors are closely related to the microstructure of soft interlayers. [ABSTRACT FROM AUTHOR]

Abstract The mechanical behavior of carbonate sand reinforced with horizontal layers of geotextile is invetigated using a series of drained compression triaxial tests on unreinforced and reinforced samples. The main factors affecting the mechanical behavior such as the number of geotextile layers, their arrangement in specimens, confining pressure, particle size distribution, geotextile type and relative density of samples were examined and discussed in this research. To make a precise comparison between the behavior of reinforced siliceous and carbonate sand, triaxial tests were performed on both types of sands. Results indicate that geotextile inclusion increases the peak strength and strain at failure, and significantly reduces the post-peak strength loss of carbonate specimens. The amount of strength enhancement rises as the number of geotextile layers increases while two other parameters including confining pressure and particle size affect adversely. The strength enhancement of reinforced carbonate sand is greater than the corresponding siliceous sample at high axial strains. Reinforced and unreinforced carbonate specimens exhibit more contractive behavior than their corresponding siliceous samples and tend to dilate at higher axial strains. By increasing the relative density of the samples, the peak strength of reinforced specimens rises due to enhanced interlocking between geotextile layers and sand particles. This process continues as long as the geotextile is not ruptured. The utilization of geotextiles with high mass per unit areas was found to be uneconomical due to slight differences between the strength augmentation of geotextiles with high and low mass per unit areas. It should be noted that geotextile layers limit the lateral expansion of specimens which leads to changing the failure pattern from a shear plane to bulging between the adjacent layers of geotextile. [ABSTRACT FROM AUTHOR]

• Dynamic shear behaviors of copper are studied from 6000 s−1 to 45,000 s−1 at different temperatures. • The effects of stress state and strain rate have been decoupled successfully at high strain rates. • The stress state effect on the plastic behaviors of copper are clearly exhibited. • The shear constitutive model shows much better performance than the compression model. • The stress state should be considered in the selection of constitutive model for engineering computation. Abstract A new double shear specimen (DSS) is used under the traditional Split Hopkinson pressure bar (SHPB) technique to study the constitutive behaviors of pure copper under dynamic shear loading. Shear stress-shear strain curves are obtained at 288–673 K and in a wide range of shear strain rates between 6000–45,000 s−1. A shear dominated stress state is obtained in the shear zone, in which the stress triaxiality and the Lode angle parameter are both very low. The influence of stress state on the plastic flow properties of the material is observed through comparison of the test results with the experimental data in compression. With the aid of finite element analysis (FEA), it's seen that the determined constitutive model JC1 can give much more precise prediction on the shear testing results than the compression-based model, JC2. The result implies that the commonly adopted compression or tension test data may not be suitable for description of shear dominated deformation conditions. In engineering application, the actual stress/strain state must be considered in the determination or selection of the constitutive models to obtain a precise computation result. [ABSTRACT FROM AUTHOR]

• Shear behavior of HFRP reinforced concrete beams without stirrups was studied. • The span-to-depth ratio has significant influences on the shear behavior of beams. • A calculation method was proposed about the shear capacity of FRP reinforced concrete beams without stirrups. This paper investigated the shear behavior of carbon/glass hybrid fiber reinforced polymer (HFRP) bars reinforced concrete beams without stirrups. Seven beams with different span-to-depth ratios were tested under four-point loading. Results showed that the span-to-depth ratio had a significant effect on the shear behavior of the beams. According to the test data in this study and published relevant literature, a database containing 468 specimens was established to conduct an in-depth study of the factors that affect the shear capacity of FRP reinforced concrete members without stirrups. By comparing the predicted shear capacity of specimens according to the existing specifications and models with the experimental results in the database, it was found that the predicted results were relatively discrete. The factors influencing shear capacity considered by the specifications and proposed models are inconsistent, and the influence of the span-to-depth ratio was not taken into account. On this basis, a more comprehensive calculation method that considers the influence of span-to-depth ratio was proposed to predict the shear capacity of FRP reinforced concrete beams and presented better prediction results within the experimental. [ABSTRACT FROM AUTHOR]

• The shear performance of a novel single-box double-chamber steel-bamboo composite (SBC) beam was investigated. • The nonlinear analytical models were developed to predict the shear stress of the section and shear capacity of the SBC beam in the ultimate limit state (ULS). • The nonlinear constitutive law of the SBC beams was considered. This study reported the findings of experimental and nonlinear analytical investigations of the shear performance of novel single-box double-chamber steel-bamboo composite (SBC) beams. Eight SBC beams with various parameters were prepared, and then the shear tests were performed to evaluate the shear behavior of the beams. The experimental performances, failure modes, and mechanical behavior were observed and analyzed based on the experimental phenomena and data. The influences of different parameters on deformation behavior, failure modes, and shear capacity were revealed, and analytical models were developed for estimating shear stress and shear capacity in the ultimate limit state (ULS). The results demonstrated that (1) the shear behavior of the beams was excellent, and lateral instability and local buckling behaviors were effectively avoided, the steel and bamboo can maintain excellent synergy and function together before the beams failed; (2) two failure modes were identified, primarily determined by the shear span-to-depth ratio; (3) shear resistance was improved by reducing the shear span-to-depth ratio and steel height/thickness ratio, and increasing the flange bamboo width/thickness ratio and height of the web; (4) the analytical models provided accurate predictions for the beams, and the largest discrepancy was controlled within 10%. [ABSTRACT FROM AUTHOR]