Retrofitted Reinforced Concrete Beams Research Articles

Machine learning models for predicting concrete beams shear strength externally bonded with FRP

This paper focuses on preparing a database that covers a wide range of experimental data encompassing all the variations in concrete design and fiber reinforced polymer (FRP) composition in reinforced concrete (RC) beams. Artificial intelligence technique is applied to develop 10 machine learning models for estimating the shear capacity of RC beams strengthened in shear using FRP. This study is unique in the sense that it covers the largest data regarding T-beams available in literature so far and is not limited to a particular beam cross section or FRP composition. A comparison among several design guidelines is done to evaluate the efficiency of the guidelines as well as the models developed in shear capacity estimation of FRP retrofitted RC beams. The results reveal that the ensemble learning models developed in this paper namely, random forest, CatBoost and XGBoost give the highest precision in estimating shear capacity of the FRP retrofitted RC beams. For rectangular beams the R2 and MAE values from CatBoost are 0.871 and 0.214 kN, respectively whereas those for XGBoost are 0.870 and 0.202 kN, respectively. The R2 and MAE values for T-beams using random forest are 0.897 and 0.128 kN, respectively and those using CatBoost are found to be 0.899 and 0.127 kN, respectively. The most significant input feature by Shapley Additive exPlanations is found to be the effective depth for the rectangular beams whereas height of FRP layers in the case of T-beams. The proposed ensemble models in this paper are proved to be superior to the existing mechanics-driven models currently being used for design practices.

Monitoring and characterizing the debonding in CFRP retrofitted RC beams using acoustic emission technology

Reinforced concrete (RC) beams are retrofitted in flexure using externally bonded CFRP sheets to enhance strength and ductility. However, the strength of the CFRP is not completely utilized because of the debonding failure which is abrupt in nature. Additionally, the presence of interfacial defects further exacerbates the bond capacity. To ensure structural safety, continuous monitoring of the retrofitted members is necessary. Acoustic emission technology is the most feasible option for monitoring because of its non-invasive nature and continuous monitoring capability. Therefore, the capability of acoustic emission technology in detecting the debonding mechanism has been experimentally investigated. Furthermore, the effect of interfacial defects on debonding has also been studied. Three RC beams tested in flexure and monitored using acoustic emissions. It was found that the complex debonding mechanism can be detected and characterized using acoustic emissions and the presence of interfacial defects contributes to the debonding mechanism.

Experimental and numerical investigation of flexural behavior of RC beams retrofitted with reinforced UHPFRC layer in tension surface

Ultra-high-performance fiber-reinforced concrete (UHPFRC) has recently been used in reinforced concrete (RC) full-cast or strengthened beams because it has better mechanical properties and durability. However, the main parameters that affect the flexure behavior of retrofitted RC beams with a UHPFRC layer need more study. This paper investigates experimentally and numerically the major parameters that control the effectiveness of retrofitting RC beams with an additional reinforced UHPFRC layer applied to the tensile surface. One non-strengthened RC beam and seven retrofitted RC beams (divided into three groups) were experimentally tested under a four-point loading test. The effects of different parameters, such as the length (0.50, 0.60, and 0.80 times the length of the strengthened beams), the thickness of the UHPFRC layer (30 and 40 mm), and the retrofitting technique (with or without the concrete cover), on the crack patterns and failure modes, load–deflection behavior, load carrying capacity, energy absorption, and stiffness, were studied. The results showed that retrofitted beams exhibited significantly improved ultimate load, stiffness, and energy absorption ability compared to the control beam. UHPFRC layer length and thickness were the most significant parameters; moreover, increasing the UHPFRC layer thickness can compensate for the reduction in its length. Lastly, the validated finite element (FE) model was used to study the effect of different parameters, such as the length (0.40, 0.70, and 0.90 times the length of the strengthened beams), the thickness of the UHPFRC layer (50 mm), and the reinforced bar diameter (12 and 16 mm) in the UHPFRC layer, on the flexural behavior of the strengthened RC beams.

Structural behaviour of the strengthened reinforced concrete beams using ultra high-performance fibre reinforced concrete layer

PurposeDamage to reinforced concrete (RC) structural elements is inevitable. Such damage can be the result of several factors, including aggressive environmental conditions, overloading, inadequate design, poor work execution, fire, storm, earthquakes etc. Therefore, repairing and strengthening is one way to improve damaged structures, so that they can be reutilized. In this research, the use of an ultra high-performance fibre-reinforced concrete (UHPFRC) layer is proposed as a strengthening material to rehabilitate damaged-RC beams. Different strengthening schemes pertaining to the structural performance of the retrofitted RC beams due to the flexural load were investigated.Design/methodology/approachA total of 13 normal RC beams were prepared. All the beams were subjected to a four-point flexural test. One beam was selected as the control beam and tested to failure, whereas the remaining beams were tested under a load of up to 50% of the ultimate load capacity of the control beam. The damaged beams were then strengthened using a UHPFRC layer with two different schemes; strip-shape and U-shape schemes, before all the beams were tested to failure.FindingsBased on the test results, the control beam and all strengthened beams failed in the flexural mode. Compared to the control beam, the damaged-RC beams strengthened using the strip-shape scheme provided an increase in the ultimate load capacity ranging from 14.50% to 43.48% (or an increase of 1.1450 to 1.4348 times), whereas for the U-shape scheme beams ranged from 48.70% to 149.37% (or an increase of 1.4870–2.4937 times). The U-shape scheme was more effective in rehabilitating the damaged-RC beams. The UHPFRC mixtures are workable, as well easy to place and cast into the formworks. Furthermore, the damaged-RC beams strengthened using strip-shape scheme and U-shape scheme generated ductility factors of greater than 4 and 3, respectively. According to Eurocode8, these values are suitable for seismically active regions. Therefore, the strengthened damaged-RC beams under this study can quite feasibly be used in such regions.Research limitations/implicationsObservations of crack patterns were not accompanied by measurements of crack widths due to the unavailability of a microcrack meter in the laboratory. The cost of the strengthening system application were not evaluated in this study, so the users should consider wisely related to the application of this method on the constructions.Practical implicationsRehabilitation of the damaged-RC beams exhibited an adequate structural performance, where all strengthened RC beams fail in the flexural mode, as well as having increment in the failure load capacity and ductility. So, the used strengthening system in this study can be applied for the building construction in the seismic regions.Social implicationsAside from equipment, application of this strengthening system need also the labours.Originality/valueThe use of sand blasting on the surfaces of the damaged-RC beams, as well as the application of UHPFRC layers of different thicknesses and shapes to strengthen the damaged-RC beams, provides a novel innovation in the strengthening of damaged-RC beams, which can be applicable to either bridge or building constructions.

Full-scale experimental evaluation of flexural strength and ductility of reinforced concrete beams strengthened with various FRP mechanisms

Carbon fiber reinforced polymer (CFRP) is used for enhancing the structural performance of reinforced concrete (RC) beams. Due to the high resistance of FRP against corrosion and decay, as well as its low specific weight, it has good luck in strengthening the main structural members. Since the FRP system is mainly used for retrofitting than design, its implementation methods are important. In this research, four various implementation methods are evaluated and defined as CFRP sheet, CFRP laminate, Near-surface mounted (NSM method) and combination of NSM and laminate (Hybrid). Full scale tests were done by 1000 kN capacity hydraulic jack. Four points loading is considered and simple support is used. Validation analysis is done and compared with ACI instruction and reasonable results have been achieved. In the past works extensive research has been done on the retrofitting RC beams with FRP and more focused on the internal FRP bars and NSM method. Various external methods are used for strengthening and retrofitting of the RC beams and all tests were done on the real size and full-scale beams. This paper presents an experimental program on five RC beams. One beam is defined as control beam that constructed with typical material and other four beams are retrofitted with various external FPR methods. Findings from the present work shows that maximum flexural capacity achieved by hybrid method. Moreover, the main achievement of this research is that hybrid type led to increase in the ductility and hardening than control beam.

Experimental investigation on shear performance of reinforced concrete beams retrofitted by pre-stressed steel strips

Due to the material deterioration and the update of design codes, some existing reinforced concrete (RC) beams need to be strengthened. The strapping method available in the packaging industry using pre-stressed steel strips can be applied in retrofitting engineering because of its low cost and high confinement effect. To guide the application of steel strips on RC beams under shear, the parameters in this paper are the steel strip spacing, strip layers and chamfer edges. The shear-compression failure and diagonal compression failure of the specimens were observed. The test results indicated that the shear strength of the retrofitted RC beams was enhanced by a maximum of 95%, and the displacement increased by 86% compared with the control specimen. Among the three parameters, the spacing of the steel strips exhibited the most significant effect on the strength and deformability of the retrofitted beams, while the strip layer and chamfer process improved the ductility more than the shear strength. The shear mechanism of the retrofitted RC beams was analyzed on the basis of the softened strut-and-tie model, and the steel strip was considered as a tie model to contribute to the shear strength. A theoretical equation and a design equation considering the parameters of steel strips were proposed to predict the shear capacity of the retrofitted RC beams and then validated by the experimental data.

Retrofitting of Reinforced Concrete Beams using Lightweight RC Jacket Containing Silica Nano Particles and Glass Fiber

The concrete jacket method is a common method used in retrofitting buildings. Although this method has many advantages, engineers criticize it due to an increase in the structure's weight. In the present study, lightweight concretes containing silica nanoparticles (SNPs) and glass fibers (GF) have been used in concrete jackets to strengthen concrete beams. Several reinforced concrete (RC) beams were constructed and retrofitted using the proposed lightweight concrete jackets and their response to four-point loading was evaluated. The SNPs amount in the lightweight concrete jackets was 0, 2, 4, and 6% by weight of cement and the amount of GF was 1.5% by volume of concrete. Load-deflection curves were extracted and the response of the beams was examined by parameters such as crack load, yield load, maximum load, energy absorption capacity, and ductility. The proposed lightweight concrete jacket containing 1.5% of GFs in which 0, 2, 4, and 6% of SNPs were used, increased the energy absorption capacity by 33%, 54%, 61%, and 62%, respectively. The presence of SNPs in lightweight concrete reinforced by GFs leads to the filling of small cavities in the concrete. Also, the bearing capacity of the retrofitted RC beams increased with an increase in SNPs in the concrete jacket. A portion of this increase can be attributed to an increase in tensile and compressive strength of the proposed concrete, and the other part can be attributed to the effect of SNPs on the surrounding surfaces of the main beam and jacket.

Combined Flexural and Shear Strengthening of RC T-Beams with FRP and TRM: Experimental Study and Parametric Finite Element Analyses

Due to inadequacies of reinforcement design in older structures and changes in building codes, but also the change of building use in existing structures, reinforced concrete (RC) beams often require upgrading during building renovation. The combined shear and flexural strengthening with composite materials, fibre-reinforced polymer sheets (FRP) and textile reinforced mortars (TRM), is assessed in this study. An experimental campaign on twelve half-scale retrofitted RC beams is presented, looking at various parameters of interest, including the effect of the steel reinforcement ratio on the retrofit effectiveness, the amount of composite material used for strengthening and the effect of the shear span, as well as the difference in effectiveness of FRP and TRM in strengthening RC beams. Significant effects on the shear capacity of composite retrofitted beams are observed for all studied parameters. The experimental study is used as a basis for developing a detailed finite element (FE) model for RC beams strengthened with FRP. The results of the FE model are compared to the experimental results and used to design a parametric study to further study the effect of the investigated parameters on the retrofit effectiveness.

Evaluation of Effective Polymer Fiber Length on Energy Absorption Capacity of Reinforced Beams by EBR and NSM Methods

This study presents a comparison of two methods used for retrofitting Reinforced Concrete (RC) beams, namely, the Externally Bonded Reinforcement (EBR) and the Near-Surface Mounting (NSM) methods. A parametric analysis was carried out using variables such as the retrofitted, the retrofitting method (EBR and NSM), and the thickness of the Carbon Fiber-Reinforced Polymer (CFRP) sheets. To achieve this goal, the finite element method and ABAQUS software were employed. An un-retrofitted beam was also simulated as the control specimen for comparison. Beam responses were compared through load–displacement and energy absorption capacity diagrams. Results show that the higher energy absorption capacity in all CFRP-retrofitted RC beams, which was 1.69–5.54 times higher than in un-retrofitted beams. In the case where half of the beam was reinforced using CFRP sheets, the entire beam assembly and the CFRP sheet contributed to load-bearing, thus delaying crack nucleation in the beam and increasing its energy absorption capacity. As a result, the energy absorption capacity of the beam, in this case, was less than that obtained in the previous one where half the span of the beam was retrofitted.

Experimental and numerical investigations on a novel plate anchorage system to solve FRP debonding problem in the strengthened RC beams

Method of externally bonded reinforcement (EBR) is one of the most prominent systems for retrofitting reinforced concrete (RC) beams containing fiber-reinforced polymers (FRP). Many studies conducted in this field confirm the fact that the majority of the beams strengthened in this way experience failure due to the sudden detachment of FRP sheets from the concrete substrate. In this regard, an innovative plate anchorage technique was presented to solve the FRP debonding problem. In this method (EBR by Welded Steel Plates), two plates are placed near the beam supports, which are connected by welding to a longitudinal tension reinforcement through the angles. FRP sheets are placed on seat plates at both ends and fixed in their position by another plate placed over them. Ten RC beams with 150 × 200 × 2000 mm were prepared from concrete in 21 and 35 MPa strength classes. All specimens were subjected to a quasi-static four-point bending test. A comparative study was also done using an analytical method and comparing experimental results in the literature. This research results revealed that the better and more practical performance of the suggested plate anchorage system resulted in postponing or completely solving the FRP surface debonding problem.

Enhancing the Performance of CFRP Shear-Strengthened RC Beams Using “Ductile” Anchoring Devices

Reinforced concrete (RC) beams that are shear-strengthened by externally bonded (EB) fiber reinforced polymer (FRP) often yield limited structural enhancement. This is due to the inherent weaknesses of EB-FRP strengthening, including the premature debonding of the FRP, its brittle rupture, and inadequate deformation capacity of the strengthening system. In this paper, two techniques of shear strengthening using U-wrapped carbon FRP (CFRP) and effective anchoring devices are proposed and tested with the aim of enhancing both the shear strength and the ductility of retrofitted RC beams. One of the techniques involves a hybrid-bonded (HB) CFRP system with adjustable normal pressure applied to the CFRP U-strips, and the other features the CFRP U-strips fastened by an H-type end anchor (EA). The main test variables of the former and latter shear-strengthening systems are normal pressures applied to the CFRP U-strips and the width of the deformation segment (or axial stiffness) of the H-type EA, respectively. The results indicate that both strengthening systems significantly enhanced the shear capacity and ductility of the strengthened RC beams. Compared with the control member, the increments in shear capacity were as high as 54.6% and 68.5% for beams retrofitted with the HB-FRP and the EA FRP systems, respectively, and their deflections at peak shear load increased by 43.9% and 84.1%, respectively. The shear failure modes were found to be related to the parameters used in both the HB-FRP and the EA FRP systems. The critical diagonal crack (CDC) inclination of all specimens was less than 45°, ranging from 38° to 44°. Both positive and negative shear interactions were observed between Vf and Vc plus Vs.

Experimental investigation on flexural deficient RC beams retrofitting with UHMW polyethylene

An experimental investigation on Reinforced Concrete (RC) beams is conducted in this study to test the flexure behaviour by contrasting control RC beams with retrofitted RC beams. The ultrahigh molecular weight polyethylene (UHMW PE) is used as a retrofitting material. It is one type of geosynthetic material. UHMW PE sheet is bounded externally by epoxy resin and hardener in U shape. As RC beams are weak in flexure, they are retrofitted to improve the flexural strength. In this study, two sets of beams are considered. One set consisting of three control specimens with 100%, 70% and 40% of flexural reinforcement and another consists of three samples with 100%, 70%and 40% flexural reinforcement and retrofitted with UHMW PE. This study also involves the investigation of ultimate load carrying capacity, failure mode and crack pattern of the beams. The wrapping technique is used, and the results showed that the retrofitting samples had more capacity to carry load than those of control samples. Thus, retrofitting is a feasible solution to overcome the stresses in the structure.

A nonlinear semi-analytical model for predicting debonding of FRP laminates from RC beams subjected to uniform or concentrated load

A semi-analytical model is developed to determine in FRP retrofitted reinforced concrete (RC) beams the interfacial shear and peeling stresses, the FRP laminate and the RC section strain and stresses at all loading stages up to failure. The FRP is assumed to be externally bonded to the beam but can undergo slip and relative vertical displacement at its interface with the concrete. The model is developed by satisfying the requirements of equilibrium and strain compatibility while concurrently allowing for interfacial deformations. FRP is treated as a linear elastic, steel as elasto-plastic strain hardening and concrete as fully nonlinear material in compression and tension, including tension stiffening. The governing equations are formulated as two second order differential equations with their dependent variables being the strain in the FRP and the relative normal displacement of the interface. The equations are solved for discrete states (uncracked, cracked, yielded) experienced by the RC section and their associated level of interfacial slip. The model results are compared with available experimental results for several beams retrofitted with carbon FRP or steel reinforced polymer (SRP) laminates subjected to either four point bending or simulated uniform load, with satisfactory agreement between them.

Finite element modeling of creep behavior of FRP-externally strengthened reinforced concrete beams

In this study, a nonlinear numerical analysis is carried out to predict the creep response of reinforced concrete (RC) beams externally strengthened using carbon fiber-reinforced polymer (CFRP) and glass fiber-reinforced polymer (GFRP) laminates. The beams are tested under static four-point bending; the level of sustained service load is equal to 59% of the ultimate capacities of the un-strengthened beams. The Burger rheological model is used to evaluate the flexural creep response (compressive and tensile creep) and then to validate the findings with experimental results. It is shown that the Burger model effectively predicts the creep of CFRP-bonded RC. Furthermore, parametric studies are performed to investigate the effects of: three fiber orientations of CFRP composites (0°, 45° and 90°), the CFRP thickness, and the type of FRP (CFRP and GFRP) on the flexural creep of FRP-externally retrofitted RC beams based on the Burger rheological model. According to the numerical results, a major reduction in creep strain is obtained with the 45° orientation of CFRP. An increase in CFRP-thickness significantly lowers the creep strain. Moreover, the CFRP laminates prove to be more effective than GFRP in improving the creep response.

Strengthening of RC beams with externally bonded and anchored thick CFRP laminate

Premature debonding of externally bonded FRP laminate from retrofitted reinforced concrete (RC) members can lead to inefficient use of FRP and can limit the level of strength increase that can be achieved. In this investigation, π-CFRP anchors are used in an attempt to delay the onset of premature debonding and to achieve higher strength in beams retrofitted with a 1.2 mm thick and 50 mm wide CFRP laminate. This investigation consisted of testing six large scale T-beams with a 4500 mm span, 400 mm height and 500 mm flange width under four-point bending. Two beams were tested without retrofit as control beams, one beam with the laminate epoxy bonded to the beam and the remaining three beams with the laminate epoxy bonded and anchored using CFRP π-anchors. One of the beams with 30 anchors exhibited a 46% increase in the debonding load over the beam without anchors while the laminate attained a maximum strain equal to 80% of its ultimate strain capacity, a 94% increase compared to the maximum strain reached in the companion beam strengthened with only the epoxy bonded laminate. The displacement ductility ratio of the latter beam at debonding exceeded 4. The results demonstrate the π-anchoring system effectiveness and a feasible way for efficiently utilizing strong and thick laminates in strengthening RC members.

Structural Behavior of Experimented Retrofitted RC Beam Using Natural Fibers with Neural Network

Reinforced Concrete (RC) structures frequently need restoring or potentially strengthening, because of a difference in use, growing or disintegration of materials delivered by natural components, or material damage because of unexpected loads. One fundamental implementation of this retrofitting modernism with fiber sheets to give external detention to RC structures when the limit of the existing structure is inadequate. In this paper, we present a novel experimental examination dependent on retrofitting reinforced concrete beams with regular hybrid fibers comprising of sisal and coir fiber. The concrete was blended with specific design ratio dependent on the evaluation of M20, M25, M30, and M35 grades. The specimens are cast and restored before testing. The behavior of the beams is inspected with the assistance of deflection, ductility, Load Carrying Capacity (LCC), and Energy Absorption Capacity (EAC). The experimental outcomes were investigated with simulation modeling that has been completed to simulate the behavior of the considerable number of beams. For validation purpose, we have utilized Artificial Neural Network (ANN) with structure optimization process. The optimal result is finding out by comparing the retrofitted specimen into control specimens. The result found that hybrid fiber retrofitted specimen performs low deflection and ductility at high loads and then increase the LCC and EAC compared to Control beams (CB1 and CB2). The soft computing strategies decrease computational time and limit the expense in a compelling way.

Shear behaviour of RC beams retrofitted using UHPFRC panels epoxied to the sides

In this study, the shear behaviour of reinforced concrete (RC) beams that were retrofitted using precast panels of ultra-high performance fiber reinforced concrete (UHPFRC) is presented. The precast UHPFRC panels were glued to the side surfaces of RC beams using epoxy adhesive in two different configurations: (i) retrofitting two sides, and (ii) retrofitting three sides. Experimental tests on the adhesive bond were conducted to estimate the bond capacity between the UHPFRC and normal concrete. All the specimens were tested in shear under varying levels of shear span-to-depth ratio (a/d=1.0; 1.5). For both types of configuration, the retrofitted specimens exhibited a significant improvement in terms of stiffness, load carrying capacity and failure mode. In addition, the UHPFRC retrofitting panels glued in three-sides shifted the failure from brittle shear to a more ductile flexural failure with enhancing the shear capacity up to 70%. This was more noticeable in beams that were tested with a/d=1.5. An approach for the approximation of the failure capacity of the retrofitted RC beams was evolved using a multi-level regression of the data obtained from the experimental work. The predicted values of strength have been validated by comparing them with the available test data. In addition, a 3-D finite element model (FEM) was developed to estimate the failure load and overall behaviour of the retrofitted beams. The FEM of the retrofitted beams was conducted using the non-linear finite element software ABAQUS.

BEHAVIOR OF RC BEAM RETROFITTED USING ULTRA HIGH-PERFORMANCE CONCRETE UNDER IMPACT LOADS

Several new types of materials have recently been used as retrofitting materials for structural elements such as ultra-high performance concrete with steel fiber reinforcement (UHPFRC). These materials are used as jacking to enhance the strength and ductility reinforced concrete (RC) beams. Considerable attention has been focused on the response of retrofitted RC beam under static loads but the behavior of such beam under impact loading is somewhat lacking. Therefore, in this study, a 3-D finite element model (FEM) of retrofitted RC beams under impact loading using non-linear finite element software (ABAQUS) was investigated. Since experimental work on this topic is scarce, the FEM is validated using the results of retrofitted RC beam under static loads. The impact load was applied in ABAQUS as equivalent to an initial velocity of 2500 mm/s. A parametric study was carried out to study the flexural response of RC beams retrofitted with different thicknesses and strengthening configurations of UHPFRC under impact loading.

Fatigue behaviour of damaged RC beams strengthened with ultra high performance fibre reinforced concrete

This paper critically examines the performance of reinforced concrete (RC) beams retrofitted with a thin strip of ultra-high performance fibre-reinforced concrete (UHPFRC) under cyclic loading. RC beams were preloaded under static loading approximately to 70%, 80% and 90% of maximum load of control beams and then tested under fatigue loading with a stress ratio of 0.1 and frequency 2 Hz after retrofitting with a UHPFRC thin strip of 10 mm thickness. It has been found that the damaged RC beams can be successfully strengthened and rehabilitated by using a thin precast UHPFRC strip adhesively bonded to the prepared tensile surface of the damaged beams. No de-lamination of the strip was observed in any of the retrofitted beams. A finite element model was developed to predict the number of cycles to failure and load-deflection behavior of the retrofitted RC beams. The model accounts for the (i) degree of pre-damage, (ii) fracture behavior of concrete and UHPFRC through their respective specific fracture energy and stress-crack opening relation, and (iii) elasto-plastic behavior of the reinforcing steel. The model predictions are in very good agreement with the corresponding test results. It can be concluded that this UHPFRC is an excellent candidate for the repair and rehabilitation of damaged RC flexural elements.

Flexural behavior of RC beams retrofitted with ultra-high strength concrete

The performance of popular techniques of rehabilitation and strengthening of concrete elements using externally bonded steel plates and fiber-reinforced plastic (FRP) laminates has been extensively investigated and several de-lamination failures have been reported primarily due to the mismatch of their tensile strength and stiffness with that of the concrete structure. To overcome some of these drawbacks, this paper critically examines the performance of Reinforced Concrete (RC) beams retrofitted with a thin ultra-high strength concrete (UHSC) strip. All the reinforced concrete beams were retrofitted with UHSC strips of single thickness after they had been subjected to several levels of damage. It is found that the damaged reinforced concrete beams can be successfully strengthened and rehabilitated by using a thin precast UHSC strip adhesively bonded to the prepared tensile surface of damaged beams. A finite element model was developed to predict the failure load and load–deflection behavior of the retrofitted RC beams. The model accounts for the (i) degree of pre-damage, (ii) fracture behavior of concrete and UHSC through their respective specific fracture energy and stress-crack opening relation, and (iii) elasto-plastic behavior of the reinforcing steel. The model predictions are in good agreement with the test results. It is concluded that UHSC is an excellent prospective candidate for the repair and rehabilitation of damaged RC flexural elements.