Carbon Fiber Reinforced Polymer Strengthening Research Articles

Shear capacity of corrugated web steel beams strengthened with CFRP strips

In recent years, there has been significant advancement in strengthening techniques for steel structures using carbon-fiber reinforced polymer (CFRP). While numerous studies have focused on CFRP strengthening of steel beams with flat webs, similar investigations on corrugated web steel beams (CWSBs) remain limited despite their increasing application in various steel structures. This study presents numerical and analytical investigations aimed at evaluating the effectiveness of CFRP strengthening for CWSBs and developing a design procedure to predict the shear buckling capacity of strengthened CWSBs. The research employs a finite element (FE) model developed using ANSYS software, validated against previous experimental work by the same authors, which accurately reflects the overall behavior of CWSBs. A parametric study is conducted on 105 CWSBs using the validated FE model to assess the impact of various geometrical parameters, including beam web slenderness ratio, length and thickness of CFRP strips, and different CFRP strip schemes. Results demonstrate that CFRP strengthening can enhance the shear capacity of CWSBs by up to 74.50%. The study identifies the arrangement of CFRP strips on both sides of the web as the most effective parameter for controlling the efficiency of the CFRP strengthening technique. Conversely, changes in CFRP strips up to 70% of web height have minimal effect. A proposed design procedure for predicting the design shear buckling strength of CFRP-strengthened CWSBs shows good consistency with FE model results.

Carbon fiber reinforced polymer (CFRP) laminates: flexural strengthening method for prestressed concrete beams with anchorage loss

Abstract Post-tensioning (PT), a method of pre-stressing, involves the use of high-strength steel strands/ tendons to reinforce concrete or other materials. On the contrary, Carbon Fiber-Reinforced Polymers (CFRP) are lightweight, high-strength materials with used to strengthen concrete structures by adhering the polymer to the concrete element. Challenges with post-tensioned elements include reverse curvature of the post-tensioning strands, tendon misplacement, and frequent damage in the anchorage and dead-end zones. These difficulties frequently cause bulging of the surrounding concrete, even at lower stress levels, and can lead to concrete bursting when tension exceeds certain threshold. This study investigates into the potential of CFRP strengthening technique to improve the flexural capacity of post-tensioned concrete beams with anchorage loss. Through an experimental program, the study compares the performance of control beams to those reinforced with different layers of CFRP. The results of this study demonstrated that there was a significant increase in flexural capacity, ranging from 45.31% to 78.62% for single layers and 87.17% to 153% for double layers of CFRP sheet. Additionally, the research examines how different levels of prestressing and CFRP wraps influence crack formation and delamination patterns of carbon fiber, with promising results. It was also noted that optimal usage of CFRP fibers and tendons is found to be critical. The study suggests exploring alternative fiber types and orientations for future study.

Residual compressive behaviour and CFRP strengthening of SRCFST columns after combined damage of fire and lateral impact

Composite structure may be subjected to impact and fire during its service life, and the damaged member face challenges in the performance evaluation and strengthening. This study conducted an experimental and numerical investigation into the residual compressive behaviour of steel-reinforced concrete-filled steel tubular (SRCFST) columns after combined damage of fire and lateral impact. Thirteen damaged specimens under axial loading were tested, with three specimens strengthened with carbon fiber reinforced polymer (CFRP). The failure modes of specimens, residual compressive capacity, deflection distribution, and strain development were discussed. The finite element analysis model on the residual compressive behaviour of damaged SRCFST columns was then developed and calibrated. The full-range analysis on the residual performance of damaged columns was carried out, included the temperature development, distribution of axial load and bending moment, degradation mechanism of bearing capacity, stress development, and effects of fire exposure time. The parameter study was finally conducted to investigate the effects of various factors on the residual compressive performance of damaged SRCFST columns. The results indicated that increasing the fire exposure time and impact height reduces visibly the residual compressive capacity of damaged specimens. As the two damages accumulate, the axial load of each component gradually reduces, while the axial compressive capacity proportion redistributes.

An Experimental Study on the Effect of GFRP and CFRP Strengthening on the Static and Dynamic Behavior of R/C Beams Under Progressive Damage

This paper aims to investigate the effect of glass fiber-reinforced polymer (GFRP) and carbon fiber-reinforced polymer (CFRP) strengthening materials on the static and dynamic behavior of reinforced concrete (R/C) beams subjected to progressive damage. Four identical beams, each strengthened with either GFRP or CFRP, are tested under a cyclic quasi-static loading pattern. Impact hammer tests are performed for undamaged states and various damage levels of the beams. The dynamic test data are analyzed using the Enhanced Frequency Domain Decomposition (EFDD) method to estimate the dynamic characteristics of the beams. In this context, the first three vibration modes in both vertical and horizontal directions are considered. Strengthening is applied to both pre-damaged and undamaged beams, enabling a comparison of their performance before and after the strengthening procedure. Beams strengthened with CFRP exhibit a higher load-bearing capacity and stiffness but also fail at lower displacement levels compared to those strengthened with GFRP, which demonstrate more ductile behavior. Furthermore, the modal frequency ratios indicate that the first vibration mode is more sensitive to damage than the second and third modes. This study highlights the effectiveness of both strengthening materials in enhancing the structural performance of both undamaged and damaged beams.

Fire performance of CFRP-strengthened piloti-type columns with fire-resistant materials during standard fire exposure

This paper presents a numerical investigation into the fire endurance of carbon fiber reinforced polymer (CFRP)-strengthened columns, shielded with fire-resistant materials, in piloti-type reinforced concrete buildings. The strengthened column, equipped with a fire protection system, underwent exposure to the ASTM E119 standard time-temperature curve for a duration of 4 h. To comprehensively evaluate the thermal and structural performance of the strengthened column at elevated temperatures and substantiate the effectiveness of the fire protection system, a fully coupled thermal-stress analysis was conducted. The numerical modeling approach employed in this study was rigorously validated through previous experimental studies in conjunction with adherence to the ACI design guideline, specifically ACI 440.2R-17. Using the validated structural fire model, the thermal and structural behaviors of the RC column with an insulated CFRP strengthening system were investigated based on four key performance criteria: glass transition temperature, ignition temperature of polymer matrix, critical temperature of reinforcing bars, and the design axial load capacity at elevated temperatures. Furthermore, a comparative assessment of fire endurance was performed using diverse fire-resistant materials, including Sprayed Fire-Resistive Material (SFRM) and Sikacrete®-213 F, with insulation thicknesses ranging from 10 to 30 mm, during the 4-hour fire exposure period.

Comparison of Concrete Strengthened with Carbon Fibre-Reinforced Polymer (CFRP) and Carbon Textile-Reinforced Mortar (CTRM)

Applying new composite material for strengthening and repairing existing structures is an important research topic. Carbon Fiber Reinforced Polymer/Plastics (CFRP) and Carbon Textile Reinforced Mortar (CTRM) are two common structural external reinforcement materials. 18 concrete specimens strengthened with CFRP and CTRM are prepared in this study. The quasi-static single-sided shear tests combined with the Digital Image Correlation (DIC) method is applied. The results show that the interface bonding strength of CFRP strengthening (0.76-0.96 MPa) is 65.0% to 74.8% higher than the CTRM-concrete interface (0.43-0.63 MPa). The ductility and energy dissipation capacity of CTRM strengthening is better than that of CFRP strengthening, and the effective bonding length is 125 to 300 mm. In practical work, CFRP is preferred for improving the strength of concrete components, while CTRM is preferred for improving ductility and seismic resistance. Keywords: Carbon fibre-reinforced composites (CFRP); Carbon textile-reinforced mortar (CTRM); Digital image correlation method (DIC); Single-sided shear test

Enhancing the Flexural Capacity of Deteriorated Low-Strength Prestressed Concrete Beam Using Near-Surface Mounted Post-Tensioned Carbon Fiber-Reinforced Polymer Bar

This study aimed to address the critical issue of age deterioration in prestressed concrete (PSC) structures by investigating the strengthening of aged PSC structures using a near-surface mounted (NSM) post-tensioned carbon fiber-reinforced polymer (CFRP). A total of nine PSC beams, each with a length of 6.5 m, were fabricated for a four-point bending test. Various experimental parameters were taken into account, including the strengthening method, compressive strength of concrete in the PSC beam, and the prestressing force of the PSC beam. The results indicated that the NSM post-tensioned CFRP strengthening system proved more efficient when compared to the NSM non-post-tensioned CFRP strengthening system. The flexural capacity of the NSM post-tensioned CFRP strengthening system, under the deteriorated low-strength PSC beam, increased by up to 30.9% compared to the PSC reference beam. Additionally, the experimental results were compared to a finite-element analysis, and a parametric study was conducted to examine the material properties of the PSC beam. Consequently, the NSM post-tensioned CFRP strengthening system is expected to be an effective solution for addressing the issue of deteriorated low-strength PSC structures.

Compressive behavior of fiber-reinforced concrete strengthened with CFRP strips after exposure to temperature environments

Abstract Reinforced concrete constructions are extremely vulnerable to fire damage over their lifespan. Despite its non-flammability, concrete is nonetheless affected by fire exposure, which impacts its stress–strain characteristics and durability. Therefore, developing strengthening methods is an economical option compared to the costs of demolishing and rebuilding constructions. This article aims to experimentally and numerically examine the strengthening of fiber-reinforced concrete cylinders by using carbon fiber-reinforced polymer (CFRP) strips after exposure to 600°C. Four different concrete mixtures have been investigated. A total of 48 cylinders were subjected to axial compression testing. The testing program primarily focused on three variables: (i) exposure temperature (600°C); (ii) the effect of using various types of fibers (steel fiber, polypropylene, and hybrid fibers); and (iii) CFRP strengthening. Finite element (FE) models were created using the ABAQUS program to conduct numerical analysis of concrete cylinders in exposure to heating scenarios and strengthen them with CFRP strips. The results show that when subjected to a temperature of 600°C, the compressive strength decreased significantly, ranging from 23.7 to 53.3%. The presence of fibers significantly impacted compressive strength, regardless of the fiber type, leading to an enhanced ratio of up to 34.7% in comparison to the control cylinders (i.e., unheated and unstrengthened cylinders). The suggested strengthening procedures using CFRP strips effectively repaired the heat-damaged cylinders, surpassing the initial compressive strength of unheated cylinders. The FE prediction shows satisfactory, consistent results in comparison to experimental data.

Mechanical response of coal pillar-backfill composite confined by CFRP jackets: parametrical study

The composite structure consisting of the coal pillar and backfill material is the critical component for the room-and-pillar mining system, the stability of which is mainly relevant to the interface in between. To eliminate the premature instability and potential disasters attributed to the breakage of the weak interface, the innovative strengthening technique incorporating the carbon fiber-reinforced polymer (CFRP) jacket was recently developed and the comprehensive studies including the uni-axial compression tests and the numerical investigation were carried out. In the present study, the digital interface of the coal-backfill composite was initially reconstructed with the 3D laser scanning and then imported into the mesoscopic continuum-discontinuity coupling model via the PFC-FLAC coupling method. Based on the analysis of the deformation characteristics and damage patterns of the coal -backfill composite, the strengthening mechanism of the exterior CFRP jacket was discussed. The results showed that both the load-bearing performance and the stability of the coal-backfill composite interface have been well enhanced mainly attributed to the effective lateral confinement provided by the exterior CFRP jacket. Moreover, the application of the CFRP jacket enhances the energy dissipation capacity of the coal-backfill composite as suggested by laboratory tests. It is also suggested that both the peak strength and elastic modulus of the coal-backfill composite exhibited the initial decrease and then rising as the interface angle increases. As demonstrated by the systematic research, the CFRP strengthening technique is effective in maintaining the stability of the coal-backfill composites for underground mines.

Effects of CFRP sheets on the flexural behavior of high-strength concrete beam

Abstract The aim of this study is to evaluate numerically the effects of carbon fiber-reinforced polymer (CFRP) sheets strengthening on the flexural performance of high-strength concrete (HSC) beam using ABAQUS 3D finite element (FE) modeling software. The developed FE models were verified against the experimental results found in literature. The FE models can accurately estimate the performance of CFRP-strengthened high-strength reinforced concrete (RC) beams. Subsequent parametric analysis was performed to assess the performance of CFRP-strengthened concrete beams considering various parameters including compressive strength of concrete, CFRP width, thickness, length, number of CFRP layers, and CFRP strengthening schemes. Based on the results of FE analysis. It was demonstrated that using HSC significantly enhances the performance of CFRP-strengthened RC beams. It was also confirmed that width, thickness, and layer number of CFRP sheets improve the flexural behavior of CFRP-strengthened HSC beams by increasing the ultimate loads and strain-hardening behavior of the specimens. The strengthening schemes contribute to delaying or inhabiting the debonding especially when the CFRP sheets are added along the bottom of the beams. It was demonstrated that using CFRP sheets U-wrapping contributes to the prevention or delay of debonding and increases the capability of resisting the stress imposed on the concrete. Therefore, installing the CFRP sheets at the bottom face of beam below the tensile reinforcement enhances the performance of CFRP-strengthened HSC beams.

Study on CFRP-Strengthened Welded Steel Plates with Inclined Welds Considering Welding Residual Stress.

Welded steel plates are widely used in various structural applications, and the presence of inclined welds is often encountered in practical scenarios. Carbon fiber reinforced polymer (CFRP) has been proven to be effective for strengthening steel structures. However, the behavior of CFRP-strengthened welded steel plates with inclined welds, particularly considering the influence of welding residual stress, is limited. This paper aims to investigate the tensile behavior of CFRP-strengthened welded Q355 steel plates with inclined welds considering welding residual stress (WRS). First, WRS data were obtained by the X-ray diffraction (XRD) method at different locations. The maximum tensile and compressive residual stresses are 0.39 and 0.14 times the yield strength of the steel, respectively. Then, finite element models were established to investigate the effects of weld angles, weld width, and height on the WRS distribution of welded steel plates. Finally, the tensile performance of CFRP-strengthened welded plates with WRS was studied by numerical simulation. The results showed that the weld angles have little effect on the distribution pattern of residual stress but significantly affect the peak tensile WRS. When the weld angle changes from 0° to 60°, the peak tensile WRS decreases significantly from 0.32 to 0.06 times the yield strength of steel; furthermore, the influence of weld width and height on WRS is relatively limited. Under tension loading, the maximum stress occurs near the weld. The ends of the weld enter the yielding state later than the middle part of the weld due to the distribution of the WRS. As the weld angle increases and the length of the weld increases, the stress in the weld zone decreases, while the stress in the base material zone correspondingly increases. In addition, CFRP strengthening can reduce the magnitude of stress. This study provides preliminary references for understanding the tensile behavior of CFRP-strengthened welded steel plates with inclined welds.

Flexural behavior of reinforced concrete beams strengthened with gradually prestressed near surface mounted carbon fiber-reinforced polymer strips under static and fatigue loading

The near surface mounted (NSM) carbon fiber-reinforced polymer (CFRP) strengthening technique, combined with gradually anchored prestressed technique, is utilized to delay the occurrence of concrete cover separation (CCS) and enhance the ductility of reinforced concrete beams. The load-carrying capacity of fully prestressed beams and gradually prestressed beams are investigated under both static and fatigue loading conditions. The study focused on the effect of gradient prestress on flexural behavior of strengthened beams, analyzed the failure mode, characteristic load, ductility, and stress distribution at CFRP-concrete interface under both prestress and load conditions. Results indicate that gradually prestressed beams outperform fully prestressed ones in restraining crack development, delaying yield of tensile reinforcement, improving bearing capacity and avoiding CCS failure. Bearing capacity was significantly increased by up to 35.48%, while ductility was greatly improved by 100.33% with ultimate deflection for gradually prestressed beams compared to fully prestressed ones. The fatigue life of gradually prestressed beams, which experienced a transition from CCS failure mode to fatigue fracture of tensile reinforcement, was significantly extended. Additionally, their ductility at failure was also greatly enhanced, thus confirming the effectiveness of gradually prestressed NSM CFRP strengthening technique.

Influence of deteriorated stirrups on the shear performance of RC beams incorporating fly ash and enhanced with carbon fiber-reinforced polymer strengthening

Influence of deteriorated stirrups on the shear performance of RC beams incorporating fly ash and enhanced with carbon fiber-reinforced polymer strengthening

Factors affecting flexural properties of RC beams strengthened with gradually prestressed NSM CFRP strips

In this study, the gradually anchored technique is combined with the prestressed near-surface-mounted (NSM) carbon fiber-reinforced polymer (CFRP) strengthening technique to reduce the stress concentration caused by prestress transfer at the CFRP end section and improve the failure mode and bearing capacity of strengthened beams. Flexural performance tests are conducted on one fully prestressed and six gradually prestressed NSM CFRP-strengthened reinforced concrete beams under static loads. The influencing factors include the gradient prestress, CFRP bond length, concrete cover thickness, and steel reinforcement type. The failure mode, characteristic load, shear stress distribution at the CFRP end section, as well as the crack development under prestress and load are analyzed. The test results indicate that the gradually prestressed beam is superior to the fully prestressed beam in reducing the stress concentration at the CFRP end, thereby inhibiting the development of cracks at the CFRP end, improving the bearing capacity, and delaying the separation of concrete cover. The bearing capacity and ductility of the strengthened beams are significantly improved, with a maximum increase of 35% and 100.33% for them respectively, confirming the effectiveness of the gradually prestressed NSM CFRP strengthening technique. Finite element analysis is conducted to further investigate the effect of gradient prestress on flexural performance of strengthened beams and propose design suggestions.

CFRP strengthening of web perforated CFS lipped channel short columns: An experimental study

Web perforations provided in the columns or studs of light-gauge steel buildings to meet the functional requirements, decrease the axial capacity and lead to localized failure. Hence, the aim of this study is to experimentally investigate the influence of carbon fiber reinforced polymer (CFRP) strengthening on the stability, axial strength, and stiffness of the CFS web-perforated lipped channel short columns (of 600 mm length) subjected to monotonic axial compression. A total of 20 specimens, provided with circular perforation at mid-height and at the centre of the web, were tested by adopting different CFRP skin-strengthening configurations, considering Uni-Directional CFRP (CF_UD) and Bi-Directional CFRP (CF_BD) laminas or laminates. From the tests conducted, it was observed that CF_UD and CF_UD / UD were found to result in an increase in axial capacity of 11.12% and 22.23% for the cases of single- and double-layered CFRP, respectively. Similarly, the axial stiffness increased by 9.23% and 26.07%, respectively. However, the only considered triple-layered laminate, CF_UD / UD / BD has outperformed among the entire adopted strengthening configurations, with an increase in axial strength and stiffness of 28.90% and 38.33%, respectively, in comparison to the bare steel specimens. Notably, a local-distortional interactive buckling mode of failure was noticed in the cases of both bare steel and CFRP-strengthened specimens.

Flexural behavior of RC beams externally reinforced with CFRP composites using various strategies

Abstract The external composite material bonding is an effective and practical method for flexural strengthening of reinforced concrete (RC) beams, providing a large opportunity to develop high-performance and cost-effective structures. Numerous uses exist for carbon fiber-reinforced polymer (CFRP) materials as RC-member strengthening methods. However, issues with bonding and de-bonding continue to be a barrier to this technique's accomplishment. In this research, the CFRP sheets were integrated as an external strengthening material to evaluate their contribution to the flexural performance and so determine how well the CFRP sheets are being used. The experimental work includes one control beam and ten RC beams with CFRP sheets as external strengthening. All beams have the same dimensions: a length of 1.7 m and a sectional area of 20 cm × 25 cm. Experimental tests were carried out with varying CFRP types, lengths, numbers, and arrangements. Each beam’s performance was evaluated in terms of failure mode, ultimate load capacity, ultimate deflection, and a load–deflection curve. The findings demonstrate the effectiveness of CFRP strengthening by demonstrating a considerable improvement in the majority of the study variables. Furthermore, the CFRP strengthening offered an exterior crack-arresting mechanism.

Improved Bond Stress-Slip Relationships for Carbon Fibre-Reinforced Polymer-Strengthened Masonry Triplets

Carbon fibre-reinforced polymer (CFRP) emerges as a viable solution for reinforcing unreinforced masonry (URM) walls subjected to shear loads. While masonry structures are straightforward to construct, the complexity of the construction materials, especially in terms of their mechanical properties, poses challenges for numerical studies of their structural behaviour. Walls, being fundamental components in masonry construction, play a crucial role in transferring both horizontal and vertical lateral forces. This study investigates the enhancement of masonry wall behaviour through the reinforcement of CFRP. CFRP reinforcement increases ductility and strength, reducing the risk of failure under shear conditions. Additionally, CFRP composites present a practical solution to strengthening masonry structures compared to traditional reinforcement. However, brick, mortar, and CFRP have not been thoroughly investigated. Experimental tests on the bond behaviour of different configurations of CFRP-retrofitted masonry triplets have not been performed before and are therefore presented in this paper. Triplet specimens, comprising three bricks and two mortar joints, both with and without CFRP strengthening, were subjected to bond testing. The study affirms that masonry triplets strengthened with CFRP under shear loads exhibit strength levels at least four to six times greater than those without CFRP. The experimental work was carried out with eight different CFRP configurations on triplet masonry, and each test was repeated four times. Further, the bond stress-slip relationship in the case of masonry triplets with and without CFRP was predicted with new mathematical equations based on the conducted test results. These equations were included in the commercial finite element software ANSYS and used to conduct simulations of CFRP-reinforced masonry triplets. The numerical results indicate good agreement between the finite element model and the test results. The outcome of this research improves the current knowledge on the use of CFRP to reinforce masonry walls with brick and mortar, which will contribute to the understanding of the effect of CFRP on masonry structures.

Experimental and Numerical Study of CFRP Laminate Strengthened Concrete Beams Under Hygrothermal Environment

Carbon fiber reinforced polymer (CFRP) laminates are widely used to strengthen and retrofit deteriorated concrete structures, yet their long‐term performance and durability under varied environmental conditions remain critical areas of investigation. This study comprehensively examined the behavior of small concrete beams externally bonded with CFRP laminates under three distinct hygrothermal regimes: immersion in water at 23, 45, and 60°C for up to 112 days. The experimental program encompassed direct tension pull‐off testing of the CFRP–concrete assembly and four‐point bending tests on the beams. Pull‐off tests revealed complex failure modes, with bonding epoxy failure (43%) and concrete substrate cohesion failure (39%) being dominant. Notably, pull‐off strength exhibited nonmonotonic trends across all environments, suggesting that environmental degradation is not solely time‐dependent. Flexural capacity increased by 20%, 49%, and 11% for room temperature (RT), moderate temperature (MT), and high temperature (HT) conditions, respectively, after 112 days, highlighting the synergistic effect of CFRP strengthening and ongoing concrete curing. A calibrated three‐dimensional finite element model, developed using Abaqus, accurately replicated the experimental results and facilitated parametric studies on factors influencing CFRP‐strengthened beam performance. This included concrete compressive strength, number of CFRP layers, laminate thickness, and FRP type. The study elucidates the complex interplay between environmental exposure, material properties, and structural performance, contributing valuable insights for enhancing durability predictions and design guidelines for CFRP‐strengthened concrete structures in diverse climatic conditions.

Geopolymer adhesive for sustainable NSM CFRP strengthening of RC structures

Carbon fiber reinforced polymer (CFRP) composites are known to be a very effective materials for strengthening and rehabilitation of reinforced concrete (RC) structures. Near surface mounted (NSM) technique, has been used as an effective method for this purpose, over the past two decades. The conventional technique benefits from the superb properties of polymeric adhesives like epoxy resins, to ensure a successful transfer of stresses between the CFRP and concrete substrate. However, the vulnerability of polymeric matrices to high temperatures motivated researchers to focus on developing cement-based adhesives for NSM CFRP systems for special applications where fire safety is an issue. Recently, efforts led to promising outcomes for the future of these novel systems. This upgrade not only fulfills the fire safety measures but also is necessary from the environmental point of view, due to the pollution and health problems associated with the usage of epoxy resins as conventional adhesives for FRP systems. While improvements occurred in the bond performance of the NSM CFRP systems with cement-based adhesives, using innovative sand-coated CFRP strips, the alternative sustainable approaches could be also investigated. This paper is dedicated to assessing the adoption of a geopolymer adhesive, to serve as a matrix for NSM strengthening techniques, using special sand-coated CFRP strips. Bond tests have been performed in ambient and thermo-mechanical conditions, and results showed promising performance of adoption of geopolymer in this technique. Also, a brief analysis of the environmental impact of using geopolymer as an alternative sustainable matrix is discussed, compared with epoxy resin and cement-based adhesive as its competitors, for eco-friendly strengthening systems for RC structures.

Numerical analysis of SCF of Tubular T-joints strengthened with prestressed CFRP

Fatigue failure is one of the main concerns of welded tubular joints owing to inevitable welding defects and severe stress concentration along the intersection. In addition, the complex geometry of the joint makes it inconvenient to reinforce by traditional repair methods. Carbon fiber-reinforced polymer (CFRP) composite has been widely used for structural strengthening due to superior strength-to-weight ratio, good fatigue and corrosion resistance, as well as ease of installation. Although tubular joints strengthened by using non-prestressed CFRP sheets have been investigated in references, application of prestressed CFRP has not been reported. This study proposed a form of prestressed CFRP sheets for the fatigue strengthening of tubular T-joints. Three-dimensional finite element models were developed for both CFRP-strengthened and unstrengthened tubular T-joints to calculate the hot spot stress distribution, which was verified using experimental test data and Lloyd’s Register (LR) equations. A parametric study was then carried out to explore effects of CFRP strengthening parameters on the SCF reduction coefficient ψ, including the prestressing level (p), CFRP width (w), and CFRP layers (n). It was found that prestressing CFRP changed the stress distribution and values along the weld toe. With the increase of prestress, the position of the maximum stress gradually moved from the saddle point to the crown point. Besides, the strengthening parameters had significant effects on reduction of the hot spot stress along the weld toe.