Thèses (M.Sc.A.)--Université de Sherbrooke (Canada), 2001. / Titre de l'écran-titre (visionné le 20 juin 2006). Publié aussi en version papier.

Th.--Sci.--Lyon 1, 1977. N°: 77. / 50.

Dans le contexte de la transition énergétique, la pile à combustible devient l'une des sources d'énergie alternatives les plus prometteuses. Récemment, la recherche a mis l’accent sur les piles à combustible, et plus particulièrement sur celles à membrane échange de protons (Proton Exchange Membrane Fuel Cell ou Polymer Electrolyte Membrane Fuel Cell ou PEMFC) qui est l'une des meilleures candidates pour les applications stationnaires et transport. Même si cette technologie évolue constamment, elle n'est pas encore prête pour un déploiement industriel à grande échelle en raison de sa durabilité et de sa fiabilité limitées. Le "Prognostics and Health Management" (PHM) est une approche récente pour gérer et prolonger la durée de vie des systèmes. Les techniques de pronostic sont capables de fournir une estimation de l'état de santé (State of Health ou SOH) des piles à combustible et une prédiction de leur durée de vie résiduelle (Remaining Useful Life ou RUL) afin d’aider les fabricants à améliorer les performances et à gérer leur durée de vie de ces systèmes.Ce travail a pour objectif de développer de nouvelles méthodes d’estimation de la durée de vie adaptée à la complexité des systèmes PEMFC. En effet, ces systèmes sont multi-échelle et multi-physique, et présentent divers défis sont à relever:1. La définition du SOH pour construire un indicateur de dégradation.2. La coexistence de phénomènes de dégradation à la fois réversibles et irréversibles.3. La prise en compte des différentes causes de détérioration et des effets des conditions opératoires.Dans la première partie, nous effectuons une analyse bibliographique de l’utilisation du PHM pour les PEMFCs, dans le but de proposer une définition de SOH et de construire un indicateur de dégradation. Etant donné que les mesures PEMFC sont peu nombreuses, nous avons également exploré l'état de l'art sur les batteries au lithium, qui sont d'autres cellules électrochimiques.Dans la deuxième partie, nous développons un algorithme de pronostic basé sur le filtrage particulaire utilisant la mesure de puissance de la PEMFC. Les premiers résultats montrent que l'algorithme de pronostic est perturbé par la dégradation réversible existante. L’ambiguïté peut être levée en estimant la dégradation irréversible grâce à des tests de caractérisation, tels la spectroscopie d'impédance électrochimique (Electrochemical Impedance Spectroscopy ou EIS), appliquée de temps en temps. Nous proposons donc un algorithme de pronostic étendu et adapté, prenant en compte deux indicateurs : la dégradation de la puissance et le SOH estimé à partir de la caractérisation EIS. La performance de l'algorithme proposé est évaluée par différentes indicateurs de performance, et les résultats montrent l'intérêt de cette approche.Dans la troisième partie, les problèmes sont abordés d'un point de vue plus théorique. En effet, l’évolution de la dégradation d'un système est souvent corrélée à des covariables internes et externes qui sont généralement difficiles d'accès en raison des coûts de mesure élevés. Par conséquent, nous avons d'abord développé une approche comprenant des inspections en ligne de la covariable de dégradation à un autre niveau, puis nous avons proposé une approche d’estimation de la RUL basée sur un ensemble de modèles en utilisant différentes sources à différents niveaux. Les RULs prédites par les deux modèles sont agrégées dynamiquement sur la base des performances évaluées sur les données historiques. Par conséquent, la précision de la prédiction est améliorée car les inconvénients des deux modèles ont été surmontés en tirant parti de leurs avantages. Dans la dernière partie, le problème est étendu au pronostic multi-niveaux qui ouvre de nouveaux aspects pour la recherche future sur le pronostic et la gestion de la PEMFC. / In the context of the energy transition, fuel cell becomes one of the promising alternative energy sources. Recently the spotlight is on fuel cell systems research, and more particularly on Proton Exchange Membrane Fuel Cell (PEMFCs) which is one of the best candidates for both stationary and transportation applications. Even if this technology is close to being competitive, it is not yet ready to be considered for a large scale industrial deployment because of its limited durability and reliability. Prognostics and Health Management (PHM) is a recent approach to manage and possibly extend life duration of technological systems. Prognostic techniques can provide an estimation of fuel cell State Of Health (SOH) and a prediction for their Remaining Useful Life (RUL) to help the manufacturers improving fuel cell performance and managing its lifespan.The objective of this work is to develop prognostic methodologies for the RUL prognosis adapted to the complexity of PEMFCs. Indeed, the PEMFC is a multi-scale and multi-physics system, and various challenges are faced:1. The definition of SOH to build a degradation indicator.2. The coexistence of both reversible and irreversible degradation phenomena.3. Taking into account different deterioration causes and effects of operating conditions.In the first part of our work, we conduct a state of the art analysis on PHM for PEMFCs, with the aim of proposing a SOH definition and building a degradation indicator for PEMFC prognosis purposes. And since PEMFC measurements are scarce, the state of the art on Lithium batteries, other electrochemical cells, is also explored.In the second part, we develop a particle filtering based prognostic algorithm for PEMFC, based on output power measurements. The first results show that the prognosis algorithm is disturbed by the existing reversible degradation. However, the irreversible degradation can be estimated thanks to characterization tests, such as Electrochemical Impedance Spectroscopy (EIS), which is applied from time to time. We propose thus an adapted & extended prognostic algorithm to take into account both health indicators: the output power degradation and the SOH degradation estimated from EIS characterization. The performance of the proposed algorithm is evaluated by different prognostic performance metrics, and the results show the interest of this approach.In the third part, the problem is addressed from a more theoretical point of view. Indeed, a system's degradation behavior is often correlated with internal and external covariates which are usually difficult to access owing to expensive measurement cost. Therefore, we first developed a prognostic approach with online inspections on the degradation covariate at a different level, and then we propose an approach for RUL prognosis based on an ensemble of models using different sources at different levels. The RUL predictions of both models are dynamically aggregated on the basis of prognostic performance evaluated on a set of historical data. Consequently, the prediction accuracy is improved by overcoming both models' drawbacks and leveraging their strengths. In the last part, we extend the problem to multi-level prognostics and explore new possibilities, which open new aspects for future research on PEMFC lifetime prognosis and management.

Made available in DSpace on 2014-06-11T19:25:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-07-14Bitstream added on 2014-06-13T18:06:59Z : No. of bitstreams: 1 delpinojunior_a_me_ilha.pdf: 1935500 bytes, checksum: bece074c3516a80e3d98e5f2153fe19f (MD5) / Neste trabalho foi estudada a interação solo-estrutura para estacas escavadas com trado mecânico, de concreto armado (com diâmetro de 32 cm e 8,71 m embutida no solo), instaladas em solo arenoso de comportamento elástico-linear, solicitadas a carregamento transversal, através da análise e execução de provas de carga, no Campo Experimental da Unesp, Campus de Ilha Solteira. A partir das curvas de carga horizontal versus deslocamento horizontal, obtidas nas provas de carga, foi possível obter a variação do coeficiente horizontal de reação do solo (nh) em função do deslocamento horizontal na superfície do terreno (yo), por meio dos métodos de Matlock & Reese (1960) e Reese (1976). Escolhido o intervalo de yo entre 7 mm a 12 mm, obteve-se o valor de nh igual a 8 MN/m3, o que permitiu a determinação dos deslocamentos, das rotações, dos momentos fletores, dos esforços cortantes e das pressões atuantes no solo, ao longo do fuste das estacas, considerando a variação ou não da rigidez flexional (EI) das estacas. A influência da rigidez flexional se mostrou bem mais expressiva do que a influência da rigidez do solo no comportamento das estacas; para o nível de carregamento analisado, considerando a máxima carga utilizada nas provas de carga. / In this work was studied the soil-structure interaction for bored piles of armed concrete (with 32 cm od diameter and 8,71 m length), installed in arenaceous soil of elastic-linear behavior, requested the transversal load, through the analysis and execution of load tests, in the Experimental Field of the Unesp, Campus of the Ilha Solteira. From the curves horizontal load versus horizontal displacement, gotten in the load tests, it was possible to get the variation of coefficient of horizontal subgrade reaction (nh) in function of the ground horizontal displacement (yo), by means of the methods of Matlock & Reese (1960) and Reese (1976). Chosen the interval of yo enter 7-12 mm, got the equal value of nh 8 the MN/m3, what it allowed the determination of the horizontal displacements, the rotations, bending moments, shear forces and soil reactions, in depth, considering the variation or not of the flexional rigidity (EI) of the piles. The flexional rigidity had more influence on the piles behaviour that the soil, for the analyzed loading level, considering the maximum load used in the load tests.

Les fondations profondes sont largement utilisées et peuvent subir différent types de sollicitations axiales. Ces dernières peuvent avoir un caractère monotone ou cyclique. Le développement de méthodes de calcul pour prévoir le comportement des pieux sous ces deux types de chargements en termes de tassement et d’évolution de capacité portante, est d’une grande utilité pour l’ingénierie géotechnique. Le travail de cette thèse est une contribution à une meilleure prévision du comportement des pieux sous charges axiales monotones et cycliques. La thèse comporte deux parties principales. La première partie traite la problématique de la prévision du tassement d’un pieu sous charge axiale monotone. Un intérêt particulier est porté aux tassements car le dimensionnement d’un pieu requiert une estimation adéquate à la fois de la capacité portante et du déplacement en tête de pieu. La méthode utilisée dans cette partie est celle des courbes de transfert. L’étude commence tout d’abord par une analyse statistique du modèle habituellement utilisé pour le calcul de tassement nommé Frank et Zhao. Ensuite, deux nouveaux modèles de calcul de tassement sont proposés et analysés. Une analyse comparative entre les trois modèles de calcul de déplacement d’un pieu est réalisée dans cette étude. L’objectif de cette analyse est d’estimer la dispersion des modèles de calcul en comparant les tassements calculés aux tassements mesurés et répertoriés dans la base de données de l’IFSTTAR. La seconde partie s’intéresse à la problématique des chargements cycliques. En effet, plusieurs types de structures sont sollicités cycliquement et peuvent subir des désordres du fait de l’accumulation de déplacements en tête des fondations. L’objectif de cette partie de la thèse est de proposer un modèle permettant de rendre compte principalement de l’évolution de la capacité portante du pieu au cours des cycles, et aussi de proposer une estimation des déplacements. Le modèle développé se base sur la méthode des courbes de transfert, et est associé à deux procédures de dégradation du frottement axial limite. Il est tout d’abord présenté et ensuite appliqué à un exemple théorique. Afin de valider ce modèle, ses résultats sont comparés aux résultats d’essais de pieux en vraie grandeur / Different types of loads can be applied to deep foundations which are widely used nowadays. Piles can be subjected to monotonic or cyclic loads. Thus, geotechnical engineering needs the development of calculation methods to predict the behavior of piles under these types of loads in terms of displacements and bearing capacity. The study presented in this thesis aims to ameliorate the prediction of the behavior of piles under axial monotonic and cyclic loads. This thesis is divided into two parts. The issue of the first part is the prediction of the settlement of a pile submitted to monotonic and axial load. This part focuses on the estimation of settlements because a correct design of a pile requires a correct estimation of bearing capacity as well as displacements. The approach used in this part is the load transfer method. The study starts by a statistical analysis of the t-z model of Frank and Zhao which is generally used for the calculation of pile settlements. Two new t-z models of settlement calculation are presented and analyzed later. Moreover, a comparative analysis between the three t-z models is presented in this study. The aim of this analysis is to estimate the dispersion of the models using the comparison between calculated settlements and measured settlements listed in IFSTTAR’s database. The second part of the thesis deals with the issue of cyclic loads. Indeed, different structures can be subjected to cyclic loads and disorders can be noted due to the accumulation of displacements at the top of the pile. The aim of this part is to propose a calculation model allowing essentially the estimation the evolution of bearing capacity during cycles. It permits also the estimation of displacements. The model developed in this part is based on load transfer approach, and is associated to two calculation methods of degradation of shaft friction. This model is firstly presented, and then it is applied to a theoretical case. In order to validate this model, its numerical results are compared to experimental results of full scale pile tests

Ce travail de thèse s’inscrit dans un contexte de développement de nouvelles méthodes de production d’énergie. Parmi les nombreuses technologies proposées, les piles à combustible à membrane échangeuse de protons (PEMFC) sont particulièrement prometteuses. Cependant, certaines limitations subsistent quant à leur utilisation à grande échelle, notamment au niveau de leur trop courte durée de vie et du coût trop élevé des différents matériaux qui les composent. Cette thèse, inscrite dans un projet de recherche intitulé HYLIFE, a pour but de synthétiser par des méthodes plasma à pression atmosphérique des couches catalytiques et une membrane échangeuse de protons et de les caractériser dans le but d’une application en pile.Nous avons dans un premier temps utilisé une torche plasma radiofréquencée pour produire des couches catalytiques. Le traitement de l’acétylacétonate de platine (II), ou Pt(acac)2, en post-décharge a permis la formation de nanoparticules (NPs) métalliques de taille comprise entre 1 et 4 nm dans des conditions optimisées. Les espèces réactives du plasma comme les argons métastables ont été identifiés comme acteurs principaux dans la dégradation du précurseur et dans la réduction, directe ou indirecte (par formation de CO), du platine. Le greffage (renforcé ou non par un prétraitement O2 ou N2) des NPs a pu être réalisé sur différents supports carbonés et la caractérisation électrochimique des couches catalytiques a mis en évidence des performances en pile équivalentes à celles obtenues pour des électrodes commerciales et une bonne résistance à la dégradation. L’injection de H2 dans la torche plasma a permis la formation de NPs de cobalt à partir de Co(acac)2 et un phénomène de compétition entre le Pt et le Co lors de la formation de nanostructures bimétalliques a été mis en évidence.La formation de nanoparticules de platine a également été étudiée dans le cas du traitement par microplasma d’une solution méthanolique de Pt(acac)2. Du fait de sa densité électronique élevée et de ses interactions avec les éléments constitutifs du milieu comme les ligands organiques du précurseur et du solvant lui-même, le microplasma nous a permis de former des NPs métalliques de diamètre inférieur à 3 nm en absence d’agents réducteurs et stabilisant. Les mesures électrochimiques ont démontré le greffage des particules lors de l’addition d’un support carboné à la solution colloïdale et l’activité catalytique de celles-ci. Des expériences similaires ont été menées dans le cas de l’injection du précurseur sous forme de vapeur directement dans la décharge microplasma et ont permis le dépôt de nanoparticules et de films de morphologies diverses directement sur un substrat en fonction de la pression dans le réacteur, de la nature de ce substrat et du temps de dépôt.Enfin, nous avons synthétisé des membranes de polystyrène sulfoné par DBD. Nous avons montré qu’il était possible, à partir de styrène et d’acide triflique, d’obtenir des films denses et épais (plus de 50 microns) caractérisés par une bonne conservation des noyaux aromatiques et des fonctions sulfonées. La capacité d’échange a pu être vérifiée mais la conductivité protonique reste encore limitée, probablement à cause de problèmes de connexion entre les groupements échangeurs ioniques. L’activation par plasma de la réticulation d’une solution sulfonée de polystyrène-block-poly(éthylène-ran-butylène)-block-polystyrène en présence d’un agent réticulant, le vinyltriméthoxysilane, a été étudiée comme une alternative à la polymérisation plasma. Nous avons, dans ce cas, produit des membranes épaisses et conductrices ioniques avec un degré de réticulation variable en fonction du nombre de passages dans la DBD déroulante. L’imprégnation de la membrane en interaction avec la surface d’une électrode a également été brièvement étudiée et a montré des résultats encourageants concernant les contacts entre les deux matériaux. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

This thesis explores the quality of hand-manufactured carbon-epoxy IsoTruss® grid structures for use as reinforcement in concrete piles. Large IsoTruss® grid structures were manufactured and embedded in 14.0" (35.6 cm) diameter concrete to create IsoPiles™. The IsoPiles™ were designed to have flexural characteristics similar to steel reinforced concrete piles of equal diameter. Bending stiffness was matched based on the longitudinal members. A method for comparing transverse steel reinforcement to helical IsoTruss® members was developed, along with equations to facilitate the design of IsoTruss® structures with rounded nodes. Compression tests were performed on 3.0 ft (0.91 m) long sections taken from the ends of each of the two 30 ft (9.14 m) long IsoTruss® grid structures manufactured. Fiber volume fraction, void fraction, and cross section area inspections were performed on IsoTruss® samples to determine quality. The strength, stiffness, and fiber volume fraction data obtained from these tests are compared to values obtained previously [1] for the same consolidation method. The quality of hand-manufactured large IsoTruss® grid structures was quantified by performing microscopic inspection of the members, by testing the reinforcement cage in compression, and by testing short section of IsoTruss® and steel reinforced concrete piles in compression. Compression tests were performed on short sections taken from the ends of the IsoPile™ specimens. These were compared with compression tests performed on equivalent steel-reinforced piles to evaluate the viability of the IsoTruss® as reinforcement in concrete piles. Insufficient tension on the fiber during manufacturing and insufficient radial compression during the cure resulted in an average fiber volume fraction 13% lower than previously obtained, causing the ultimate compressive strength and Young's modulus of the IsoTruss® reinforcement cages to be 51% and 22% lower, respectively, than previous data. The IsoTruss®–reinforced piles had an ultimate compressive load that was within 4% of the ultimate compressive load of the steel-reinforced piles.

Traditionally, geothermal boreholes have utilized the ground energy for space heating and cooling. In this system, a circulation loop is placed in a small-diameter borehole typically extending to a depth of 200-300 ft. The hole is then backfilled with a mixture of sand, bentonite and/or cement. The loop is connected to a geothermal heat pump and the fluid inside the loop is circulated. The heat energy is fed into the ground for cooling in the summer and withdrawn from the ground for heating in the winter. Geothermal heat pumps work more efficiently for space heating and cooling compared to air-source heat pumps.  The reason is ground-source systems use the ground as a constant temperature source which serves as a more favorable baseline compared to the ambient air temperature. A significant cost associated with any deep geothermal borehole is the drilling required for installation. Because Energy Piles perform the dual function of exchanging heat and providing structural support, and are only installed at sites where pile foundations are already required, these systems provide the thermal performance of deep geothermal systems without the additional drilling costs. Low maintenance, long lifetime, less variation in energy supply compared to solar and wind power, and environmental friendliness have been cited as additional Energy Pile advantages. Case studies show that they can significantly lower heating/cooling costs and reduce the carbon footprint. Energy cost savings for typical buildings outfitted with Energy Piles could be as much as 70 percent. The use of Energy Piles has rapidly increased over the last decade, especially in Europe where more than 500 applications are reported. Primary installations have been in Germany, Austria, Switzerland and United Kingdom. Notable projects include the 56-story high Frankfurt Main Tower in Germany, Dock E Terminal Extension at Zurich International Airport in Switzerland and the One New Change building complex in London U.K. Energy piles have seen very little use in the North America, only a handful of completed projects are known; Marine Discovery Center in Ontario, Canada, Lakefront Hotel in Geneva, New York and the Art Stable building in Seattle, Washington. Energy Piles are typically installed with cast-in-place technology (i.e. drilled shafts, continuous flight auger piles, micropiles etc.) while some driven pile applications are also reported. Other types of geotechnical structures in contact with the ground, such as shallow foundations, retaining walls, basement walls, tunnel linings and earth anchors, also offer significant potential for harnessing near-surface geothermal energy. Energy Pile design needs to integrate geotechnical, structural and heat exchange considerations. Geotechnical characteristics of the foundation soils and the level of the structural loads are typically the deciding factors for the selection and dimensioning of the pile foundations. The geothermal heat exchange capacity of an Energy Pile is a key parameter to be considered in design. Thermal characteristics of the ground as well as the heating and cooling loads from the structure need to be considered for the number of piles that will be utilized as heat exchangers. Therefore, the thermal properties of the site need to be evaluated for an Energy Pile application in addition to the traditional geotechnical characterization for foundation design. Energy Piles bring new challenges to geotechnical pile design. During a heat exchange operation, the pile will expand and contract relative to the soil as heat is injected and extracted, respectively. These relative movements have the potential to alter the shear transfer mechanism at the pile-soil interface.  Furthermore, the range of temperature increases near the pile surface, though limited by practical operational guidelines, can have a significant effect on pore pressures generation and soil strength. This dissertation provides answers for several research questions including the long-term performance of Energy Piles, the applicability of the thermal conductivity tests to Energy Piles.  Furthermore, it presents the results and a detailed discussion about the full scale in-situ thermo-mechanical pile load test conducted at Virginia Tech. / Ph. D.

One common software program developed for analyzing single laterally loaded piles is called LPILE. Soil properties are required as input into LPILE. For sands, the soil properties required are effective soil unit weight, γ’; subgrade modulus, k; and the internal friction angle, ϕ’. There are two commonly used methods to obtain ϕ’ and subsequently k: the API method and Bolton method. Fourteen different pile test sites were used in the analysis of the API and Bolton methods to obtain soil strength properties in sands for laterally loaded single pile tests. Between the fourteen pile test sites, a total of 26 piles were tested in the field and analyzed in LPILE using the API method and Bolton method to calculate the soil strength properties of the sands. After each pile test was analyzed in LPILE and compared to the field measured results, the two methods were compared graphically and percent errors were calculated between each method and the measured results to determine the optimal method in single laterally loaded pile design. Using the Bolton method to determine the soil strength properties gives more accurate load-deflection values with respect to measured values from field tests. The Bolton method accounts for dilation and the type of sand as well as the relative density and the mean effective stress of the soil. This leads to soil strength properties more characteristic of the soil at the site.

Typically, foundation piles are made of materials such as steel, concrete, and timber. Problems associated with use of these traditional pile materials in harsh marine environments include steel corrosion, concrete deterioration, and marine borer attack on timber piles. It has been estimated that the U.S. spends over $1 billion annually in repair and replacement of waterfront piling systems. Such high repair and replacement costs have led several North American highway agencies and researchers to investigate the feasibility of using composite piles for load bearing applications, such as bridge substructures. As used here, the term "composite piles" refers to alternative pile types composed of fiber reinforced polymers (FRPs), recycled plastics, or hybrid materials. Composite piles may exhibit longer service lives and improved durability in harsh marine environments, thereby presenting the potential for substantially reduced total costs. Composite piles have been available in the North American market since the late 1980's, but have not yet gained wide acceptance in civil engineering practice. Potential disadvantages of composite piles are high initial cost and questions about engineering performance. At present, the initial cost of composite piles is generally greater than the initial cost of traditional piles. Performance questions relate to driving efficiency, axial stiffness, bending stiffness, durability, and surface friction. These questions exist because there is not a long-term track record of composite pile use and there is a scarcity of well-documented field tests on composite piles. This research project was undertaken to investigate the engineering performance of composite piles as load-bearing foundation elements, specifically in bridge support applications. The objectives of this research are to: (1) evaluate the soil-pile interface behavior of five composite piles and two conventional piles, (2) evaluate the long-term durability of concrete-filled FRP composite piles, (3) evaluate the driveability and the axial and lateral load behavior of concrete-filled FRP composite piles, steel-reinforced recycled plastic composite piles, and prestressed concrete piles through field tests and analyses, and (4) design and implement a long-term monitoring program for composite and conventional prestressed concrete piles supporting a bridge at the Route 351 crossing of the Hampton River in Virginia. A summary of the main findings corresponding to each of these objectives is provided below. A laboratory program of interface testing was performed using two types of sands and seven pile surfaces (five composite piles and two conventional piles). The interface behavior of the different pile surfaces was studied within a geotribology framework that investigated the influence of surface topography, interface hardness, and particle size and shape. In general, the interface friction angles, both peak and residual, were found to increase with increasing relative asperity height and decreasing relative asperity spacing. The interface shear tests for the three pile types tested at the Route 351 bridge showed that, for medium dense, subrounded to rounded sand, with a mean particle size of 0.5 mm, the residual interface friction angles are 27.3, 24.9, and 27.7 degrees for the FRP composite pile, the recycled plastic pile, and the prestressed concrete pile, respectively. Interface shear tests on these same piles using a medium dense, subangular to angular sand, with a mean particle size of 0.18 mm, resulted in residual interface friction angles of 29.3, 28.8, and 28.0 degrees for the FRP composite pile, the recycled plastic pile, and the prestressed concrete pile, respectively. A laboratory durability study was completed for the FRP shells of concrete-filled FRP composite piles. Moisture absorption at room temperature caused strength and stiffness degradations of up to 25% in the FRP tubes. Exposure to freeze-thaw cycles was found to have little effect on the longitudinal tensile properties of saturated FRP tubes. Analyses were performed to investigate the impact of degradation of the FRP mechanical properties on the long-term structural capacity of concrete-filled FRP composite piles in compression and bending. The impact was found to be small for the axial pile capacity due to the fact that the majority of the capacity contribution is from the concrete infill. The impact of FRP degradation was found to be more significant for the flexural capacity because the FRP shell provides most of the capacity contribution on the tension side of the pile. Full-scale field performance data was obtained for two composite pile types (concretefilled FRP composite piling and steel-reinforced recycled plastic piling), as well as for conventional prestressed concrete piles, by means of load test programs performed at two bridge construction sites: the Route 351 bridge and the Route 40 bridge crossing the Nottoway River in Virginia. The field testing at the two bridges showed no major differences in driving behavior between the composite piles and conventional prestressed concrete piles. Pile axial capacities of the composite piles tested at the Route 351 bridge were between 70 to 75% of the axial capacity of the prestressed concrete test pile. The FRP and prestressed concrete piles exhibited similar axial and lateral stiffness, while the steel-reinforced plastic pile was not as stiff. Conventional geotechnical analysis procedures were used to predict axial pile capacity, axial load-settlement behavior, and lateral load behavior of the piles tested at the Route 351 bridge. The conventional analysis procedures were found to provide reasonable predictions for the composite piles, or at least to levels of accuracy similar to analyses for the prestressed concrete pile. However, additional case histories are recommended to corroborate and extend this conclusion to other composite pile types and to different soil conditions. A long-term monitoring program for composite and conventional prestressed concrete piles supporting the Route 351 bridge was designed and implemented. The bridge is still under construction at the time of this report, therefore no conclusions have been drawn regarding the long-term performance of concrete-filled FRP composite piles. The longterm monitoring will be done by the Virginia Department of Transportation. In addition to the above findings, initial cost data for the composite piles and prestressed concrete piles used in this research were compiled. This data may be useful to assess the economic competitiveness of composite piles. The initial unit cost of the installed composite piles at the Route 40 bridge were about 77 % higher than the initial unit cost for the prestressed concrete piles. The initial unit costs for the composite piles installed at the Route 351 bridge were higher than the initial unit cost of the prestressed concrete piles by about 289% and 337% for the plastic and FRP piles, respectively. The cost effectiveness of composite piles is expected to improve with economies of scale as production volumes increase, and by considering the life-cycle costs of low-maintenance composite piles. / Ph. D.