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Sulphate attack is a major cause of concrete deterioration in marine environments and its interaction with wave-induced cyclic loading exacerbates the damage. This study has evaluated strengths and fatigue performance (i.e. fatigue life, strain and residual displacement) of sulphate-attacked concrete containing silicomanganese slag, fly ash (FA) and silica fume (SF). Compressive strength, tensile strength and sulphate profile of sulphate-attacked concrete were measured experimentally. Sulphate-induced damage constitutive relations were formulated and used with concrete damaged plasticity (CDP) model to simulate fatigue loading. Experiment showed that incorporating silicomanganese slag lowered sulphate resistance by 4.8–6.6% due to increased sulphate intrusion, but synergy with FA and SF enhanced the resistance by 7.3–13.8% at 365 days. The sulphate penetration depth was 0–20 mm, and the intruded sulphate increased exponentially over time. To evaluate fatigue loading in CDP model, the non-uniform damage was determined as correlation between strength degradation and integral area of sulphate profile. Numerical results were in good agreement with experimental data from literature, with differences of 5.8–26.2% in fatigue life, 9.1–30.1% in fatigue strain and 18.1–41.9% in residual displacement. In long-term deterioration, numerical analysis found that increasing sulphate concentration significantly shortened fatigue life. Despite silicomanganese slag lowered concrete sulphate and fatigue resistance, the inclusion of FA and SF improved the durability and sustainability of concrete for potential marine applications. [ABSTRACT FROM AUTHOR]

The mechanical properties and fracture behavior of concrete are controlled by aggregate characteristics, and the distribution of aggregates is uncertain. Traditional studies on concrete crack propagation mainly conduct deterministic analysis based on the position and size of the aggregates, rarely considering the uncertainty of aggregate distribution. Based on the Peridynamics (PD) theory, random distribution functions are introduced to describe the geometric characteristics and positional parameters of concrete aggregates. Simulating the effect of random distribution of aggregates on concrete crack propagation by presetting random aggregates. For the first time, the Boundary Damage Ratio (BDR) is proposed to quantitatively describe the influence of cement mortar and aggregate on crack propagation, revealing the influence rules of random aggregate parameters on concrete damage provides a new method for studying concrete crack propagation. The research results show that the size and position of aggregates determine the crack propagation path during concrete failure. The BDR can indicate the quality of the concrete grading and the intensity of the aggregate's guiding effect on crack propagation. It was found that the aggregate size and the BDR follow a Weibull distribution; the larger the aggregate size, the smaller the shape parameter. [ABSTRACT FROM AUTHOR]

This paper showcases shear testing conducted on seven reinforced concrete deep beams featuring square openings, aimed at demonstrating the efficacy of a shear strengthening approach utilizing textile-reinforced concrete (TRC). This experimental program researches two types of openings of 150 × 150 mm and 200 × 200 mm at the centre of the shear spans. The solid beam undergoes testing for comparison with both the unstrengthened and strengthened beams containing openings. The study evaluates the effectiveness of TRC through a comparison of load-displacement curves, cracking patterns, and strains in reinforcements between the strengthened and un-strengthened beams. The experimental results indicate that the TRC strengthening technique effectively boosts the shear-carrying capacity of beams. Examination of the tested beams reveals a significant enhancement in stiffness at the point of maximum force, with improvements ranging from 22% to 86%, depending on the opening size and the number of reinforced textile layers. Rupture in TRC and crushing in the concrete strut are observed in the strengthened beams, whereas the un-strengthened beams show severe crushing in concrete at failure. The test results are compared with calculations based on code provisions, revealing that the prediction model consistently yields values 11 to 44% higher than the experimental results. [ABSTRACT FROM AUTHOR]

This paper establishes fatigue life prediction models using the soft computing method to address insufficient parameter consideration and limited computational accuracy in predicting the fatigue life of fiber-reinforced polymer (FRP) strengthened concrete beams. Five different input forms were proposed by collecting 117 sets of fatigue test data of FRP-strengthened concrete beams from the existing literature and integrating the outcomes from Pearson correlation analysis and significance testing. Using Gene Expression Programming (GEP), the effects of various input configurations on the accuracy of model predictions were examined. The model prediction results were also evaluated using five statistical indicators. The GEP model used concrete compressive strength, the steel reinforcement stress range ratio to the yield strength, and the stiffness factor as input parameters. Subsequently, using the same input parameters, the Multi-Objective Genetic Algorithm Evolutionary Polynomial Regression (MOGA-EPR) method was then employed to develop a fatigue life prediction model. Sensitivity analyses of the GEP and MOGA-EPR models revealed that both could precisely capture the fundamental connections between fatigue life and multiple contributing variables. Compared to existing models, the proposed ones have higher prediction accuracy with a coefficient of determination reaching 0.8, significantly enhancing the accuracy of fatigue life predictions for FRP-strengthened concrete beams. [ABSTRACT FROM AUTHOR]

The recycling of waste glass as an auxiliary cementitious material in concrete is a sustainable solution. However, it introduces a challenge in terms of the toughness of the resultant concrete. To address this, the present study investigated the enhancement of toughness in waste glass powder concrete through the incorporation of polyvinyl alcohol (PVA) fibers. The research assesses the compressive strength and splitting tensile strength of concrete samples containing waste glass powder and PVA fibers that were cured for 7 and 28 days, respectively. In addition, the microstructural characteristics and interfacial transition zones of the concrete were examined by scanning electron microscopy and energy-dispersive spectroscopy. These findings indicate that the integration of PVA fibers effectively mitigates the strength reduction in waste glass powder concrete. The optimal fiber concentration was identified as 1%, transitioning the failure mode of the concrete from brittle to ductile. The presence of PVA fibers does not alter the element type at the aggregate–cement matrix interface but influences the element content. The –C–OH groups in PVA fibers form hydrogen bonds with –OH groups in cement hydration products, aided by the non-circular cross section and molecular structure of the fibers, enhancing adhesion at the cement matrix interface. An appropriate amount of PVA fibers increases the Ca/Si ratio in waste glass powder concrete, reducing C–S–H production at the interfacial bond and thereby improving the internal structure of the concrete. However, excessive PVA fiber content diminishes these benefits. [ABSTRACT FROM AUTHOR]

Hydraulic concrete is quite different from normal concrete in the terms of aggregate gradation and construction-induced interfaces. To explore their influences on the dynamic mechanical behaviors of hydraulic concrete, several mesoscale numerical models with different aggregate gradations and interfaces were established and subjected to dynamic compressive or tensile loadings. The results show that aggregate gradation significantly affected hydraulic concrete failure patterns under dynamic loads, but interface effects were less obvious, and stressing uniformity improved with an increasing loading rate. The dynamic compressive and tensile strengths of hydraulic concrete showed a strain rate effect independent of gradation, but decreased with larger coarse aggregates, especially at higher rates. Weak-bonding interfaces significantly reduced strength at low loading rates, with a more pronounced effect on tensile strength than compressive strength. The results of this study provide a theoretical basis for the application of hydraulic concrete containing large-size aggregates in practical engineering. [ABSTRACT FROM AUTHOR]

To investigate the bond properties of concrete reinforced with fibre-reinforced-polymer bars (FRPBs) under different loads, FRPB-reinforced concrete specimens were subjected to pull-out tests. Three types of FRPBs were used in the experiment – ordinary steel rebars, carbon-fibre-reinforced polymer (CFRP) bars and glass-fibre-reinforced polymer (GFRP) bars. Pull-out tests were first conducted under monotonic load to determine the effect of concrete strength and reinforcement diameter on the bond performance of FRPB-reinforced concrete and steel-reinforced concrete. The variation in bond performance for the different reinforcements was investigated. Fatigue tests were then performed, followed by further pull-out tests to determine the bond stress–slip curves between concrete and reinforcements, and the influence of fatigue action on the bond stress–slip curve was then examined. Formulae to calculate the stress were developed, which can be applied to determine the bond failure pattern, bond strength and bond–slip curve. [ABSTRACT FROM AUTHOR]

The article discusses the stochastic modeling of structural fatigue damage in High Strength Steel structures, focusing on the probability of failure due to material fatigue. It explores computational models for predicting fatigue failure, including the Direct Optimized Probability Computation method. The study compares the results of Monte Carlo simulations with the DOProC method, demonstrating the effectiveness of parallel computing in reducing computation times while maintaining accuracy. The research aims to improve the prediction of fatigue damage in engineering structures, particularly those made of high-strength steel, for practical applications in civil engineering. [Extracted from the article]

In this study, an analytical model was developed for the local bond degradation behavior between a near-surface mounted (NSM) fiber-reinforced polymer (FRP) and concrete under fatigue loading. A trilinear local bond stress–slip relationship was adopted to characterize the fundamental bond behavior at the FRP-epoxy-concrete interface at different stages of elastic, softening and debonding. A series of post-fatigue direct pull-out tests (DPTs) of NSM FRP-bonded concrete blocks was conducted to provide the local bond degradation laws for the analytical model. The bond region was discretized into finite elements to include the effect of bond degradation to different extents, and a closed-form solution was derived by virtue of appropriate boundary conditions in each fatigue cycle. The model is capable of predicting the FRP strain distribution, local bond stress distribution and relative slip development at a targeted number of fatigue cycles. The reliability of the analytical model was confirmed by experimental data, and its sensitivity to various parameters such as local bond strength, the residual bond strength ratio and Young's modulus of FRP reinforcement was also assessed in this study. [ABSTRACT FROM AUTHOR]

In order to study the mechanical properties and stress–strain relationship of geopolymer lightweight aggregate concrete (GLAC), 13 groups of different mix proportions were designed. The influence of the binder ratio, alkali–binder ratio, alkali activator modulus, steel fiber volume content, coarse aggregate volume content, and water–binder ratio on the cube compressive strength, splitting tensile strength, flexural strength and axial compression performance of GLAC was analyzed. The failure process and characteristics of GLAC under axial compression were analyzed, the stress–strain curve of GLAC was obtained, and the calculation model for characteristic points and the piecewise constitutive model of GLAC are proposed. The results show that GLAC has the characteristics of being lightweight and having early strength. The dry apparent density of the prepared concrete is within the range of 1712–1902 kg/m3. The cube compressive strength at 3 days and 7 days can reach 45–85% and 66–98% of the 28-day compressive strength, respectively. The mechanical properties of GLAC increase with the increase of slag content, alkali–binder ratio, and steel fiber volume content, and decrease with the increase of the alkali activator modulus and the coarse aggregate volume content. Moreover, both overly high and overly low water–binder ratios will reduce the strength of GLAC. The failure mode of GLAC is aggregate fracture failure. Incorporating steel fibers can effectively improve the failure mode of the concrete. The proposed calculation model for characteristic points and the constitutive model can predict the axial compression behavior of GLAC relatively accurately. [ABSTRACT FROM AUTHOR]

The shear resistance performance of small shear stud in steel-concrete composite deck is examined through a series of push-out tests, involving four different small shear stud connectors. Particularly, the failure modes, load capacity, load-slip relationships, and load-strain relationships are explored. The applicability of current formulas used to predict bearing capacity and rigidity is evaluated based on test results. The results show that the failure mode is related to the relative rigidity between the shear stud and the concrete. Small-diameter studs tend to shrink, while larger-diameter studs lead to concrete failure. However, lengthening the shear stud can significantly enhance the bearing capacity and prolong the stiffness decay process of the shear stud connectors. When the length of the shear stud increases from 40 mm to 60 mm, the bearing capacity Pu increases by about 16.7% while the slip Su corresponding to the peak load decreases by about 25.3%, and the ultimate slip Sm increases by 38.5%. Additionally, the patterns of crack formation and failure modes in concrete slabs with small shear stud connectors deviate from those observed in traditional deep-embedded shear stud push-out samples. The existing capacity calculation formulas, as per Chinese and American standards, demonstrates substantial discrepancies. In contrast, as per Japanese and European standards, the ratios of calculated values to the tested values are average 0.94 and 1.09 respectively without considering the safety factor, offering better estimations of bearing capacity. It is recommended to use these methods for bearing capacity calculation. Lastly, the connector's rigidity in elastic stage is the greatest and the recommended formula in the Chinese specification could be effectively used to predict shear rigidity. Even though shear studs are subjected to a combination of bending, tension, and shearing forces, the shear force is the primary factor. [ABSTRACT FROM AUTHOR]

Steel fiber-reinforced concrete material has garnered significant attention in structure design due to its excellent resistance to fatigue damage. The application of the plain concrete microplane model is extended to steel fiber-reinforced concrete by modifying the stress-strain boundary conditions on the microplane and then extended to fatigue damage analysis by considering fatigue-related material stiffness, mainly concerned with tensile damage, mainly concerned with tensile damage. The normal positive strain on the micro-plane is regarded as the fatigue variable, and the fatigue history variable is the accumulation of the fatigue variable during the loading. The relationship between the fatigue history variable and the material stiffness fatigue degradation function is established. In the numerical implementation, the crack band model is combined to reduce the mesh sensitivity caused by strain localization. During the numerical simulation, the parameters of plain concrete, steel fiber-reinforced concrete, and the material fatigue degradation function can be calibrated sequentially, requiring only a few benchmark tests for accurate parameter calibration. The numerical results show that this model can be used for the fatigue damage analysis of plain concrete and steel fiber-reinforced concrete material. It is expected to be used for the refined analysis of concrete structures under complex loading conditions and structural forms in the future, providing convenience to engineering design, evaluation, and optimization. [ABSTRACT FROM AUTHOR]

The current codes and standards for the design of anchorages against concrete cone breakout failure require the base plate to be rigid such that each anchor is subjected to almost equal load under concentric tension, and there is a linear distribution of anchor forces for groups under eccentric tension or bending. These are the basic requirements for the application of concrete capacity design (CCD) method, but in many cases, satisfying these requirements may need a rather thick base plate, which gets impractical. Using the CCD method for design of anchorages with flexible base plates (resulting in nonlinear distribution of anchor forces) can lead to rather unsafe designs. In this article, a new method for design of anchor groups with flexible base plate is proposed that modifies the resistance obtained by the CCD method based on the anchor force distribution to obtain the resistance valid for the anchorages with flexible base plate. First, the analytical method is conceptualized for its validity on simple cases and then it is extended for its application to more complicated cases. The results of the calculation method are compared and validated by the results of few available tests and further on several cases analyzed using the nonlinear spring model. The comparison of results show that the proposed method is suitable for the design of anchor groups with any given base plate thickness that results in a linear or nonlinear anchor force distribution. [ABSTRACT FROM AUTHOR]

This study has been adopted to examine the effect of carbon fibre‐reinforced polymer (CFRP) sheet strengthening methods on the flexural behaviour of modified foamed concrete beams reinforced with different steel reinforcement ratios, and it deals with the enhancement in flexural behaviour of conventional nonstrengthened FC beams. Twelve modified foamed concrete beams were produced in three groups depending on the reinforcement ratio (under, balanced and over) and strengthened with externally bonded CFRP sheets applied in different methods (bottom layer, U jacket and hybrid). The examined flexural variables in four‐point bending were ultimate load, fracture mode, crack width, ductility, stiffness and deflection. The results showed an increase in the carrying capacity of foamed concrete beams strengthened with CFRP sheets by (2.5%–109%) compared to the reference nonstrengthened foamed concrete beams. The stiffness of the concrete samples reinforced with CFRP sheets were improved by 13%–306% compared to nonstrengthened foamed reference beams. For a given reinforcement ratio, it was found that the best CFRP sheets strengthening method was by applying the CFRP sheets in hybrid (wrap 0° + 90°). [ABSTRACT FROM AUTHOR]

Concrete structures in cold regions are affected by freeze–thaw cycles (FTCs) and carbonation, which lead to the premature failure of concrete structures. The carbonation depth, relative dynamic elastic modulus (RDEM), compressive strength, porosity, and pore size distribution of concrete under FTC conditions were tested through an accelerated carbonation experiment to study the carbonation performance evolution. The freeze–thaw effect mechanism on concrete carbonation was further analyzed via the obtained relationship between carbonation depth and pore structure. The results showed that the FTC, as a powerful source of concrete damage, accelerates the carbonation reaction. Carbonization products fill some microcracks caused by the freeze–thaw process, improve the compressive strength and dynamic elastic modulus, and alleviate the damage to concrete caused by the FTC. After carbonization under freeze–thaw damage conditions, the content of macropores with d > 1000 nm decreases, while the content of transition pores with d ≤ 10 nm increases, which is the direct reason for the decrease in porosity and the improvement in strength. Therefore, the carbonation durability of concrete under freeze–thaw conditions can be improved by controlling the content of macropores with d > 1000 nm and increasing the content of transition pores with a pore size of 10 nm ≤ d < 100 nm. In addition, the relationship between carbonation depth and pore structure under freeze–thaw conditions was established, and the research results can provide a reference for the study of the carbonation performance of concrete under freeze–thaw conditions. [ABSTRACT FROM AUTHOR]

Concrete is used as a material in the construction of several types of structures. The structural behavior of concrete is constrained by its lower tensile strength, bending strength, and toughness. Fiber-reinforced concrete is gaining importance in various concrete applications. Research has been carried out to use multiple types of fibers in concrete in different combinations to improve its mechanical characteristics, such as toughness, strength, ductility, and durability. In traditional concrete, microcracks have developed before loading the structure because of volume changes and drying shrinkage. When the load is applied, the microcracks start opening and propagating. Therefore, failure of the concrete member occurs. Hence, the usage of fibers helps arrest the growth of the crack and improves concrete characterization. The goal of this research study is to examine mechanical properties of concrete when used in combination with steel, basalt, and glass fibers. Steel fiber is useful in arresting macrocracks, whereas basalt and glass fibers are effective in preventing microcracks. In this research, the specimens incorporated hybrid (steel, glass, and basalt) fibers in the concrete mix with various percentage proportions at a 0.5% volume fraction. Experiments were carried out to assess the bending strength, compression strength, and splitting tensile strength. Therefore, this research can show comparative analysis for different percentages of fibers to enhance the qualities of concrete and can show the optimum fiber percentage among the proportions selected for this study. [ABSTRACT FROM AUTHOR]

With the growth of global air traffic and the popularity of large aircraft, the design and life prediction of airport pavements have received increasing attention from scholars. However, concrete airport pavement evaluations based on cracking patterns are often uncertain. A thermodynamic-based failure analysis of the FAA Phase 4 Construction Cycle 8 (CC8) strength and fatigue traffic test is conducted in this work to investigate the failure laws of airport concrete pavements. First, this work equates concrete pavement failure to a phase transition. It converts strain data from full-scale traffic tests into state variables. Based on the Wilson theory definition of phase transition, network-free renormalisation is applied to reveal the concrete slab stressing state evolution and phase transition features. The clustering algorithm that utilises the attractor effect of phase transition points determines characteristic points. In summary, this work applies network-free renormalisation and clustering algorithms to reveal robust concrete pavement failure points, which can provide a reference for airport pavement design, assessment, and failure warning. Furthermore, this work further validates the stressing state theory and network-free renormalisation under high-speed time-varying conditions. [ABSTRACT FROM AUTHOR]

Within the last decade, a construction‐friendly design principle using flexible wire ropes instead of traditional u‐bars for connecting wall elements has gained popularity. However, anchoring wire ropes in T and L connections remains a complex challenge. Here, the wire ropes stick out of the side of the wall element and are bent in the anchorage zone. This paper presents the findings of an extensive experimental program with 40 specimens, investigating the anchorage capacity of wire ropes in wall elements under these conditions. The study reveals that specially designed reinforcements significantly increase the anchorage capacity, while traditional wall reinforcements have minimal impact. Failure mechanisms primarily involve concrete cone failures, providing valuable insights for construction‐friendly connections. Based on the observed failure mechanism, the paper presents an analytical failure mechanism. The model is based on the upper‐bound theorem of plasticity theory. The model predicts both the capacity and the failure mechanism with satisfactory accuracy. [ABSTRACT FROM AUTHOR]

Chloride penetration is one of the main causes of failure of reinforced concrete structures, especially in undersea tunnels, which is also accompanied by stress and seepage-induced calcium leaching. The chloride penetration resistance of concrete under the single and dual effects of stress and calcium leaching were investigated in this work. The microscopic mechanisms were evaluated using scanning electron microscopy and X-ray diffraction analysis. The results showed that the chloride diffusion depth and chloride content increased linearly with the stress level in the tensile zone and decreased linearly in the compressive zone; the change was more obvious in the tensile zone. At stress levels of 15%, 30% and 45%, the diffusion depth in the tensile zone increased by 11.4%, 36.6% and 43.5%, respectively, while the change ratios of chloride content were 1.2%, 11.2% and 19.4%. No significant synergistic effect between stress and calcium leaching on the chloride diffusion depth was found, but the effect on chloride content was obvious, especially when the tensile stress level was below 15% and the compressive stress level was above 30%, for which the differences caused by considering the synergistic effect or not were approximately 6% and 15%, respectively. [ABSTRACT FROM AUTHOR]

Punching shear failure represents one of the most critical and perilous challenges that slabs may encounter under load-bearing conditions. Numerous studies have delved into the mechanics of punching shear and the methods for assessing the strength of slabs against punching shear failures. However, owing to the inherent complexity of the punching shear phenomenon, a universally applicable relationship has remained elusive. This article introduces a mathematical framework for analyzing the punching shear strength of two-way reinforced concrete slabs. The framework leverages a dataset of 218 laboratory test results compiled from various literature sources. To achieve the objective, the authors preprocessed the database, optimized the computational architecture, established the computational structure, and extracted mathematical relationships from the resulting system, respectively. The punching shear values generated by the computational model presented in this article were also compared with those determined using existing relationships. The framework surpasses existing methods by achieving a demonstrably lower error rate in predicting punching shear strength. This translates into a significant advantage for engineers, enabling them to design two-way reinforced concrete slabs with greater confidence and accuracy. Furthermore, it can be a valuable tool for assessing the viability of strengthening strategies for existing slabs or guiding rehabilitation efforts to ensure structural integrity. By facilitating these applications, the proposed framework holds immense promise for enhancing the safety, reliability, and lifespan of two-way RC slabs. [ABSTRACT FROM AUTHOR]

In order to investigate the interfacial bonding properties of high-strength steel stainless wire mesh-reinforced ECC (HSSWM-ECC) and concrete, a finite element model was established for two types of interfaces based on experimental research. The results show that the failure modes observed in the 21 groups of simulations can be classified into three categories: debonding failure, ECC extrusion failure and concrete splitting failure. The failure mode was mainly affected by the type of interface. The effective anchorage length is inversely proportional to the strength of the concrete and proportional to the stiffness and thickness of the HSSWM-ECC. The capacity of the roughening interface is positively correlated with the concrete strength and bonding length, but negatively correlated with the interfacial width ratio. Increasing both the number and width of grooves within the effective range enhances the interfacial capacity, whereas higher concrete strengths tend to reduce it. Based on the above results, calculation models for the effective anchorage length and bearing capacity were established separately for the two types of interfaces. The theoretical model for the interfacial bonding property between HSSWM-ECC and concrete has been refined. These advancements establish a theoretical groundwork for the design of concrete structures strengthened with HSSWM-ECC. [ABSTRACT FROM AUTHOR]

Concrete structures are subjected to static and fatigue loads during long-term service, and temperature changes can cause changes in the volume of concrete, leading to stress changes and fatigue damage, which affect the mechanical properties and service life of a structure. In response to the current lack of three-dimensional analysis and the exploration of the mechanical behavior and damage evolution processes of concrete structures under variable temperature environmental conditions, this paper relies on the Fenghuangjing Pump Station project involving the Yangtze River and Huaihe River and constructs a concrete thermo-mechanical-fatigue-damage model based on the power exponent function damage constitutive model. By using multiple coupled simulation calculations to predict the performance of concrete structures; analyzing the stress, deformation, and fatigue damage of structures from construction to operation; comparing measured data; dynamically optimizing inversion to obtain concrete thermal parameters; proposing key control parameters; and warning indicators and thresholds, the research results can provide reference for the long-term safe operation of similar projects. [ABSTRACT FROM AUTHOR]

The rock-socketed pier anchored by inclined anchors (RPIA) is a new type of foundation developed by combining a rock-socketed pier and inclined anchors. Current research on RPIA is relatively limited, and the impact of design parameters on its bearing performance remains unclear. To investigate the uplift-bearing performance of RPIA, a finite-element model that considers the nonlinear properties of materials and multidirectional interactions was developed and verified. Based on this model, numerical simulations were performed on twenty-five RPIA that were designed using the L25 orthogonal array proposed by the Taguchi method, and the uplift load–displacement curve for each RPIA was obtained. Based on the interpretation of the elastic limit, uplift resistance, initial stiffness, and the ductility index for each simulated RPIA, the sensitivity of each factor was examined by analyzing the signal-to-noise ratio and variance. The results indicated that rock strength and pier diameter were the main factors determining the uplift performance of the RPIAs, while the angle of inclined anchors is the most influential factor affecting the ductility of RPIA. The primary role of the inclined anchor is to reduce the extraction of the pier after failure of the side resistance between the pier and rock mass, thus significantly enhancing the ductility of the uplift-loaded RPIA. The addition of reinforcements around the connection joints of the pier and anchors may prevent concrete failure and to fully execute the role of inclined anchors. [ABSTRACT FROM AUTHOR]

This paper investigates the static and fire resistance behavior of a new type of composite beam, consisting of prefabricated concrete slabs with reserved grout holes connected to steel sections using steel studs. It reports the detailed results of two ambient temperature (reference) tests and eight full-scale standard fire resistance tests, all conducted under four-point bending. The key variables in the tests were degree of shear connection (complete or partial), heating duration (by using unprotected or protected steel sections), and load ratios (0.7 or 0.3). The experimental results confirm that the oversized grout holes facilitated easy construction and had no adverse effects. Due to using solid slabs without steel decking, shear failure of the concrete slab may happen under concentrated load with wide spacing between shear connectors. Nevertheless, this did not affect the bending resistance of the beams. The current design methods for static and fire resistance calculations for conventional composite beams in Eurocode 4 are generally applicable to this new type of composite beam, including calculations of equivalent steel stud and concrete temperatures and plastic design assumption. However, the assumption in EN 1994-1-2 about uniform temperature distribution in the steel section did not accord with the measured steel temperature results. [ABSTRACT FROM AUTHOR]

Relatively few studies have explored the shear behavior of concrete deep I-beams. This study presents a series of 12 shear tests on concrete deep I-beams with shear span-to-height ratios (av/h) of 1.0 and 1.5. The effects of horizontal and transverse web reinforcement on structural deformation and shear strength are compared. The findings indicate that a minimum horizontal and transverse reinforcement ratio (ρv=ρh=0.28%) significantly enhances the shear capacity. Additionally, an increase in vertical reinforcement (ρv=1.26%) shifts the failure mode from shear tension to web crushing. Increasing horizontal web reinforcement has little influence on shear capacity at av/h=1.5 , while it significantly enhances strength at av/h=1.0. The upper limit of shear strength for deep I-beams, as specified by ACI 318-19, appears conservative; a limit of 0.225fc′bwd is recommended. The Strut-and-Tie Model (STM) used in ACI 318-19 is conservative, demonstrating an average experimental-to-predicted shear strength value, Vexp/Vpred=3.24 , with a standard deviation of 0.63. Conversely, VecTor2 exhibits an average Vexp/Vpred of 1.07, with a standard deviation of 0.10. The panel element-based model, such as Mau's model, is proven suitable for the analysis of deep I-beams. [ABSTRACT FROM AUTHOR]

The present work describes an elasto‐plastic constitutive formulation aimed at simulating the failure behavior of Fiber Reinforced Cementitious Composites (FRCCs). This proposal, based on the Microplane Theory and Smeared Crack Approach (SCA), assumes a hyperbolic maximum strength criterion for the cementitious matrix in terms of normal and shear (micro‐)stresses, evaluated on generally oriented planes (microplanes). A combination of an associated/non‐associated plastic flow rule in conjunction with a fracture energy‐based softening law is defined to complete the modeling approach. The Mixture Theory is applied with the aim of characterizing the fiber‐to‐concrete interactions, described by considering two fundamental interaction phenomena: bridging debonding effects and dowel actions. Numerical analysis of FRCC failure behavior at the constitutive level is performed. Particularly, the soundness and capabilities of this approach are assessed against experimental data from tensile, shear, and compressive tests on FRCC samples. Simple shear tests are also evaluated to analyze the influence of the microplanes approximation over the unit microplane hemisphere. Comparisons against a discontinuous zero‐thickness interface model are proposed. Numerical results also illustrate the capabilities of the proposed constitutive theory to reproduce brittle or localized failure modes in limit stress states through discontinuous bifurcation analysis. [ABSTRACT FROM AUTHOR]

The choice of constitutive model significantly affects the accuracy of concrete perforation simulation. This study analyzes four concrete constitutive models, HJC, RHT, KCC, and TCK, focusing on their strength models, damage evolution, and strain rate effects. Combining the damage pattern and erosion cracks, the effectiveness of the four constitutive models in simulating the penetration of reinforced concrete targets is evaluated using LS-DYNA 11.0. The results indicate that the RHT and TCK models accurately depict the concrete damage and failure modes under the same test conditions. In contrast, the KCC and HJC models demonstrate superior capability in predicting the residual velocity of the projectile. Additionally, this study highlights the significant impact of the erosion parameters on the simulation results. This study offers a valuable reference for the application and parameter set of constitutive models in simulating concrete target perforation. [ABSTRACT FROM AUTHOR]

Low strength and low impact toughness are two of the main issues affecting the use of lightweight aggregate concrete in harsh cold environments. In this study, the strength of concrete was improved by adding high-strength fibers to bear tensile stress and organize crack propagation. Four sets of comparative experiments were designed with freeze–thaw cycles of 0, 50, 100, and 150 to study the mechanical properties of fiber-reinforced lightweight aggregate concrete under freeze–thaw conditions. A detailed study was conducted on the effects of freeze–thaw on the compressive strength, flexural strength, impact toughness, and microstructure of concrete with different fiber contents (3, 6, and 9 kg/m3). The results show that for ordinary lightweight aggregate concrete, under the freeze–thaw cycle, the internal pore water of the concrete froze and generated expansion stress, resulting in tensile cracks inside the concrete. The cracks gradually accumulated and expanded, ultimately leading to cracking and damage of concrete structures. After 150 cycles, the strength loss rate exceeded 25%. When adding a reasonable amount of fiber (6 kg/m3), the fiber took on the tensile stress and hindered the development of internal cracks, significantly enhancing the splitting tensile strength, flexural strength, and impact toughness of lightweight aggregate concrete. And the failure pattern of concrete was significantly improved. At the beginning of the freeze–thaw cycle, the internal tensile stress was less than the fiber tensile strength and the fiber–matrix bonding strength, and the strength reduction rate of the concrete was slow. Relying on the friction absorption capacity between the fiber and the matrix, the fiber used its own deformation to resist the tensile stress. In the late stage of the freeze–thaw cycle, due to the destruction of the fiber–matrix transition zone structure, the bond strength decreased, the crack resistance and toughening effect decreased, and the strength of the concrete decreased rapidly. Moreover, the reduction in impact toughness was greater than the compressive strength and flexural strength under static load. [ABSTRACT FROM AUTHOR]

Alkali‐activated cement (AAC) is an alternative binder with a promising potential to replace ordinary Portland cement (OPC) and mitigate its environmental issues. The use of fiber‐reinforced polymer (FRP) reinforcements with AAC concrete enables the development of corrosion‐resistant, environmentally friendly reinforced concrete structures. Bond behavior is critical in reinforced concrete structures and must be thoroughly studied for such new alternative materials. This study employs pullout tests to investigate the bond behavior between FRP bars and fine‐grained AAC concrete. Three fine‐grained AAC concretes with low to high strength, glass and carbon FRP bars and wrapped, milled, and smooth surface treatments were examined. The effect of bar casting position was also investigated. The compressive strength showed a significant influence on the bond strength. An average bond strength of approximately 18 MPa was observed for both glass and carbon FRP bars when used with 65 MPa concrete. Both the glass and carbon FRP bars with wrapping showed a lower bond strength than their milled FRP bars counterparts. The carbon bars without surface preparation (smooth bars) resulted in a much lower bond strength, around 4 MPa. In terms of casting positions, the bars cast in the middle section of the concrete block showed a higher bond strength than those at the bottom and top. [ABSTRACT FROM AUTHOR]

The mix design of concrete is an important aspect that affects its strength and durability. This paper aims to revisit the existing mix design method given in IS 10262:2019 through a capacity-based approach. The approach involves identifying the possible failure modes in concrete and eliminating the undesirable ones leading to significant reduction in dispersion. This is accomplished by utilizing coarse aggregates that meet a specific minimum strength requirement or threshold (e.g., ~ 77 MPa for M95 grade of concrete), which is determined through a priori estimating the cohesion and friction angle of the concrete. The methodology to estimate the cohesion and friction angle from a single unconfined compression test is proposed based on the Mohr–Coulomb theory and using the orientation of failure plane of fractured specimen as a supplemental information from the same experiment. This paper also offers a simple and approximate test procedure to estimate the aggregate's compressive strength (~ 106 MPa in this mix design) reasonably which is essential for the capacity-based mix design. An experimental programme is also carried out to design the concrete mix using the proposed capacity-based approach. The results indicate that M95 concrete is achieved with a low standard deviation and coefficient of variation (~ 3%), falling in class of excellent quality control as per ACI 214R-11. This quality control is crucial in seismic structural design as variations in concrete strength is likely to negate the underlying principle of strong column–weak beam philosophy resulting in the triggering of undesirable shear modes of failure. [ABSTRACT FROM AUTHOR]

Fatigue performance tests on concrete specimens were conducted using a three-point equal amplitude loading method. As the number of fatigue loadings increased, microcracks inside the concrete extended and expanded, forming through-cracks that gradually developed into macroscopic, large cracks that rapidly propagated across the entire cross-section. Under different stress levels, the specimens exhibited a relatively stable ultimate residual strain value when fatigue failure occurred, while the maximum strain varied significantly. The development of bending fatigue deformation followed a three-stage pattern. Microscopic testing methods such as SEM electron microscope scanning and mercury intrusion porosimetry (MIP) were employed to analyze the whole process of deterioration and evolution of microcracks and pore structures in fatigue-damaged concrete. Fatigue loading damage resulted in a significant reduction in harmless and less harmful pores, or micropores, inside the concrete, while the proportion of harmful and more harmful pores increased substantially. Macroscopically, this was manifested as further intensification of fatigue performance deterioration. The entire fatigue development pattern is a process of continuous damage accumulation, culminating in instantaneous brittle fatigue fracture at failure. Based on the fundamental theory of continuum damage mechanics, the damage degree D was determined by quantifying the cumulative damage of concrete using residual strain. A fatigue damage evolution equation was derived from theoretical deductions, and a calculation model for the fatigue damage degree of concrete was proposed. [ABSTRACT FROM AUTHOR]

The rock–concrete interface serves as the weak point of concrete structures based on rocks; the initial failure of the interface under stress waves can easily cause instability and failure of rock concrete composite structures. This study conducted a range of numerical investigations using MAT-COHESIVE-MIXED-MODE cohesive element to describe the failure properties of rock–shotcrete's interface transition zone (ITZ). The research results can reveal ITZ's failure mechanism and mechanical property under different stress wave incidence orientations and confining pressures. It can be concluded that under multi-directional dynamic stress waves, the failure mode of the ITZ is represented as a complete failure with the angle from 0° to 45°, the local penetration failure of the ITZ with the angle from 60° to 90°, and the highest failure rate of only 4.89%. Under different confining pressure, the 40 MPa as a threshold can reduce the failure rate of the ITZ from 100% to 41.74%. The confining pressure delayed the stable stage initial angle of tensile and shear displacement from 60° to 75° under the coupling effect of the multi-directional stress wave and confining pressure. For interface displacement control, the incidence angle should be better than 75° under confining pressure, and the angle can be controlled above 60° without confining pressure. Therefore, for tunnel surrounding rock support, attention should be paid to displacement and deformation control at positions where the angle between the excavation blasting direction and the primary lining surrounding rock bonding surface is less than 75°. Highlights: The failure evolution law of rock–shotcrete ITZ subjected to multi-directional stress waves is investigated. The effect of confining pressure on the interface failure mechanism and the ITZ stress distribution of the rock–shotcrete was obtained. The interface stress and displacement of the rock–shotcrete acted upon by the coupling effect of stress waves and confining pressure were explored. [ABSTRACT FROM AUTHOR]

Cyclic loading can induce brittle fractures at stress levels below the strength threshold, prompting extensive experimental and numerical investigations into the fatigue characteristics of various elements. This study introduces a purpose-built machine designed to empirically explore the fatigue behavior of concrete beams. The proposed machine employs a rotational beam system with a consistent load applied to the beam's end. By placing a single point on the rotating beam, cyclic flexural moments are generated, inducing maximum tensile stresses at the support. This machine enables continuous long-term testing, adjustment of load amplitude and loading frequency, and tracking the number of cyclic loads until specimen failure. The stress-number cyclic loading test is performed on diverse samples of both reinforced and unreinforced concrete beams. Furthermore, the study assesses the impact of loading frequency on fatigue behavior. The findings validate existing relationships proposed for the durability limit in terms of tensile strength. [ABSTRACT FROM AUTHOR]

This paper presents a detailed analytical approach for the bending analysis of reinforced concrete beams, integrating both structural mechanics principles and Eurocode 2 provisions. The general analytical expressions derived for the curvature were applied for the transverse displacement analysis of a simply supported reinforced concrete beam under four-point loading, focusing on key limit states: the initiation of cracking, the yielding of tensile reinforcement and the compressive failure of concrete. The displacement's results were validated through experimental testing, showing a high degree of accuracy in the elastic and crack propagation phases. Deviations in the yielding phase were attributed to the conservative material assumptions within the Eurocode 2 framework, though the analytical model remained reliable overall. To streamline the computational process for more complex structures, a simplified model utilising a non-linear rotational spring was further developed. This model effectively captures the influence of cracking with significantly reduced computational effort, making it suitable for serviceability limit state analyses in complex loading scenarios, such as seismic impacts. The results demonstrate that combining detailed analytical methods with this simplified model provides an efficient and practical solution for the analysis of reinforced concrete beams, balancing precision with computational efficiency. [ABSTRACT FROM AUTHOR]

Nuclear power plants, where steel-plate concrete (SC) structures are commonly adopted, require large-scale components to withstand significant loads, such as those caused by sudden explosions. As a result, SC modular members used in nuclear power plants must have thicker walls filled with concrete compared to standard-sized ones. These large walls also require additional components, such as tie bars and H-shaped steel sections, to reinforce adhesion and resist shear stresses. This study focuses on tie bars placed adjacent to studs and evaluates their influence on the tensile strength of wall structures. To investigate this, we conducted experimental tests using full-scale specimens, including various combinations ranging from single stud to combined stud-tie configurations. Based on the results of these performance tests, we propose a design recommendation for estimating the tensile capacity of SC structures, considering the influence of tie bars. [ABSTRACT FROM AUTHOR]

This study experimentally assessed the shear performance of reinforced concrete (RC) beams strengthened with U-shaped High-Performance Fibre-Reinforced Concrete (HPFRC) under static and fatigue loading. Key parameters included HPFRC jacket thickness and beam shear span–depth (a/d) ratio. Five beams were tested under static loads to determine ultimate shear strengths, followed by fatigue tests on identical beams at 30–70% of ultimate shear strengths at 4 Hz. In static loading experiments, all the HPFRC jacketing proved effective, increasing the shear strength of RC beams by 95% to 130%. Although the strengthening system did not change the failure mode of the beams, the strengthened beams exhibited pseudo-ductile behaviour. As the a/d increased, the shear enhancement capability of the HPFRC jackets decreased. In fatigue loading experiments, all the HPFRC systems improved the fatigue life of RC beams. Specifically, in beams with an a/d ratio of 2.0, the fatigue life was extended from 75 cycles to a maximum of 951 cycles, while in beams with an a/d ratio of 3.5, it increased from 12,525 cycles to 48,786 cycles. In addition, a predictive model has been developed for the fatigue life of HPFRC/UHPFRC shear-strengthened beams, utilising the maximum fatigue load and the design's ultimate shear strength under static loading conditions. [ABSTRACT FROM AUTHOR]

The acoustoelastic technique shows considerable potential for in situ stress measurement in concrete. However, the current technology is not fully developed, and challenges primarily arise from the intricate nature of concrete, along with various factors affecting its acoustoelastic properties, such as material strength, aggregate size, porosity, temperature, and humidity. A comprehensive understanding of how these factors influence the acoustoelastic characteristics of concrete is essential for advancing acoustoelastic technology in engineering applications. This study specifically focuses on the material strength, a pivotal factor influencing the quality of concrete, and explores its correlation with the acoustoelastic coefficient (AEC). An initial theoretical investigation was conducted to establish a theoretical model between the two factors, involving two steps: (1) integrating the empirical formula correlating material strength and Young's modulus into the acoustoelastic equations for bulk waves to derive the formula connecting AECs and concrete strengths; (2) applying qualitative analysis and statistical methods to assess the monotonic properties of the formula within its defined domain. To validate the accuracy of the theoretical model, acoustoelastic tests were conducted on prismatic concrete specimens with five different strength levels under axial compressive stress. The findings revealed a consistent pattern, demonstrating that the AECs of concrete decrease with an increase in material strength under axial compressive stress. The outcomes of this study make a substantial contribution to establishing a theoretical foundation for the development of concrete stress monitoring technology based on the ultrasonic method. Practical Applications: The safety of concrete structures is paramount. Currently, structural performance assessment relies primarily on on-site inspections and evaluations by professionals to detect visible cracks and deformations. Typically, cracks become apparent only once the damage has reached a critical level. Failure to identify deterioration processes before reaching this critical stage necessitates significant repairs to prevent premature failure of concrete structural components. If the in situ stress information of structures can be nondestructively obtained would be highly beneficial for warning the early deterioration, tracking the evolution of crack or damage, and forecasting the remaining service life of structures. Acoustoelastic techniques have demonstrated significant potential in achieving this objective. Nonetheless, concrete acoustoelastic effects are influenced by various factors, such as material strength, aggregate size, porosity, and environmental conditions, which impede further advancement of this technology. Therefore, this study investigated the dependence of concrete acoustoelastic effects on material strength. Correlation equations between concrete strength and acoustoelastic coefficients have been formulated. The application of these equations in practice can mitigate the impact of material strength on acoustoelastic measurements. This research contributes to advancing the engineering applications of acoustoelastic techniques in concrete stress assessment. [ABSTRACT FROM AUTHOR]

This study investigated the flexural fatigue performance of pavement-grade geopolymer concrete (GPC) developed using low-carbon binders containing waste clay bricks (WCB), slag, and fly ash. Concrete was developed using two types of binders, one with a ternary blend of WCB, slag, and fly ash and one with only slag and fly ash as a full replacement for ordinary portland cement (OPC). Test specimens were subjected to flexural fatigue by four-point bending under three levels of stress which are equivalent to 75%, 80%, and 85% of the maximum static flexural strength. A two-parameter Weibull distribution was considered in the probabilistic analysis of fatigue life data, which corresponds to the number of cycles until failure. At all stress levels, GPC showed better fatigue performance compared to OPC concrete. At lower stress levels, the performance of GPC with WCB in the binder was better than the performance of conventional GPC with only slag and fly ash. However, GPC with WCB shows reduced performance at higher stress ratios. Survival probability of all concrete types (i.e., GPC and OPC concrete) decreased with increasing stress level. At a selected stress level, the fatigue life of all concrete types increased with the decrease of survival probability. The ultimate fatigue strength of GPC was higher than the OPC concrete. GPC with WCB binders showed an ultimate fatigue strength of more than 68% considering 107 repeated loading cycles. Practical Applications: Improving sustainability within the construction industry is a current major challenge, and all the while it is becoming an indispensable necessity. Transitioning from conventional materials with high negative environmental impacts such as OPC to more sustainable alternatives can significantly enhance sustainability in the construction industry. However, absence of data regarding the overall performance of newly identified low-carbon materials is a limiting factor to the industry uptake of these alternatives. The findings from this research characterize the fatigue behavior of low-carbon concrete that is developed using WCB-based binders and designed for pavement applications specifically. Understanding the fatigue performance is crucial for any material intended for use in pavement applications. The results from the current work provide valuable insights into the targeted application of these innovative materials, addressing a critical gap in information. [ABSTRACT FROM AUTHOR]

This study examines the feasibility and effectiveness of the sprayed-in-place pipe (SIPP) technology for concrete pipe repair, with a focus on a dual-component, high-strength spray lining material enhanced with an epoxy resin sealing layer. The research was conducted using a simulated experiment rig, tailored to specific environmental characteristics and the specifications of BONNA pipe, a type of precast reinforced concrete pressure pipe. This setup allowed for a detailed feasibility study of an automated spray process under simulated working conditions. The experimental process involved applying the lining material to concrete substrates, achieving a smooth, pinhole-free surface, with quality control managed using a high-voltage spark tester. The lining demonstrated exceptional impermeability, showing no penetration under 3 MPa water pressure, and maintained strong adhesive strength with the substrate, exceeding 6 MPa as indicated by substrate concrete failure during testing. Furthermore, the technique's applicability in complex scenarios was tested, including automatic spraying inside 90° elbows, with lining thickness variations staying within acceptable limits. These findings suggest that the process is highly suitable for on-site pipeline conditions, offering a robust and reliable solution for enhancing the durability and integrity of pipeline infrastructures. This study provides practical engineering references for the SIPP repair method, demonstrating its potential as a significant advancement in pipeline repair and maintenance. [ABSTRACT FROM AUTHOR]

Fluid–structure interaction (FSI) is ubiquitous in various engineering disciplines, and effectively managing FSI often appears to be the key for successful failure analysis and safety-oriented design. Smoothed particle hydrodynamics (SPH) serves as a potent nonlocal meshfree method for fluid dynamics modeling, while peridynamics (PD) demonstrates exceptional capability in addressing structural dynamics involving large deformations and discontinuities. Thus, leveraging their respective strengths in a combined approach holds significant promise for tackling FSI challenges. In this work, we propose a new peridynamics–smoothed particle hydrodynamics (PD-SPH) coupling model for addressing FSI. A stable and efficient coupling algorithm for data transfer between PD and SPH is put forward. In this coupling strategy, a PD particle directly participates in solving the SPH governing equations when it is identified to be within the support domain of an SPH particle. This can be done since the SPH quantities including the density, velocity, and pressure of a PD particle are naturally attainable within the framework of non-ordinary state-based peridynamics theory. Concurrently, in solving PD governing equations, reaction forces from SPH particles act as external forces for PD particles, determined straightforwardly through Newton's third law. As such, the proposed PD-SPH coupling strategy is straightforward to implement and offers high computational efficiency. Validation examples demonstrate that the proposed PD-SPH coupling model is computationally robust and adept at capturing physical phenomena in diverse FSI scenarios involving breaking free surfaces of fluid and large structural deformations of solid. Moreover, the proposed PD-SPH coupling model is flexible introducing no constraint conditions for applications and can accommodate different particle resolutions for PD and SPH domains. These features enable a broad application range of the proposed PD-SPH coupling model including simulations of explosion-induced soil fragmentation, rock fracture, and concrete dam failure, which will be conducted by authors in the near future. [ABSTRACT FROM AUTHOR]

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For the past several decades, there has been an ongoing academic challenge to understand the shear-transfer mechanism in reinforced concrete (RC) members, particularly in those with small shear span-depth ratios, also known as deep beams. Analytical uncertainty regarding shear strength inevitably increases when those deep members are strengthened in shear using externally bonded fiber-reinforced polymer (FRP) composites. This study aims to investigate the complex, interrelated effects of short shear span-depth ratios and FRP composites on RC deep beam members. To this end, the fundamental formulations of the dual potential capacity model (DPCM) are extended to RC deep members reinforced with externally bonded FRP composites. The proposed model can consider the various types of FRP composites, fiber bonding configurations, and fiber layouts, and various failure modes of concrete and FRP reinforcements are also reflected. A total of 131 shear test results of RC deep and short members with externally bonded FRP composites are carefully collected, and those are added to the existing database of RC slender members strengthened with FRP composites. On this basis, the proposed approach is verified by comparing test results with analysis results, and a reasonable level of analytical accuracy is achieved. The statistical data distribution of strength ratios between the test and analytical results is consistent across a range of shear span-depth ratios from approximately 0.7 to 4.0. Overall, the proposed DPCM approach provides a useful tool for analyzing the shear strength of RC deep beam members strengthened with externally bonded FRP composites. [ABSTRACT FROM AUTHOR]

In the present study, shear-friction tests were conducted under cyclic loading to investigate in-plane shear transfer across a thin and long interface between new and existing concrete slabs. For shear reinforcement across the interface, concrete shear keys and steel shear plates were used in combination with adhesive anchors (that is, post-installed reinforcing bars). Test results showed that the shear behavior of the thin slab interfaces was significantly affected by the types and details of interface reinforcements. The concrete shear keys and shear plate effectively restrained relative slip across the interface during the initial behavior and increased the peak strength, while the adhesive anchors contributed to the peak strength and post-peak residual strength. Failure modes were concrete failure around the concrete shear keys (that is, local crushing and shearing-off) and in the anchorage zone of the shear plate (that is, cracking and spalling-off). The nominal shear strengths of the thin slab interfaces were calculated by summing the shear-friction strength of adhesive anchors, local crushing strength around concrete shear keys, and shear yield strength of shear plates. The predicted strength agreed with the test results. Based on the results, design considerations of shear transfer across an interface between thin concrete slabs were discussed. [ABSTRACT FROM AUTHOR]

In this paper, some recent analytical expressions including those of codes for shear strength calculation of reinforced concrete (RC) beams without and with stirrups are discussed and verified against experimental data available in the literature. An analytical expression proposed by the author is also introduced and discussed. Two different sets of experimental data were analyzed: one for beams without stirrups composed of 719 data and the other one for beams with stirrups composed of 152 data. Comparison between experimental data and analytical results showed that all of the analytical expressions of international codes are conservative in prediction. The proposed equation gives the same grade of accuracy of the other existing analytical expressions for the prediction of experimental data, and it is derived by a mechanical approach. Comparison shows that although most of the analytical expressions give safe and conservative results, more effort is still necessary to reduce the high scatter of prediction of all the expressions used here, especially for beams without stirrups. [ABSTRACT FROM AUTHOR]

The synergistic interaction inreinforced concrete systems originates from the strong bond between steel reinforcement and concrete, enabling them to collaborateunder load and optimize structural performance. This study applied various sludge-modified magnesium phosphate cement mixtures to the surfaces of plain round steel bars and ribbed steel bars to prepare steel-reinforced concrete specimens. The characterization of the bond performance of the sludge-modified magnesium phosphate cement reinforcement coating for steel bars and concrete was achieved through analyzing the failure modes, bond strength, and slip values of different groups. Microscopic analysis was performed using a scanning electron microscope. The results revealed that the primary failure mode of the steel-reinforced concrete specimens was steel bar pull-out, with some specimens exhibiting concrete splitting failure. Coating application on plain round steel bars increased bond strength, while on ribbed steel bars, it decreased bond strength. The application of the coating slightly reduced slip values to some extent. [ABSTRACT FROM AUTHOR]

To study the damage characteristics of concrete with different coarse aggregate sizes, umaxial compression tests were carried out on 6 groups of concrete specimens with 4.75 ~ 9.50 mm, 9.50 ~ 16.00 mm, 16.00~ 19.00 mm, 19.00 ~ 26.50 mm, 26.50 ~ 31.50 mm and continuous particle sizes by using acoustic emission (AE) and digital image correlation (DIC) technology. Damage information of the entire failure process of the concrete specimens was collected in real-time from both micro-scale and macro-scale. Damage evaluation model for concrete specimens with different coarse aggregate sizes was established based on AE energy count. The results show that based on the evolution laws of the AE energy count and b value, the damage process of 6 groups of concrete specimens can be divided into 3 damage stages: the initial stage, the cracks stable development stage, and the cracks rapid expansion stage. The displacement cloud diagrams captured by DIC technology can explain the micro-scale information of AE parameters from macro-scale and provide a strong basis for the classification of damage stages under uniaxial compression. The concrete specimens with different coarse aggregate sizes exhibit variations in internal structure, which affect the rate of rapid crack propagation in concrete. The established damage evaluation model can effectively characterize the damage stages of concrete with different coarse aggregate sizes, and realize quantitative analysis and evaluation. [ABSTRACT FROM AUTHOR]

Rubber concrete (RC) has been used in fatigue-resistant components due to its durability, yet the numerical simulation of its fatigue properties remains in its early stages. This study proposes a cohesive zone model (CZM) that accounts for the accumulation of fatigue damage at the mesoscale to investigate the fatigue performance of RC. The model integrates static and fatigue damage in the CZM, effectively capturing damage caused by fatigue loading. Validation was conducted using experimental data from the existing literature. Based on this validation, four concrete beams with varying rubber replacement rates (0%, 5%, 10%, and 15%) were tested. The CZM was employed to describe the mechanical behavior of the interface transition zones (ITZs) and the mortar interior, which were simulated and analyzed under different stress levels. The results demonstrate that the model accurately simulates crack propagation paths, interface damage evolution, and the fatigue life of RC beams under fatigue loading. A functional relationship between fatigue life and stress level was established for various rubber replacement rates. This study provides a reference model for numerical simulations of RC under fatigue loading conditions and introduces new approaches for analyzing the fatigue performance of other materials. [ABSTRACT FROM AUTHOR]

As conventional machine learning models often struggle with scarcity and structural variation of training data, this paper proposes a novel regression transfer learning framework called transferable tabular regressor (TransTabRegressor) to address this challenge. The TransTabRegressor integrates natural language processing (NLP) for feature encoding, transformer for enhanced feature representation, and deep learning (DL) for robust modeling, facilitating effective transfer learning across tabular datasets using reducing input parameters. By leveraging the NLP data processor, the framework embeds both parameter names and values, enabling it to recognize and adapt to different expressions of similar parameters. For instance, the bond strength of fiber‐reinforced polymer (FRP) bars embedded in ultra‐high‐performance concrete (UHPC) is critical for ensuring the integrity of FRP‐UHPC structures. While pullout tests are widely adopted for their simplicity to generate substantial data, beam tests provide a closer approximation to actual stress conditions but are more complex thus resulting in limited data size. As a verification, the framework is applied to predict the bond strength of FRP bars embedded in UHPC using limited beam test data. A pre‐trained model is first established using 479 pieces of pullout test data. Subsequently, two transfer learning models are developed by fine‐tuning on 115 pieces of beam test data, where 66 correspond to concrete splitting failure and 49 correspond to pullout failure. For comparative analysis, XGBoost and neural network models are directly trained on the beam test data. Evaluation results demonstrate that the transfer learning models achieve significantly improved prediction accuracy and generalization capability. This study significantly highlights the effectiveness of the proposed TransTabRegressor in handling data scarcity and variability in input parameters across various engineering applications. [ABSTRACT FROM AUTHOR]

FRP profile‐concrete hybrid beam, composed of a FRP profile beam, a concrete slab made of normal concrete (NC) or ultra‐high‐performance‐concrete (UHPC), and shear connectors, shows significant potential for employment in large‐span bridges due to its excellent corrosion resistance, lightweight, and easy construction. The structural behavior of such hybrid beam was simulated using a three‐dimensional non‐linear finite element model (FEM) in Abaqus. The Hashin failure model and concrete damage plastic (CDP) model were employed to characterize the progressive failure of FRP, NC, and UHPC, respectively. The FEM considered partial shear connection by utilizing shear load‐slip model and the orthotropic behavior of the FRP profile. The proposed FEM was validated through comparisons with experimental data in terms of load‐midspan deflection curve, load‐end slip curve, and failure modes. A parametric study was subsequently conducted to identify the effects of various factors, including concrete strength, bolt spacing, concrete slab width, concrete slab height, FRP flange and web thickness, and shear span. Based on the results yielded from FEM analysis, the accuracy of the calculation method in Chinese standard (GB‐50608) for predicting the loading capacity of hybrid beams was evaluated and found too conservative. [ABSTRACT FROM AUTHOR]