Performance Of Fiber Reinforced Polymer Research Articles

Evaluating the impact of different anchor configurations and patch arrangements on the performance of fiber-reinforced polymer (FRP) anchors

The use of fiber-reinforced polymer (FRP) anchors to enhance the efficiency of externally bonded (EB) FRP systems has received considerable attention in recent years. However, their widespread application has been constrained by the challenges associated with their installation due to complexity in anchor detailing. To date, there has been limited research aimed at simplifying anchor detailing while maintaining its efficiency. This paper presents an extensive experimental study involving 88 tests on concrete beams with anchored FRP material, with variations in the number of FRP strips, anchor material ratio (AMR), fan length, and rounding radius of the anchor hole. The study focuses primarily on different aspects of the anchor configuration. The first part of the study compares the performance of two anchor details, while the second part assesses the impact of different FRP patch arrangements on enhancing the performance of the anchors. The efficiency of the newly suggested end anchor detail was found to be equivalent to the previously used end anchor detail. The use of FRP patches over anchors proved very effective in certain cases but ineffective in others.

Shape Memory Hybrid Composites.

Smart structures can help to resolve many issues related to conventional materials that are being used in different industries. Shape memory alloys (SMAs) are smart materials with better actuation response, vibration damping characteristics, and large strain recovery, making them good candidates due to their high strength and corrosion resistance for various engineering applications. The performance of fiber-reinforced polymer (FRP) composite materials that are replacing many conventional materials due to their good strength, stiffness, and lightweight potential especially in fuel-consuming industries such as aerospace and automotive, can further be improved by impregnation with SMAs. This review discusses the SMA-reinforced FRP composites, leading to shape memory hybrid composite materials, the issues and limitations in composite manufacturing, and their uses in different research arenas including impact and damping applications, seismic protection applications, crack closure applications, shape morphing applications, and self-deployable structures.

FRP-laminated Rubber Isolator: Theoretical Study and Shake Table Test on Isolated Building

ABSTRACT Performance of fiber-reinforced polymer (FRP)-laminated rubber isolators has been investigated through theoretical and experimental analyses. Effective horizontal stiffness of FRP rubber isolator is analyzed by the cyclic quasi-static experiment. A 1/3 scale shake table tests have been carried out to assess the seismic behavior and the efficiency of the FRP-laminated rubber isolator under the ground motions in different site conditions. The effective horizontal stiffness of the isolator has been derived which has been compared with the experimental results. Experimental studies have shown that FRP-laminated rubber bearings with many advantages can be applied to building structures to enhance seismic capacity.

Analytical and statistical study of the bond of FRP bars with different surface characteristics

Bond performance of Fibre Reinforced Polymer (FRP) bars to concrete can considerably differ from those of traditional steel because of the different physical and mechanical properties. The surface of FRP bars is most often greatly different from the ribbed shape of steel bars. This study focuses on the influence of surface type on the bond characteristics of FRP bars. Analytical expressions of the constitutive bond stress-slip laws, describing the bond behaviour, can be applied to define characteristics such as the development length. Available models (e.g., mBPE and CMR) involve parameters to be defined by calibrating to the experimental results. In this paper data from 184 pull-out tests are used to calibrate the parameters of mBPE and CMR models. Next, a comprehensive statistical analysis methodology has been developed to study the statistical significance of the influence of included factors on the experimental bond characteristics (bond strength and corresponding slips) and analytical parameters (α, β, sr). The studied factors involve bar surface (sand coated (SC), helically wrapped (HW), helically wrapped and sand coated (HWSC), indented (In) and ribbed (Rb)) and diameter (6 to 12 mm) as well as concrete compressive strength (35 and 66 MPa). Due to similar mechanical properties, both Glass FRP (GFRP) and Basalt FRP (BFRP) bars were used. The statistical methodology was applied to the bond strength results and to the parameters of the ascending branch of the mBPE model corresponding to free end slip (i.e., αfe). Statistically significant difference was observed in the bond strength not just in case of bars having different surface profiles but within the same surface category as well. Furthermore, the interaction between the influence of bar surface and diameter as well as between the bar surface and concrete strength was found to be statistically significant. Based on the statistical model, coefficients are provided –to account for the influence of involved factors. Analytical parameters were defined dependant on the surface category.

Life-Cycle Cost and Life-Cycle Assessment Analysis at the Design Stage of a Fiber-Reinforced Polymer-Reinforced Concrete Bridge in Florida

Abstract To support and promote the deployment of innovative technologies in infrastructure, it is fundamental to quantify their implications in terms of both economic and environmental impacts. Glass Fiber-Reinforced Polymer (GFRP) bars and Carbon Fiber-Reinforced Polymer (CFRP) strands are validated corrosion-resistant solutions for Reinforced Concrete (RC) and Prestressed Concrete (PC) structures. Studies on the performance of Fiber-Reinforced Polymer (FRP) reinforcement in seawater and salt-contaminated concrete have been conducted and show that the technology is a viable solution. Nevertheless, the economic and environmental implications of FRP-RC/PC deployment have not been fully investigated. This article deals with the Life-Cycle Cost (LCC) and Life-Cycle Assessment (LCA) analyses of an FRP-RC/PC bridge in Florida. The bridge is designed to be entirely reinforced with FRP bars and strands and does not include any Carbon Steel (CS) reinforcement. Furthermore, the deployment of seawater concrete in some of the elements of the bridge is considered. LCC and LCA analyses are performed at the design stage. Data regarding equipment, labor rates, consumables, fuel consumption, and disposal were collected during the construction phase, and the analysis was refined accordingly. The FRP-RC/PC bridge design is compared with a traditional CS-RC/PC alternative. Salient differences are discussed to determine the least-impactful solution from both an economic and environmental perspective.

Experimental study on seismic behavior of shear wall with fiber reinforced polymer concrete

In order to improve the seismic performance of common concrete shear wall with concealed bracings, fiber reinforced polymer modified concrete instead of ordinary concrete was applied to the shear wall as described in this paper. In this paper, the experimental study on the seismic performance of two different types of shear walls under cyclic loading was carried out, and also the failure characteristics, bearing capacity, ductility, hysteretic curve, stiffness attenuation and energy dissipation performance of the proposed shear wall were analyzed systematically. The test results show that the seismic performance of fiber-reinforced polymer modified concrete shear wall is significantly improved because its the damping ratio, deformation capacity and energy dissipation capacity are greatly improved compared with ordinary concrete shear wall with concealed bracings, which ensures its better stiffness stability in the later stage.

Performance of FRP confined and unconfined geopolymer concrete exposed to sulfate attacks

In this study, the effects of magnesium sulfate on the mechanical performance and the durability of confined and unconfined geopolymer concrete (GPC) specimens were investigated. The carbon and basalt fiber reinforced polymer (FRP) fabrics with 1-layer and 3-layers were used to evaluate the performances of the specimens under static and cyclic loading in the ambient and magnesium sulfate environments. In addition, the use of FRP materials as a rehabilitation technique was also studied. For the geopolymerization process of GPC specimens, the alkaline activator has selected a mixture of sodium silicate solution (Na2SiO3) and sodium hydroxide solution (NaOH) with a ratio (Na2SiO3/NaOH) of 2.5. In addition to GPC specimens, an ordinary concrete (NC) specimens were also produced as a reference specimens and some of the GPC and NC specimens were immersed in 5% magnesium sulfate solutions. The mechanical performance and the durability of the specimens were evaluated by visual appearance, weight change, static and cyclic loading, and failure modes of the specimens under magnesium sulfate and ambient environments. In addition, the microscopic changes of the specimens due to sulfate attack were also assessed by scanning electron microscopy (SEM) to understand the macroscale behavior of the specimens. Results indicated that geopolymer specimens produced with nano-silica and fly ash showed superior performance than the NC specimens in the sulfate environment. In addition, confined specimens with FRP fabrics significantly improved the compressive strength, ductility and durability resistance of the specimens and the improvement was found higher with the increased number of FRP layers. Specimens wrapped with carbon FRP fabrics showed better mechanical performance and durability properties than the specimens wrapped with basalt FRP fabrics. Both FRP materials can be used as a rehabilitation material in the sulfate environment.

Seismic behavior of concrete bridge columns confined with fiber-reinforced polymer stay-in-place formwork

One of the applications of fiber-reinforced polymers in bridge construction is stay-in-place formwork. Fiber-reinforced polymer stay-in-place formwork, in the form of preformed tubes, provides easy form assembly, protection of steel reinforcement and concrete against corrosion and chemical attacks while also improving the strength and ductility of structural elements in earthquake resistant construction. Experimental research was conducted to investigate the seismic performance of fiber-reinforced polymer stay-in-place formwork for bridge columns. Tests of large-scale specimens were conducted under simulated seismic loading. The experimental program included circular and square columns confined with carbon fiber–reinforced polymer tubes. The results indicate that the use of carbon fiber–reinforced polymer tubes increases column inelastic deformability significantly. Bridge columns under low levels of axial compression exhibit inelastic drift capacities in excess of 4% before failing in flexural tension due to the rupturing of longitudinal reinforcement. These observations and experimental results were used to develop a displacement-based design procedure for concrete confinement for fiber-reinforced polymer–encased concrete columns. This article presents an overview of the experimental program and the design approach developed.

Axial and lateral load transfer of fibre-reinforced polymer (FRP) piles in soft clay

This paper presents the results of an experimental investigation on the performance of fibre-reinforced polymer (FRP) piles in soft clay. The load transfer behaviour of small-scale FRP piles manufactured using either glass or carbon fibres is analysed and compared to that of traditional steel piles, in order to assess the viability of FRPs as piling materials. In addition, the effects of FRP material and fibre orientation on pile behaviour are investigated with the goal of identifying the optimal conditions for best performance. In all cases, the FRP piles present higher or at least similar capacity compared to steel piles. FRP surface topology, pile texture and waviness pattern dictated by the fibre weaving and orientation were found to exert a significant influence on the pile axial capacity. The lower stiffness of the FRP piles leads to increased pile head displacement under lateral loading compared to steel piles.

The Interface Behavior between External FRP Reinforcement and Masonry

The need to guarantee higher safety levels of masonry structures under both short and long term conditions, have led to the use of new materials and technologies, in conjunction or in place of traditional ones. In this context, fiber-reinforced composite materials have gained an increasing success, mostly for strengthening, retrofitting and repair existing structures. As well known, the analysis of the interface performance of FRP (Fiber Reinforced Polymer) composites and masonry substrate is a critical problem as it influences the effectiveness of the technique. The present paper reports part of a large research project, still in progress, focused on the analysis of the bond performance between FRP sheet and different type of masonry substrates. The obtained experimental data were analysed in terms of bond strength and the kind of failure. The influence of the deformability of the strengthening material as well as the mechanical performance of the substrates are also discussed.

Confining of square RC columns with FRP sheets using corner strip–batten technique

The application of fiber reinforced polymer (FRP) composites has been successfully promoted for external strengthening of reinforced concrete (RC) columns. Recent studies showed that when these jackets are formed in a wet lay-up process for confinement of columns, an average rupture strain of FRP in specimens substantially fall below those of flat coupon tensile tests. The problem is more important in rectilinear columns because of premature rupture of FRP at corners due to stress concentration.In this paper, a new method is introduced for confinement of square concrete columns as using FRP strips at corners and FRP battens at sides. In this method, FRP battens do not experience any curvature in confining of section and are stretched as completely flat strips similar to flat coupons. To compare the new proposed method with other FRP-confining techniques, sixteen square RC columns with 133×133mm cross section and 500mm height were experimentally tested under uniaxial compression. The test parameters included continuity or discontinuity of corner strips along height of column, the volume of fibers used, and the number of confining layers. The experimental results clearly demonstrated that confining battens in the new method of corner strip–batten are uniformly stretched under the tension stresses of confinement; therefore, more uniform distribution of confining pressure on section occurs and the stress concentration at corners is eliminated. Thus, in the proposed method, better performance of FRP in confinement was observed and the compressive behavior of the strengthened column was significantly improved compared to those confined using conventional FRP wraps.

Debonding failure analysis of FRP-retrofitted concrete panel under blast loading

Even though fiber reinforced polymer (FRP) has been widely used as a retrofitting material, the FRP behavior and effect in FRP retrofitted structure under blast loading, impulsive loading with instantaneous time duration, has not been accurately examined. The past studies have focused on the performance of FRP retrofitted structures by making simplifications in modeling, without incorporating accurate failure mechanisms of FRP. Therefore, it is critical to establish an analytical model that can properly consider the specific features of FRP material in evaluating the response of retrofitted concrete structures under blast loading. In this study, debonding failure analysis technique for FRP retrofitted concrete structure under blast loading is suggested by considering FRP material characteristics and debonding failure mechanisms as well as rate dependent failure mechanism based on a blast resisting design concept. In addition, blast simulation of FRP retrofitted RC panel is performed to validate the proposed model and analysis method. For validation of the proposed model and analysis method, the reported experimental results are compared with the debonding failure analysis results. From the comparative verification, it is confirmed that the proposed analytical model considering debonding failure of FRP is able to reasonably predict the behavior of FRP retrofitted concrete panel under blast loading.

Performance of FRP-Strengthened RC Beams with Different Concrete Surface Profiles

Performance of fiber-reinforced polymer (FRP) composites in repair and retrofit of concrete structures depends to a great extent on the substrate condition to which it is bonded. The present research investigated the effect of concrete surface roughness on the bond behavior and general performance of FRP strengthening systems. The study included flexural testing of 26 specimens with two different carbon FRP systems (wet layup and precured) and three different levels of surface roughness. The influence of six different levels of anchorage by means of U-straps was also evaluated. Additionally, 10 bond specimens were tested in double shear for the wet layup FRP system to compare with the results of beam tests and to further investigate the debonding issue. Bond-dependent coefficient was analyzed with respect to different levels of surface roughness and shear span-to-depth ratio, and was then compared with other test results available in the literature. Surface roughness did not appear to have a significant i...

Fire Endurance of Fiber-Reinforced Polymer Strengthened Concrete T-Beams

Understanding the performance of fiber-reinforced polymer (FRP)-strengthened members in fire is critical to the widespread application of FRPs as repair materials for infrastructure. An investigation was undertaken to examine and document the performance of FRP-strengthened reinforced concrete T-beams under standard fire conditions. Two full-scale reinforced concrete T-beams were strengthened in flexure with FRP sheets and insulated with a patented two-component fire insulation system. The specimens were subsequently exposed to a standard fire under full sustained service load. Member deflections, strain in the steel reinforcement, and temperatures throughout the section were measured and recorded throughout the tests. A numerical heat transfer model was used to predict temperatures within the section at any time during the fire. The predicted temperatures are compared with those observed during the fire tests and are shown to agree satisfactorily. The results indicate that appropriately designed and insulated FRP-strengthened reinforced concrete T-beams can achieve fire endurances of more than 4 hours.

Development, Shake Table Testing, and Design of FRP Seismic Restrainers

The development and performance of fiber-reinforced polymer (FRP) fabrics as an alternative to steel for restrainers to reduce bridge relative movements at hinges during earthquakes was explored. Glass, carbon, and hybrid (glass/carbon) restrainers were developed and tested on a representative in-span hinge using a shake table at the large-scale structures laboratory at the University of Nevada, Reno. The components of the study presented in this article are: (1) the FRP restrainer development and testing; (2) comparisons among FRP, steel, and shape memory alloy restrainers; and (3) development and evaluation of a simple restrainer design method and a numerical example. Important findings of the study were that compared to steel restrainers, the FRP restrainers were effective in substantially reducing the relative hinge displacements and pounding at hinges. The method to develop the flexible portion of the FRP restrainers and the bond to superstructure was successful in accomplishing the target performance. The proposed restrainer design method provides a rational yet simple tool to design FRP or other types of restrainers.

Design of submersible pressure hulls in composite materials

The use of fibre-reinforced polymer (FRP) composites in the pressure hulls of submersible vehicles is examined with reference to material and fabrication options, alternative structural configurations, evaluation of stresses, deformations and buckling behaviour and other aspects of design. The performance of FRP is contrasted with that of steel and light alloy construction. Reference is made to two illustrative trial designs, one corresponding to a manned submersible for shallow-water operation and the other to a deep-water autonomous underwater vehicle.