Este trabalho analisou o comportamento estrutural de polímeros reforçados com fibra de vidro - PRFV em elementos pré-moldados de concreto, com aplicações específicas em vigas de concreto. Realizou-se um estudo comparativo do comportamento de vigas pré-moldadas reforçadas com armadura convencional, segundo a norma brasileira NBR 6118:2003, e reforçadas com armadura de barras pultrudadas de PRFV, segundo o ACI 440.1R-06. O estudo visa obter subsídios para a aplicação de barras de reforço de PRFV, em relação ao Estado Limite de Serviço - ELS, em obras realizadas em regiões de alta agressividade ambiental. Posteriormente fez-se os mesmos modelos de cálculo em elementos finitos, onde foram comparados e analisados os resultados obtidos com o cálculo prescrito pelas normas. Nem todos os parâmetros da norma americana foram inseridos, uma vez que alguns coeficientes internos que contam com efeitos sísmicos e com a neve estão embutidos nos cálculos. Os resultados obtidos, principalmente no cisalhamento, foram altamente satisfatórios, validando a aplicação do PRFV nas vigas consideradas. / This work studied the behavior of precast beams when subjected to shear stress according to the brazilian standard NBR 6118:2003 reinforced with steel bar compared to the american standard ACI 440.1R-06 when the structural member was reinforced with glass fiber reinforced polymer - GFRP pultruded bars. The goal of this work is to acquire subsidies to apply the GFRP in aggressive environmental sites. Also the same model calculations were performed by using Finite Element Method and compared to the results of the calculation prescribed by the standards. Some parameters indicated in the ACI standard were not followed since they are related to seismic and snow effects. The obtained results mainly in shear loading were highly satisfactory which validates the use of GFRP in the considered beams.

A study to investigate the behavior of glass fiber reinforced polymer (GFRP) anchors was conducted at the Ferguson Structural Engineering Laboratory as part of a project funded by the Texas Department of Transportation, Project number 0-6873. The purpose of this study was to test the effectiveness of GFRP anchors by comparing their performance to that of anchors made from carbon fiber reinforced polymer (CFRP). The findings of this research give insight into the advantages and disadvantages of using alternative materials in the design of FRP anchorage systems and provides a means for developing quality control procedures of GFRP anchors. Quantitative comparisons were made between results from beam tests that used GFRP anchors and the results from those that used CFRP anchors. It was found that specimens with GFRP anchors exhibited similar trends to specimens with CFRP anchors. Similarities were achieved in concrete cracking loads, strength capacities, and in some cases duration of force transfer, suggesting that GFRP anchors are equally as effective as CFRP anchors for strength development. However, material differences played a major role in the explanation of GFRP and CFRP behavior. Notable advantages in material handling was observed with the GFRP anchors since the fibers were found to be easier to bend as well as easier to install into drilled anchor holes. On the other hand, the lower tensile strength of GFRP presented a potential need for larger sized anchors to achieve the equivalent strength of a CFRP anchor. Finally, a pull-out failure mode was observed in GFRP anchors that had not been previously observed in CFRP anchors. It was suggested that the pull-out failure mode was a function of differences in deformation capacity between the two materials. However, little information regarding the cause of performance differences demonstrates the need for quality control tests for GFRP anchors. As a result, recommendations for further studies were made. / text

Reinforced concrete beam-column joints (BCJs) are commonly used in structures such as parking garages, multi-storey industrial buildings and road overpasses, which might be exposed to extreme weathering conditions and the application of de-icing salts. The use of the non-corrodible fiber-reinforced polymer (FRP) reinforcing bars in such structures is beneficial to overcome the steel-corrosion problems. However, FRP materials exhibit linear-elastic stress-strain characteristics up to failure, which raises concerns on their performance in BCJs where energy dissipation, through plastic behaviour, is required. The objective of this research project is to assess the seismic behaviour of concrete BCJs reinforced with FRP bars and stirrups. An experimental program was conducted at the University of Manitoba to participate in achieving this objective. Eight full-scale exterior T-shaped BCJs prototypes were constructed and tested under simulated seismic load conditions. The longitudinal and transversal reinforcement types and ratios for the beam and the columns were the main investigated parameters. The experimental results showed that the GFRP reinforced joints can successfully sustain a 4.0% drift ratio without any significant residual deformation. This indicates the feasibility of using GFRP bars and stirrups as reinforcement in the BCJs subjected to seismic-type loading. It was also concluded that, increasing the beam reinforcement ratio, while satisfying the strong column-weak beam concept, can enhance the ability of the joint to dissipate seismic energy. An analytical investigation was conducted through constructing a finite element model using ANSYS-software. The model was verified against the experimental results in this research. Then, a parametric study was performed on number of different parameters known to affect such joints including column axial load, concrete compressive strength, flexural strength ratio and joint transverse reinforcement. It was concluded that 70% of the column axial load capacity can be recommended as an upper limit to the applied axial loads on the column to avoid damage occurrence within the joint. It was also concluded that a minimum flexural strength ratio of 1.50 is recommended to ensure the strong-column weak-beam mechanism. In addition, a minimum joint transverse reinforcement ratio of 0.60% is recommended to insure that the failure will not occur in the joint zone.

Reinforced concrete beam-column joints (BCJs) are commonly used in structures such as parking garages, multi-storey industrial buildings and road overpasses, which might be exposed to extreme weathering conditions and the application of de-icing salts. The use of the non-corrodible fiber-reinforced polymer (FRP) reinforcing bars in such structures is beneficial to overcome the steel-corrosion problems. However, FRP materials exhibit linear-elastic stress-strain characteristics up to failure, which raises concerns on their performance in BCJs where energy dissipation, through plastic behaviour, is required. The objective of this research project is to assess the seismic behaviour of concrete BCJs reinforced with FRP bars and stirrups. An experimental program was conducted at the University of Manitoba to participate in achieving this objective. Eight full-scale exterior T-shaped BCJs prototypes were constructed and tested under simulated seismic load conditions. The longitudinal and transversal reinforcement types and ratios for the beam and the columns were the main investigated parameters. The experimental results showed that the GFRP reinforced joints can successfully sustain a 4.0% drift ratio without any significant residual deformation. This indicates the feasibility of using GFRP bars and stirrups as reinforcement in the BCJs subjected to seismic-type loading. It was also concluded that, increasing the beam reinforcement ratio, while satisfying the strong column-weak beam concept, can enhance the ability of the joint to dissipate seismic energy. An analytical investigation was conducted through constructing a finite element model using ANSYS-software. The model was verified against the experimental results in this research. Then, a parametric study was performed on number of different parameters known to affect such joints including column axial load, concrete compressive strength, flexural strength ratio and joint transverse reinforcement. It was concluded that 70% of the column axial load capacity can be recommended as an upper limit to the applied axial loads on the column to avoid damage occurrence within the joint. It was also concluded that a minimum flexural strength ratio of 1.50 is recommended to ensure the strong-column weak-beam mechanism. In addition, a minimum joint transverse reinforcement ratio of 0.60% is recommended to insure that the failure will not occur in the joint zone.

A study of existing research shows a need for an investigation of the bond properties of anchorage systems for GFRP bars including; straight, anchor heads and bends. The standard pullout test was modified to improve testing efficiency, accommodate bend tests, as well as reduce variability of concrete properties across specimens. Based on the results of the experimental work it was concluded that the surface profile of GFRP bars influences the post-peak phase of the bond stress-slip curve. It was also found that GFRP bars with anchor heads would still require a considerable embedment length to develop the bars’ full strength. Bend strengths of three GFRP manufacturers were determined to be between 58 and 80% of the strength of the straight portion of the same bar, while the development length of a two legged stirrup was found to be between five and ten times the bar diameter for all bar types.

A study of existing research shows a need for an investigation of the bond properties of anchorage systems for GFRP bars including; straight, anchor heads and bends. The standard pullout test was modified to improve testing efficiency, accommodate bend tests, as well as reduce variability of concrete properties across specimens. Based on the results of the experimental work it was concluded that the surface profile of GFRP bars influences the post-peak phase of the bond stress-slip curve. It was also found that GFRP bars with anchor heads would still require a considerable embedment length to develop the bars’ full strength. Bend strengths of three GFRP manufacturers were determined to be between 58 and 80% of the strength of the straight portion of the same bar, while the development length of a two legged stirrup was found to be between five and ten times the bar diameter for all bar types.

This study presents experimental results from nine large-scale circular concrete columns reinforced with longitudinal and transverse glass fiber-reinforced polymer (GFRP) bars. These specimens were tested under lateral cyclic quasi-static loading while simultaneously subjected to constant axial load. Based on the measured hysteretic loops of moment vs. curvature and shear vs. tip deflection relationships, a series of parameters related to ductility and flexural strength are used to evaluate the seismic behavior of each column. The results showed that concrete columns reinforced with GFRP bars have stable post-peak branches and can achieve very high levels of deformability. Longitudinal GFRP bars maintained their stiffness at high strains and transverse GFRP spirals provided increasing confinement for the entire duration of the test without any spiral damage. The tests showed that, as an innovative material with excellent corrosion resistance GFRP bars can be successfully used as internal reinforcement in ductile concrete columns.

This study presents experimental results from nine large-scale circular concrete columns reinforced with longitudinal and transverse glass fiber-reinforced polymer (GFRP) bars. These specimens were tested under lateral cyclic quasi-static loading while simultaneously subjected to constant axial load. Based on the measured hysteretic loops of moment vs. curvature and shear vs. tip deflection relationships, a series of parameters related to ductility and flexural strength are used to evaluate the seismic behavior of each column. The results showed that concrete columns reinforced with GFRP bars have stable post-peak branches and can achieve very high levels of deformability. Longitudinal GFRP bars maintained their stiffness at high strains and transverse GFRP spirals provided increasing confinement for the entire duration of the test without any spiral damage. The tests showed that, as an innovative material with excellent corrosion resistance GFRP bars can be successfully used as internal reinforcement in ductile concrete columns.

Four beam-bond test specimens, two in accordance with RILEM TC-RC5 recommendation, labelled as RILEM and two based on a modified form of the ACI 208 beam-bond test method, labelled as Notched, were tested in four-point bending to investigate the bond stress distribution and values along the bar embedment length of a 15 𝑚𝑚 nominal diameter GFRP rebar. The beams experienced failure through the rupturing of the longitudinal GFRP tensile reinforcement. In addition, two Modified and ten Standard pullout specimens were tested using the same bar. The beam-bond and the Modified pullout specimens had embedment length of 600 𝑚𝑚 while the Standard pullout specimens had, in accordance with CSA S806, 60 𝑚𝑚 embedment, or four times the bar nominal diameter. The first Modified pullout specimen experienced concrete splitting failure and as a result, the second was lightly confined and failed by GFRP bar rupture. All ten Standard pullout specimens failed due to bar pullout. It was determined that the actual bond stress distribution as a function of the embedment length is practically parabolic and can be described by the derivative of a modified form of the logistic growth function used to approximate the strain distribution along the embedment length. Furthermore, the maximum bond stress location progressively moves from the loaded-end towards the unloaded-end as the bond continues to deteriorate with increasing GFRP stress levels. The development length recommendations by ACI 440.1 and to a lesser degree, CSA S806 and CSA S6 are quite conservative compared to that which is required. It is observed that pullout tests alone cannot provide sufficient knowledge regarding the bond behaviour of FRP reinforcement; consequently, the results of beam-bond testing are more appropriate. Standard pullout tests may be incorporated into quality assurance programs with the understanding that they cannot provide valuable information regarding bond stress distribution and required development length in real structural elements with large embedment lengths. In terms of the beam-bond test method, the RILEM TC-RC5 design recommendation appears to be superior since it eschews severe stress perturbation caused by incidence of flexural cracks at beam midspan. As a result, it produces stability in the terms of the data gathered from the strain gauges placed on the GFRP bar. This benefit outweighs the ease of constructability of the Notched beams as well as their resemblance to real beams. / Thesis / Master of Applied Science (MASc) / The force that bonds a reinforcing rod to concrete is determined using three test methods. Each method is recommended by some design standards, but it is unclear how the results of these tests compare to each other. To shed light on the issue, a 15 𝑚𝑚 fibre glass rod was tested using three well-known test methods. It was discovered that two of the methods give results that are reasonably close while the third gives variable results that generally do not agree with the results of the other two. It was also discovered that the required embedment length recommended for such a bar by design codes and standards are relatively excessive because they underestimate the actual bond strength of the rod. Since sometimes it may be difficult to provide such long length in practice, it is recommended that the code requirements be revisited.

The concept of stay-in-place (SIP) structural formwork has the potential to simplify and accelerate the construction process to a great extent. Fibre-reinforced polymer (FRP) SIP structural formwork offers further potential benefits over existing formwork systems in terms of ease and speed of construction, improved site safety and reduced long-term maintenance in corrosive environments. However, it is not without its limitations, including primarily the possibility of a lack of ductility, which is a key concern regarding the use of FRP structural formwork in practice. This thesis presents the findings of an experimental and analytical investigation into a novel FRP SIP structural formwork system for a concrete slab with a particular emphasis on its ability to achieve a ductile behaviour. The proposed composite system consists of a moulded glass fibre-reinforced polymer (GFRP) grating adhesively bonded to square pultruded GFRP box sections. The grating is subsequently filled with concrete to form a concrete-FRP composite floor slab. Holes cut into the top flange of the box sections allow concrete studs to form at the grating/box-section interface. During casting, GFRP dowels are inserted into the holes to further mechanically connect the grating and box sections. An initial experimental investigation into using GFRP grating as confinement for concrete showed that a significant increase in ultimate strength and strain capacity could be achieved compared to unconfined concrete. This enhanced strain capacity in compression allows greater use of the FRP capacity in tension when used in a floor slab system. Further experimental investigation into developing ductility at the grating/box-section interface showed that the proposed shear connection exhibited elastic-‘plastic’ behaviour. This indicated the feasibility of achieving ductility through progressive and controlled longitudinal shear failure. Following these component tests on the concrete-filled grating and the shear connectors, a total of six (300 x 150 x 3000) mm slab specimens were designed and tested under five-point bending. It was found that the behaviour of all specimens was ductile in nature, demonstrating that the proposed progressive longitudinal shear failure was effective. A three-stage analytical model was developed to predict the load at which the onset of longitudinal shear failure occurred, the stiffness achieved during the post elastic behaviour and, finally, the deflection at which ultimate failure occurred. Close agreement was found between experimental results and the theory.