Tensile Reinforcement Research Articles

Study on the intermediate crack-induced debonding strain of FRP-strengthened concrete members using the updated BP neural network

Fiber reinforced plastics (FRP) are often used to enhance the capacity of the reinforced concrete beam (RC beam). However, the debonding failure is often observed due to the effect of the complex environment and the random loads. The debonding failure includes three types: plate end interfacial debonding (PE debonding), critical diagonal crack-induced debonding (CDC debonding), and intermediate flexural crack-induced interfacial debonding (IC debonding). In order to investigate the IC debonding strain of RC beam strength by FRP, this paper proposed some data-driven models to explore the IC debonding strain, based on the machine learning approaches The concrete strength, shear span proportion, the proportion of anchorage length to shear width, tensile reinforcement proportion, steel yield strength, stirrup reinforcement ratio, FRP stiffness, and the proportion of sheet span to beamwidth were regarded as the input parameters. The IC debonding strain was regarded as the output. It was found that the BP model can predict the IC debonding strain well. However, the BP data-driven model is easy to fall into a local minimum, and it is very difficult to converge, which has a negative effect on the accuracy of the model. The Sparrow Search Algorithm (SSA) was proposed to update it. The results indicated that the neural network optimized by SSA with lowest relative error, which can predict the IC debonding strain well. In addition, a study on the importance of each input found that the concrete strength, shear span proportion, and reinforcement yield strength will have a big impact on the IC debonding strain.

Experimental Study on Steel Fiber Reinforced Concrete

Abstract: As of today, there are no official set of rules for designing fiber reinforced structures, but there are several suggestions for rules which are described in the report. Mechanical properties of concrete and mortar reinforced with randomly distributed smooth steel fibers were investigated to understand the mechanism of fiber reinforcing. Different volumes, lengths, orientations and types of fibers were used. Fibers were compared with conventional reinforcement in flexure, tension and compression. It was observed that the significant reinforcing effect of fibers is derived after the cracks are initiated in the matrix, just as with conventional tensile and stirrup reinforcement. The post-cracking resistance of fibers is considerably influenced by their lengths, orientation, and stress-strain relationship. The spacing of reinforcement appears to have little influence on crack propagation below a certain length. This Project consist of M20 Grade concrete where the compression test and split tensile test are done. The cubes and cylinders are casted for 7,14 and 28 days of curing. Steel fibers are used in this project with three different volume percentage of fibres (0.50%,0.75% and 1.0%). The inclusion of fiber showed improvement of compression strength and tensile strength.

Flexural performance of steel-reinforced geopolymer concrete one-way slabs: Experimental and numerical investigations

This paper investigated the out-of-plane flexural performances of ambient-cured steel-reinforced slag and fly ash-based geopolymer concrete one-way slabs, in which the activator was the blend of NaOH and sodium silicate solutions (SiO2/Na2O = 3.1–3.3). Twelve specimens were prepared and tested, which included six OPC concrete specimens. The test parameters were concrete type (i.e., geopolymer and ordinary Portland cement (OPC) concrete), concrete compressive strength (i.e., 30 MPa, 40 MPa, and 50 MPa) and longitudinal tensile reinforcement ratio (i.e., 0.82 % and 1.20 %). The failure modes, crack patterns, load–deflection relationships and load–strain relationships of all specimens were carefully studied and reported. Further, a two dimensional (2D) finite element (FE) analysis was conducted to validate the test results. The results of the study indicated that: (1) the geopolymer concrete specimens presented lesser crack width and crack spacing owing to the improved bond between rebar and geopolymer concrete; (2) the cracking load and initial stiffness of geopolymer concrete specimens were slightly lower than that of OPC concrete counterparts; (3) the current Codes of Practice GB50010-2010 and ACI 318-19 provided reasonable predictions of the cracking load and flexural load capacity of the steel-reinforced geopolymer concrete specimens; (4) the developed FE model provided a good prediction of the flexural performance of the tested slabs, and could be used for further parametric investigation.

A linear elastic design model for sprayed liners in damaged reinforced concrete pipes

Reinforced concrete pipes experiencing unsafe levels of deterioration, and which require repair or replacement may be rehabilitated using trenchless technologies that avoid traffic impediments and costly excavations. One such trenchless solution involves the application of cementitious liners which are centrifugally sprayed out onto the interior of the host pipe to provide additional structural capacity and/or hydraulic repairs to the buried pipe. This paper presents a method for selecting the required liner thickness to prevent cracking and further deterioration in damaged reinforced concrete pipes. The design method is dependent on the burial conditions and extent of deterioration present in the host pipe: cracking, loss of concrete cover, loss of tensile reinforcement or the total breakdown of the host pipe. The bending moments resulting from earth loads are considered the controlling load source governing design. Design equations are developed to permit selection of minimum liner thickness needed for each of the deterioration types, considering composite interactions between the sprayed liner and the remaining components (concrete and steel) of the reinforced concrete pipe. Sample calculations are presented for the liner thicknesses required to rehabilitate Class 3, Class 4 and Class 5 pipes experiencing varying extents of deterioration. The results from the design models are evaluated using finite element simulations of the repaired pipe system. Comparisons between the strain distributions calculated using the design model and the finite element analyses demonstrate that the design model produces safe estimates of required liner thicknesses.

Experimental tests and analytical model for reinforced polyvinyl alcohol‐engineered cementitious composite beams in bending

AbstractPolyvinyl alcohol‐engineered cementitious composite (PVA‐ECC) exhibits strain hardening and multiple cracking characteristics under tension. Its superior tensile behavior may also influence the flexural behavior of reinforced PVA‐ECC beams. This paper investigates the load capacity and failure mode of reinforced PVA‐ECC beams in bending. Seven beams with different tensile reinforcement ratios, including six PVA‐ECC beams and one conventional concrete beam, were tested in the experimental program. The influence of reinforcement ratio on load capacity and failure characteristics was discussed in detail. Test results showed that with increasing reinforcement ratio, the ultimate load of beams was increased, but the failure mode was changed from fracture of PVA‐ECC in the tension zone to crushing in the compression zone, thereby limiting the full development of beam ductility. An analytical model is proposed to calculate the load and the vertical deflection of beams. In the model, the tension‐stiffening effect of reinforcement after cracking of PVA‐ECC is considered by defining the bond–slip relationship of reinforcement embedded in PVA‐ECC. Comparisons are made between experimental results in the literature and those calculated by using the analytical model to show the accuracy of the model in predicting the load–deflection relationship, the moment–rotation relationship, and the moment–curvature relationship.

The effect of reinforcement ratio on the flexural performance of alkali-activated fly ash-based geopolymer concrete beam

Alkali activated fly ash (AAFA) based geopolymer concrete structure is getting attention due to its eco-friendly construction characteristics and improved engineering properties. However, comprehensive studies on the structural performance of hardened properties of AAFA geopolymer concrete is not well addressed, especially on non-linear fracture behavior. This paper aims to present the reinforcement ratio effect on the flexural performance and non-linear fracture characteristics of alkali activated fly ash based geopolymer concrete beams. Sixteen finite element (FE) and four experimental models were used to study the effect of reinforcement ratio on the flexural performance and non-linear fracture characteristics. Four groups of concrete specimens with an average compressive strength of 19.30 MPa, 32.60 MPa, 38.2,0 MPa, and 41.70 MPa were utilized under this study. To investigate the effect of reinforcement ratio on flexural performance of the beams, reinforcement ratios of 0.03, 0.042, 0.045, and 0.063 were used for each compressive strength class. The result showed that the ultimate load carrying capacity of the beam showed significant improvement by about 36.38% by increasing of reinforcement ratio from 0.03 to 0.063 by keeping the compressive strength of concrete constant. However, it was observed that the effect of compressive strength was not such substantial as reinforcement ratio in enhancing the ultimate load bearing capacity. The experimental result showed that the increase in ultimate load by keeping the reinforcement ratio constant is about 12.20% for different compressive strength. Furthermore, the crack formation in the concrete was highly associated with the tensile reinforcement ratio, i.e., smaller reinforcement ratio led to higher strain growth in the concrete. Moreover, the validation study between the numerical simulation and test results showed a good agreement.

Reliability-Based Design Analysis for FRP Reinforced Compression Yield Beams.

Fiber-reinforced polymers (FRPs) provide promising prospects for replacing steel bars in traditional reinforced concrete structures. However, the use of FRP as tension bars in concrete beams leads to insufficient ductility because of its elastic characteristics. A newly developed compression-yielding (CY) beam has successfully solved this issue. Instead of tensile reinforcement yield, the ductile deformation of a CY beam is realized by the compression yield of a CY block in the compressive region. Another important feature is that the CY block is also the fuse of the beam, where material damage to the beam is concentrated in the CY block region and can be easily replaced. As a load-bearing recoverable and ductile structure, it is necessary to conduct a reliability-based design analysis and recommend reduction factors for this new structure. In this study, the function for calculating the failure probability of CY beams is proposed, semi-probabilistic design recommendations are presented, and Monte Carlo simulation (MCS) is adopted as a reliability analysis method. This study discusses the influence of the possible characteristics of the critical variables on reliability and provides the reliability index with different reduction factors to guide the design of the CY beam. These analyses indicate that the reliability index can be improved from the material design of the CY block in greater strength fb, smaller depth, smaller coefficient of variation of fb, and yield modulus ratio ξ. This study also shows that compared with the design of FRP concrete beams, the ductile failure mode of the CY beams allows a lower safety factor to meet safety requirements, which significantly reduces construction costs and avoids over-designing the load-bearing capacity.

A new method to investigate the intermediate crack-induced debonding strain

In order to investigate the interfacial debonding (IC) strain of the reinforced concrete structures strengthened by fiber-reinforced polymer (FRP), this paper proposed some data-driven models to explore it, considering the effect of random factors both in material and environment. The concrete strength, shear span proportion, the proportion of anchorage length to shear width, tensile reinforcement proportion, steel yield strength, stirrup reinforcement ratio, FRP stiffness, the proportion of sheet span to beamwidth, ratios of environmental temperature to the maintenance standard temperature, and ratios of environmental humidity to the relative humidity were regarded as the inputs, the IC debonding strain was regarded as the output. The results indicate that the neural network optimized by the sparrow search algorithm not only has a relatively small error but also has stronger robustness. In addition, a study on the importance of the inputs on the IC debonding strain indicates that the concrete strength, FRP stiffness, and ratios of environmental temperature to the maintenance standard temperature are the most significant factor to influence the IC debonding strain.

Performance Flexural of RC Beams Without Concrete at Tension Cross-section

This study aims to analyze the flexural capacity of RC without concrete in a tension cross-section using an experimental method. The number of specimens is three pieces, namely a spiral reinforced concrete beam (SBC) and a vertical reinforced concrete beam (CBN); both of these blocks are without concrete in the cross-section of the reinforcement and 60D tensile steel reinforcement in the support area, where D is the primary diameter, and a conventional concrete beam as the control beam (CB). The beam size is 3100×150×200 mm. The beams are supported by simple supports with a span of 3000 mm. The concrete in the structural beam elements, which work optimally to withstand the load, is the outermost fibre part of the side, while the concrete on the tension side does not have a direct role in determining the magnitude of the resisting moment. Therefore, the quality of the concrete in the concrete beam section must be optimized, while the concrete in the tension section must be minimized. Eliminating concrete in tension areas reduces the construction's self-weight and use of concrete-making materials. The main variables in this research are bending behaviour and crack pattern. The beam specimens were tested with two-point loading monotonically. By observing the crack pattern and failure mode, the results showed an increase in the capacity load of SBC by 21.58% CBN but a decrease of 27.57% compared to the CB control beam. Flexural cracks and beam failures resembled under-reinforcing. The flexural capacity was analyzed based on static analysis and then validated by calculating the ratio between the theoretical nominal moment and the experimental moment. This finding shows that changing the conventional shear reinforcement model to spiral can increase the flexural of the beam without concrete in the tension cross-section. Doi: 10.28991/CEJ-2022-08-11-014 Full Text: PDF

Evaluation of Flexural Behavior of Concrete Members Using CFRP Grids as Tensile Reinforcement

Evaluation of Flexural Behavior of Concrete Members Using CFRP Grids as Tensile Reinforcement

Stress–strain relationship of ductile materials and flexural behavior of ductile over-reinforced concrete beams

This paper aimed to investigate the effect of using ductile materials in the compression zone on the flexural performance of over-reinforced concrete beams. In order to avoid brittle compression failure, partial replacement of concrete with ductile materials layer in the compression zone was used. Four over-reinforced concrete beams of size 120 × 180 × 1,300 mm were cast and tested under three-point loading conditions. The steel fibers reinforced concrete (SFRC), slurry infiltrated fiber concrete (SIFCON), and ultra-high performance fiber reinforced concrete (UHPFRC) were used as ductile materials. The flexural capacity of the beams, failure modes, crack patterns, load-deflection relationships, ductility index, and toughness were investigated. The results showed that using ductile materials in the compression zone is an effective technique to increase the ultimate load, ductility, and toughness by up to 52.46, 84.78 and 279.93%, respectively, compared to the reference beam. In addition, the failure mode changed from brittle to ductile failure. Noting that the use of SFRC layer enhanced the ductility of over-reinforced concrete beams more than using UHPFRC and SIFCON layers. Also, one of the main advantages of this technique is led to increase the tensile reinforcement ratio up to 8.548% without needing the compressive reinforcement. Thus, ductile composite beams with a high flexural capacity were generated using an economical amount of ductile materials.

Shear behavior of RC pile cap beams strengthened using ultra-high performance concrete reinforced with steel mesh fabric

Although pile cap bases of structures are the most significant element in the construction and one of the most difficult parts in strengthening applications, previous studies on this element, particularly strengthening, are quite limited. The most extensively utilized, highly efficient, and simple to implement solution is ultra-high performance concrete (UHPC). In this study, six-half scaled pile cap beams were prepared and experimentally tested. Three of them were strengthened with UHPC (one in shear with connectors only, one in shear with connectors and steel mesh fabric (SMF), and one in shear and punching with connectors and SMF), while the other three were not strengthened to explore the influence of side bars. The bottom bars of the all six beams were identical, consisting of main longitudinal tensile and secondary lateral reinforcement. The load-displacement response, ultimate carrying load, failure mechanisms, energy dissipation capacity, and shear ductility of pile cap beams were all thoroughly investigated. The results revealed that using side bar reinforcement and UHPC with various techniques significantly enhanced the shear strength and ductility of pile cap beams. Except for the specimen including additional internal side bars, there were no appreciable differences in the peak load of un-strengthened reinforced concrete (RC) pile cap beams. The gain in peak load was 59% due to use of side bars. The RC pile cap beam strengthened in shear and punching with connectors and SMF exhibited the highest peak load and the highest energy dissipation capacity among all tested specimens.

Predicting the Response of RC Beam from a Drop-Weight Using Gene Expression Programming.

For structures and load-bearing beams under extreme impact loading, the prediction of the transmitted peak impact force is the most challenging task. Available numerical and soft computing-based methods for finding peak impact force are not very accurate. Therefore, a simple and user-friendly predictive model is constructed from a database containing 126 impact force experiments of the simply supported RC beams. The proposed model is developed using gene expression programming (GEP) that includes the effect of the impact velocity and the impactor weight. Also identified are other influencing factors that have been overlooked in the existing soft computing models, such as concrete compressive strength, the shear span to depth ratio, and the tensile reinforcement quantity and strength. This allows the proposed model to overcome several inconsistencies and difficulties residing in the existing models. A statistical study has been conducted to examine the adequacy of the proposed model compared to existing models. Additionally, a numerical confirmation of the empirical model of the peak impact force is obtained by reference to 3D finite element simulation in ABAQUS. Finally, the proposed model is employed to predict the dynamic shear force and bending moment diagrams, thus rendering it ideal for practical application.

Experimental study on the mechanical behaviour of short chopped basalt fibre reinforced concrete beams

The use of short chopped basalt fibres (CBFs) in concrete structures, as a promising alternative to conventional fibres, is of great importance to the sustainable development and plays a well-balanced role between strength improvement and workability in construction. Hence, this paper successively presents two series of test programs. Series Ⅰ as the preliminary material tests is conducted to understand the effects of short CBFs on concrete matrix, while Series Ⅱ as the beam tests is primarily to explore the flexural performance of concrete beams mixed with CBFs based on various three kinds of parameters. The results showed that in Series Ⅰ, the inclusion of CBFs can relieve the crack patterns from a sudden failure to a more ductile behaviour, and effectively upgrade the flexural strength of concrete. While in Series Ⅱ, concrete beams mixed with CBFs can help enhance the crack-resistance ability and greatly improve the flexural behaviour during the working stage. In addition, the improvement effects were enlarged with increasing fibre length, and that were reduced as the tensile reinforcement ratio increases. An FRL height ratio of 0.35 was suggested to ensure that the composite beams worked well and to avoid potential interface issues. Finally, the calculated methods of cracking moment and section stiffness during the service life, were proposed and verified by collecting other test data.

Experimental investigation on seismic behaviors of precast concrete shear walls with sleeve grouting defects

The grouted sleeve connector is one of the most widely used connections in precast concrete shear wall structures. Due to the technology limit of the assembly workers, the sleeve grouting often has defects, which could significantly weaken their practical performance. Only considering the effect of defects on the bearing capacity of the sleeve connector cannot simulate the effect of defects in actual engineering. To this end, an experiment was carried out to investigate the seismic performance of precast concrete shear walls with sleeve grouting defects. Four full-scale precast concrete shear walls with different defect levels of insufficient grouting were designed and tested under cyclic loads. The development of concrete cracking, failure mode, hysteresis features, load-bearing capacity, stiffness degradation, structural ductility and energy-dissipation capacity are analyzed to reveal the influence of the sleeve grouting defects on precast concrete shear walls. The test results indicated that with the increase of the defect level, the opening gap between the bottom of the wall and the top of the foundation beam widened, and the failure mode changed from tensile fracture of reinforcing steel bar to anchorage failure of the tensile reinforcement on the defective side. Meanwhile, as the level of grouting defects increased, the bearing capacity decreased, and the specimen failed prematurely. The effect of the grouting defects on cracking load was minor, while they had a significant influence on the yield bearing capacity, peak bearing capacity and ultimate bearing capacity. The experimental results also indicated that the grouting defects caused the weakening of the stiffness, ductility and energy dissipation of the precast concrete shear walls. The presented work could be used for defect prevention and evaluation of precast concrete shear walls with sleeve grouting defects.

Flexural performance of reinforced HS-HVFA-SCC beam with spliced plain bar

This research presents the use of flexural performance criteria for determining the required spliced length of tensile plain bar embedded in unconfined high strength-high volume fly ash-self compacting concrete (HS-HVFA-SCC) beam. Subsequently, the obtained splice length is compared with the splice length database of other concrete types. For the purpose of the investigation, five beams are designed with various spliced bars within the pure bending area. In addition, a beam with continuous bar is prepared as a reference beam. The beams are tested by a four-point loading scheme. The results show that splice lengths within a 342–570 mm (34.2db–57db) range provide sufficient development of strength in the reinforcements to sustain a higher flexural load than the reference beam. However, in term of stiffness and ductility, only beams with a splice length of at least 380 mm (38db) are superior compared to the reference beam. Based on the above consideration, the minimum splice length of tensile plain reinforcement for the investigated beams is 380 mm (38db). Comparison of the result with other concrete types suggests that the required splice length of tensile plain bar embedded in HS-HVFA-SCC follows the equations for estimating splice length of general concrete and self-compacting concrete (SCC) even though the equations are derived for deformed bars. This finding implies that an efficient splice length in HS-HVFA-SCC beam can be expected.Article HighlightsHS-HVFA-SCC beam with a lap-spliced plain bar of 38db gives an equal flexural performance to the beam with continuous bar.The required splice length of plain bar in HS-HVFA-SCC beam is comparable to that of deformed bar in other concrete types.An expected efficiency of splice length can encourage the use of HS-HVFA-SCC for a variety of structural applications.

The development length of tensile reinforcement embedded in High Volume Fly Ash-Self Compacting Concrete (HVFA-SCC)

• The development length of reinforcement in concrete is affected by the concrete types. • The observed bond failure in the beams with and without stirrups are splitting and slippage, respectively. • Stirrup increases the bond strength of HVFA-SCC to the reinforcement. • The proposed model gives a good estimation to the experimental results. This research evaluates the development length of tensile reinforcement in High Volume Fly Ash-Self Compacting Concrete (HVFA-SCC), which is a new type of concrete combining SCC and HVFA concepts. The development length of reinforcement is an important supportive property applied to HVFA-SCC, as a structural element. To ensure good load transfer between reinforcement and concrete, a sufficient development length is essential, with the length requirements being specified in the codes, formulated based on the bond strength of normal concrete experiments. Previous studies discovered that the bond strength of HVFA-SCC was greater than normal concrete, subsequently affecting the development length requirements. Therefore, this study proposes an equation to determine the development length required for reinforcement embedded in HVFA-SCC beams. Data were obtained from beam analysis, with several tests being carried out on 42 beams having the dimensions 150 × 250 mm and length 2 m, respectively. The investigated parameters were the reinforcement diameter and splice lengths, as well as the confinement effects of stirrups along the lap splice. The proposed equation was then compared with those suggested in the literature for other types of concrete. The results showed that the proposed equation gives a closer estimation to the experimental results compared to previous equations suggested in the literature.

A mechanical evaluation of polyvinyl alcohol hydrogels for temporomandibular joint disc replacement

The temporomandibular joint (TMJ) is a bilateral ginglymoarthroidal joint containing a fibrocartilaginous disc which distributes compressive stress and reduces friction on the articulating surfaces of the joint. Initially, conservative treatments can address disorders of the TMJ, but surgical procedures such as discectomy may be employed if dysfunction persists. Unfortunately, discectomy increases friction and alters the mechanical behavior of the TMJ when the disc is not replaced. An ideal replacement for the TMJ disc would restore healthy function of the joint and prevent further degeneration. Rigorous evaluation of materials is necessary to ensure the safety and efficacy of novel implants. Poly(vinyl) alcohol (PVA) hydrogels have been suggested as a good candidate for artificial cartilage replacement in other applications and are promising for replacing the TMJ disc due to their biocompatibility, low friction, and biomimetic levels of hydration. The objective of this study was to mechanically characterize hydrogel formulations of 15, 20, and 25% PVA and to compare them with the ovine TMJ disc to investigate the appropriateness of PVA hydrogels for TMJ disc replacement in a translational model. Experimental evaluations were conducted in indentation, unconfined compression, friction, and uniaxial tension. There were no statistically significant differences in the coefficient of friction between the PVA hydrogels and ovine TMJ disc. No statistically significant differences were found between at least one PVA hydrogel group and the TMJ disc for the indentation properties or the unconfined compression properties at low stretch magnitudes. The 20% PVA and 25% PVA hydrogels exhibited significantly higher failure stretch as compared to the ovine TMJ disc, and they were not statistically different in ultimate tensile strength from the TMJ disc in the mediolateral direction. However, the ovine TMJ disc tensile elastic moduli were 630 times larger in the anteroposterior direction and 53 times larger in the mediolateral direction than the stiffest PVA hydrogel. Ultimately, the 25% PVA hydrogel was the best candidate for TMJ disc replacement, demonstrating the most similarity to the ovine TMJ disc compressive properties; however, tensile reinforcement of the hydrogels would be necessary to approach the tensile modulus of the native TMJ disc.

Perencanaan Bak Penampungan Air yang Berasal Dari Mata Air di Lingkungan Universitas Jambi

Jambi University is one of the State Universities in Indonesia which is currently in the phase of sustainable development which is currently focusing on increasing development, especially water resource infrastructure. Planning for water reservoirs with reinforced concrete is an option in long-term infrastructure planning. The planned reservoir is in the form of a reservoir that functions as a container for storing clean water in the water treatment system at the Jambi University. Planning focuses on the design of the capacity and structural elements of the reinforced concrete reservoir. Planning refers to ACI-350M using the LRFD method, as well as SNI 7509:2011. The reservoir capacity is planned according to (Al-Layla et al., 1977)at 39% of the maximum water discharge, and the structural elements of the reservoir are planned in the form of beams, columns, upper, lower plates and walls. Based on the design, the reservoir capacity is 216 m3 with a length of 12 m, a width of 6 m and a height of 3.5 m. In planning the structural elements used concrete quality 21 MPa with the type of reinforcement BJTP-28. Based on the design results, the column size is 20 cm x 20 cm with 4D12 reinforcement details, then for beam sizes 30 cm x 20 cm using 4D12 for tensile reinforcement and 3D12 for compression reinforcement, and for plates using a thickness of 150 cm with reinforcement details D12-150 for top plate and D12-200 for bottom plate and wall plate.

Experimental and theoretical study on the flexural behavior of RC beams strengthened with cementitious grout

In this study, we experimentally and theoretically studied the flexural behavior of RC beams that were strengthened with cementitious grout based on the static loading test of beam specimens with two reinforcement positions and three thicknesses of reinforcement layers. We compared and assessed the failure modes, moment–deflection relationship, strain distribution along the height of the cross-section, strain of tensile longitudinal reinforcement, and the cracking behavior of the RC beams. The results showed that the RC beams strengthened with cementitious grout exhibited similar or greater flexural capacity compared to conventional RC beams, as well as a significantly greater ultimate deflection. Therefore, we concluded that the cementitious grout can be used to repair and reinforce existing RC beams with degraded performance, and can effectively restore or improve the bearing capacity of RC beams. Moreover, the reinforcement position and thickness significantly impacted the reinforcement effect of the RC beams. The results of the crack development analysis showed significant differences in the moment–crack width relationship between the RC beams strengthened with cementitious grout and the control beams. Thereafter, we proposed a rational calculation method to predict the flexural bearing capacity and deflection of RC beams strengthened with cementitious grout by considering the reinforcement positions and thicknesses of reinforcement layers. Additionally, the calculated results using the proposed method and the experimental results were found to be in good agreement, which indicates that the proposed method is accurate and can be used in engineering applications.