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.

Lightweight structures in vehicles are a proven way to reduce fuel consumption and the environmental impact during the use. Lower structural weight can be achieved by using high performance materials such as composites or using the material efficiently as a sandwich structure. Traditional composite materials such as carbon or glass fiber reinforced polymers have high weight specific mechanical properties but are inherently brittle and expensive. They consist of at least two different materials making recycling a difficult endeavor.The best composite material would have good weight specific properties and is ductile, cheap and comprises of a reinforcement and matrix material based on the same recyclable material making recycling easy. In self-reinforced polymer (SrP) composite materials, reinforcing fibers and matrix material are based on the same recyclable thermoplastic polymer making recycling to a straightforward process. SrP composite materials are ductile, inexpensive and have a high energy absorption potential. The aim of this thesis is to investigate the potential of SrP composites in structural applications. Firstly, the quasi-static and dynamic tensile and compression properties of a self-reinforced poly(ethylene terephthalate) (SrPET) composite material are investigated confirming the high energy absorption potential. Sandwich structures out of only SrPET with a lattice core are manufactured and tested in quasi-static out-of-plane compression showing the potential of SrPET as core material. Corrugated sandwich structured out of only SrPET are manufactured and tested in out-of-plane compression over a strain rate range10−4 s−1 - 103 s−1. The corrugated SrPET core has similar quasi-static properties as commercial polymeric foams but superior dynamic compression properties. Corrugated sandwich beams out of only SrPET are manufactured and tested in quasi-static three-point bending confirming the high energy absorption potential of SrPET structures. When comparing the SrPET beams to aluminum beams with identical geometry and weight, the SrPET beams shows higher energy absorption and peak load. The experimental results show excellent agreement with finite element predictions. The impact behaviorof corrugated SrPET sandwich beams during three-point bending is investigated. When comparing SrPET sandwich beams to sandwich beams with carbon fiber face sheets and high performance thermoset polymeric foam with the same areal weight, for the same impact impulse per area, the SrPET shows less mid-span deflection. / <p>QC 20151012</p> / ECO2

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.

Fibre reinforced polymer (FRP) composites have been used for strengthening concrete structures since early 1990s. More recently, FRP has been used for retrofitting concrete structures for high energy events such as impact and blast. Debonding at the FRP-to-concrete interface is one of the predominant failure modes for both static and dynamic loading. Although extensive research has been conducted on the static bond behaviour, the bond-slip mechanics under high strain rates is not well understood yet. This thesis is mainly concerned with the FRP-to-concrete bond behaviour under dynamic loading. Because debonding mostly occurs in the concrete adjacent to the FRP, the behaviour of concrete is of crucial importance for the FRP-to-concrete bond behaviour. The early emphasis of this thesis is thus on the meso-scale concrete modelling of concrete with appropriate consideration of static and dynamic properties. Issues related to FE modelling of tensile and compressive localization of concrete are first investigated in detail under static condition using the K&C concrete damage model in LS-DYNA. It is discovered for the first time that dilation of concrete plays an important role in the FRP-to-concrete bond behaviour. This has led to the development of a model relating the shear dilation factor to the concrete strength based on the modelling of a large number of static FRP-to-concrete shear tests, forming the basis for dynamic modelling. Concrete dynamic increasing factor (DIF) has been a subject of extensive investigation and debate for many years, but it is for the first time discovered in this study that mesh objectivity cannot be achieved in meso-scale modelling of concrete under high strain rate deformation. This has led to the development of a mesh and strain rate dependent concrete tension DIF model. This DIF model shall have wide applications in meso-scale modelling of concrete, not limited to the topic in this thesis. Based on a detailed numerical investigation of the FRP-to-concrete bond shear test under different loading rates, taking on the above issues into careful consideration, a slip rate dependent FRP-to-concrete dynamic bond-slip model is finally proposed for the first time. The FE predictions deploring this proposed bond-slip model are compaed with test results of a set of FRP-to-concrete bonded specimens under impact loading, and a FRP plated slab under blast loading, validating the model.

In this study, a total of twelve beams continuous over two spans of 2,800 mm each were constructed and tested to failure. The beams were divided into two series. Series 1 included six T-beams under symmetrical loading, while Series 2 dealt with six rectangular beams under unsymmetrical loading conditions. In Series 1, the test variables included material type, assumed percentage of moment redistribution, spacing of lateral reinforcement in flange, arrangement of shear reinforcement, and serviceability requirements. In Series 2, three different loading cases were considered, I) loading both spans equally, II) loading both spans maintaining a load ratio of 1.5 and III) loading one span only. Under the loading case II, the parameters of reinforcing material type, assumed percentage of moment redistribution and serviceability requirements were investigated. The test results of both series showed that moment redistribution from the hogging to the sagging moment region took place in GFRP-RC beams which were designed for an assumed percentage of moment redistribution. In Series 1, the decrease of the stirrups spacing from 0.24d to 0.18d enhanced the moment redistribution percentage. Also, decreasing the spacing of lateral reinforcement in the flange from 450 to 150 mm improved the moment redistribution through enhancing the stiffness of the sagging moment region. In Series 2, the unsymmetrical loading conditions (loading case II and III) reduced the moment redistribution by reducing flexural stiffness in the heavily loaded span due to extensive cracking. Regarding serviceability in both series, the GFRP-RC beam designed for the same service moment calculated from the reference steel-RC beam, was able to meet the serviceability requirements for most types of the structural applications. / February 2017

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

Master of Science / Department of Civil Engineering / Hani G. Melhem / Fiber Reinforced Polymer (FRP) is a relatively new material used in the field of civil engineering. FRP is composed of fibers, usually carbon or glass, bonded together using a polymer adhesive and formed into the desired structural shape. Recently, FRP deck panels have been viewed as an attractive alternative to concrete decks when replacing deteriorated bridges. The main advantages of an FRP deck are its weight (roughly 75% lighter than concrete), its high strength-to-weight ratio, and its resistance to deterioration. In bridge design, AASHTO provides load distributions to be used when determining how much load a longitudinal beam supporting a bridge deck should be designed to hold. Depending on the deck material along with other variables, a different design distribution will be used. Since FRP is a relatively new material used for bridge design, there are no provisions in the AASHTO code that provides a load distribution when designing beams supporting an FRP deck. FRP deck panels, measuring 6 ft x 8.5’, were loaded and analyzed at KSU over the past 4 years. The research conducted provides insight towards a conservative load distribution to assist engineers in future bridge designs with FRP decks. Two separate test periods produced data for this thesis. For the first test period, throughout the year of 2007, a continuous FRP panel was set up at the Civil Infrastructure Systems Laboratory at Kansas State University. This continuous panel measured 8.5 ft by 6 ft x 6 in. thick and was supported by 4 Grade A572 HP 10 x 42 steel beams. The beam spacing’s, along the 8.5 ft direction, were 2.5 ft-3.5 ft-2.5 ft. Stain gauges were mounted at mid-span of each beam to monitor the amount of load each beam was taking under a certain load. Linear variable distribution transformers (LVDT) were mounted at mid-span of each beam to measure deflection. Loads were placed at the center of the panel, with reference to the 6 ft direction and at several locations along the 8.5 ft direction. Strain and deflection readings were taken in order to determine the amount of load each beam resisted for each load location. The second period of testing started in the fall of 2010 and extended into January of 2011. This consisted of a simple-span/cantilever test set-up. The test set-up consisted of, in the 8.5 ft direction, a simply supported span of 6 ft with a 2.5 ft cantilever on one side. As done previously both beams had strain gauges along with LVDTs mounted at mid-span. There were also strain gauges were installed spaced at 1.5ft increments along one beam in order to analyze the beam behavior under certain loads. Loads were once again applied in the center of the 6 ft direction and strain and deflection readings were taken at several load locations along the 8.5 ft direction. The data was analyzed after all testing was completed. The readings from the strain gauges mounted in 1.5 ft increments along the steel beam on one side of the simple span test set-up were used to produce moment curves for the steel beam at various load locations. These moment curves were analyzed to determine how much of the panel was effectively acting on the beam when loads were placed at various distances away from the beam. Using these “effective lengths,” along with the strain taken from the mid-span of each beam, the loads each beam was resisting for different load locations were determined for both the continuously supported panel and the simply supported/cantilever panel data. Using these loads, conservative design factors were determined for FRP panels. These factors are S/5.05 for the simply supported panel and S/4.4 for the continuous panel, where “S” is the support beam spacing. Deflections measurements were used to validate the results. Percent errors, based on experimental and theoretical deflections, were found to be in the range of 10 percent to 40 percent depending on the load locations for the results in this thesis.

Thesis. (M.Tech. (Dept. of Civil Engineering and Building, Faculty of Engineering and Technology)) -- Vaal University of Technology, 2011. / This research focused on the structural performance of Fibre Reinforced Polymer (FRP) re-bars in structural foundation compared to steel reinforcement re-bars. The corrosion of steel re-bars is the main reason of deterioration of reinforced concrete. However, use of FRP re-bars as alternative reinforcement will address the deterioration of reinforced concrete. Carbon and Glass Fibre Reinforced Polymer re-bars were used as reinforcing bars and traditional steel reinforced concrete was used as the reference. Thirty six specimens of reinforced concrete bases were tested for flexural capacity at different ages. The simulation of Soil Bearing Pressure of this study was derived from the model of beam finite length on elastic foundation. The foundation base was treated as a beam while the soil was modelled as series of timber elements acting as springs. The mathematical model to reflect the model was as documented by Timoshenko (1976:18) and Den Hartog (1952:160). Results showed that stress in the steel re-bars of reinforced concrete was higher than that of Carbon Fibre Reinforced Polymer (CFRP) and Glass Fibre Reinforced Polymer (GFRP) re-bars by 227 MPa (5.99 percent) and 284 MPa (7.61 percent), respectively. The stress in CFRP re-bars was 57 MPa or 1.53 percent higher compared to GFRP re-bars of FRP reinforced concrete. Furthermore, the experimental ultimate moments of CFRP and GFRP reinforced concrete foundation – bases on the 28th day were 23.917 kNm (79.0 percent) and 23.529 kNm (77.7 percent) higher than the theoretical ultimate moments, respectively. However, steel reinforced concrete foundation – bases had the higher calculated deflection than FRP reinforced concrete. With high resistance to corrosion as a property, FRP re-bars appeared to be a better alternative reinforcement to steel in corrosion in an aggressive environment. / Vaal University of Technology