Number Of CFRP Layers Research Articles

Influences of interface bonding behavior on the arresting performance of CFRP buckle arrestors - Part I: Experiments

CFRP can effectively serve as buckle arrestors for subsea pipelines in virtue of the advantages of lightweight, high strength, and corrosion resistance. In this paper, the interface bonding tests were firstly carried out to assess the bonding performance between the CFRP and pipelines. Three types of tests were designed to evaluate the circumferential, axial, and radial bonding properties, respectively, covering the double-strap joint shear test, axial tensile test, and normal tensile test. The stress-bonding slip responses were measured and various failure modes were identified. The effect of CFRP thickness, type of adhesive, adhesive thickness, and interface roughness on the interface bonding property was explored. Subsequently, SS304 pipe specimens wrapped with CFRP buckle arrestors were tested in a hyperbaric vessel. The pressure-variation in volume curves were obtained, and the flattening and U-shape modes were observed. The influences of adhesive type, adhesive thickness, interface roughness, number of CFRP layers, CFRP thickness, and CFRP length on the crossover pressure were examined. The results demonstrate that the number of CFRP layers and CFRP thickness remarkably affect the arresting performance of CFRP arrestors, and the influence of interface bonding properties on the arresting ability is not as significant as the adhesive strength.

Mechanical properties of CFRP and shrinkage compensating concrete actively confined and strengthened short columns under freeze–thaw cycles

AbstractThis paper investigates the use of CFRP precast tubes filled with shrinkage‐compensating self‐consolidating concrete (SSCC) for strengthening columns. Compared to ordinary self‐consolidating concrete (OSCC), SSCC can address the stress hysteresis issue caused by the poor cooperation between CFRP and concrete structures, while also enhancing the mechanical properties of columns. Experimental and theoretical studies were conducted to examine the tensile mechanical properties of CFRP materials and the axial compressive mechanical properties of CFRP precast tubes strengthened with OSCC or SSCC under freeze–thaw cycles. Various variables were considered, such as freeze–thaw cycles, types of strengthening concrete, and the number of CFRP layers. The results indicate that freeze–thaw cycles do not affect the ultimate tensile strength of CFRP but significantly reduce its ultimate tensile strain. SSCC‐strengthened specimens exhibit higher load‐carrying capacity and better ductility compared to OSCC‐strengthened specimens. In addition, compared to the strengthening of two‐layer CFRP and SSCC, the strengthening of one‐layer CFRP and SSCC more effectively demonstrates the advantage of the post‐tensioning effect. However, the ductility coefficient of the columns decreases with an increase in the number of freeze–thaw cycles, regardless of the number of CFRP layers or type of strengthened concrete. Modified theoretical model accurately predicts the normalized peak stress and strain of the strengthened specimens.

Axial compressive behavior of FRP-confined square CFST columns reinforced with internal latticed steel angles for marine structures

This paper investigates the mechanical response of axially loaded FRP-confined square CFST columns strengthened with internal latticed angles (F-SRCFST) through experimental and analytical methods. The influence of three parameters on the performance is examined, including dimensions of the specimens, configuration of latticed steel angles, and number of CFRP layers. Experimental results demonstrate that concrete crushing in the specimens confined by CFRP exhibits a higher degree of uniformity, with cracks appearing more densely. The latticed steel angles can prevent the development of concrete cracks into the core concrete, while noticeable local buckling of the steel angle between the battens is observed. The enhancement coefficient of steel angles on the load-bearing capacity and energy dissipation ability of F-SRCFST columns is more pronounced when compared to CFRP. The utilization of CFRP and latticed steel angles can effectively improve the problem of inconsistency in square steel tube deformation under axial loading, and both parts exhibit similar effects on the dilation behavior of square CFST columns. A composite confined model was developed to consider the triple constraints of CFRP, external steel tube, and latticed steel angles, and a predictive formula was developed to estimate the load-carrying capability of F-SRCFST columns. The comparative study shows that the predictive formula agrees well with the ultimate axial strengths of F-SRCFST columns.

Research on Axial Compression Test and Finite Element Analysis of Sea Sand Concrete Filled CFRP-Steel-CFRP Composite Circular Tubular Stub Column

In order to study axial pressure performance of sea sand concrete filled CFRP-steel-CFRP composite circular tubular stub column, the finite element model of composite constrained short column was established by using ABAQUS, based on experimental research. The accuracy of the finite element model was validated by comparing the finite element with the experimental data. Furthermore, the influence of the number of CFRP layers, the tensile strength of CFRP and the thickness of steel tube on the mechanical properties of components was explored. Finally, the applicability of the existing algorithms for bearing capacity was discussed and a simplified calculation formula was proposed. The results indicate that the structural parameters are directly proportional to the bearing capacity of the components, and the increase of CFRP layers is the most significant. With the increase of CFRP layers, the stiffness of the linear strengthening section of load-displacement curve can also be significantly improved. The existing relevant bearing capacity algorithms are relatively conservative for the combined structure, and the simplified calculation formula presented in this paper has little deviation from the experimental value.

Behavior of Circular Reinforced Concrete Columns Strengthened by Different Techniques Subjected to Axial Loading

Abstract In recent years, CFRP is the most popular material in strengthening RC members (columns, beams, slabs…etc.) as well as the textile-reinforced mortar (TRM) was also used as an alternative method for strengthening RC columns. The present study includes fifteen circular RC columns: One control column, ten columns strengthened by one or two layers of CFRP using EBR or EBROG methods, two columns was strengthened by textile-reinforced epoxy on grooves and last two columns were strengthened by textile reinforced mortar without grooves. The parameters of this investigation are type of strengthening technique (EBR, EBROG and TRM), number of CFRP layers, and the grooves configuration. The results showed that the columns strengthened longitudinally with one or two layers of CFRP strips using EBR technique enhanced the load-carrying capacity by 2 and 7.13%, respectively, when compared with control column. However, the load carrying capacity of RC columns strengthened by EBROG increased by the range of 11.65% to 71.4%. in comparison with control column. Finally, TRM strengthening method enhanced the load carrying capacity by about 21% to 58.5%. Also, the results showed that the EBROG and TRM approaches were improved the stiffness and ductility of the columns in comparison with EBR method.

Axial compression tests on CFRP strengthened CFS plain angle short columns

A comprehensive test program was performed to experimentally investigate the effect of CFRP strengthening on the axial strength and stability of CFS plain angle short columns subjected to monotonic axial compression. A total of 28 specimens were tested by varying the CFRP strengthening configurations for different column heights. Both uni-directional (CF_UD) and bi-directional (CF_BD) CFRP were considered. The influence of various parameters such as the type of CFRP, fiber orientation, and number of CFRP layers was investigated and discussed in detail. For single layer (ply) of CFRP, CF_UD-0° strengthening configuration resulted in maximum increase of axial capacity by 58.33% and 45.72% (in comparison to bare steel specimens), corresponding to 0.5 m and 1.0 m column lengths respectively. All the bare steel and skin-strengthened specimens failed predominantly due to torsional–flexural buckling mode. Additional layer of CFRP wrapping was found to enhance the axial capacity further and CF_UD-0°/BD was found to possess greater capacity in the case of double layer of CFRP. Adopting cardboard in-fill in addition to CF_UD-0° wrap has prevented the torsional mode of buckling and resulted in a peak increase of axial capacity by 192.55% and 240.61% corresponding to 500 mm and 100 mm long specimens, respectively.

Experimental and numerical investigation on the crashworthiness performance of double hat‐section Al‐CFRP beam subjected to quasi‐static bending test

AbstractNowadays, hybrid structures, which combine low‐density composites with low‐cost thin‐walled metals, have shown great effect in enhancing the performance of automotive body structures, especially the energy absorber components. This study focuses on the experimental and numerical investigation of the bending energy absorption behavior of CFRP/aluminum hybrid double hat‐section beams used in the side part of the car body. In the experimental section, two types of double hat‐section beams were fabricated: aluminum and Al/CFRP. These beams were then subjected to quasi‐static three‐point bending tests. The results demonstrated that the hybrid beam exhibited superior energy absorption capabilities compared to the single beam. Subsequently, a finite element model was developed using LS‐Dyna software and was validated by comparing the experimental and numerical load–displacement results. In‐depth numerical analyses were conducted to investigate the influence of various design parameters, including CFRP‐reinforcement configuration, numbers of CFRP layers, CFRP ply‐angle, CFRP reinforced length, and aluminum/CFRP mass, on crashworthiness indicators. The numerical findings indicate that the hybrid beam with , ply‐angles exhibited better crash force efficiency (CFE) and specific energy absorption (SEA) compared to other ply‐angles, respectively. Furthermore, increasing the number of CFRP layers within the total beam's mass improved its energy absorption capacity. It was also revealed that the CFRP length on the upper and lower hats could be considered as 42.5% of the total aluminum beam length, as opposed to the full CFRP length, providing enhanced energy absorption capabilities.Highlights Bending behavior of the Al and Al/CFRP double hat section beams. Effects of variable thickness and identical mass on the double hat section beam. Effects of variable ply angle and number of CFRP layers on the hybrid beams. Discrete effect of CFRP reinforcement configurations and inner CFRP lengths.

Stress–strain characteristics of FRP–PVC confined spontaneous combustion gangue concrete columns

A total of 40 fiber reinforced polymer (FRP) and polyvinyl chloride (PVC) confined spontaneous combustion gangue coarse-aggregate concrete (SAC) specimens were subjected to axial compression tests and theoretical studies. The main analysis focused on the impact of the replacement rate of spontaneous combustion gangue (SCG), the type of CFRP confinement, and the number of CFRP layers on the axial compression performance of CFRP–PVC confined SAC (CFRP–PVC–SAC). The results show that CFRP–PVC confinement can effectively enhance the axial compressive capacity, axial deformation, and lateral deformation of the components. The increase in strength ranges from 1.68 to 3.48 times, while the increase in strain ranges from 5.21 to 11.98 times. The crack patterns and expansive behavior of the coal gangue concrete under confinement exhibit significant differences compared to ordinary concrete. In addition, based on the framework of the existing FRP-confined plain concrete model, a modified model is established to facilitate prediction of stress–strain relationships for short columns of CFRP–PVC–SAC, with the calculated results in good agreement with experimental values.

Experimental study and finite element analysis on axial compression performance of CFRP-PVC confined coral seawater and sea-sand concrete columns

In this paper, a composite column using carbon fibre reinforced plastics and polyvinyl chloride composite tube (CFRP-PVC) to constrain coral aggregate seawater sea-sand concrete (CSSC) was proposed, and CFRP was pasted on the inner and outer walls of the PVC tube. To investigate the effects of the number of CFRP layers and void defects on the axial compression performance of PVC tubes, six specimens were made for axial compression loading tests and finite element parameter analysis. The results indicate that due to PVC improving the integrity of CFRP, PVC tube provide a stress transfer path for CFRP, placing CSSC in a triaxial compression state. When both the inner and outer walls of the tube are pasted with CFRP, brittle failure of CFRP-PVC tube can be effectively avoided and have relatively superior mechanical properties. In the same situation, when one layer of CFRP is pasted on the inner wall of the tube, it has better ductility and bearing capacity. When two layers of CFRP are pasted on the outer wall of the tube, the coefficient of constraint stress increase is as high as 121.5%, and the void defect only has a significant impact on ductility. A finite element model of CFRP-PVC confined CSSC columns considering Hashin damage criterion was established based on ABAQUS, accurately predicting the failure process and CFRP damage morphology of test columns under axial load. Parameter analysis shows that when the confinement coefficient of CFRP-PVC confined CSSC columns is less than 0.3 and the height-diameter ratio is greater than 15, the load-displacement curve will lose the strengthening stage, and increasing the number of outer CFRP layers will slightly increase the stiffness of the strengthening stage. A bearing capacity calculation method suitable for CFRP-PVC confined CSSC was proposed based on the model of steel tube confined concrete, with an error of 1.2%.

Fatigue performance and parameter optimization of CFRP-reinforced steel plate considering elevated temperature

This article aims to investigate the effect of elevated temperature on the fatigue performance of CFRP-reinforced cracked steel plates and optimize the design parameters for their reinforcement. Based on the self-developed adhesive GY34, a finite element model of the CFRP-reinforced central cracked steel plate is established by the ABAQUS software. Parametric analysis is carried out on different bonding methods of CFRP plates and different thicknesses of adhesive layers for CFRP-reinforced cracked steel plates. The effect of elevated temperature on the reinforcement is also studied to verify the excellent performance of GY34 adhesive. Furthermore, the enhancement of fatigue life for cracked steel plates reinforced with CFRP plates at different temperatures is investigated using the Paris model and modified Newman model. The results show that double-sided reinforcement with CFRP is more effective than single-sided reinforcement. All of the different bonding methods could reduce effectively the stress intensity factor of cracked steel plates and improve significantly the bearing capacity of the steel plates. Among them, increasing the number of CFRP layers and their elastic modulus yield the most significant improvement on the reinforcing effect. Elevated temperatures effect greatly on the mechanical properties of adhesively bonded CFRP-reinforced steel plates. The effective bonding length and the stress intensity factor amplitude at the crack tip of the steel plate increases with temperature rises, which may accelerate the growth rate of fatigue crack and reduce the reinforcing effect on fatigue life.

Parametric study on the crashworthiness of the Al/CFRP/GFRP hybrid tubes under quasi-static crushing

Metal/composite hybrid structures have attracted widespread attention due to great characteristics. This study aimed to explore the effects of different parameters on the energy absorption characteristics of Al/CFRP/GFRP hybrid tubes under axial loading, and the interactive effects among Al, CFRP and GFRP of hybrid tubes were analyzed. Four hybrid tubes with different mixed winding modes were designed, and then numerical models were established and verified by experimental results. The failure modes and crashworthiness of Al/CFRP and Al/CFRP/GFRP tubes were analyzed and compared. Parametric studies were conducted to explore the effects of mixed winding modes, material thickness, number of CFRP/GFRP layers and stacking sequences of the hybrid tubes. The results showed that mean crushing force (MCF) of the Al/CFRP/GFRP tube was 2.11, 8.81 and 4.90% higher than the Al/CFRP tube, Al/GFRP tube and Al/GFRP/CFRP tube, respectively. Increasing the thickness of Al tube and the number of CFRP layers, the specific energy absorption (SEA) exhibited a generally upward trend. However, the SEA first decreased and then increased as the winding angle of CFRP layers increased, while the number of GFRP layers had relatively little effect on SEA. The proper proportion of 90° layers in CFRP and GFRP walls could improve the SEA.

A Study on Fatigue Crack Reinforcement of Bridge Deck and U-Rib Weld after Considering Residual Stress

In order to study the fatigue performance of the initial crack between the CFRP reinforced deck and the U-rib weld after considering the residual stress, the welding residual stress of the deck and the U-rib weld was analyzed by the welding subprogram of ABAQUS, and then the segment model of the deck and the U-rib of the steel bridge deck was established by using the interaction technology of FRANC 3D-ABAQUS, and the stress intensity factor of the crack between the deck and the U-rib weld under the vehicle-only, vehicle-residual stress combined loads, and CFRP-strengthened combined loads were analyzed. The growth analysis of cracks before and after reinforcement was carried out. The results show that the amplitude of the stress intensity factor of the crack tip is less than the threshold when only the vehicle is applied, and the crack will not spread. After considering the residual stress, the maximum KI value of the crack at the welding toe is increased by 6.9 times compared with the maximum value of the vehicle only, and the maximum KI value at the welding root is increased by 10.7 times; the reinforcement method of CFRP pasted on the lower surface has a reinforcement effect on the fatigue crack at the welding toe, but the fatigue crack at the welding root has no reinforcement effect; the reinforcement effect of the welded toe crack increases with the increase of the number of CFRP layers, length, and width. When the weld toe crack after reinforcement extends to half the thickness of the deck, the number of car-residual stress combined load cycles increases by 43% compared to when it is not reinforced.

Crashworthiness analysis and multi‐objective optimization of Al/CFRP hybrid tube with initial damage under transverse impact

AbstractDamage can cause uncontrollable changes during the service of a structure, leading to a reduction in mechanical properties and ultimately to structural failure. This paper presents an experimental and numerical study of the crashworthiness of thin‐walled Al/CFRP hybrid tubes with pre‐existing transverse compression damage under transverse impact loading. Experiments shows that initial damage has a more limited effect on the energy absorption capacity of hybrid tubes under impact loading, but has a greater effect on their deformation pattern and the evolution of damage. After impact, cracks on the surface of the damaged tube propagate into multiple, discontinuous cracks with a total length similar to the length of the tube. Conversely, only short cracks are generated on the intact tube. Subsequent finite element simulations demonstrate the validity and accuracy of a coupled multi‐loads model and explore the effect of different structural parameters (winding angle and number of CFRP layers, and thickness of Al tube) on the crashworthiness of the hybrid tubes. Finally, a multi‐objective snake optimizer algorithm (MOSO) was used to obtain an optimal hybrid tube structure for multiple loading conditions in order to minimize the effect of initial damage on the crashworthiness of the hybrid tube. In comparison to the simulation outcomes for the original structure, the peak crushing force (PCF) decreased by 28.46%, whereas the specific energy absorption (SEA) increased by 44.59%.Highlight The effect of pre‐existing damage on the crashworthiness and deformation pattern of hybrid tube structures is investigated by means of experimental and numerical simulations. A multi‐step finite element model was developed using the restart method to realize the crashworthiness analysis of the hybrid tube under multiple load coupling conditions. The prediction accuracy of four surrogate models for the crashworthiness of hybrid tubes is compared and analyzed. The multi‐objective snake optimizer algorithm (MOSO) is proposed to obtain the optimum hybrid tube structure for multiple loading conditions.

Mechanical behavior of CFRP confined seawater sea-sand recycled concrete-filled circular aluminum-alloy tube columns under axial compression

This paper presents an experimental study and theoretical analysis of the mechanical behavior of CFRP-confined seawater sea-sand recycled concrete-filled circular aluminum-alloy tube short columns (CFRP-CFAT) under axial compression. A total of 12 circular cross-section specimens were tested, including 4 concrete-filled circular aluminum-alloy tube (CFAT) specimens and 8 CFRP-CFAT specimens. The effects of the number of CFRP layers, the thickness of the aluminum tubes, and the strength of the concrete were investigated. The test results indicate that CFRP can effectively delay or even suppress the local buckling of aluminum alloy tubes and significantly improve the ultimate load capacity of the specimens, and the enhancement is approximately linear with the number of CFRP layers. Based on the experimental results, a modified axial strain-lateral strain response model for core concrete is proposed. In addition, a new analysis-oriented model applicable to circular CFRP-CFAT short columns is established and compared with the test results for verification. Meanwhile, the CFRP-CFAT ultimate load-bearing capacity calculation method is proposed based on the superposition theory and the analysis-oriented model. The predicted results are in high consistency with the experimental results.

Flexural behavior of circular concrete filled steel tubular members strengthened by CFRP sheets

The flexural behavior of CFRP-strengthened circular concrete filled steel tubular (CFRP-C-CFST) members was investigated experimentally and theoretically. A total of nine specimens were tested through four-point bending method, including a comparative CFST specimen without CFRP strengthening (C-CFST), and eight CFRP-C-CFST specimens. Based on experimental results, the effects of different CFRP wrapping length, number of CFRP layers and wrapping schemes on the flexural behavior of the CFRP-C-CFST specimens are analyzed. Two failure modes, including CFRP debonding and CFRP fracture, are observed from the tested CFRP-C-CFST specimens. Increasing the length of CFRP delays debonding, while increasing the number of CFRP layers causes debonding to occur earlier. The flexural capacity of CFRP-C-CFST specimens with two-four CFRP layers is increased by about 20%-70% compared to the C-CFST specimens. A theoretical model based on fiber element method is proposed. This model considers the bi-directional stress state of the steel tube and the effect of bending moment on the confinement factor. A representative test result is selected to calibrate the distribution law of the confinement factor, and all the test results are predicted based on the calibrated parameters. The comparison between the predicted and the test results shows that the fiber element model can simulate the bending moment-deflection curves of C-CFST and CFRP-C-CFST members, and hence it can predict the flexural capacity, stiffness and ductility accurately.

Axial compression performance of concrete filled double skin (SHS outer and CHS inner) steel tubular columns strengthened by CFRP

This paper reports the compressive behavior of concrete-filled double skin steel tubular (CFDST) columns strengthened by CFRP under axial loading. The outer skin was made of square hollow sections (SHS), while the inner skin was made of circular hollow sections (CHS). Twelve CFDST columns strengthened by CFRP and three CFDST columns were tested. The failure mode, load-displacement relationship, axial load-carrying capacity and initial stiffness are given and analyzed. The results showed that the CFDST columns strengthened by CFRP have better mechanical properties than the column without CFRP reinforcement (i.e. the CFDST columns). The CFDST columns strengthened by CFRP eventually failed due to CFRP rupture or buckling of the external steel tube near the end and cracked concrete damage from the outer steel tube. The stiffness and axial load bearing capacity of the column can be improved as the number of CFRP layers increases. A simplified design formula of CFDST columns strengthened by CFRP is proposed, which is in good agreement with the experimental results.

Experimental and numerical studies on bending characteristics of woven CFRP reinforced aluminum thin-walled automotive structures

Metal/composite hybrid thin-walled structure is the most preferential approach to achieve dual contradictive objectives of high crashworthiness and lightweight of auto body. Its collapse with regard to different fiber layup patterns is one of the governing mechanisms of energy dissipation, which is yet to be explored. Especially, the effect of different fiber layup angles and layup sequences on bending collapse, which is one of the most significant performance indicators, has received little attention. To this gap, this study investigates experimentally and numerically the bending characteristics of aluminum/carbon fiber reinforced plastic (Al/CFRP) hybrid structures with different layup angles and layup sequences. To start with, three-point bending tests are carried out on specimens to derive the bending failure behavior and crashworthiness, and the internal section damage is observed by CT scan. Finite element model is then constructed and benchmarked against the test results to be proficient. On this basis, the effects of Al thickness, number of CFRP layers and CFRP wrapping range on the bending performance of hybrid tube are analyzed numerically. The simulation results show that layup angle has greater effect on the bending performance than layup sequence. Increasing Al thickness and the number of CFRP layers can effectively improve the bending resistance of structure, and appropriate partial wrapping of CFRP can increase the specific energy absorption (SEA) by 10.92% compared with that of complete wrapping. The revelation from this study provides sound reference for the crashworthiness design of metal/composite hybrid thin-walled structure.

Effect of stress-strain models and sectional analysis methods on the axial-flexural interactions of discontinuously FRP strengthened square RC columns

This study analytically investigated the axial-flexural (P-M) interactions of quare reinforced concrete (RC) columns discontinuously strengthened swith fibre reinforced polymers (FRP). Six FRP confined concrete stress-strain models and two sectional analysis methods were used to develop the analytical P-M interactions of discontinuously FRP strengthened square RC columns. The developed analytical P-M interactions were validated against experimental data available in the literature. It was found that the selection of the stress-strain models had a substantial effect on the analytical P-M interactions, while the influence of the sectional analysis methods heavily depended on the selected stress-strain models. It was also found that the three available design codes for concrete structures externally strengthened with FRP yielded different analytical P-M interactions of discontinuously FRP strengthened square RC columns. A parametric analysis was undertaken and found that the corner radius and confinement ratio significantly affected the P-M interactions of discontinuously FRP strengthened square RC columns. Also, discontinuously FRP strengthened square RC columns with a higher number of FRP layers and smaller corner radius obtained lower flexural and axial strengths than their counterparts with a lower number of CFRP layers and higher corner radius.

Cyclic lateral behavior of NLFEA heat-damaged circular CFT steel columns confined at the end with CFRP composites

In this study, the nonlinear finite element analysis (NLFEA) method has been adopted to prove the CFRP's effectiveness in restoring the performance of heat-damaged CFT circular steel columns and controlling the columns' failure mode. The simulated CFT column model was firstly checked for validity using previously-conducted experimental research. Then, the model was extended to investigate the impact of the number of CFRP layers (0, 5, 6, 7, 8, 9, and 10 layers) and elevated temperature (20 °C, 200 °C, 400 °C, and 600 °C). Therefore, this study provides an NLFEA of twenty-eight models for CFT circular steel columns wrapped with various layers of CFRP composites at its end region, which represents the critical location in terms of the lateral load capacity. Also, wrapping the specimens' ends helps prevent the occurrence of outward local buckling, resulting in enhancing the specimens' strength, enlarging net drift, and increasing energy dissipation. The study results showed that using five to ten CFRP layers significantly improved the performance of the NLFEA CFT circular steel column models. Nevertheless, using nine or ten CFRP layers had almost the same impact of using eight layers. The NLFEA results showed that the external repairing of heated damaged CFT column with CFRP composite enhanced the cyclic performance, and the efficiency of CFRP composite increased with the heat damage level.

Behavior of CFRP-strengthened RC beams with circular web openings in shear zones: Numerical study

In practice, especially the basement floor beams are drilled and damaged by the users. In some cases, this damage to the beams can be significant for the load-bearing element and the whole structure. In this study, the behavior of reinforced concrete beams with circular openings and the failure types resulting from strengthening these beams with CFRP are parametrically investigated. The diameter of the opening/beam height ratio (D/H), concrete compressive strength, stirrup spacing, the position of the opening to the beam support, the type of CFRP application, CFRP ply orientation, and the number of CFRP layers were selected as parameters. Numerical models were verified using 9 specimens having different circular openings with/without CFRP strengthening and the analyses of 95 numerical models with the selected parameters were carried out utilizing the finite element program, ABAQUS. The ultimate load capacity, ductility, stiffness, energy dissipation capacity and failure modes of the beams were determined. As a result of the study, it was observed that there was no significant loss in ductility for the beams with D/H ≤ 0.3 and the number of CFRP layer and type of application did not have a significant effect on D/H ≤ 0.44. However, for the beams with D/H > 0.64, the CFRP application that completely surrounds openings should be preferred instead of partial CFRP strengthening. In addition, the concrete strength is an effective parameter for the beams with D/H ≤ 0.44. The effect of the stirrup spacings in the beam on the ductile behavior was also limited with the increase in the hole diameter. The number of CFRP layers should theoretically be 4 for an effective strengthening in beams with D/H > 0.44. Finally, U wrapping is recommended instead of using full wrapping. It has been seen that the location and diameter of the hole are very important parameters in the failure type of the beam.