Effect Of Reinforcement Ratio Research Articles

Effect of Reinforcement Ratio and Particle Size on the Physical and Mechanical Performance of Epoxy Matrix Panels and Waste Wood from Iroko Chlorophora excelsa from Cameroon

The use of local materials developed from natural reinforcements remains a major challenge for many researchers in the development of the industry and the fight against pollution. The wood industry generates large quantities of environmental waste, including Iroko wood. To give Iroko a second life, this study uses Iroko sawdust waste to make an epoxy matrix composite material. The composite was produced using a cold pressing technique based on moving the top and bottom plates to a thickness of 10 mm. On this basis, three particle sizes [t < 0.35[, [0.35–0.63[, and [0.63–1[ were used, as well as three reinforcement (R)/matrix (M) percentages of 50R/50M, 60R/40M, and 70R/30M, where R is the reinforcement percentage and M is the matrix percentage. The physical tests, apparent and real density, porosity, moisture content, water absorption rate, absorption and desorption kinetics, diffusion theory, and activation energy were determined by the gravimetric method. A three-point bending test was carried out in accordance with the ASTM D790 for mechanical tests. The results show that the addition of Iroko particles lightens the material by reducing its density. The hydrophilic nature of Iroko particles increases the absorption rate and porosity, with good diffusion capacity as the particle size and percentage increase. The material produced can be light and porous, with possible applications in thermal insulation. In terms of kinetics, Verma et al.’s model best correlates the experimental desorption points for the 3 isotherms, while Page’s model best correlates the water absorption points. The mechanical results show that Young’s modulus and stress at break decrease with an increase in the reinforcement percentage and particle size. The mechanical results can be used to define the material’s applications in construction and furniture. In accordance with the EN312 standard, the composites produced can be classified as type 2 lightweight materials, suitable for use in dry and damp areas.

Dynamic response of concrete beams reinforced with GFRP and steel bars under impact loading

This study explores the dynamic response of concrete beams reinforced with hybrid glass fiber-reinforced polymer (GFRP) and steel bars under impact loading. A detailed three-dimensional nonlinear finite element model of concrete beams is developed, considering the strain rate effects for concrete, GFRP and steel bars. The accuracy of the numerical model is validated against experimental results available in existing literature. Based on the simulation results, the impact responses of hybrid GFRP-steel RC beams are discussed and compared with steel-RC and GFRP-RC beams. The study results reveal that increasing the effective reinforcement ratio of hybrid GFRP-steel RC beams enhances impact performance, with values above 1% found to be crucial for mitigating severe damage and deflection. Hybrid GFRP-steel RC beams with an effective reinforcement ratio ranging from 1.04% to 1.30% demonstrated enhanced impact resistance compared to GFRP-RC and steel-RC beams. Additional parameters affecting the impact response of hybrid GFRP-steel RC beams, such as impact location, configuration of tensile longitudinal bars, impact velocity and drop weight inclination angle, are explored.

Effect of reinforcement ratio and textile pre-impregnation on the mechanical properties of flax textile reinforced sulfoaluminate matrix

This study evaluates the effect of reinforcement ratio and textile pre-impregnation on the tensile behavior of flax textile, embedded in an inorganic CSA matrix (sulfoaluminate cementitious matrix), known as Fabric Reinforced Cementitious Matrix (FRCM). Two reinforcement ratios of (3 and 6%) and two impregnation techniques (polymeric and mineral) are applied. Direct tensile tests are conducted on FRCM specimens as well as on bare flax textiles featuring three configurations: NP (non-impregnated), PP (polymeric-impregnated), and PM (mineral-impregnated), between 1L (one layer) and 2L (two layers) of flax textile. The results show a direct correlation between the reinforcement ratio and the enhancement of mechanical properties, with a notable 44% increase in mechanical strength observed for NP FRCM specimens between 1L and 2L of flax textile. Mineral pre-impregnation enhances yarn-cement matrix bonding inside FRCM, while FRCM specimens with polymeric-impregnated textiles have limited influence on the mechanical properties due to premature failure. Polymeric impregnation has a pronounced effect when applied to bare flax textiles, with PP flax textiles demonstrating exceptional mechanical strength and rigidity, reaching up to 480 MPa and 37 GPa, respectively. In contrast, this effect was mitigated when employing PP textiles in FRCM specimens, where the lowest fabric efficiency reached 12% for the 2L.PP configuration suggests significant chemical incompatibility between epoxy resin and CSA matrix. Mineral-impregnated specimens display consistent efficiency regardless of reinforcement ratio, suggesting a novel and homogeneous distribution of cement matrix particles within the yarns of textiles. Two distinct failure modes of FRCM are observed in this study, a delamination for PP configurations and a fiber pullout for NP and PM configurations. No effect of reinforcement ratio is remarked on the failure mode. The cracking mode in PM FRCM configurations showcased improved aesthetics, durability, and elongation after rupture (6.28%). As a result, 2L.PM FRCM is the best configuration in terms of mechanical strength, rigidity, ductility, and durability.

Experimental study on flexural behaviors of FRP and steel bars hybrid reinforced concrete beams

To investigate the flexural behaviors of Fiber-reinforced polymer (FRP) and steel bars hybrid reinforced concrete (Hybrid-RC) beams, twelve beams were designed and manufactured, including one steel bars reinforced concrete (Steel-RC) beam, one GFRP reinforced concrete (GFRP-RC) beam, and ten Hybrid-RC beams. The effects of FRP bars type, concrete strength, and effective reinforcement ratio on the flexural behaviors of Hybrid-RC beams were studied through experiments and compared with the predicted results of theoretical models. The research results indicated that when the reinforcement area and service load were the same, the crack width, deflection, ultimate bearing capacity, and ductility of Hybrid-RC beams were between Steel-RC and GFRP-RC beam. The flexural bearing capacity of Hybrid-RC beams might also be increased by using FRP bars with a higher elastic modulus or by increasing the effective reinforcement ratio; however, it would reduce the ductility of the beams. In contrast, increasing the concrete strength could simultaneously increase the Hybrid-RC beams’ flexural bearing capacity and ductility. The equation for calculating the stress of FRP bars in the ultimate state of Hybrid-RC beams was obtained by fitting regression based on the test results, and the equation’s predicted results and test results showed good agreement. In addition, the predicted results of the flexural behaviors of Hybrid-RC beams using the theoretical model agreed with the experimental results.

Experimental Calibration of a Homogeneous Substitute Material Model for Reinforced High-Performance Concrete Modeling.

The purpose of this work was to develop a substitute material model for the analysis of reinforced concrete structures. This paper presents proposals to solve the problem of limited calculation time, both to perform simulation models and to perform effective numerical or analytical analyses of structural elements in order to achieve results consistent with experimental results. Achieving this aim is conditional upon the determination of the material model parameters, taking into account the type of structure, the system of reinforcement, and the static strength-deformation parameters of the component materials. A universal procedure is proposed for determining the parameters of the substitute material model on the basis of the homogenization function, in which the homogenization coefficient is assumed as being equal to the effective reinforcement ratio of real reinforced concrete structural elements. In addition, the introduction of a new concrete constraint coefficient to this procedure, which corresponds to the proportionality coefficient of biaxial to uniaxial compressive strength, is proposed. On the basis of the conducted comparative analyses, the possibility of using the hypothetical substitute material model for the design of building elements and structures was confirmed. The average values of the obtained results for individual research series did not differ from the experimental results by more than 8.5%, for both the numerical and analytical models.

Numerical simulation and experimental study on mechanical behavior of the gusset for nuclear power plant containment

The gusset of a nuclear power plant containment, which serves as the junction between the shell and the raft foundation, is a critical area that poses a significant challenge due to its irregular shape and complex mechanical properties. Studying the stress mechanism of this area is crucial to understanding the overall structural performance of the containment. To achieve this, ABAQUS software was used to simplify the containment model and develop a gusset model, which was validated by comparing it with a fan-shaped containment model. Two 1:3 scale specimens were then designed and fabricated based on the gusset model to conduct static tests under two loading combinations. The effectiveness of the finite element model (FEM) was verified by comparing the failure mode, load–strain relationship of the rebars, and load–displacement relationship with that of the test. Through finite element parameterization analysis, the effects of reinforcement ratio and thickness on the mechanical performance of the gusset were investigated. The results showed that tripling the reinforcement ratio in rows H1 to H3 and column S1 or increasing the specimen thickness by 500 mm significantly improved the tensile damage of concrete, yield of rebars and structural displacement. Additionally, removing rebars from columns S8 to S13 had little effect on the structure. The findings of this study can guide the optimization of containment structural reinforcement and provide essential data support for FEM.

The effect of reinforcement ratio on corrosion properties in Al2O3 reinforced composites with AA2024 aluminum matrix produced by hot pressing

In this study, corrosion properties of AA2024 aluminum alloy matrix composite materials reinforced with Al2O3 in three different ratios were investigated. After mixing the aluminum alloy matrix material powders and the reinforcement material powders at 10%, 20% and 30% Al2O3 ratios homogeneously, composite materials were produced by keeping them in an axial mold under 50 MPa pressure and 550 °C for 1 hour by hot pressing method. According to the corrosion test results, the corrosion resistance of the composite materials containing 20% and 30% Al2O3 reinforcement was very close to each other. The corrosion rates of these two samples were determined to be lower than the sample containing 10% Al2O3 reinforcement.

Effect of Reinforcement Ratio and Bond Characteristic on Flexural Behavior of Carbon Textile-Reinforced Concrete Panels.

Textile-reinforced concrete (TRC) is highly anticipated as an alternative to reinforced concrete due to its ability to enable lightweight design, free formability, and improved ductility. In this study, TRC panel test specimens were fabricated and four-point loading flexural tests were performed to examine the flexural characteristics of TRC panels reinforced with carbon fabric, and to investigate the effect of the fabric reinforcement ratio, anchorage length, and surface treatment of fabric. Furthermore, the flexural behavior of the test specimens was numerically analyzed using the general section analysis concept of reinforced concrete and compared with the experimental results. Due to bond failure between the carbon fabric and the concrete matrix, the TRC panel showed a large decrease in flexural performance in terms of flexural stiffness, flexural strength, cracking behavior, and deflection. This low performance was improved by increasing the fabric reinforcement ratio, anchoring length, and sand-epoxy surface treatment of the anchorage. Comparing the numerical calculation results with the experimental results, the deflection of the experimental results was approximately 50% larger than the numerical calculation results. This is because the perfect bond between the carbon fabric and the concrete matrix failed, and slip occurred.

Experimental study and performance analysis of the flexural strength of reinforced ice slabs

In recent years, interest in the prefabricated ice rink for international competition has increased. The ice sheet, whose support is extruded polystyrene foam board, is prone to bending failure. To maintain the advantage of recycling prefabricated ice rinks, the method of reinforcing ice slabs with welded steel mesh (SRI) was proposed. However, the flexural properties of SRI remain unclear. Therefore, three-point bending tests, theoretical derivation, and finite element analysis were conducted in this study to better understand SRI. First, the three-point bending tests with 17 specimens were performed considering the effects of reinforcement ratio (0%∼0.812%). The results showed that the SRI's cracking load capacity and ultimate load capacity improved significantly with 1.84 and 4.49 times higher than the plain ice slab at most. Additionally, reinforcement can reduce the stiffness drop caused by cracking, which can be increased to 0.913 at most. Then, the calculation formula of the cracking load, which is a segmentation function, is derived based plane section assumption and gets good agreement with experimental results. At the same time, the calculation formula of the ultimate load is derived, although the calculation result is conservative, it can reflect the trend of the ultimate load with the variation of reinforcement ratio. Finally, finite element simulation analysis of three-point bending tests of SRI were conducted, using the brittle cracking model and the Coulomb-Moore plasticity model, respectively. Simulation results show that using both models alone have the limitation of use range. As a result, a B + C combined numerical model (the brittle cracking model is used for the tension zone and the Coulomb-Mohr plasticity model is used for the compressive zone) was proposed, and the simulation results agree well with the cracking load of both experiment and formula. Taken together, the welded steel mesh effectively improves the flexural performance of ice slabs and the findings of this study are beneficial for the design and finite element analysis of SRI in the future.

Flexural performance of Metal-Reinforced glass Beams: Numerical and analytical investigation

Reinforced glass beam (RG beam) is a promising but under-researched structural typology. Existing analytical models for RG beams have provided unsafe residual resistance predictions, indicating the need for better theoretical methods.As a basis for the theoretical model, this paper conducts a numerical study and validates the applied finite element method (FEM) with previous experiments. To improve computational efficiency, a simplified 2D modelling method is proposed that applies equivalent material models for both laminated glass and adhesive layers, for in-plane flexural behaviour. The applied 2D finite element (FE) model is verified against experimental data.The effects of reinforcement ratio, reinforcement material, adhesive performance, and shear span to depth ratio on the in-plane flexural performance of the RG beam are then extensively investigated using the proposed FEM model. Numerical results help understanding the failure mechanisms of different failure modes, with an emphasis on the significance of adhesive behaviour.Adopting the composite beam theory, an analytical method is proposed to address different limit states of the RG beams and is validated against the FEM and experimantal results.

Experimental and analytical investigations on tension stiffening of reinforced engineered cementitious composites members

Experimental and analytical investigations on the performance of reinforced ECC members in tension were studied in this paper through direct tension load. The applied load and elongation of members were measured during testing. The number and width of major cracks in specimens were determined at failure. The influences of the cross-sectional dimension and steel reinforcement diameter on the tension stiffening of members were investigated. Comparisons were made among reinforced ECC members with different cross-sectional dimensions or reinforcement diameters in terms of the cracking load, ultimate load and ultimate strain. Experimental results showed that the load-deformation relationship of reinforced ECC members could be divided into three stages, namely, initial elastic stage, multiple cracking stage and major cracking stage. In addition to experimental tests, an analytical model for the tension stiffening behaviour of reinforced ECC members was proposed. The interaction between ECC and steel reinforcement was considered at different stages in this model. Comparisons with experimental data suggest that the analytical model could accurately predict the relationship between load and deformation of reinforced ECC members. The cracking load obtained by this model is conservative as compared with test data. Based on the validated analytical model, a parametric study was carried out on the effects of reinforcement ratio and bond stress on tension stiffening of reinforced ECC. The direct tension tests and analytical results in this study can be used to predict the load and deformation behaviour of reinforced ECC members in tension.

The effect of B4C reinforcements on the microstructure, mechanical properties, and wear behavior of AA7075 alloy matrix produced by squeeze casting

Aluminum and its alloys have become the most popular materials in applications aiming to provide lightness due to their low density. However, the low mechanical properties compared to other competitors are among the disadvantages of aluminum and its alloys. This is an important motivation factor in researching strength increasing mechanisms in aluminum and its alloys. In this study, the effects of reinforcement ratio and type on the microstructure, mechanical properties, and wear behavior of the AA7075/B4C composite produced by squeeze casting method were investigated. Two types of materials were produced and compared—non-reinforced AA7075 alloy and AA7075 allo matrix composite reinforced by 4, 8, 10, and 12 wt% B4C. Microstructures of two materials were analyzed by optical microscope, scanning electron microscope and energy distribution spectrometer. In addition, the mechanical and tribological properties of these materials were investigated. Microstructure and scanning electron microscope analysis reveals that the increasing B4C reinforcement ratio increased the tendency of agglomeration in the matrix. Although B4C reinforcement tends to agglomerate, B4C reinforcement positively affected the AA7075 alloy's hardness, tensile and bending strengths, elasticity modules, and wear resistance.

Experimental study on creep of short performance-based alkali-activated concrete column

Performance-based alkali-activated concrete overcomes the fatal disadvantage of short setting time and poor workability. In this paper, The creep test of this kind of concrete is carried out to explore the influence of strength grade and reinforcement ratio on the creep coefficient under the condition of constant temperature and humidity environment. Results show that specific creep and creep coefficient of alkali activated concrete decrease with strength grade. The ratio of creep coefficients of C30, C50 and C70 is 1:0.89:0.80. The creep coefficients were compared with the creep models adopted by the American Code, the European Code, and the Chinese Code, which are not suitable for predicting the creep coefficient of alkali-activated concrete. At the same time, considering the use of reinforcement in practical applications, the effect of reinforcement ratio on the creep coefficient of alkali-activated concrete is studied. The results show that reinforcement can reduce the creep coefficient. The greater the reinforcement ratio, the smaller the creep coefficient. The creep coefficient of alkali-activated concrete with reinforcement ratio of 1.1% and 2.0% is 11.1% and 18.7% smaller than that of concrete without reinforcement. Based on the aging theory method, according to the force balance condition and deformation coordination condition, the creep coefficient calculation formula considering the influence of the steel bar can be deduced. The theoretically calculated value is in good agreement with the measured data. This formula can be used to predict the creep coefficient of alkali-activated reinforced concrete.

Orthogonal Analysis of Flexural Capacity of Beams Reinforced by High Strength Reinforcement and Ultra High Performance Concrete with Coarse Aggregate

In order to study the influencing factors of the flexural capacity of ultra high performance concrete with coarse aggregate (UHPC-CA) beams with high strength reinforcement, the orthogonal test method was used to analyze the influence of reinforcement grade, reinforcement diameter, section effective height and concrete strength grade on the flexural capacity of UHPC-CA beams with high strength reinforcement. The results show that the diameter of reinforcement is an important significant factor affecting the flexural capacity of UHPC-CA beams with high-strength reinforcement, and the grade of reinforcement and the effective height of section are general significant factors. With the increase of the three factors, the flexural capacity of the beam is gradually improved. The influence of concrete strength grade on the flexural capacity of UHPC-CA beams with high-strength reinforcement is small. With the increase of concrete strength grade, the flexural capacity first decreases slightly and then increases slightly. The effect of reinforcement ratio on flexural capacity of UHPC-CA beams with ordinary strength reinforcement is greater than that of UHPC-CA beams with high strength reinforcement.

Failure mechanisms and loading capacity prediction for rectangular UHPC beams under pure torsion

This study presents an experimental investigation of the loading capacity and failure mechanism of ultra-high-performance concrete (UHPC) beams under pure torsion. Twelve rectangular solid beams were fabricated and tested. The investigated parameters include the volumetric fraction of steel fibers (1.5%, 2.5%, and 3.5%), the longitudinal reinforcement ratio (0–1.54%), and the stirrup ratio (0–1.29%). The torsional behavior, including the crack propagation and failure modes, torque–twist curves, torque–strain curves, cracking and ultimate strengths, and effectiveness of steel fibers were evaluated and presented. Considering the UHPC high tensile strength, a formula for UHPC solid beams was proposed and verified by a reliability analysis. The results showed that compared to conventional concrete beams, the UHPC beams exhibited similar suitably reinforced, partially over-reinforced, and over-reinforced failure modes. Additionally, two different failure modes (type-I and type-II barely reinforced) were identified for UHPC beams. The additional steel fibers improve the torsional properties and directly determine the effective reinforcement ratio. Moreover, the steel fibers with 1.5% or higher volume fractions were proven to be sufficient to replace stirrups, and the proposed formula is effective in predicting the torsional strength of UHPC rectangular solid beams.

Influence of casting position on cracking behavior of reinforced concrete elements and evaluation of latest proposal for EN‐1992 and MC2020: Experimental study

AbstractThis article describes an experimental program aimed at studying the influence of casting position on the cracking behavior of reinforced concrete elements. The effect of other parameters such as concrete cover, ratio between diameter and effective reinforcement ratio (ϕ/ρs,ef) and type of loading (tension or bending) is also studied. The experimental program was conceived in order to compare the results obtained for crack spacing and crack width for beams with the main reinforcement cast in good and poor bond conditions. The possible influence of this factor was documented, on the strength of test results, in a previous article. A specific test program, reported in this article, was carried out at the Technical University of Madrid in order to confirm this phenomenon.

Effective reinforcement ratio of RC beams: Validation of modelling assumptions with high‐resolution strain data

AbstractConcrete tensile stresses influence the cracking behaviour and the stiffness of reinforced concrete (RC) members. Most design codes account for this tension stiffening effect using an effective reinforcement ratio. Although this ratio has a significant influence on the design of RC structures, its quantification is controversial in many cases, and typically relies on empirical geometry‐based expressions. One main reason for this knowledge gap is that the area of concrete in tension can only be verified indirectly, for example, through crack widths and spacings and using a suitable mechanical model. This indirect validation is subject to considerable uncertainty as it depends on parameters that scatter (e.g., bond stresses and the concrete tensile strength), and further assumptions relating internal stresses to the applied loads are required. This article outlines how refined measurements of the reinforcing steel strains and the concrete deformations in the compression zone, combining distributed fibre optic sensing (DFOS) and digital image correlation (DIC), can be used in order to obtain a more reliable quantification of the parameters affecting tension stiffening and hence, the effective reinforcement ratio. Selected models are validated against experimental data of an RC beam tested under four‐point bending, underlining the potential of DFOS and DIC as valuable tools for a better understanding of RC structures and the enhancement of mechanical models.

Flexural behavior of all lightweight reinforced concrete beams externally strengthened with CFRP sheets

The usage of structural Lightweight concrete (LWC) has increased over the years and received significant attention owing to its lower density, better economical design, and mechanical properties as compared to conventional normal weight concrete (NWC). However, limited research efforts and codes provisions deal with retrofitting and strengthening of lightweight concrete structures. Therefore, the main objective of this investigation is to evaluate the flexural performance of all lightweight concrete (ALWC) beams externally strengthened using Carbon Fibre Reinforced Polymer (CFRP) sheets. A total of fifteen ALWC beams were divided into three series based on their reinforcement ratio and strengthened with externally bonded CFRP sheets. The test variables studied in the experimental program were the effective reinforcement ratio, number of CFRP layers, and the percentage of pre-loading. All the beams were tested under four-point bending and the experimental results show that the CFRP sheet has significantly increased the ultimate load carrying capacity of pre-loaded and non-preloaded strengthened specimens. The increase in flexural capacity ranged from 28% to 102% over the unstrengthened control specimen. The ultimate load capacity was also predicted using different design standards and compared with the experimental load. The comparison showed that the current design standards have overestimated the flexural capacity of CFRP strengthened ALWC specimens.

Effects of reinforcement ratio on seismic performance of hypothetical stations determined by full-scale central column tests

Effects of reinforcement ratio on seismic performance of hypothetical stations determined by full-scale central column tests

Investigation of Mechanical Properties of Si3N4 Reinforced Composites Produced from Aluminum Waste

In this study, first of all, waste aluminum beverage cans were melted and poured into molds to obtain matrix material in the form of ingots. Stir casting process was used for composite material production. 0.5%, 0.75% and 1% by weight Si3N4 reinforcement was added to the matrix material. The effects of reinforcement ratios on the density, hardness, tensile strength, impact strength and microstructure of composite materials were investigated. In Si3N4 reinforced composites, tensile strength increased from 54,5 MPa to 105,17 MPa, impact strength increased from 4,94 J to 13,18 J, and hardness increased from 70 HV to 87,9 HV depending on the increased reinforcement ratio. Also, in the density measurements, density and porosity ratio increased with the increase of the reinforcement ratio. From the scanning electron microscope (SEM) images of the produced composites, it was determined that the particle distribution increased with the increase in the reinforcement ratio and the reinforcement material was homogeneously dispersed.