Use Of FRP Research Articles

Seismic performance of slit steel plate shear walls strengthened by FRP laminate

Steel plate shear walls with slits are widely used in high–rise building structures due to their flexible arrangement and high ductility. After long-term service, cracks may occur in the slit steel plate shear walls due to repeated buckling and stress concentration. In this study, an FRP–steel composite slit steel plate shear wall was proposed to improve its mechanical performance and service function. Experimental and finite element analysis were conducted to investigate the performance of slit steel plate shear walls reinforced with FRP under low cycle reciprocating load. It was shown that the use of FRP to strengthen slit steel plates can effectively improve the out–of–plane stability of the structure and reduce the stress concentration at the slits. The stiffness and load–bearing capacity of the reinforced slit steel plate shear walls were significantly enhanced. The reinforcement effect of FRP did not significantly affect the energy dissipation capacity of the shear walls. A numerical study was performed to investigate the optimal orientation of the FRP arrangement. The analysis revealed that when the carbon fibers were arranged horizontally and vertically orthogonally, the structure exhibited better seismic properties. This study can not only improve the seismic performance of slit steel plate shear walls, but also have engineering implications for the seismic reinforcement of existing slit steel plate shear walls.

3D nonlinear finite element investigation of laminated bamboo plate strengthened prestressed concrete slab

Due to environment and recycling concerns, interest in applying natural fiber reinforced polymer (NFRP) as an alternative for glass/carbon FRP to strengthen concrete structures has been increasing. This study developed a 3D nonlinear finite element (FE) model for laminated bamboo (LB) plate strengthened prestressed concrete slab. By involving temperature load on defined temperature sensitive material, the proposed model provided good simulation of prestressing process. The accuracy of the developed model was confirmed through comparisons with experimental data, representing peak load discrepancies of only 6.5% and 8.2% for un-strengthened and strengthened slabs, respectively. The parametric study examined the impact of LB plate dimensions and tensile strength, alongside the use of FRP wraps, on concrete slab performance. The results show that the 15 mm thick LB plate can enhance the slab’s peak load by 83.2%. Variations in LB plate tensile strength by up to 10% do not significantly affect the performance of the strengthened prestressed concrete. The increases of the peak load for strengthened cases with LB plate width of 150 mm, 300 mm and 460 mm were 29.4%, 41.9% and 50.2%, respectively. It also shows that FRP end wraps can increase the performance of thick LB plate strengthened prestressed concrete slab.

Bond Behavior of Recycled Tire Steel-Fiber-Reinforced Concrete and Basalt-Fiber-Reinforced Polymer Rebar after Prolonged Seawater Exposure

The integration of basalt-fiber-reinforced polymer (BFRP) rebars into concrete design standards still remains unrealized due to limited knowledge on the performance of the rebars in concrete, particularly in terms of bond durability in harsh conditions. In this work, we investigated the bond durability characteristics of BFRP rebars in fiber-reinforced self-compacting concrete (FRSCC) structures. To this aim, a number of 24 FRSCC pullout specimens reinforced with either BFRP rebar or glass-fiber-reinforced polymer, GFRP, rebar, which is a commonly used type of FRP, were fabricated. Half of these specimens were submerged in simulated seawater for a two-year span, while the other 12 similar specimens were maintained in standard laboratory conditions for comparative purposes. Subsequently, all 24 specimens underwent monotonic and fatigue pull-out tests. The exploration in this study focused on investigating the influence of the environmental condition, reinforcement type, and loading type on the bond stress versus slip relationship, maximum bond stress, and failure mode of the specimens. Based on the results obtained and by adopting the durability approach of industry standards for prediction of the bond retention of FRP-reinforced concrete, the bond strength retention between BFRP/GFRP and FRSCC after 50 years of exposure to seawater was estimated. The outcomes of the study are expected to enhance engineers’ confidence in the use of FRP, especially BFRP, for constructing durable and sustainable reinforced concrete structures in aggressive environments.

Repair and Retrofit of Bridge structural elements: New Cementitious Materials

AbstractThe condition of infrastructure, the constant need to repair and maintain them and the increasing costs associated with the maintenance has led to the search for replacements for steel in new concrete infrastructure around the world. Further, alternatives for repair and strengthening of existing concrete structures ranging from the use of FRP as plates or fabrics wraps to the use of ultra‐high‐performance concrete (UHPC) elements as external reinforcements to achieve requisite strength and serviceability requirements are being attempted. The present study evaluates the performance of repaired/retrofitted structural concrete elements and sub‐assemblages damaged in flexure or shear using different repair schemes including those based on use of FRP plates or wraps, UHPC elements, etc., to restore the capacity of damaged structural concrete elements. An ANSYS based finite element model that accounts for both the constitutive properties of the primary structure in its damaged state and the repair material is used in this study to assess the different repair schemes. The analysis is shown to predict the test results very well. The importance of considering bond slip between rebar and surrounding concrete in the analysis is highlighted. Likewise, the consequence of bond between repair material and the primary structure on the overall structural performance is clearly seen. Performance of normal and high performance of concrete under high temperature resulting in spalling and significant damage from a fire and its rehabilitation with geopolymer concrete will be shown in lab scale tests and simulations. Finally, a field application of load testing of a defunct masonry arch bridge, its retrofit strategy and subsequent deployment with cementitious mixes as a repair to operationalise the bridge with significant cost saving will be illustrated.

Positive and negative valences, personal innovativeness and intention to use facial recognition for payments

PurposeFacial recognition payment (FRP) has been attracting attention as an alternative payment mode. This research aims to investigate the future use of FRP for both mobile payment and point of sale payment.Design/methodology/approachThe body of information on this topic is promoted by proposing the valence framework, where the authors used relative advantage, initial trust, perceived playfulness and need for uniqueness as positive valence, and perceived risk, technophobia and perceived complexity as negative valence. This study also investigated the moderating effect of personal innovativeness on consumers' behavioral intention to use FRP-based payments. The authors collected data from 392 FRP users from China to test the model. The authors used structural equation modeling (SEM) to evaluate the significant determinants influencing FRP use.FindingsThe authors found that relative advantage and privacy risk are the two most influential predictors of FRP use. The findings indicate that personal innovativeness acts as a moderator between negative valence and behavioral intention. This study provides valuable policy guidelines for the mobile or point of sale (POS) payment companies for adding FRP service into their default payment method.Originality/valueFRP is a relatively new technology that has not received much research attention in information system (IS) literature. Most studies on payment investigated enablers, and less effort has been given to study both enablers and inhibitors together. Furthermore, the authors employed SEM-based analysis to identify the most important factors influencing consumers' future use decisions.

Editorial: Innovative Use of FRP and Nanofiber-Based Materials in Engineering

Editorial: Innovative Use of FRP and Nanofiber-Based Materials in Engineering

Experimental and analytical study on the behavior of hybrid GFRP/steel bars in reinforced concrete deep beams

Abstract The deep beam is one of the essential members of high-rise buildings structures, so the deep beams are used as a transfer girder; in walls water structures, the deep beam behavior is different from the slender beam behavior; the deep beam plane section before does not remain plane after bending. In recent years, the use of FRP as a composite material in reinforced concrete structures has been growing up to cover problems by weight of structure buildings, corrosion, repairing, and construction cost. This paper presents an experimental, analytical study to assign the variation of mechanical properties of reinforced concrete deep beams using vertical and horizontal GFRP stirrups. This paper investigates the mechanical properties of test specimens for deep beams reinforced in shear with GFRP or steel bars as web reinforcement. The deep beams are reinforced with glass fiber reinforced polymer (GFRP) in various ratios as a web reinforcement configuration (0, 0.25%, and 0.40%) rather than traditional steel web reinforcement. All tested specimens have the same span to depth ratio of 0.40 (a/d); the primary and secondary reinforcement is steel bars. The web reinforcement ratio significantly affected deep beams’ load capacity and mechanical behavior. The GFRP enhancement the mechanical behavior of the reinforced concrete deep. Increasing the GFRP web reinforcement ratio enhances the deep beam load capacity. The test results compared with the traditional ACI design method strut-tie model to demonstrate the effect of web reinforcement ratio on deep beam load capacity and strut width. The test results have been verified by ABAQUS 6.13.

Fiber-Reinforced Polymers in Freeform Structures: A Review

This article is a survey discussing the application of fiber-reinforced polymer composites in freeform structures and their impact on the design and shape generation process. The analysis of case studies showed that the use of FRP composites not only helps to overcome some challenges in the construction of objects with complex geometry, but also creates brand new types of structures and design approaches. On the other hand, there is a problem—although FRP materials are frequently used in construction, the shapes of structures and design methods are often traditional and are simply copied from materials such as wood, concrete, and steel. FRP composites have been applied in civil engineering for several decades, since the 1960s, as building envelopes, façade skins, load-bearing structures, and internal and external reinforcement. The article aims to analyze this accumulated experience and to explore the role of FRP materials in the design of buildings with free, complex, fluid, and organic shapes. A new classification of freeform composite structures is proposed. They are classified in this article according to the methodology applied at the conceptual design stage: structures created by using a geometric approach, a form-finding (equilibrium) approach, or a biomimetic approach. Each approach is described in its own separate section, with a thorough literature and state-of-the-art review.

Major aproaches of the use of FRP and Bio-Oss® in bone regeneration and elevation for implantology: a concise systematic review

Introduction: In the scenario of maxillary sinus surgery for the later practice of implantology, several surgical techniques can be used to reconstruct the atrophic alveolar ridge, isolated techniques or associated with autogenous, allogeneic, xenogenous, and alloplastic biomaterials. The autogenous bone graft is the only one capable of presenting three important biological properties (osteogenesis, osteoinduction, and osteoconduction) guaranteeing a self-regenerative potential. Platelet concentrates have been proposed as regenerative materials in tissue regeneration procedures. Among the platelet concentrates proposed in the literature, there is FRP that act as autogenous platelet aggregates with osteoinductive properties. As an example of xenografts, Bio-Oss® stands out, being a bovine bone biomaterial. The excellent osteoconductive properties of Bio-Oss® lead to predictable and efficient bone regeneration, becoming an integral part of bone structure and volume. Objective: To carry out a brief systematic review of the main considerations for the use of fibrin-rich plasma and Bio Oss® in bone regeneration for implant dentistry. Methods: The survey was conducted from May 2021 to July 2021 and developed based on Scopus, PubMed, Science Direct, Scielo, and Google Scholar, following the rules of Systematic Review-PRISMA. Study quality was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results: The lack of bone in the alveolar crests has been a major problem in functional aesthetic recovery in patients who have suffered dentoalveolar trauma, traumatic tooth extractions, congenital tooth loss, maxillary and mandibular pathologies, in addition to infections due to the emotional and possibility of deformity. In this context, implant dentistry stands out as a modern method of oral rehabilitation for totally or partially edentulous patients. For this method to develop properly, bone integration of the implant into the recipient bone tissue must occur. It was documented that the combination of biomaterial and FRP significantly improved bone regeneration in the peri-implant area. Placing the implant with the simultaneous use of the FRP creates a good relationship between hard tissue and soft tissue. FRP is used as an adjuvant to Bio-Oss® particles for bone augmentation in the maxillary sinus. Conclusion: Based on literary findings, it was shown that FRP is favorable for bone formation processes for dental implants, especially when combined with Bio-Oss®.

The use of FRP of increased thickness for strengthening structures

The external reinforcement system based on carbon fiber has been used for decades to strengthen reinforced concrete elements. At the same time, it is impossible not to recognize that the existing calculation methods are largely based on empirical dependencies obtained from experimental studies. One of these issues is related to the application of the methodology for materials of heterogeneous origin-tapes and laminates. In general, the possibility of applying the calculation methods accepted in the norms for laminates of generally accepted thicknesses up to 1.6 mm is determined. The question related to the possibility of using laminates of greater thickness is not sufficiently studied. This article deals with the calculation of the reinforcement of the normal cross sections of the bent reinforced concrete elements with the reinforcement of laminates with a thickness of 5 mm.

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.

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

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

Artificial Neural Networks (ANN) Based Compressive Strength Prediction of AFRP Strengthened Steel Tube

The use of FRP composites as external confinement has recently become a very important system to consider when reinforcing concrete and steel structures. Many constitutive models have been proposed to design such structures. However, the emergence of artificial neural network offers a better alternative with a strong prediction capability. In this research, an artificial neural network (ANN) based model is used to estimate the compressive strength, maximum stresses and strains of AFRP strengthened circular hollow section steel tubes under axial compression. A database of 129 cases of finite element model (FEM) was analyzed using ANSYS Workbench 19.0 and ACP Tool. The FEM was validated with a previously done experimental test. Different geometric criteria have been taken into account to better address the complexity of the problem. Using this FEM database, ANNs have been trained using two approaches. The first approach was using the neural network toolbox in MATLAB. The second approach was using a built-in neural network tool in ANSYS Workbench. The successfully trained ANN is further used to predict the new cases, as an alternative to FE Analysis. Following, a parametric study and a sensitivity analysis were also carried out to investigate the effect of different parameters on the load capacity. The predicted results of the ANN models show a good correlation with the experimental and FEM results. Moreover, comparative analysis of performance result reveals that the ANSYS-ANN had better accuracy in terms of mean squared error and regression value (R2) compared to MATLAB-ANN. The ANN is quite an efficient tool in determining the strength of the AFRP strengthening steel tubes. Such a technique can be used to reduce computation time and labor.

Application of GFRP Reinforcement in the Design of Concrete Structures and its Experimental Evaluation

Abstract In the past, research on the use of FRP in civil engineering has been focused on strengthening existing structures where FRP reinforcements were applied to the surface of concrete elements. Recently, the application of FRP reinforcements has been studied to replace steel reinforcements for use in areas of increased environmental loads, with a need to exclude the corrosion of the reinforcement or to ensure the electromagnetic neutrality of the individual elements of the load-bearing structure. The GFRP reinforcement ratio was verified considering failure modes in flexure and the bond of the GFRP reinforcement with concrete. Besides classical reinforcements, GFRP has also been used in prestressed variants, and the possibility of its use as permanent formwork has been verified. In terms of extending the use of non-metallic reinforcements, it is important to note the long-term exposure and possible degradation of the mechanical properties.

Soft Computing-based Approach on Capacity Prediction of FRP Strengthened RC Joints

Shear failure of the RC beam-column joints is a brittle failure which has no priorwarning and can induce tremendous damages because of collapse of column and joint before theconnected beam. This paper is focused on one particular method of strengthening the RC joints,that is, the use of FRP composites as confining element. The results of previous studies have shownthat strengthening the RC beam-column joints with FRP composites can improve their shearcapacity. In this study, the data collected from the existing standards and studies regarding the FRp strengthened RC joints were used to develop an artificial neural network model for predicting theshear strength contribution of FRP jacket. The developed model was then used to evaluate the roleof different parameters on this contribution, and finally derive a formula for contribution of FRp jacket to the shear strength of the RC beam-column joints.

Theoretical model for seawater and sea sand concrete-filled circular FRP tubular stub columns under axial compression

The use of FRP with seawater and sea sand concrete (SWSSC) holds great potential for marine and coastal infrastructure, and concrete-filled FRP tubular columns are among the attractive forms of structural members for such applications. This paper presents a theoretical model for the compressive behaviour of seawater and sea sand concrete-filled circular FRP tubular stub columns. FRP tubes can be manufactured to possess considerable strength and stiffness in the longitudinal direction, so the behaviour of concrete-filled FRP tubes differed substantially from that of concrete columns with an FRP wrap (also referred to as “concrete-filled FRP wraps”) which commonly contains fibres only in the hoop direction. Many theoretical models have been proposed for concrete-filled FRP wraps, but very limited work has been conducted on the theoretical modelling of concrete-filled FRP tubes. In the present study, an existing dilation model for concrete-filled FRP wraps is combined with a biaxial stress analysis of the FRP tube so that the effect of the Poisson’s ratio of the FRP tube is properly accounted for. In order to predict the buckling of the FRP tube, a maximum strain buckling failure criterion is proposed and is shown to be in reasonable agreement with the experimental results. Moreover, the load carried by the FRP tube is studied, and a simplified model is proposed to determine the load shared by the FRP tube during the entire loading process. Finally, a theoretical model for SWSSC-filled FRP tubular columns is proposed, in which the behaviour of both the concrete and the FRP tube as well as their interactions are explicitly modelled (i.e., an analysis-oriented model). The proposed model gives reasonably close predictions of the existing experimental data.

Experimental investigation of thermal expansion and concrete strength effects on FRP bars behavior embedded in concrete

One of the reasons behind the widespread use of the reinforced concrete system as a construction system is that steel bars and concrete show similar elongation and shrinkage behaviors under heat. In recent years, the use of FRP in the construction industry has increased, and is now being produced in the form of bars and used in concrete. Thus, it is important to know the thermal expansion behavior of FRP bars within concrete.In this study, the thermal expansion coefficient was determined for FRP bars with four different fiber types (Glass, Carbon, Aramid, and Basalt), and their behavior within concrete was examined. Firstly, the thermal expansion coefficients of FRP bars were determined through experiment. In order to find the compatibility of the bars with concrete under heat change effect, prismatic concrete samples of three different strength classes were produced, and FRP were placed inside of these samples together with the steel bars. Concrete samples reinforced with bars were repeatedly exposed to increasing temperatures in order to observe any deformations formed in concrete. Thus, we determined how fiber type, concrete strength, and temperature change periods affected FRP bar-embedded concretes under the effect of thermal expansion, and compared that with steel bar-embedded concrete.

Laboratory Investigation on Performance of Strengthening Techniques of RCC Beam

Reinforced concrete members are the most abundantly used construction elements in civil engineering. These members are normally designed to sustain various types of loads. But due to several reasons the members experience much more load beyond their capacity. Inadequate attention during design and construction of new additional RCC story in our country has raised question about the performance of existing structures. RCC beam is such an important member which sometimes needs to be strengthened. There are various methods of strengthening that have been studied by the researchers such as section enlargement, use of additional bars, use of FRP and CFRP, use of ferrocement, steel plates, etc. This thesis work aims to study and compare the effect of three distinct strengthening techniques- providing additional steel bars from underneath with U shaped shear reinforcement, use of wire mesh and providing single layer of geo-textile with adhesive. The experimental results show that the percentage increase in ultimate load carrying capacity for the steel, wire mesh and geo-textile were found to be 51.96%, 26.5% and 14.5% respectively with respect to reference beams. The value of deflection at failure were 5.63mm, 6.18mm and 5.83 mm respectively while for reference beam the value was 5.33mm. The performance of geo-textile was very poor. The use of wire mesh provides greater value of deflection at failure compared to other two methods but the increase in load carrying capacity is about half of that for steel bar. The application of additional steel is labor intensive compared to other two methods but in terms of ultimate load, it overweighs the advantages compared to other two strengthening techniques.

Research on Waste FRP Fiber Reinforced Adhesive Mortar

The use of FRP in industry results in large amount of waste FRP. If not treated properly, it will pollute the environment. In our study, waste FRP powder was used in mortar to substitute part of sand in mortar. The use of short waste FRP fibre can further increase the mechanical strength. The Waste FRP fibre reinforced adhesive mortar was prepared with the material proportioning: cement-sand ratio 1:2, polymer 8% (cement based ), waste FRP fibre 3% (based on the total solids ). The performance of the mortar conforms to JCT 547-2005 with excellent adhesive characteristics.

Coreless Winding and Assembled Core – Novel fabrication approaches for FRP based components in building construction

In the current paper the authors present a series of case studies which expose innovative use of FRPs in engineering and architecture. A particular focus is set on the development of novel fabrication processes specifically devised for the projects, namely the Coreless Winding and the Assembled Core methods. The Assembled Core method stems from ongoing research in the field of FRPs production technology. This approach primarily focuses on the optimisation of the core geometry, allowing to produce complex components from a single winding core, thus reducing material waste and enhancing the efficiency of the fabrication process. After production the segments are extracted from the original core geometry and reassembled into the whole component, later serving as mould for concreting and eventually as reinforcement for the structure. The fabrication process was applied to the construction of a concrete bench, displaying the potential and capacities of this method. The second manufacturing process presented as part of the current research, the Coreless Winding technique, offers an alternative to classical filament winding by replacing the positive mould with a linear steel frame, which provides the armature onto which the resin-soaked fibres are tensioned. Coreless Winding was successfully implemented in the production of a full-scale architectural prototype, an entirely carbon and glass fibre based monocoque shell. The second case study demonstrates the use of FRP based components for the production of a large scale structure. The Coreless Winding technique is adapted to the production of small size elements, which later serve as basic components for the assembly of a modular and double layer structure, allowing a larger span and the optimal transfer of global bending moments. The requirement of fabrication flexibility is resolved by adopting a specific robotic fabrication setup and an adaptive winding frame. Along with the planning of these alternative winding techniques, specific computational tools had to be developed to accurately simulate the fabrication processes and the mechanical response of the final structures.