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Experimental tests were carried out to assess the failure model of steel fiber reinforced concrete beams. Experimental research was focused on observing changes in the behavior of the tested elements depending on the amount of shear reinforcement and the fiber. Model two-span beams with a cross-section of 80x180 mm and a length of 2000 mm were test...
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Knowledge of time-dependent characteristics for any concrete is vital for his use as constructive material. In the definition field of the fiber reinforced concrete rheological characteristics there are a small number of experiments, because these studies require considerable resources and time. Previous studies suggest that special attention shoul...
![Figure 1. Distribution of parameters in database [91]: (a) beam width...](publication/374709761/figure/fig1/AS:11431281198397695@1697289088792/Distribution-of-parameters-in-database-91-a-beam-width-and-b-beam-height_Q320.jpg)
![Figure 2. Distribution of parameters in database [91]: (a) effective...](publication/374709761/figure/fig2/AS:11431281198348108@1697289088870/Distribution-of-parameters-in-database-91-a-effective-height-and-b-span-length_Q320.jpg)
![Figure 3. Distribution of parameters in database [91]: (a) shear span...](publication/374709761/figure/fig3/AS:11431281198348109@1697289088946/Distribution-of-parameters-in-database-91-a-shear-span-to-depth-ratio-and-b_Q320.jpg)
![Figure 4. Distribution of parameters in database [91]: (a) maximum...](publication/374709761/figure/fig4/AS:11431281198337355@1697289089004/Distribution-of-parameters-in-database-91-a-maximum-aggregate-size-and-b_Q320.jpg)
![Figure 5. Distribution of parameters in database [91]: (a) fiber volume...](publication/374709761/figure/fig5/AS:11431281198317220@1697289089059/Distribution-of-parameters-in-database-91-a-fiber-volume-and-b-aspect-factor_Q320.jpg)
The shear strength of fiber reinforced elements is usually predicted through analytical models calibrated from experimental tests. Few results obtained from these tests consider the mechanical characterization of the material, allowing to evaluate the different performances of fiber reinforced concrete. This work evaluates the possibility of replac...
Concrete that is reinforced with steel fibers to enhance its structural integrity and performance is known as Steel Fibre Reinforced Concrete (SFRC).Due tothe integration of steel fibers into concrete, the shear behaviour of SFRC beams diverges significantly from conventional Reinforced Concrete (RC) beams. The intricate interaction of the steel fi...
Concrete is second most widely used material other than water,its more versatile but madern day engineering structures require more demanding concrete owing to the huge apllied load on smaller area and increasing adverse environmental conditions.In this work tried to utilize fibers as a strength enhancement agent in SCC to obtain higher strength wi...
In steel fiber reinforced concrete, the interface is a very complex and weak structure. It is because of the weak interface layer between the steel fiber and the matrix that the reinforcing and toughening properties of the steel fiber cannot be fully exerted. The interface bond performance is the core of the meso-mechanical properties of steel fibe...
Citations
... The whole database comprises 488 tests of SFRC beams containing longitudinal rebar (mild steel only) and no shear reinforcement (screening rules to determine usable shear test results are detailed in [28]; they commonly include casting and curing conditions and loading and measuring methods). Almost all of the tests reported were carried out on simply supported beams under three-or four-point bending, with two exceptions: (i) two-span beams in [38] that generated a negative moment at the middle support and (ii) six short-span beams in [39] that used special setups to prevent the development of arching action. ...
The shear transfer mechanism of steel fiber reinforced concrete (SFRC) beams without stirrups is still not well understood. This is demonstrated herein by examining the accuracy of typical empirical formulas for 488 SFRC beam test records compiled from the literature. To steer clear of these cognitive limitations, this study turned to artificial intelligence (AI) models. A gray relational analysis (GRA) was first conducted to evaluate the importance of different parameters for the problem at hand. The outcomes indicate that the shear capacity depends heavily on the material properties of concrete, the amount of longitudinal reinforcement, the attributes of steel fibers, and the geometrical and loading characteristics of SFRC beams. After this, AI models, including back-propagation artificial neural network, random forest and multi-gene genetic programming, were developed to capture the shear strength of SFRC beams without stirrups. The findings unequivocally show that the AI models predict the shear strength more accurately than do the empirical formulas. A parametric analysis was performed using the established AI model to investigate the effects of the main influential factors (determined by GRA) on the shear capacity. Overall, this paper provides an accurate, instantaneous and meaningful approach for evaluating the shear capacity of SFRC beams containing no stirrups.
... Alnahhal et al. [34] observed that the flexural bearing capacity of the recycled aggregate BFRC beam after BMF inclusion was significantly increased compared with that of ordinary reinforced concrete. Kosior-Kazberuk et al. [35] found that the flexural toughness of concrete considerably increased when BFs were used and the addition of BFs leads to the improvement in fracture parameters. This paper presents a new composite beam, which is composed of BFRC and ordinary concrete. ...
Three specimens of composite beams were tested under a four-points bending test to study the effect of BFRC height on the flexural behavior of the composite beam. The numerical software MATLAB was used to numerically study the bending moment-curvature (M-φ) relationship of the composite beams. The finite element software (ABAQUS) was used to simulate the flexural behavior of the composite beams, and the parameter analysis is carried out to study the effect of strength and height of BFRC, strength and ratio of steel reinforcement on the flexural performance of BFRC-concrete composite beams. The study results show that the flexural capacity of the composite beam is higher than that of the normal concrete beam. With the increase of the height of the BFRC, the flexural capacity increases, and the bottom crack propagation is significantly inhibited. The BFRC height has a negligible effect on the ductility of the composite beam. The results illustrate the assumption of the plane section is valid, and the bonding behavior between steel bar and BFRC as well as the co-working between BFRC and ordinary concrete are perfect. Based on the experimental results, formulae are developed for predicting the cracking, yield, and ultimate moment bearing capacity of the composite beam, and a simplified formula is also developed for predicting the ultimate bearing capacity of composite beam with a balanced reinforcement ratio. The prediction results are consistent well with the test results, and the simulation results exhibit a good agreement with the test results of composite beams.
... This is due to the high complexity of the shear transfer mechanisms, the different types of failure and the internally interdependent forces in the beam. Kosior-Kazberuk [12] indicated that shear strength (Vc) consists of: the strength resulting from aggregate interlock, the shear strength of the concrete in the compression zone, the dowel action of the longitudinal reinforcement and residual tensile strength of concrete across the crack. The stiffness of composite rebars is much lower than that of steel reinforcement. ...
This paper investigates composite reinforcement with regard to its use as longitudinal reinforcement. The methods used to calculate the shear strength of concrete members reinforced with fibre-reinforced polymer (FRP) bars are analysed. The main parameters having a bearing on the shear strength of beams reinforced with composite bars are defined. A comparative analysis of the shear strength calculating algorithms provided in the available design recommendations concerning FRP reinforcement and formulas derived by others researchers is carried out. A synthesis of the research to date on sheared concrete members reinforced longitudinally with FRP bars is made. The results of the studies relating to shear strength are compared with the theoretical results yielded by the considered algorithms. A new approach for estimating the shear capacity of support zones reinforced longitudinally with FRP bars without shear reinforcement was proposed and verified. A satisfactory level of model fit was obtained—the best among the available proposals. Taking into account the extended base of destructive testing results, the estimation of the shear strength in accordance with the proposed model can be used as an accompanying (non-destructive) method for the empirical determination of shear resistance of longitudinally reinforced FRP bars.
... Bentz et al. [16] indicated that the above also implies differences in the behavior of support zones reinforced longitudinally with FRP bars. Oller et al. [17] and Kosior-Kazberuk [18] indicated that, in accordance with the superposition principle, the shear load capacity of an element loaded with transverse force is dependent on the following factors: shear reinforcement contribution, load capacity resulting from aggregate interlocking, the load capacity of concrete in the compressed zone, the dowel action of longitudinal reinforcement, and the residual tensile strength of concrete across the crack. Composite reinforcement is characterized by a much lower modulus of elasticity than steel reinforcement. ...
The article presents experimental tests of a new type of composite bar that has been used as shear reinforcement for concrete beams. In the case of shearing concrete beams reinforced with steel stirrups, according to the theory of plasticity, the plastic deformation of stirrups and stress redistribution in stirrups cut by a diagonal crack are permitted. Tensile composite reinforcement is characterized by linear-elastic behavior throughout the entire strength range. The most popular type of shear reinforcement is closed frame stirrups, and this type of Fiber Reinforced Polymer (FRP) shear reinforcement was the subject of research by other authors. In the case of FRP stirrups, rupture occurs rapidly without the shear reinforcement being able to redistribute stress. An attempt was made to introduce a quasi-plastic character into the mechanisms transferring shear by appropriately shaping the shear reinforcement. Experimental material tests covered the determination of the strength and deformability of straight Glass Fiber Reinforced Polymer (GFRP) bars and GFRP headed bars. Experimental studies of shear reinforced beams with GFRP stirrups and GFRP headed bars were carried out. This allowed a direct comparison of the shear behavior of beams reinforced with standard GFRP stirrups and a new type of shear reinforcement: GFRP headed bars. Experimental studies demonstrated that GFRP headed bars could be used as shear reinforcement in concrete beams. Unlike GFRP stirrups, these bars allow stress redistribution in bars cut by a diagonal crack.
... The influence of fibers on concrete properties was referred to the results obtained for the reference concrete without fibers. The content of both types of fibers was determined on the basis of the previous test results conducted on concrete specimens [33] and model reinforced concrete beams [34]. The analysis of the test results [33] showed a significant effect of 0.19% of basalt fibers addition on the fracture toughness of concrete, and further increase in the fiber content did not improve the properties of the concrete. ...
... The analysis of the test results [33] showed a significant effect of 0.19% of basalt fibers addition on the fracture toughness of concrete, and further increase in the fiber content did not improve the properties of the concrete. The volume fraction of steel fibers 1.0% ensured the significant effect of fibers in concrete on the shear behavior of beams and further increase in fiber content required special treatment to evenly distribute them in concrete mix [34]. Portland cement CEM I 42.5R was used to make concrete for structural elements. ...
The presented study was conducted to assess the shear capacity and the mechanical behavior of fiber reinforced concrete two-span beams in a five-point bending test. Experimental research was focused on observing changes in the behavior of tested elements depending on the amount of shear reinforcement (stirrups) and the fiber type used. The beams had varied stirrup spacing and two sorts of fibers were used as dispersed reinforcement. The steel fiber content was 78.5 kg/m³ and the basalt fiber content was 5.0 kg/m³. Concrete beams without addition of fibers were also examined as reference ones. The effectiveness of both sorts of fibers as shear reinforcement was assessed on the basis of strain development and crack pattern analysis. The digital image correlation technique was used to monitor the development of cracks around the central support of beams. It was shown that fibers control the cracking process and deformations in reinforced concrete beams and they can be effectively used as additional or the only shear reinforcement. The results of shear capacity obtained in the experiment were also compared with the shear capacity calculated according to current design approaches. This analysis has shown that fibers enhance the ultimate shear strength of reinforced concrete beams.
... The notations used in this database are given in the "List of notations". For a number of references [42,44,50,52,54,59,67,[69][70][71][72][73][75][76][77][78]80,81,[83][84][85]88,89,94,[96][97][98][99][100][102][103][104]106,107,[109][110][111][112][115][116][117][118][119]123,124] information about the geometry of the support and loading plate was missing. These values were then approximated based on figures of the test setup in the original reference. ...
... Most specimens are rectangular beams, but the specimens in [73,81,94,99] are T-beams, in [89,90] I-beams, and in [114] non-prismatic beams. Almost all experiments are on simply supported beams in three-or four-point bending, with exception of the two-span beams in [117] and the special setup by [127] for short spans that does not allow for the development of arching action. ...
... The values from the drawings are used for the database. The ratio a v /d reported in [117] is 2.7. For the database entries, the size of the support plate measured from the technical drawings is used, and the effective depth is calculated assuming a cover of 10 mm. ...
Adding steel fibers to concrete improves the capacity in tension-driven failure modes. An example is the shear capacity in steel fiber reinforced concrete (SFRC) beams with longitudinal reinforcement and without shear reinforcement. Since no mechanical models exist that can fully describe the behavior of SFRC beams without shear reinforcement failing in shear, a number of empirical equations have been suggested in the past. This paper compiles the existing empirical equations and code provisions for the prediction of the shear capacity of SFRC beams failing in shear as well as a database of 488 experiments reported in the literature. The experimental shear capacities from the database are then compared to the prediction equations. This comparison shows a large scatter on the ratio of experimental to predicted values. The practice of defining the tensile strength of SFRC based on different experiments internationally makes the comparison difficult. For design purposes, the code prediction methods based on the Eurocode shear expression provide reasonable results (with coefficients of variation on the ratio tested/predicted shear capacities of 27–29%). None of the currently available methods properly describe the behavior of SFRC beams failing in shear. As such, this work shows the need for studies that address the different shear-carrying mechanisms in SFRC and its crack kinematics.
In this study, an artificial intelligence tool called gene expression programming (GEP) has been successfully applied to develop an empirical model that can predict the shear strength of steel fiber reinforced concrete beams. The proposed genetic model incorporates all the influencing parameters such as the geometric properties of the beam, the concrete compressive strength, the shear span-to-depth ratio, and the mechanical and material properties of steel fiber. Existing empirical models ignore the tensile strength of steel fibers, which exercise a strong influence on the crack propagation of concrete matrix, thereby affecting the beam shear strength. To overcome this limitation, an improved and robust empirical model is proposed herein that incorporates the fiber tensile strength along with the other influencing factors. For this purpose, an extensive experimental database subjected to four-point loading is constructed comprising results of 488 tests drawn from the literature. The data are divided based on different shapes (hooked or straight fiber) and the tensile strength of steel fiber. The empirical model is developed using this experimental database and statistically compared with previously established empirical equations. This comparison indicates that the proposed model shows significant improvement in predicting the shear strength of steel fiber reinforced concrete beams, thus substantiating the important role of fiber tensile strength.
This paper presents a semi-empirical model to estimate the ultimate shear strength of steel fiber-reinforced concrete (SFRC) beams without shear reinforcement using the gene expression programming (GEP) technique. An extensive, reliable dataset consisting of the data of 266 SFRC beams with no stirrups was established for the development of this model. The most effective variables including the compressive strength (fc'), ratio of shear span-to-effective depth (a/d), ratio of flexural reinforcement (ρ), and fiber factor (F) were employed as input parameters in the GEP-based modeling. The accuracy of the proposed model was verified by its ability to predict a portion of data that had not been used in the training phase. Moreover, the performance of the model was evaluated using different statistical criteria. Sensitivity analysis and parametric studies were conducted on the proposed model to determine its ability to correctly consider the effect of input parameters for predicting the ultimate shear strength. In addition, the proposed model was compared with some other models proposed in the literature, and it was found that the proposed model demonstrates the best performance and accuracy among the considered shear strength prediction models.
The incorporation of steel fibers in a concrete mix enhances the shear capacity of reinforced concrete beams and a comprehensive understanding of this phenomenon is imperative to have an accurate estimation in engineering designs. Although significant studies have been carried out on shear capacity estimation, mechanics-based models are not yet available due to the complex underlying phenomenon. This paper presents a data-driven approach to the shear strength of SFRC beams and incorporates the largest database compilation of 507 experimental data. Input features considered in this study are the ratio of shear span to effective depth, concrete compressive strength, longitudinal reinforcement ratio, volume fraction, aspect ratio, and type of fiber. Eleven machine learning (ML) models, namely linear regression, ridge regression, lasso regression, decision tree, random forest, support vector machine, k-nearest neighbors, artificial neural network, XGBoost, AdaBoost, and CatBoost, are evaluated to examine their shear strength estimation of SFRC beams. The XGBoost is resulting in the most accurate predictions (85%) with the lowest root mean squared error and low mean absolute error. A study on the importance of the input parameters reveals that shear span to effective depth ratio, longitudinal reinforcement ratio, concrete strength, and volume fraction of fiber are the most influential parameters of shear strength of SFRC.
