The primary objective of this research was to examine the strength degradation of Glass Fiber Reinforced Polymer (GFRP) bars at high temperature and alkalinity and determine if an Arrhenius type relationship can be used as a means of projecting life. The work done includes a thorough literature review, experiments and development of strength prediction models. The experimental work involves exposure of GFRP bars incased in cement mortar to lime-water solution at 30, 45 and 57°C. Overall 100 specimens were included in the experimental program. The tensile strength and modulus of elasticity retention after 180 days of exposure at 57°C was 57% and 82% respectively. The secondary objective was to determine the moisture absorption properties of GFRP bars. The moisture absorption data available is till 80 days from the immersion of the specimens in the tank. The collected data was used in the development of strength retention models. Two strength prediction models, Time Shift Method and Fickian Model for moisture absorption are formulated. Using the Fickian Model, strength is predicted for GFRP bars, if used in bridge decks in Roanoke, Virginia. The strength loss predicted was 45% after 50 years of exposure in real life environment. A linear relationship was observed when the moisture content and strength retention were plotted. The study estimates a strength loss higher than the ACI-440H recommended environmental degradation factor of 0.7 to calculate the design ultimate tensile strength. / Master of Science

The primary objective of this project was to test a full-scale prototype of an actual bridge deck containing GFRP bars as the top mat of reinforcement. The purpose of the tests was to verify that the design would resist the loads for which it was designed and provide assurance that the deck would not unexpectedly fail due to the use of this new material. Behavior of the bridge and deck, such as failure load, failure mode, cracking load, crack widths, deflections, and internal stresses, were examined. Four tests were performed on the deck, all of which tested the deck in negative moment regions. From the tests, it was concluded that the design of the deck was very conservative and that unexpected failure should be of no concern. The secondary objective of this project was to comment on the construction of a bridge deck reinforced with GFRP bars and to note its advantages and disadvantages along with a critique of the current state-of-the-art of designing bridge decks with FRP reinforcement. It was found that the advantages of construction with GFRP bars far outweighed the disadvantages, and that the placing of the top mat of GFRP bars was much easier than the placing of the bottom mat of steel bars. It was also concluded that the current state-of-the-art of designing bridge decks reinforced with GFRP is, for the most part, inaccurate in its prediction of behavior and that more research is needed to create more accurate design equations and procedures. Although current methods do not result in accurate predictions of behavior, they do, as mentioned above, result in conservative designs. / Master of Science

Master of Science / Department of Civil Engineering / Hayder A. Rasheed / The Kansas Department of Transportation’s (KDOT) Bridge 059-045 is a reinforced concrete box girder bridge constructed in 1965 to connect the rural Shawnee Drive across Interstate 135 near McPhearson, Kansas, in between Salina and Wichita. The bridge was observed, during an annual inspection in 1998, to have experienced some settlement, which was further found to be due to its proximity to a sinkhole. This settlement progressed to noticeable levels in 2012 necessitating a semi-annual elevation profile survey that was consistently conducted by KDOT. In April 2016, KDOT determined that the bridge required a detailed finite element analysis to determine the safety and suitability of the bridge to stay open to traffic. Accordingly, a two-level Finite Element Analysis was performed using RISA 3D and Abaqus to assess the level of distress in the bridge due to the continuous differential settlement as a result of the active sinkhole deep in the soil under the bridge. The force-moment results were taken from the RISA 3D model for further analysis of various structural components that make up the bridge, including the box girder, piers, and piles. The stress distribution results from the Abaqus model were investigated for the same components of the bridge. A strengthening design scheme using near surface mounted fiber reinforced polymer rebar was developed to extend the service life of the bridge.

No description available.

Doctor of Philosophy / Department of Civil Engineering / Hayder Rasheed / Recent applications in reinforced concrete columns, including strengthening and extreme loading events, necessitate the development of specialized nonlinear analysis methods to predict the confined interaction domain of axial force, shear, and bending moment in square and slightly rectangular concrete columns. Fiber-reinforced polymer (FRP) materials are commonly used in strengthening applications due to their superior properties such as high strength-to-weight ratio, high energy absorption and excellent corrosion resistance. FRP wrapping of concrete columns is done to enhance the ultimate strength due to the confinement effect, which is normally induced by steel ties. The existence of the two confinement systems changes the nature of the problem. Existing research focused on a single confinement system. Also, very limited research on rectangular sections was found in the literature. In this research, a model to estimate the combined behavior of the two systems in rectangular columns is proposed. The calculation of the effective lateral pressure is based on Lam and Teng model and Mander model for FRP wraps and steel ties, respectively. The proposed model introduces load eccentricity as a parameter that affects the compression zone size, and in turn the level of confinement engagement. Full confinement corresponds to zero eccentricity, while unconfined behavior corresponds to infinite eccentricity. The model then generates curves for eccentricities within these boundaries. The numerical approach developed has then been extended to account for shear interaction using the simplified modified compression field theory adopted by AASHTO LRFD Bridge Design Specifications 2014. Comparisons were then performed against experimental data and Response-2000, an analytical analysis tool based on AASHTO 1999 in order to validate the interaction domain generated. Finally, the developed models were implemented in the confined analysis software “KDOT Column Expert” to add FRP confinement effect and shear interaction.

Master of Science / Department of Mechanical and Nuclear Engineering / Youqi Wang / Two fiber reinforced polymer (FRP) bridge deck specimens were analyzed by means of acoustic emission (AE) monitoring during a series of loading cycles performed at various locations on the composite sandwich panels' surfaces. These panels were subjected to loads that were intended to test their structural response and characteristics without exposing them to a failure scenario. This allowed the sensors to record multiple data sets without fear of having to be placed on multiple panels that could have various characteristics that alter the signals recorded. The objective throughout the analysis ias to determine how the acoustic signals respond to loading cycles and various events can affect the acoustical data. In the process of performing this examination several steps were taken including threshold application, data collection, and sensor location analysis. The thresholds are important for lowering the size of the files containing the data, while keeping important information that could determine structurally significant information. Equally important is figuring out where and how the sensors should be placed on the panels in the first place in relation to other sensors, panel features and supporting beams. The data was subjected to analysis involving the response to applied loads, joint effects and failure analysis. Using previously developed techniques the information gathered was also analyzed in terms of what type of failure could be occurring within the structure itself. This somewhat aided in the analysis after an unplanned failure event occurred to determine what cause or causes might have lead to the occurrence. The basic analyses were separated into four sets, starting with the basic analysis to determine basic correlations to the loads applied. This was followed by joint and sensor location analyses, both of which took place using a two panel setup. The last set was created upon matrix failure of the panel and the subsequent investigation.

La détérioration des infrastructures au Canada due à la corrosion des armatures est l'un des défis majeurs de l'industrie de la construction. Les progrès récents dans la technologie des polymères ont conduit au développement d'une nouvelle génération de barres d'armature à base de fibres renforcées de polymères (PRF), (en particulier les fibres de verre). Ces barres, résistant à la corrosion, ont montré un grand potentiel d'utilisation pour mieux protéger les infrastructures en béton armé contre les effets dévastateurs de la corrosion. Avec la publication du nouveau code S807-10 "Spécifications pour les polymères renforcés de fibres" et la production de barres en PRF de très haute qualité, celles-ci représentent une alternative réaliste et rentable par rapport à l'armature en acier pour les structures en béton soumises à de sévères conditions environnementales. La conception des éléments en béton armé de barres en PRF est généralement gouvernée par l'état de service plutôt que l'état ultime. Par conséquent, il est nécessaire d'analyser les performances en flexion et le comportement en service en termes de déflexion et de largeur de fissures des éléments en PRF sous charges de service et de vérifier que ces éléments rencontrent les limites des codes. Aussi, de récents développements dans l'industrie des PRF ont conduit à l'introduction des barres en PRF avec des configurations de surface et des propriétés mécaniques différentes. Ces développements sont susceptibles d'affecter leur performance d'adhérence et, par conséquent, la largeur des fissures dans les éléments en PRF. Cependant, les codes de conception et les guidelines de calcul fournissent une valeur unique pour le coefficient d'adhérence (k[indice inférieur b]) en tenant compte des configurations de surface et en négligeant le type de barre en PRF, le diamètre de la barre, et le type de béton et de sa résistance. En outre, le code canadien S807-10 "Spécifications pour les polymères renforcés de fibres" fournit une étape en classant les barres en PRF par rapport à leur module d'élasticité (E[indices inférieurs frp]). Ces classifications ont été divisées en trois classes : Classe I (E[indices inférieurs frp]<50 GPa), Classe II (50 GPa [plus petit ou égal] E[indices inférieurs frp]< 60 GPa) et Classe III (E[indices inférieurs frp] [plus grand ou égal] 60 GPa). Ce programme de recherche vise à étudier expérimentalement le comportement en flexion des éléments en béton en service armé avec différents paramètres sous charges statiques. Le programme expérimental est basé sous plusieurs paramètres, dont les différents ratios de renforcement, différents types de barres (différentes classes comme classifiées par le CAN/CSA S807-10), le diamètre et la surface de la barre, la configuration ainsi que la résistance du béton. De plus, les recommandations actuelles de design pour les valeurs de k[indice inférieur b] et la vérification de la dépendance des valeurs de k[indice inférieur b] sur le type de barres (verre ou carbone), le diamètre des barres et le type de béton et sa résistance ont été étudiées. Le programme expérimental comprenait la fabrication et les essais sur 33 poutres à grande échelle, simplement appuyées et mesurant 4250 mm de long, 200 mm de large et 400 mm de hauteur. Vingt et sept poutres en béton ont été renforcées avec des barres en PRF à base de verre, quatre poutres en béton ont été renforcées avec des barres de PRF à base de carbone, et deux poutres ont été renforcées avec des barres en acier. Toutes les poutres ont été testées en flexion quatre points sur une portée libre de 3750 mm. Les paramètres d'essai étaient: le type de renforcement, le pourcentage d'armature, le diamètre des barres, configurations de surface et la résistance du béton. Les résultats de ces essais ont été présentés et discutés en termes de résistance du béton, de déflection, de la largeur des fissures, de déformations dans le béton et l'armature, de résistance en flexion et de mode de rupture. Dans les trois articles présentés dans cette thèse, le comportement en flexion et la performance des poutres renforcées de barres en PRFV et fabriquées avec un béton normal et un béton à haute performance ont été investigués, ainsi que les différentes classes de barres en PRFV et leurs configurations de surface. Les conclusions des investigations expérimentales et analytiques contribuent à l'évaluation des équations de prédiction de la déflection et des largeurs de fissures dans les codes de béton armé de PRF, pour prédire l'état de service des éléments en béton renforcés de PRF (déflection et largeur de fissures). En outre, à la lumière des résultats expérimentaux de cette étude, les équations de service (déflection et largeur des fissures) incorporées dans les codes et guidelines de design [ACI 440.1R-06, 2006; ISIS Manual No.3, 2007; CAN/CSA-S6.1S1, 2010; CAN/CSA-S806, 2012] ont été optimisées. En outre, les largeurs de fissures mesurées et les déformations ont été utilisées pour évaluer les valeurs courantes de k[indice inférieur b] fournies par les codes et les guidelines de calcul des PRF. En outre, les conclusions ne prennent pas en charge la valeur unique de k[indice inférieur b] pour les barres en PRF de types différents (carbone et verre) avec des configurations de surface similaires et s'est avéré être dépendant du diamètre de la barre.

Different strategies can be used to repair, rehabilitate and strengthen existing structures. Techniques based on Fiber Reinforced Polymer (FRP) materials appear to be innovative alternatives to traditional solutions because of their high tensile strength, light, weight, and ease of installation. One of the most common and useful FRPs is Carbon Fiber Reinforced Polymer (CFRP) used in sheets and anchors attached on the concrete surface to strengthen the section through addition of tensile capacity. The purpose of this study was develop a technique for assesses the strength of anchors for quality control purpose. However, to transfer tensile capacity to a concrete surface, the sheets are bonded to the surface with epoxy adhesive. As tension increase, CFRP sheets lose adherence of the epoxy from the concrete surface and finally debond. To avoid this failure, CFRP anchors are applied in addition at the epoxy. The CFRP anchors allow the CFRP sheets to utilize their full tensile capacity and maximize the material efficiency of the CFRP retrofit. The number and size of anchors play a critical role. However the capacity of CFRP anchors has not been investigated extendedly. A methodology for assessing the quality of CFRP anchors was developed using plain concrete beams and reinforced externally with CFRP sheets attached with epoxy and CFRP anchors. Applying load to the beam, allowed the development a tensile force in the CFRP sheets and a shear force on the CFRP anchors. The shear forces in the CFRP anchors were defined by the load applied to the beam and compared with forces based on measured stress in CFRP sheets. / text

The main weakness of soil is its inability to resist tensile stresses. Civil engineers have been trying to address this problem for decades. To increase the tensile and shear strengths of soil, different methods of reinforcing such as using geosynthetics have been used in different types of earth structures such as retaining walls, earth dams, slopes, etc. Due to the excellent corrosion resistance of polymers, the use of geosynthetics has increased dramatically in recent years. However, there are some significant problems associated with geosynthetics, such as creep and low modulus of elasticity. In this research, a new Geo-Composite which is made of Carbon Fiber Reinforced Polymer (CFRP) is used to overcome some of the short comings of the existing geosynthetics. The new Geo-Composite has all the benefits of the geotextiles plus higher strength, higher modulus and no creep. In first part of the investigation, over eighty experiments were carried out using direct shear test. The interface properties of the Geo-Composite (CFRP) and fine sand were investigated. Tests showed that the interface shear behavior between Geo-Composite and fine sand depended on the normal forces during the curing of epoxy and curing age of epoxy. The two methods used to prepare the specimen are pre-casting and casting in place, and the results of these two methods are compared. In the second part of the investigation, the pull-out test device was designed and assembled using a triaxial loading device and a direct shear device. In the pull-out test, the normal force applied by the triaxial loading and pull out force is applied by a direct shear device. CFRP samples were prepared in the lab, and pre-cast and cast-in-place samples were tested using fine sand. The pull-out force and corresponding displacements of each of the materials were recorded and compared. In the third part of the investigation, the behavior of the interface between coarse sand and modified CFRP has been studied in larger scale using a device known as Cyclic Multi Degree of Freedom (CYMDOF) device. A constitutive Model, Hierachical Single Surface (HISS) model, is used to characterize the behavior of the interfaces. The constitutive model is verified by predicting the laboratory behavior of interface. In the forth part of the investigation, using the laboratory test data results, a finite element procedure with the hardening model is used to simulate field behavior of a CFRP reinforced earth retaining wall, and compare the results with a geotextile reinforced earth retaining wall. This section shows the advantages and disadvantages of using CFRP in MSE walls.

Les structures sont parfois soumises à des sollicitations extrêmes telles que des chocs et des séismes, dont les conséquences peuvent être désastreuses. La réduction de la vulnérabilité au séisme du bâti existant est un enjeu de société de première importance. Le renforcement d'éléments structuraux par matériaux composites collés offre une solution intéressante, mais les règles de dimensionnement concernant l'application de tels matériaux pour le renforcement parasismique n'ont pas encore toutes été clairement établies. Le présent travail de thèse se propose de contribuer à l'établissement de ces règles pour le renforcement de poteaux en béton armé, par matériaux composites. Une campagne expérimentale a donc été menée sur plusieurs poteaux en béton armé, d'échelle représentative ; diverses configurations de renforcement ont été appliquées sur ces corps d'épreuve, qui ont ensuite été testés en flexion composée alternée. Ces différents essais nous ont permis d'analyser le comportement des poteaux selon la présence ou non de confinement (tissu de fibres de carbone), de renforcement à la flexion (lamelles), et d'ancrage des lamelles de renfort en matériaux composites. Cette notion d'ancrage des composites a fait l'objet d'une campagne expérimentale complémentaire, visant à caractériser une technique d'ancrage innovante et à en vérifier les performances. Grâce à ces différents essais, les gains en termes d'énergie dissipée apportés par les différentes configurations de renforcement, les gains en termes de ductilité globale de la structure ainsi qu'en termes d'augmentation de la charge portante ont été vérifiés. Outre ces aspects quantitatifs, ce travail a permis de proposer des pistes pour l'établissement de règles de dimensionnement de ces renforts spécifiques à la réhabilitation parasismique, en lien avec les normes actuelles, et notamment l'Eurocode 8 / Structures can be submitted to severe loadings, especially impacts and earthquakes, and reducing the seismic vulnerability of existing structures is thus an important issue. Retrofitting by Fibre-Reinforced Polymer (FRP) is an interesting technical solution but design rules have to be developed concerning their application for seismic strengthening. This thesis aims to contribute to the development of design rules concerning the strengthening of reinforced concrete columns by FRP. For this purpose, an experimental campaign carried out on full-scale reinforced concrete columns has been undertaken. Different strengthening configurations have been applied to columns, which were then tested under combined axial and lateral load. Those tests helped to analyze the behaviour of columns depending on the FRP confinement (carbon FRP jacket), on flexural reinforcement (carbon plates) and on anchorage of FRP. An additional experimental campaign has been undertaken in order to characterize an innovative anchoring system and assess its performance. The purpose of the study was to evaluate the effectiveness of the different strengthening configurations in increasing the dissipated energy and the ductility. In addition to the quantitative aspects, it was made possible to propose design rules for the use of FRP in seismic rehabilitation, linked to current rules, especially Eurocode 8