Application Of FRP Research Articles

Flexural behavior of BFRP bar–hybrid steel fiber reinforced UHPC beams

Ultra-high-performance concrete (UHPC) has the potential to overcome the durability limitations of conventional concrete. Basalt Fiber Reinforced Polymer (BFRP) bars can mitigate the corrosion effects of steel bars and fully exploit the properties of UHPC. Industrial Steel Fibers (ISF) are a widely used component in the preparation of UHPC. To reduce environmental pollution and costs, this study proposes using recycled tire steel fibers (RTSF) instead of ISF in the production of UHPC. RTSF will be combined with BFRP bars to prepare hybrid steel fiber UHPC beams. The study investigates the effects of RTSF substitution for ISF and BFRP reinforcement ratio on the flexural performance of UHPC beams. The study indicates that the beam's bending failure modes include concrete crushing, equilibrium, and BFRP bar tensile failure. The replacement rate of RTSF has a dual effect on the flexural performance. As the RTSF replacement rate increases from 0 % to 100 %, the cracking load and ultimate capacity of the beams decrease by 2.86 % and 10.38 %, respectively, while the mid-span deflection of the beam increases by 7.94 mm when it reaches failure. When the replacement rate of RTSF is 60 %, the beams exhibit optimal bending performance, and their ultimate capacity can be increased by 2.95 % compared to the capacity when the replacement rate is 0 %. The failure mode of the beams is significantly influenced by the reinforcement ratio of the BFRP bars. Increasing the BFRP reinforcement ratio from 1.12 % to 7.12 % resulted in a 65.8 % decrease in maximum crack width and a 57.6 % decrease in mid-span deflection, while the ultimate load is increased by 78.6 %. The proposed theoretical calculation formula can effectively predict the flexural capacity of BFRP bar hybrid steel fiber UHPC beams, providing a theoretical basis for the application of FRP reinforced hybrid steel fiber UHPC beams.

Study on mechanical properties and molecular simulation of nano‐SiO2‐modified hybrid fiber reinforced polymer bar under the dry and alkaline environment

AbstractFiber reinforced polymer (FRP) bars have received extensive promotion and application in the structural engineering. However, due to the limitations inherent in using single material, FRP reinforced concrete structures often encounter issues, such as brittle failure and inadequate energy dissipation, particularly in complex natural environments and under various loading conditions. In this study, the preparation of nano‐SiO2‐modified carbon/basalt hybrid FRP bars was carried out using the pultrusion‐winding process and ultrasonic treatment. The objective was to investigate the influence of the fiber volume ratio and mass fraction of nano‐SiO2 on the mechanical properties of FRP bars under drying and alkaline conditions. Molecular dynamics simulations were performed to construct interface models between fibers and epoxy resin in order to elucidate the toughening mechanism of nano‐SiO2 and the degradation mechanism in alkaline conditions. The research results show that elevating the substitution rate of carbon fibers and incorporating nano‐SiO2 doping bring about alterations in the brittle fracture characteristics of BFRP bars and enhance the post‐yield performance and interlaminar shear properties of hybrid FRP bars, concurrently mitigating the degradation of mechanical properties induced by exposure to alkaline solutions. MD simulations indicate that the addition of nano‐SiO2 improves the binding rate of hydrogen bonds between BF and epoxy resin, resulting in a higher interfacial energy between BF/epoxy resin compared to CF/epoxy resin. Moreover, nano‐SiO2 effectively mitigates the impact of alkaline solutions on the formation of interfacial hydrogen bonds. The findings of this study serve as a valuable reference for the design and application of FRP reinforced concrete structures.Highlights Nano‐SiO2 modified B/CFRP bars made via extrusion‐winding & ultrasonic treatment. Improved mechanical properties and plastic deformation in Nano‐SiO2 modified B/C FRP bars. Nano‐SiO2 inhibits B/CFRP bars degradation in alkaline solution. Nano‐SiO2 bind more at BF/epoxy than CF/epoxy interface. Nano‐SiO2 reduces alkaline solution effect on interfacial H‐bonding.

Research and Applications of FRP in Large-Diameter Shield Tunnel Engineering

Research and Applications of FRP in Large-Diameter Shield Tunnel Engineering

Research Progress of Bond Slip at The Interface of FRP Bars and Concrete

The bond between FRP bars and concrete is the key to the strength and durability of FRP reinforced concrete members, and it is the decisive factor to make full use of the light, high strength and corrosion resistance of FRP bars. In this paper, according to the research results of bond properties of FRP bars and concrete at home and abroad, the paper analyzes four aspects, including test method of bond properties of FRP bars, bond mechanism, factors affecting bond properties of FRP bars and bond slip constitutive relationship model. The shortcomings of the existing research results and the problems to be solved are analyzed and compared comprehensively. At last, some references and suggestions are provided for the further research and application of FRP reinforced concrete structures.

Repair and strengthening of existing structures using FRP composites externally-bonded with toughened epoxy adhesives

This literature review investigates the efficacy of toughened epoxy adhesives for structural repair and strengthening of existing structures with FRP composites. Highlighting the limitations of traditional epoxy adhesives, such as susceptibility to fatigue loading and impact actions, the study explores the potential of toughened formulations to mitigate fracture propagation issues. Through the incorporation of additional phases like rubber particles or nanomaterials, toughened adhesives offer increased fracture toughness and improved structural performance. However, this could also lead to trade-offs, including potential reductions in mechanical properties, glass transition temperature reduction and possible health and environmental concerns. This study presents an overview of the main toughening mechanisms occurring in modified epoxy resins. Two toughening techniques are described and discussed, namely the rubber-toughening and nanomaterial-toughening. The study further investigates the effects of the use of toughened adhesives in externally-bonded FRP strengthening/repair applications, involving both steel and concrete substrates. Eventually, the difference in bond-slip behavior of toughened and traditional adhesives is described, with reference to currently available literature studies on the topic. This review paper shed light on the promising advantages of using toughened epoxy adhesives in FRP applications, in terms of higher bond and strain capacity and enhanced bond transfer mechanisms between composite and substrate, if compared to traditional adhesives.

RC beams externally strengthened by steel plates: experimental database and preliminary analysis

External steel plating is a popular technique for the flexural strengthening of RC beams thanks to the ease of application which does not require skilled labor, the relatively low-cost and the optimal mechanical properties of the steel material. Research on externally plated RC beams is much older than the literature related to the strengthening methods employing fiber reinforced (FRP) materials which were more recently developed. Despite this, the number of FRP applications is far greater than those available for steel applications, as also corroborated by the widespread of several international guidelines for the FRP strengthening design of RC structures. Conversely, the in-situ applications with steel plates are still very common and often preferred to FRPs, but they are not well supported by clear design indications. This paper contributes to filling this knowledge gap by presenting the results of a preliminary study on the flexural performance of steel-plated RC beams. A large experimental database was compiled from the literature, which includes three/four- point bending tests performed on RC members variably reinforced with external steel plates. The database is in-depth examined by considering the following main parameters: layout of the external steel plating, shape of beam’s cross section, mechanical percentages of both external steel plate and beam’s longitudinal steel reinforcement in tension, and failure mode. The collected data is useful for a theoretical study on beams’ flexural performance, which is under preparation.

Major cellular and molecular processes and clinical outcomes in bone regeneration for successful dental implantation: a systematic review

Introduction: In the context of bone regeneration, bone defects still represent a major challenge in oral and maxillofacial clinical and surgical treatment. The biomimetic design of biomaterials by simulating the natural structure and composition of bone tissue has gradually become a point of research interest due to its advantages of simplicity and efficiency. Objective: It was to carry out a systematic review on cellular and molecular processes, as well as to present the main clinical approaches of bone regeneration for dental implants. Methods: The present study followed a systematic review model, following the rules of systematic review – PRISMA. The search strategy was performed in the PubMed, Cochrane Library, Web of Science and Scopus, and Google Scholar databases. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results: A total of 142 articles were found. A total of 84 articles were fully evaluated and 33 were included in this study. Literary findings have shown that the lack of bone in the alveolar ridges has been a major problem in functional aesthetic recovery in patients who have suffered dentoalveolar trauma. The osteoinduction process is influenced by several factors, requiring the presence of inducers, which include β-glycerolphosphate, ascorbic acid, and dexamethasone. Mesenchymal stem cells acquire the morphology and components of osteoblastic membranes and begin to express alkaline phosphatase to deposit extracellular matrix rich in calcium and certain proteins, such as osteopontin and osteocalcin. The Bio Oss® (Geistlich) biomaterial, because it is biodegradable, biocompatible, non-toxic, and has low immunogenicity and bio stimulators, can act in the regeneration of bone tissue. Application of FRP and implant placement provides stable clinical results for severely atrophic maxilla 2-4 mm. Bovine xenograft alone and in combination with liquid FRP are both successful in achieving bone augmentation around implants and produce a small change in marginal bone level and a high implant survival rate after loading. Conclusion: Through the results of the present study, it was evidenced that the success of the dental implant is directly related to successful osseointegration.

Axial compressive behavior of CFRP confined rectangular CFT columns using high-strength materials: Numerical analysis and carrying capacity model

The concrete-filled steel tubular columns using high-strength steel and concrete have the advantages of high strength and small cross-section. However, the rectangular concrete-filled steel tubular (RCFT) columns using high-strength materials are susceptible to local buckling and lower ductility. The experimental study on the axial compression behavior of FRP confined concrete-filled steel tubular columns using high-strength materials show that FRP could restrain the deformation of steel tube and concrete and delay the local buckling of steel tube effectively. Based on the experimental study, the finite element model of FRP confined RCFT columns was established and verified by comparing the carrying capacity and load-displacement curves of test including ten specimens. Parametric analysis considering the corner radius, number of FRP layers, width-to-thickness ratio, concrete strength and aspect ratio is conducted to analyze the influence of different parameters on the axial compressive performance. Through the analysis of test and parametric data, theoretical model and method to design the axial capacity of the FRP confined RCFT columns are proposed. The theoretical models and methods could accurately predict ultimate carrying capacity of FRP-RCFT columns under axial compression and provided theoretical support for the application of FRP confined concrete-filled steel tubular columns using high-strength materials.

Shear Strengthening of Reinforced Concrete Beams Using Fibre Reinforced Polymer: A Critical Review

The primary purpose of reinforcing bar stirrups in a reinforced concrete beam is to improve shear strength. The FRP system may significantly improve a concrete beam’s ultimate shear strength, serviceability, and ductility. The application of FRP for the repair and reinforcement of the structures has become very popular due to its low weight, high tensile strength, and simplicity of installation on uneven surfaces. FRP material outperforms other traditional materials in strengthening applications due to its high strength-to-weight and stiffness-to-weight ratios, resistance to corrosion, and ease of handling. The overall objective of this research is to investigate and improve the understanding of the recent research in the area of shear FRP strengthening of reinforced concrete beams. In this paper, recent publications were reviewed to see how different anchoring procedures, different factors that affect FRP performance and different failure scenarios affect the shear strengthening of concrete beams. The benefits and limits of FRP systems, as well as some current research trends are discussed in this project. From the research, it can be stated that type of anchorage technique and different parameter give a different impact to failure mode of the beam.

Behavior of RC columns and those strengthened with FRP composite under an innovative reversing cyclic eccentric axial loading

The fundamental role of columns in structural stability calls for an in-depth understanding of their behavior under different loadings. In this study, an innovative test was designed and the required apparatus was manufactured to apply axial eccentric cyclic loading in two opposite directions as an effort to create more realistic conditions for eccentric axial loading of columns in the structures under cyclic loads. For this purpose, six reinforced concrete (RC) columns were tested. The columns included non-strengthened specimens, those strengthened with longitudinal FRP strips installed using the externally bonded reinforcement on groove (EBROG) technique, and those strengthened with full FRP wraps. All the specimens subjected to axial loading with an eccentricity of 90 mm in both monotonic and reversing cyclic method (the innovative method developed herein) to compare the effects of both cyclic and monotonic loadings. The specimens exhibited reduced bearing capacity and ductility under cyclic loading when compared with those subjected to monotonic. Moreover, the trend of the load-deformation relationship of RC columns and those strengthened with FRP wraps were almost the same under monotonic and cyclic loads, while strengthened specimens with longitudinal FRP exhibited different load-deformation trends. Comparison of the specimens strengthened via the two methods used in this study revealed that using longitudinal FRP sheets via the EBROG technique caused a significant (about 60%) increase in bearing capacity under high eccentric loads through a reduction in ductility. Application of FRP wraps, however, exhibited almost no effect on bearing capacity under the same loads but led to the columns’ enhanced ductility.

Polyamide based amalgams in marine custom: History and forthcoming leanings

The increasing ecological concerns and the requirement to invent genuine substitutes to glass or strengthened fusions of carbon have improved the attention in polyamide amalgams filled with organic filaments, derivative of renewable and eco-friendly bases. The article’s scope is to endorse our attention towards the developed knowledge of science and technology in the field of green compound constituents to upkeep their grander application in numerous industries. Utilization of composites based on polymer and reinforced fibers (FRP) proposes numerous benefits for marine manufacturers to attain effective and dependable edifices. The trending applications of FRP in the maritime industry based on its materials, production techniques, and conservational disputes are projected to the attention of marine draftsmen, and also the potential exploration is concisely highlighted in this article.

A micro-modeling approach for the prediction of TRM bond performance on curved masonry substrates

Retrofitting of arches, vaults and domes is needed for vulnerability mitigation of historical structures. Lately, the external application of composite materials embedded within an inorganic matrix addressed the compatibility issues related to FRP applications. Great efforts have been made for a correct identification of tensile and bond properties of TRM reinforcement, but scarce data are available for understanding the effect of curvature in debonding. This paper provides a numerical approach that enables to predict the reinforcement performance on curved masonry elements, when the same is designed without having specific single lap shear tests for the adopted materials. Such an approach relies on a separate modeling of each constituent material of the reinforcement and the substrate: matrix, fibers and the interface between them, and bricks and mortar joints. The FE-based software Abaqus is used for the simulations, addressing the non-linear material properties by means of the CDP constitutive model. In order to calibrate and validate the proposed numerical approach, experimental data are used and through a comparison of the load–displacement curves obtained the capabilities of the method are discussed. Finally, an extension of such approach to curvatures not experimentally tested is presented, opening the way to future applications of the approach.

An Overview of Research and Applications of FRP in New Zealand Reinforced Concrete Structures

FRP materials, though having been around for several decades, are seeing increasing uptake in the structural engineering domain. In New Zealand, the use of FRP sheets is especially common in the seismic retrofit of buildings and bridges, though there is still minimal use of FRP bars as internal reinforcement. A number of typical uses of FRP materials are shown, highlighting the different solutions offered by the material as well as the developing familiarity of engineers and contractors of the material. Then, the direction of research into the use of FRP is touched on, showcasing the progress made in understanding FRP-reinforced and retrofitted structures and what could be next in terms of potential applications of the material. The applications discussed showcase that versatility of the material allows it to be used in a variety of areas in construction, provided more standardised manufacturing techniques are developed and key research questions on their behaviour are answered. Overall, there is a growing awareness of the properties of FRP as a structural material within the construction industry and there is ongoing research to further investigate where and how it can be used in concrete structures in pursuit of improved durability, performance and resilience.

Investigation of HFRC beams retrofitted using GFRP for enhancement in flexural capacity

The applications of FRP have been widely used in repair and upgrading of concrete structures. Research and design guidelines accomplished that externally bonded FRP could increase the load carrying capacity of RC elements efficiently. A study was undertaken to investigate the flexural behaviour of hybrid fibre reinforced concrete (HFRC) beams, which were preloaded and retrofitted by externally bonded with glass fibre reinforced polymer (GFRP) laminate to the bottom (soffit) of the beam. The compressive, split tensile and flexural strength tests were conducted to find the optimum percentage of hybrid fibre which can be used for casting of beam specimens. Two sets each containing three numbers of beams were cast and tested in this study. Based on the test results, it is found that the HFRC beams retrofitted with GFRP show an improvement in load carrying capacity of about 45% and 23% than the same set of retrofitted control beams.

Investigation of HFRC beams retrofitted using GFRP for enhancement in flexural capacity

The applications of FRP have been widely used in repair and upgrading of concrete structures. Research and design guidelines accomplished that externally bonded FRP could increase the load carrying capacity of RC elements efficiently. A study was undertaken to investigate the flexural behaviour of hybrid fibre reinforced concrete (HFRC) beams, which were preloaded and retrofitted by externally bonded with glass fibre reinforced polymer (GFRP) laminate to the bottom (soffit) of the beam. The compressive, split tensile and flexural strength tests were conducted to find the optimum percentage of hybrid fibre which can be used for casting of beam specimens. Two sets each containing three numbers of beams were cast and tested in this study. Based on the test results, it is found that the HFRC beams retrofitted with GFRP show an improvement in load carrying capacity of about 45% and 23% than the same set of retrofitted control beams.

Study on Application of Thermoplastic FRP to Concrete Member

Study on Application of Thermoplastic FRP to Concrete Member

Developing an anchored near-surface mounted (NSM) FRP system for fuller use of FRP material with less epoxy filler

Near-surface mounted (NSM) FRP systems have a number of advantages over externally bonded (EB) FRP systems. Relying exclusively on epoxy-filler bond, however, conventional NSM FRP systems cannot ensure the tensile strength of FRP reinforcements to be fully developed. The liquid characteristics of epoxy filler before curing also narrow NSM FRP applications down to negative moment regions. In this study, an anchored NSM FRP system has been developed to fully develop the FRP tensile strength with a minimum epoxy filler. Anchorages are the extended parts of FRP reinforcements embedding into predrilled holes and then overlapping FRP material within anchor regions. Experiments were conducted to validate the proposed NSM FRP system and investigate the impacts of key parameters, i.e. location and density of grooves as well as the amount of epoxy. Experimental results also suggest a great potential extending the anchored NSM FRP system to positive moment regions.

Experimental and Analytical Study on Torsional Behaviour Of RC Flanged Beams Strengthened With Glass FRP

Environmental degradation, increased service loads, reduced capacity due to aging, degradation owing to poor construction materials and workmanships and conditional need for seismic retrofitting have demanded the necessity for repair and rehabilitation of existing structures. Fibre reinforced polymers has been used successfully in many such applications for reasons like low weight, high strength and durability. Many previous research works on torsional strengthening were focused on solid rectangular RC beams with different strip layouts and different types of fibres. Various analytical models were developed to predict torsional behavior of strengthened rectangular beams and successfully used for validation of the experimental works. But literature on torsional strengthening of RC T- beam is limited. In the present work experimental study was conducted in order to have a better understanding the behavior of torsional strengthening of solid RC flanged T-beams. An RC T-beam is analyzed and designed for torsion like an RC rectangular beam; the effect of concrete on flange is neglected by codes. In the present study effect of flange part in resisting torsion is studied by changing flange width of controlled beams_ The other parameters studied are strengthening configurations and fiber orientations. The objective of present study is to evaluate the effectiveness of the use of epoxy-bonded GFRP fabrics as external transverse reinforced to reinforced concrete beams with flanged cross sections (T-beam) subjected to torsion. Torsional results from strengthened beams are compared with the experimental result of the control beams without FRP application. The study shows remarkable improvement in torsional behavior of all the GFRP strengthen beams. The experimentally obtained results are validated with analytical model presented by A.Deifalla and A. Ghobarah and found in good agreement.

The Application of FRP in the Shear Reinforcement of Bridges

The Application of FRP in the Shear Reinforcement of Bridges

Current of Decomposable Adhesives and Application ofFRP Adhesive Bonding

Current of Decomposable Adhesives and Application ofFRP Adhesive Bonding