Prestressed Research Articles

Influence of prestressing force on performance of concrete plates under impact loading

An experimental and numerical study has been performed to explore the performance of one-way pretensioned concrete plates against impact loading. The impact resistance, experimental results and damage within the pretensioned concrete have been compared with the non-pretensioned concrete. The plate specimens of concrete grades M40 and M60 have been pretensioned to prestress level 10 and 20% of the compressive strength of the concrete. While, all the tendons employed in the non-pretensioned concrete were kept unstressed. The plates were struck at the mid-span by a steel mass (242.85 kg) dropped from 0.5 to 1.0 m heights. The numerical simulations have been executed using explicit finite element code considering the Holmquist–Johnson–Cook (HJC) and the metal plasticity model for concrete and steel, correspondingly. The performance of the plates is governed by the grade of concrete, impact energy and level of the prestress within the concrete. The induced prestress within the concrete enhanced the stiffness and, consequently, the impact resistance of the pretensioned concrete plates. The pretensioned concrete hence witnessed increased impact force and reduced deflection by 18.1% and 11.0%, correspondingly, compared to the non-pretensioned concrete. The splitting and punching crack within the plates became pronounced once the drop height increased from 0.5 m to 1.0 m. The simulations have estimated the peak impact force and reaction within 19.7% and 15.5% deviation, respectively. The displacement and energy absorption have been calculated using an analytical methodology closely correlated with the actual results within 18% and 14% deviation, respectively. Further, the simulations performed on two-way pretensioned concrete have shown improved performance of the plates witnessing no splitting crack and uniform crack distribution compared to one-way pretensioned concrete.

Calibrating of a Simulation Model to Predict the Flexural Capacity of Pre-Stressed Concrete Beams

Simulation models based on finite elements are currently indispensable tools for predicting the structural behavior of both reinforced and pre-stressed concrete elements. This work develops a simulation model of structural linear elements of pre-stressed concrete, using the finite element method (FEM). The main aim was to calibrate the model to predict the flexural capacity of structural elements, and so be able to undertake a double optimization through the design and the resistant behavior of the elements. Different flexural experiments were conducted in laboratory conditions on real concrete elements of different types (pre-stressed joist and tubular pre-stressed joist). In parallel, the same structural elements were analyzed by MEF simulation to calibrate the model to the real experiments. FEM analysis was performed using the ATENA software developed by Červenka Consulting (Czech Republic), especially recommended for the analysis of structural concrete elements using non-linear methods. The model was calibrated using the results obtained in real load test experiments obtained in a loading frame of 500 kN capacity. The calibration analysis shows a good fit of the results to the actual test experiments, obtaining average errors of 6% in the analysis–experiment comparison. The results of the simulation suggest that to obtain the optimum strength levels for the different typologies analyzed, it is essential to control the pre-stressing losses in the manufacturing process of the joist. The flexural capacity of all elements can be increased by around 20–30% when the real pre-stressing losses are fitted to the theoretical ones estimated.

Dynamic amplification of multi-span simply-supported prestressed concrete girder viaducts subjected to multi-body heavy vehicles

High productivity freight vehicles (HPFVs) are used in many countries to address increasing freight demand. However, it is then necessary to assess the safety of existing bridge structures subjected to HPFVs because of their increasing mass and dimension. A critical part of this work is to assess the dynamic amplification of such vehicles, without undue conservatism, often based on vehicle–bridge interaction (VBI) modelling. In the VBI problem, the vehicle model is usually derived using the Principle of Virtual Work or Euler–Lagrange methods. However, HPFVs are characterized by multiple bodies and articulation points and these techniques quickly become intractable. Alongside the vehicle model, the bridge is often assumed to be a single simply-supported span, or a few continuous spans, whereas many urban bridge viaducts, in particular, have multiple prestressed concrete (PSC) girder simply-supported spans. Furthermore, these bridges typically have an upwards hog as a result of the prestress and it is hypothesized that certain combinations of vehicle, hog, span length, and number of spans, could produce a large dynamic amplification of static load effects. In this work, Kane’s Method is applied to heavy vehicle with multi-trailers combinations which provides a relatively easy, systematic, and numerical manipulation means of determining the vehicle dynamic equations. The 9-axle B-Double vehicle, common in Australia, is used as an example to illustrate the procedure of deriving the vehicle dynamic equations. We apply the resulting vehicle models in a comprehensive VBI model to consider the dynamic amplification of PSC girder viaducts. The results indicate that the studied PSC girder viaducts experience higher amplification than the equivalent single-span simply-supported bridges. Recommendations for future studies and practice, such as the number of spans in the viaduct to obtain the ‘convergence’ of dynamic amplification, are given.

Evaluation of experimental techniques for performance estimation of post-tensioned concrete beams

Structural health monitoring (SHM) techniques have become a significant subject in structural evaluation due to the development of non-destructive methods used to monitor and assess the integrity of structures. This paper aims to investigate the effect of damage on the flexural performance indicators and dynamic characteristics of post-tensioned concrete (PC) beams, using both static and vibration tests. The beams were tested at several load levels to reproduce different load stages of a PC member: pre-cracking, during and after the formation of initial cracks, and finally, during and after the formation of larger significant cracks. The performance of the elements is evaluated based on static data, energy calculations, and the three criteria of ACI 437 recommendations. Data from the vibration tests were used to identify the changes in modal parameters after different load levels. Acoustic emission data analysis and results were used to classify the level of damage. Experimental bending stiffness and crack length determination via visual inspection was used as control parameters to assess the deterioration levels of the beams. The outcomes of this study show the relationship level among the different experimental responses obtained: flexural performances, the presence of damage in the beams, and natural frequencies. By considering the relationships of the SHM techniques and their individual findings, the evaluation of performance indicators or damage classification in rectangular concrete prestressed beams reveals that the main limitation is the required knowledge about the previous response of the system.

Effect of strand debonding on the shear strength of existing pretensioned PC hollow slab

Pretensioned PC (prestressed concrete) beams experience strand debonding failure at the ultimate loading stage, which leads to bond-loss failure of the beams. To study the effect of strand debonding on the shear strength of pretensioned PC hollow slabs, the existing PC hollow slabs of 19 specimens with spans of 10, 13, 16 and 20 m used in Chinese expressway bridges were loaded to bond-loss failure. The strand slip, bond- loss failure mode and shear strength of 19 specimens and 31 shear tests were analyzed. The test results showed that the angles of the failure diagonal cracks were not consistent with the Ross model. Therefore, a refined model to predict the shear strength subjected to pretensioned PC hollow slabs was developed. Other factors were also considered in the refined shear strength model, including the dowel action of longitudinal reinforcements, the prestressed strand development length and the compression zone height. Compared with the shear failure controlled by strand yielding, the shear strength controlled by strand debonding was decreased by approximately 27 %. The test results showed that the debonding induced bond-loss failure could be described as follows: after the formation of the failure diagonal crack, the strand will clearly slip, and concrete parts on both sides of the failure diagonal crack rotate around the crack tip. Due to the debonding induced bond-loss failure of the pretensioned PC hollow slab, the shear strength could not be improved even by increasing the concrete strength of the compression zone. Finally, the validity of the refined model was verified by 23 test specimens.

Damage mechanism and damage evaluation of PC box girder bridge subjected to overheight vehicle impact

AbstractAccidental collisions from overheight vehicles often result in significant damage of bridges. To ensure the safety of the bridge structure, it is essential to develop a method to evaluate the damage caused by these impact loadings. This study aims to investigate the damage mechanism of a prestressed concrete (PC) box girder bridge subjected to overheight vehicle impact using the finite element analysis method. Parametric analyses were performed to study the effects of various factors on the impact force and deformation performance of the bridge. In addition, a damage assessment formula, based on the vertical residual bearing capacity, is proposed to evaluate the damage state of the impacted PC box girder. A mass–velocity (m–v) curve is developed to characterize the damage levels of the impacted PC girder under different vehicle velocity and mass conditions. Then, a theoretical equation for predicting the maximum impact force during the vehicle‐bridge collision is developed. The numerical analysis results show that vehicle‐related parameters have a significant influence on both impact force and local damage of the PC box girder bridge. The proposed mass–velocity (m–v) curve can be used to evaluate the damage state of the PC box girder by relating the performance levels of the girder to each damage index. Moreover, the predicted maximum impact force can be used as an important index to assess the extent of the local damage of the PC box girder.

Effect of Wrapping on Post-Tensioned Beams Strengthened with Natural Sisal and Jute FRP Using Finite Element Analysis

Existing buildings are retrofitted to formulate them to be more resistant to seismic activity, earth motion, and other natural disasters. Many available reinforced concrete buildings across the globe are in desperate need of rehabilitation, repair, or replacement owing to degradation caused by a variety of reasons such as corrosion, lack of detailing, and failure of beam-column bonding, among others. In the construction sector, fibre reinforced polymer (FRP) composites have been recognized as a potential option for repairing and increasing the strength of existing structures. In this study, comparisons are done in terms of load bearing capability of the beams for configurations between FE model predictions and field data (experimental). To assess the FRP retrofit, structural responses for strengthened and control post tensioned concrete (PTC) beams are compared, with strengthening using various wrapping methods. The load bearing capacities of the beams retrofitted with sisal and jute fibre employing strip and full wrapping procedures around all four sides is increased by 35.55 percent and 42.85 percent for sisal FRP and 7.14 percent and 12.01 percent for jute FRP, respectively, as compared to the control specimen. The FRP retrofit model is expected to result in a considerable increase in structural performance.

Dynamic response of bidirectional bonded prestressed concrete slabs subject to low velocity impact: Impact energy and prestress degree

Bidirectional bonded prestressed concrete (PS) structures have been widely used in energy engineering. However, the systematic studies on the failure mechanism and dynamic response of this structure suffering from impact load are still inadequate. This paper has carried out nine drop hammer impact tests and corresponding numerical models. The results reveal that overall flexure and local punching co-occur in the bidirectional PS slabs under the impact, with the local punching failure as the failure mode. The dynamic response of the slab includes: inertia loading stage, load holding stage and rebound unloading stage. Due to the influence of the membrane force enhancing effect and specimen damage weakening effect, the impact force in the load holding stage may present three conditions. The compressive prestress applied to concrete can provide in-plane constraint and limit the appearance and development of cracks, resulting in decreasing the plastic damage of the specimen and the drop hammer displacement, while improving the bearing capacity and stiffness of the specimen. For impact energy of 5.48 kJ, when the prestress degree increase from 0% to 11.6%, the equivalent impact force increases 95%, the peak drop hammer displacement, equivalent spalling and scabbing diameter decrease 40%, 22.6% and 8.6%, respectively.

Potential of Fe-Mn-Al-Ni Shape Memory Alloys for Internal Prestressing of Ultra-High Performance Concrete.

Prestressing of concrete is a commonly used technique in civil engineering to achieve long spans, reduced structural thicknesses, and resource savings. However, in terms of application, complex tensioning devices are necessary, and prestress losses due to shrinkage and creep of the concrete are unfavourable in terms of sustainability. In this work, a prestressing method using novel Fe-Mn-Al-Ni shape memory alloy rebars as a tensioning system in UHPC is investigated. A generated stress of about 130 MPa was measured for the shape memory alloy rebars. For the application in UHPC, the rebars are prestrained prior to the manufacturing process of the concrete samples. After sufficient hardening of the concrete, the specimens are heated inside an oven to activate the shape memory effect and, thus, to introduce the prestress into the surrounding UHPC. It is clearly shown that an improvement in maximum flexural strength and rigidity is achieved due to the thermal activation of the shape memory alloy rebars compared to non-activated rebars. Future research will have to focus on the design of the shape memory alloy rebars in relation to construction applications and the investigation of the long-term performance of the prestressing system.

Void Detection inside Duct of Prestressed Concrete Bridges Based on Deep Support Vector Data Description

The tendon that is inserted into the duct is a crucial component of prestressed concrete (PSC) bridges and, when exposed to air, can quickly corrode, and cause structural collapse. It can interpret the signal measured by non-destructive testing (NDT) to determine the condition (normal or void) inside the duct. However, it requires the use of expensive NDT equipment such as ultrasonic waves or the hiring of experts. In this paper, we proposed an impact–echo (IE) method based on deep support vector data description (Deep SVDD) for economical void detection inside a duct. Because the pattern of IE changes for various reasons such as difference of specimen or bridge, supervised learning is not suitable. Deep SVDD is classified as normal and defective, which is a broad distribution as a hypersphere that encloses a multi-dimensional feature space for normal data represented by an autoencoder. Here, an autoencoder was developed based on the ELMo (embeddings from language model)-like structure to obtain an effective representation for IE. In the experiment, we evaluated the performance of the IE data measured in different specimens. Thus, our proposed model showed an accuracy of about 77.84% which is an improvement of up to about 47% compared to the supervised learning approach.

Comparative study on the influence of mono fibers in the behaviour of RCC & PSC beams

One of the hopeful solutions to augment flexural behaviour of reinforced cement concrete (RCC) and prestressed concrete (PSC) is the addition of fibres. All the flexural parameters namely peak load, cracking load and crack propagation improve in the presence of fibers in the matrix. Cracks are bridged well when fibers are present in concrete. The present work, intends to evaluate the influence of steel and basalt fibers in the flexural parameters of RCC and PSC beams made of M40 grade concrete. Hardened concrete properties are evaluated by adopting the volume fractions 0.25%, 0.5% and 0.75%. Results proved that the steel and basalt fibers at 0.75% and 0.25% resulted in optimum values. These fiber volume fractions were used to cast PSC and RCC beams. Later their behaviour was compared in flexure.

Prediction of Remaining Service Life of Prestressed Concrete Girders Containing Cracks

Prediction of Remaining Service Life of Prestressed Concrete Girders Containing Cracks

Comparison of pre and post-operative stresses among Indian patients undergoing intra-oral grafting procedures.

With the advent of implantology as an important means to rehabilitate the edentulous patients, the neglect over the years post extraction leads to severe bone loss. This can be corrected by grafting procedures. Grafting procedures are complex as it takes into account various factors such as the type of graft material, surgical site, surgeon's skill and the patient's compliance. Totally 20 patients ( male n=10 ; female n=10) were included in the study, 14 patients underwent GBR, 4 patients underwent direct sinus lifts and 2 underwent block grafts. The stress levels of the patient also is an important factor to consider as varying cortisol levels will be detrimental to the healing of the surgical site. Premedication with painkillers and corticosteroids can help patients comply with the treatment and feel less anxious. The stress levels of the patient were assessed using State trait anxiety index, 50.6± 6.9 was the pre-operative stress and 36.95± 9.3 was the post-operative stress. Stress levels were significantly greater before the procedure than after it, according to statistical analysis. The females were significantly having increased stress both pre and post-operatively. Also, the patients in the age group of 41-50 years showed increased amounts of stress.

Hinge Joints Performance Assessment of a PC Hollow Slab Bridge Based on Impact Vibration Testing

Hinge joint performance during the operation of prefabricated prestressed concrete (PC) hollow slab bridges is critical to ensure their lateral collaborative working condition and safe serviceability. Traditional performance identification of hinge joints mainly relies on manual inspection, which is inefficient and inaccurate. At the same time, existing indexes (such as acceleration and strain) can only qualitatively detect the damage to hinge joints. This study proposes a novelty detection method based on impact vibration testing to rapidly perform the quantitative assessment of the working condition of the hinge joints. The relationship between hinge joint performance and lateral load distribution (LLD) is first derived in detail by theoretical analysis. And then, the quantitative analysis of collaborative performance is converted to the identification of the LLD influence line, which is innovatively established by the lateral flexibility of the hollow slab bridge. The effectiveness of the proposed method is verified through a multibeam model using ABAQUS software, and the lateral collaborative working relationship between slabs is simulated using the connector elements. Furthermore, the LLD influence lines and hinge joints performance of a PC hollow slab Yanhu Bridge are evaluated based on the impact vibration testing with sensor lateral arrangement strategy. The detection results show that the proposed method can quickly and accurately identify the damage location and the stiffness loss of hinge joints.

Seismic performance of RC frames with self-centering precast post-tensioned connections considering the effect of infill walls

This paper presents the seismic performance evaluation of self-centering precast post-tensioned concrete (SCPPTC) frames with infill walls. The SCPPTC connection system consists of all-steel bamboo-shaped energy dissipaters (SBED) and prestressed tendons, which provide energy dissipation capacity and self-centering capability, respectively. Using modeling parameters calibrated with experimental tests, nonlinear numerical models of SBED, SCPPTC connection, infill walls, and 2D SCPPTC frames were developed in OpenSees, to compare the performance of the structures with different types of infill wall layouts. Nonlinear static pushover and incremental dynamic analysis (IDA) were performed to study the effect of infill walls on the overall response of SCPPTC frames, in terms of stiffness, strength, maximum interstory drift ratio,θmax, the maximum residual interstory drift ratio, θr,max, and the normalized post-tensioned force. Using the IDA results, the study also developed fragility curves and estimated the collapse margin ratios. The results demonstrated that the shear strength of the SCPPTC frame was improved from 4.19% to 12.2%, and the initial secant stiffness of the SCPPTC frame was augmented from 22.9% to 88.3% with increasing filling rate. The totally infilled SCPPTC frame (SCPPTC-ToI) exhibits a 19.86% lower θmax than that of pilotis-infilled SCPPTC frame (SCPPTC-PiI) under rare earthquakes, and the maximum prestress of SCPPTC-ToI was also 7.14% lower than that of SCPPTC-PiI. With the increase in filling rate, θr,max increased by a maximum of 120.45%. The pronounced soft layer led to the highest failure and collapse probabilities of SCPPTC-PiI among all SCPPTC frames at the same performance level.

Time-Dependent Reliability Assessment of Long-Span PSC Box-Girder Bridge Considering Vehicle-Induced Cyclic Creep

The neglect of the cyclic creep of concrete induced by vehicles may overestimate the deflection reliability of long-span prestressed concrete (PSC) box-girder bridges and increase structural safety risks. In this paper, a novel method considering the combined effects of the shrinkage, static creep, and cyclic creep of concrete and the stress relaxation of prestressed tendons is proposed to assess the time-dependent deflection reliability of PSC box-girder bridges. By employing the Kelvin chain model, the conventional integral-type method for calculating the static creep of concrete is converted to rate-type creep analysis, which has a higher computational efficiency and can consider various nonlinear effects. The cyclic creep of concrete is estimated by the fatigue mechanics-based model and integrated into the quasi-elastic incremental constitutive model. The proposed constitutive model is implemented in a general finite-element program DIANA, in which the mechanical behavior of the thin-walled box girder is described by the composite degenerated shell elements. An importance sampling method is applied when estimating the deflection reliability to balance the computational accuracy and efficiency. The proposed method is applied to a long-span PSC box-girder bridge with a main span of 150 m. The results indicate that the cyclic creep of concrete may accelerate the reduction of the deflection reliability indexes, which may fall below the target level before the expected service life of the bridge. In addition, heavy trucks passing in pairs have a significant impact on the deflection reliability. The research findings can be used for the reliable design and optimal maintenance of long-span PSC box-girder bridges.

Gaussian process regression-based load-carrying capacity models of corroded prestressed concrete bridge girders for fast-screening and reliability-based evaluation

Fast screening and reliability-based evaluation of corroded prestressed concrete (PC) bridge girders for safety assessment requires efficient capacity prediction models. This paper aims at developing data-based prediction models to quantify corrosion effects on load-carrying capacity of PC girders that are precast and standardized for short-span bridges. The load-carrying capacity of corroded bridge girders depends on their initial design configuration (e.g., those characterized by the standardized PC girders), loading condition (e.g., shear-span-to-effective-depth ratio), and corrosion conditions (e.g., corrosion degree). To develop data-based prediction models, generating sufficient data through physical experimental tests of full-scale corroded PC girders is prohibitively costly. Thus, a virtual experimental database is generated numerically using two-dimensional continuum-based finite element (FE) models for corroded PC girders, after being validated using 9 corroded PC girders tested in the literature with flexure or shear failure. To this end, a total of 4,165 PC girders under point loading are simulated to consider various design, loading, and corrosion conditions to estimate their load-carrying capacities. With this database, probabilistic machine learning, specifically Gaussian process regression or kriging, is used to develop (1) a residual capacity factor model (i.e., the ratio between load-carrying capacities from corroded and uncorroded girders), and (2) a load-carrying capacity prediction model (i.e., to predict the load-carrying capacity of uncorroded/corroded girders). The first model is used to study the load-carrying capacity reduction of PC girders due to corrosion compared to their uncorroded counterparts; this can reveal how the increasing corrosion condition affects the load-carrying capacity of corroded PC girders together with other design and loading parameters. The second model is developed to predict the load-carrying capacity of corroded PC girders as a function of design, loading, and corrosion parameters; its application to conditional reliability analysis provides insights into corrosion effect on the probability of failure of corroded PC girders at given load levels when the capacity is affected by corrosion. The application results of the two models enable engineers to quantify the corrosion effect on PC girders in terms of (1) reduction in load-carrying capacity for fast screening and (2) increase in probability of failure for reliability-based evaluation.

Size‐scale effects in high‐performance reinforced and prestressed concrete T‐beams

AbstractReinforced concrete (RC) and prestressed concrete (PC) structural elements need to be designed in order to guarantee large plastic deformations, avoiding any loss in their load bearing capacity. In this framework, the rotation capacity of RC and PC beams has been demonstrated to be a function of concrete mechanical properties, reinforcement characteristics, and of the structural size. On the other hand, Theory of Plasticity as well as the International Standards completely disregard size‐scale effects and ductile‐to‐brittle transitions, leading to an overlook of the strain‐softening behavior of the concrete matrix and of the rotation capacity of RC beams. On the other hand, the Cohesive/Overlapping Crack Model is able to evaluate concrete cracking in tension and concrete crushing in compression, as well as snap‐back and snap‐through unstable phenomena, steel yielding and/or slippage. This Nonlinear Fracture Mechanics model predicts a reduction in the moment versus rotation plastic plateau by increasing the beam depth and/or the reinforcement percentage. The numerical investigations carried out on reinforced and prestressed high‐performance concrete beams having rectangular or T‐shaped cross‐sections highlight the size‐scale effects on plastic rotation capacity that allow to formulate new scale‐dependent upper and lower limits of reinforcement percentage to guarantee a stable and ductile postpeak behavior of reinforced concrete structures.

Experimental research on flexural behavior of post-tensioned self-compacting concrete beams with recycled coarse aggregate

Self-compacting concrete with recycled coarse aggregate (RCASCC) is a green concrete material with high performance. However, it bears the disadvantages of low elastic modulus and high brittleness compared with ordinary concretes. In this study, recycled coarse aggregate (RCA) obtained from C30 concrete block discarded in laboratory research and tests was used to produce post-tensioned self-compacting concrete (PSRC) beams, while coarse natural aggregate (NCA) was used to produce post-tensioned natural concrete (PNC) beams. The four-point bending tests were carried out on PSRC and PNC beams to analyze the variations between the flexural performance of PSRC and PNC beams. In addition, we discuss the applicability of the current design codes on PSRC beams. The results reveal that the failure mode of PSRC beams is similar to that of PNC beams, whereas it differs significantly in the number and scope of cracks. Moreover, the variations can be reduced by increasing the ratio of non-prestressed reinforcement. In general, the PSRC beam is more ductile than the PNC beam. The increase in the ratio of non-prestressed reinforcement reduced the ductility of the PSRC beam as well as the fluctuations in the ductility of PSRC and PNC beams. Compared with the PNC beam under the same conditions, the PSRC beam exhibited a similar flexural capacity, the cracking load and maximum crack width decreased significantly, and its working deflection increased slightly. According to the calculation and analysis, ACI318-08 can be applied for calculating the cracking load, flexural capacity, and working deflection of the PSRC beams, but not the maximum crack width; GB50010-2010 is applicable for calculating the cracking bending moment and flexural capacity of PSRC beams, but the calculation deviation of the working deflection and maximum crack width is large; EN1992-1-1:2004 is applicable for calculating the crack bending moment of PSRC beams, but it is not safe for evaluating the bending capacity, working deflection, or maximum crack width. Overall, the average crack spacing correction formula proposed through experimental tests in this study can be applied to determine the maximum crack width of PSRC beams, and its accuracy is higher than that of the above-stated specifications.

Experimental and Numerical Study of the Ultimate Flexural Capacity of a Full-Size Damaged Prestressed Concrete Box Girder Strengthened with Bonded Steel Plates

Using steel plates attached with epoxy resin adhesive to strengthen prestressed reinforced concrete bridges has become a common method to increase bearing capacity in engineering because of the simple technology, low cost and good strengthening effects. The strengthening method of steel plates has been gradually applied to repair damaged bridges in practical engineering. After a cross-line box girder bridge was struck by a vehicle, the steel bars and concrete of a damaged girder were repaired and strengthened by steel plates, and then the ultimate bending bearing capacity was studied through a destructive test. The results of the destructive test were compared with those of an undamaged girder to verify the effect of the repair and strengthening of the damaged girder. The results showed that the actual flexural bearing capacity of the repaired girder strengthened by steel plates was 1.63 times the theoretical bearing capacity, 36.7% more than that of the damaged girder and 95.3% of that of an undamaged girder. The flexural cracking moment of the repaired girder strengthened by steel plates reached 66.3% of that of the undamaged girder. The maximum crack width decreased by 24.6%, and the maximum deflection increased by 2.7%, compared with the undamaged girder when the repaired girder strengthened by steel plates finally failed. Moreover, this method of attaching steel plates can increase the ductility of bridges and reduce the degree of cracking. Additionally, the actual safety factor of the repaired girder was greater than three, and it had a large safety reserve.