Die vollständige Ausnutzung des Leichtbaupotentials bei der Dimensionierung von mehrschichtigen endlosfaserverstärkten Strukturbauteilen erfordert die Bereitstellung von geeigneten Optimierungswerkzeugen, da bei der Auslegung eine große Anzahl von Entwurfsvariablen zu berücksichtigen sind. In dieser Arbeit werden Optimierungsalgorithmen und -strategien zur Lösung wissenschaftlicher Fragestellungen für industrielle Anwendungen bei der Konstruktion von entsprechenden Faserkunststoffverbunden entwickelt und bewertet. Um das breite Anwendungsspektrum aufzuzeigen, werden drei unterschiedliche repräsentative Problemstellungen bearbeitet. Dabei wird für Mehrschichtverbunde die Festigkeitsoptimierung hinsichtlich eines bruchtypbezogenen Versagenskriteriums vorgenommen, ein Dämpfungsmodell zur Materialcharakterisierung entworfen sowie eine bivalente Optimierungsstrategie zur Auslegung von gewickelten Hochdruckbehältern erstellt. Die Grundlage der entwickelten Methoden bilden dabei jeweils stochastische naturanaloge Optimierungsheuristiken, da die betrachteten Aufgabenstellungen nicht konvex sind und derartige Verfahren flexibel eingesetzt werden können. / The full utilization of the light weight potential in the dimensioning of multilayer fiber reinforced composites requires suitable optimization tools, since a large number of design variables has to be taken into account. In this work, optimization algorithms and strategies for the solution of scientific questions for industrial applications are developed and evaluated in the design of corresponding fiber-plastic composites. In order to show the wide range of applications, three different representative topics have been chosen. It will carry out a strength optimization for multilayer composites with regard to a type-related failure criterion, devolop a damping model for material characterization and established a bivalent optimization strategy for the design of wound high-pressure vessels. The developed methods are based on stochastic natural-analog optimization heuristics, since the considered tasks are not convex and such methods can be used in a very flexible manner.

共著者あり。共著者名: 亘理文夫，今井徹，山方秀一，小林雅博. 日本歯科理工学会, 豊泉裕，亘理文夫，今井徹，山方秀一，小林雅博 = TOYOIZUMI, Hiroshi ; WATARI, Fumio ; IMAI, Tohru ; YAMAGATA, Shuichi ; KOBAYASHI, Masahiro, 光重合法による曲げおよびねじり剛性を有する審美性矯正ワイヤーの試作 = Fabrication of Aesthetic Wires with Flexural and Torsional Stiffness by Photo Curing Method, 歯科材料・器械 = The Journal of the Japanese Society for Dental Materials and Devices, 18(6), 1999 NOV, pp.429-440 / Hokkaido University (北海道大学) / 博士 / 歯学

This thesis focuses on transport properties and durability of liquid crystalline polymers (LCP)and fibre reinforced plastics (FRP) with regard to application in industrial process equipment.In the first part of the study the possibility of using a thermotropic LCP of type Vectra A950as lining material for FRP process equipment was investigated. Its performance wascompared to that of a fluorinated ethylene propylene copolymer (FEP) with respect tochemical and permeation resistance. Transport property and chemical resistance data wereestablished for different types of LCP film (compression molded, uniaxially and biaxiallyoriented film) exposed to selected chemicals chosen to represent typical industrial processenvironments. Annealing of the LCP, which may reduce the disclination density and henceimprove the barrier properties, induced a crystallinity increase, but did not significantlyimprove the barrier and chemical resistance properties. Different surface treatments toincrease the bonding between the LCP and FRP were explored. The conclusion was that LCPhas potential to serve as lining material for FRP in contact with water, organic solvents andnon-oxidizing acid environments, although certain issues, such as jointing techniques, stillhave to be evaluated. The second part of the study focused on transport and long-termproperties of commercial thermoset and FRP materials for industrial process equipment inaqueous environments (50 – 95 °C, water activity 0.78 – 1, exposure time ≤ 1000 days). Thewater transport properties in different thermosets were related to their chemical structureusing the solubility parameter concept. The transport of water in the thermosets with differentchemical structures could be predicted from the water activity, regardless of the actual type ofionic or non-ionic solute in the solution. An empirical relationship, independent of boththermoset chemistry and temperature, was established to describe the water concentration inthe thermoset as a function of water activity and the water concentration in pure water. Inlong-term, the water concentration in the thermosets increased with exposure time. Thisseemed to be primarily related to stress relaxation processes induced by water absorption andcertain leaching effects. The effects of hydrolysis seemed to be small. The glass fibrereinforcement may to various extents affect the water transport properties by capillarydiffusion and additional absorption around fibre bundles. The extent of such processesseemed to depend on temperature, water activity and the type of thermoset and reinforcement.The present work may be a useful contribution to an increased understanding of water effectsand durability of FRP process equipment. However, open questions still remain for a morecomprehensive durability analysis. / QC20100629

Αντικείμενο της παρούσας Διατριβής Διπλώματος Ειδίκευσης αποτελεί η πειραματική διερεύνηση της αποτελεσματικότητας της περίσφιγξης υποστυλωμάτων οπλισμένου σκυροδέματος με μεγάλο λόγο πλευρών με μανδύες ινοπλισμένων πολυμερών και με μανδύες ινοπλεγμάτων σε ανόργανη μήτρα. Για το σκοπό αυτό διενεργήθηκε εκτενές πειραματικό πρόγραμμα στο Εργαστήριο Μηχανικής και Τεχνολογίας Υλικών του Τμήματος Πολιτικών Μηχανικών του Πανεπιστημίου Πατρών. Το πειραματικό πρόγραμμα περιελάμβανε 18 υποστυλώματα υπό κλίμακα 3/5 ύψους 770 mm τα οποία χωρίστηκαν σε δύο ομάδες, ανάλογα με το λόγο των πλευρών τους (1η ομάδα: με λόγο πλευρών 1:3, 150×450mm, 2η ομάδα: με λόγο πλευρών 1:4, 150×600mm). Δύο από τα υποστυλώματα παρέμειναν χωρίς ενίσχυση και αποτέλεσαν τα δοκίμια αναφοράς για τα ενισχυμένα δοκίμια, τα οποία περισφίχθηκαν με μανδύες ΙΟΠ και ΙΑΜ. Τα συστήματα ενίσχυσης που χρησιμοποιήθηκαν περιελάμβαναν μανδύες ΙΟΠ ινών άνθρακα με μια, δύο ή τρεις στρώσεις, χωρίς ή με αγκύρια ινών άνθρακα μορφής θυσάνου καθώς και μανδύα με δύο στρώσεις περιμετρικά του δοκιμίου και μανδύα μορφής U και αγκύρια ινών. Επιπλέον, εξετάστηκαν και μανδύες με τέσσερεις στρώσεις ινοπλέγματος με ίνες άνθρακα σε ανόργανη μήτρα με και χωρίς αγκύρια ινών άνθρακα μορφής θυσάνου εμποτισμένων σε εποξειδική ρητίνη. Η παρούσα διατριβή αποτελείται από οχτώ κεφάλαια, κάθε ένα από τα οποία διαχωρίζεται σε κατάλληλες ενότητες, υποενότητες και παραγράφους. Στο πρώτο και δεύτερο Κεφάλαιο γίνεται μια εισαγωγή στα σύνθετα υλικά με περιγραφή των επιμέρους συστατικών τους, των χαρακτηριστικών ιδιοτήτων τους καθώς και των παραγόντων που επηρεάζουν τη συμπεριφορά τους. Στο τρίτο Κεφάλαιο πραγματοποιείται βιβλιογραφική ανασκόπηση για την περίσφιγξη υποστυλωμάτων, όπου αρχικά περιγράφονται συμβατικές τεχνικές ενίσχυσης που περιλαμβάνουν νέους μανδύες οπλισμένου σκυροδέματος, μεταλλικά ελάσματα, μεταλλικούς μανδύες κλπ και στη συνέχεια περιγράφονται τεχνικές ενίσχυσης με σύνθετα υλικά. Περιγράφεται ο καταστατικός νόμος που διέπει τη συμπεριφορά του περισφιγμένου με μανδύες σύνθετων υλικών σκυροδέματος και παρουσιάζονται συνοπτικά πειραματικές μελέτες από τη διεθνή βιβλιογραφία που αφορούν τη διερεύνηση της αποτελεσματικότητας της μεθόδου ενίσχυσης µε ΙΟΠ σε υποστυλώματα με μικρό και μεγάλο λόγο πλευρών. Τέλος, το κεφάλαιο ολοκληρώνεται με συνοπτική αναφορά πειραματικών μελετών σε δοκίμια περισφιγμένα με μανδύες σε ανόργανη μήτρα. Στο τέταρτο Κεφάλαιο παρουσιάζεται η πειραματική διαδικασία που ακολουθήθηκε για την κατασκευή των δοκιμίων καθώς και οι παράμετροι που διερευνήθηκαν. Συγκεκριμένα, περιγράφονται όλα τα υλικά που χρησιμοποιήθηκαν, τα διάφορα συστήματα ενίσχυσης που εφαρμόστηκαν καθώς και οι διαδικασίες που ακολουθήθηκαν από την προετοιμασία των δοκιμίων μέχρι την ενίσχυσής τους. Στο τέλος του κεφαλαίου γίνεται μια σύντομη περιγραφή της πειραματικής διάταξης και του επιμέρους μηχανικού εξοπλισμού που χρησιμοποιήθηκε για την υλοποίηση των δοκιμών μονοαξονικής θλίψης. Στο πέμπτο Κεφάλαιο παρουσιάζονται διεξοδικά τα αποτελέσματα όλων των δοκιμίων που συμμετείχαν στο πειραματικό πρόγραμμα. Πιο συγκεκριμένα, περιγράφονται οι τρόποι αστοχίας των δοκιμίων συνοδεία φωτογραφικού υλικού και παρατίθενται οι καμπύλες τάσης – παραμόρφωσης τόσο για κάθε ένα ξεχωριστά όσο και συγκεντρωτικά για κάθε ομάδα. Στο έκτο Κεφάλαιο γίνεται σύγκριση των αποτελεσμάτων όλων των πειραμάτων που διεξήχθησαν στο Εργαστήριο Μηχανικής και Τεχνολογίας Υλικών σε υποστυλώματα με λόγους πλευρών 1:3 και 1:4 περισφιγμένα με μανδύες ΙΟΠ και ΙΑΜ προκειμένου να εξαχθούν γενικότερα συμπεράσματα πάνω στην επίδραση του υλικού της μήτρας, του αριθμού των στρώσεων και της ύπαρξης αγκυρίων στην αποτελεσματικότητα της περίσφιγξης. Στο έβδομο Κεφάλαιο παρουσιάζονται τα αποτελέσματα από ένα αναλυτικό προσομοίωμα που χρησιμοποιήθηκε για την πρόβλεψη του μέγιστου θλιπτικού φορτίου και της οριακής παραμόρφωσης αστοχίας των περισφιγμένων με μανδύες ΙΟΠ και ΙΑΜ. Επιπλέον, γίνεται σύγκριση των αποτελεσμάτων του αναλυτικού προσομοιώματος με τα πειραματικά δεδομένα και εξετάζεται κατά πόσο αυτό το προσομοίωμα μπορεί να χρησιμοποιείται για υποστυλώματα με μεγάλο λόγο πλευρών, μετά από αλλαγή κάποιων παραμέτρων του. Στο όγδοο και τελευταίο Κεφάλαιο, παρουσιάζονται συνοπτικά τα τελικά συμπεράσματα που προέκυψαν αρχικά από την πειραματική διαδικασία και στη συνέχεια από τη χρήση του αναλυτικού προσομοιώματος. Τέλος, γίνονται και μερικές προτάσεις για περαιτέρω έρευνα πάνω σε υποστυλώματα με μεγάλο λόγο πλευρών. / The present study investigates experimentally the effectiveness of the confinement of reinforced concrete (RC) columns with high aspect ratio (wall-like RC columns) retrofitted either with fiber-reinforced polymer (FRP) or with textile-reinforced mortars (TRM) jackets. For this purpose an extensive experimental program was conducted at the Structural Materials Laboratory of the Civil Engineering Department at the University of Patras. A total of 18 identical rectangular reinforced concrete columns were constructed in a scale of 3/5 and 770 mm height so that the slenderness effects could be eliminated and tested in uniaxial compression. The columns were separated in two groups according to their aspect ratio; the first group consisted of seven RC column specimens with cross section dimensions 150mm by 450mm and an aspect ratio equal to 3, and the second group consisted of eleven RC column specimens with cross section dimensions 150mm by 600mm and an aspect ratio equal to 4. To facilitate FRP and TRM wrapping, the four corners were chamfered with a radius equal to 20mm. A number of parameters were investigated such as the kind of the matrix material (organic and inorganic), the number of layers of the jackets (1, 2, 3 and 4), the role of different cross section aspect ratios (3 and 4), the effectiveness of spike anchors (resin-impregnated fiber rovings) and local strengthening with U shape jacketing placed at the smaller sides of the columns. The first chapter provides general information on FRP materials describing their individual components, their characteristic properties, the factors affecting their behavior as well as the basic techniques for their application. The second chapter describes the composite materials in inorganic matrix (TRM) and presents a comparison between the two composite material strengthening systems. In the third chapter a brief literature review is provided about the confinement of columns with conventional techniques (e.g. steel plating, steel jacketing, RC jacketing) as well as with composite materials. The constitutional law of confined concrete with jackets of composite materials is described. Furthermore some experimental studies from the international literature are presented concerning the effectiveness of the confinement with FRP jackets of columns with small and high aspect ratio. Finally, the chapter concludes with a brief reference to experimental studies on specimens confined with jackets in inorganic matrix (TRM jackets). The fourth chapter presents the procedure for constructing and retrofitting the specimens including the materials used (carbon fiber fabric and textile, carbon fiber spike anchors, epoxy resin, inorganic matrix) as well as the equipment used for uniaxial compression tests. In the fifth chapter the results for each specimen are given presenting their failure mode and the corresponding load - displacement curve. In the following chapter the results for each group are compared in order to establish general conclusions on the effect of the kind of the matrix material, the number of layers and the existence of FRP anchors in confinement of wall-like RC columns. The seventh chapter presents the results of an analytical model used to predict the maximum compressive load and the ultimate deformation of specimens confined with FRP or TRM jackets. A comparison between the experimental and the analytical results is made and it is examined whether this model can be used for columns with high aspect ratio after modifying some of the parameters. The eighth chapter summarises the most important conclusions of all investigations carried out by the present project for both the experimental procedure and the analytical model. Finally, some suggestions for further research on columns with high aspect ratio are listed.

The flexural performance of composite systems made of reinforced concrete, Fibre Reinforced Polymers (FRPs) and adhesives was studied during the current research. The experimental investigation was principally concentrated on the potential use of Kevlar® 49 (aramid fibre) for RC beam strengthening. The main aims of research have been; (a) to investigate the relative merits of using Aramids in comparison to other FRPs, (b) strength optimisation of systems to prevent excessive losses of ductility, (c) to examine the failure mode and crack patterns, together with salient strength factors at ultimate limit state and (d) to carry out analytical modelling using a commercial FE package. The experimental investigation comprised of testing 55 simply supported RC beams of either 1.5m or 2.6m length. In addition to the parametric studies included in points (a)-(d) above (to assess the section characteristics), further experimentation was conducted to investigate the beam performance by varying the factors of; (e) beam shear span, (f) FRP anchorage length, (g) concrete surface preparation, (h) FRP end-anchoring, (i) beam precracking, (j) introduction of air-voids within the bond line of FRP/concrete, (k) influence of cyclic loading and, (1) exposure to aggressive environment. The results from current tests confirm elements of reports from other researchers (by thorough review of literature) that all FRPs have great potential for flexural strengthening of RC members. This is valid even in cases where additional environmental degradation and/or cracking (due to serviceability loads), had taken place. Aramid fibres were found to result in favourable outcomes concerning both strength and ductility enhancements. It was determined, both from experiments and non-linear modelling, that the amount of FRP fibre content is an important factor in every strengthening application. Experimentation showed that depending on the existing condition of the structure (concrete strength, internal reinforcement ratio, section dimensions, degradation level and load configuration), there seems to be a unique level of optimum fibre content. The FRP levels in excess of the optimum were seen to lead to premature brittle tearing-off failure modes. It was also found that to prevent premature beam failure (due to incompatibility of stress at concrete and FRP interface), a maximum possible anchorage length should be considered in order to deliver an optimum section performance. The results from the analytical modelling indicated a most satisfactory agreement with the experimental data after the initial mechanical properties were calibrated. It was found that actual representation of material properties (e.g. steel constitutive law) are of great significance, for an accurate modelling of RC element loaded behaviour. The bond developed between the FRP and concrete is one of the key parameters for achieving good performance of the systems. It was determined that concrete surface preparation and priming is beneficial, while the introduction of air-voids due to poor workmanship can reduce the section load bearing capabilities. Cyclic loading on FRP strengthened sections was found to curtail the full rotational capacity utilisation of the beam. However, even the above mentioned curtailed behaviour was more advantageous than cyclically loaded beam performance without FRP strengthening.

Dans le cadre de la mise à niveau sismique des bâtiments existants, la technique de renforcement par placage et enrobage de polymères renforcés de fibres (FRP) offre une réponse pertinente. L’objectif de cette thèse est de proposer une modélisation fiable pour la détermination de la réponse quasi-statique et dynamique d’une grande variété d’éléments de structure et d’identifier les apports possibles d’une telle modélisation à la conception. Les stratégies de modélisation s’appuient sur l’utilisation d’éléments finis massifs ou basés sur une cinématique simplifiée (coques multicouches et poutres multifibres), associés à des modèles locaux d’endommagement et de plasticité pour les matériaux en présence (béton, armatures et FRP). L’hypothèse d’adhérence parfaite, d’une part, entre les armatures et le béton, et d’autre part, entre les bandes de FRP et le béton, permet de calculer efficacement les cas des poteaux courants, des poteaux courts, des voiles longs et courts, dans les régimes quasi-statique (pushover) et dynamique. Le renforcement par placage et enrobage FRP pour des structures en béton armé, est reproduit au sein de la modélisation par un apport de matière (éléments de type barre avec les caractéristiques propres des FRP) et des modifications des paramètres de la loi de comportement du béton, justifiées par l’expérimentation et la littérature. La pertinence de l’approche est finalement démontrée en confrontant la réponse temporelle de structures à l’échelle 1, de type ossature ou de type contreventé par des voiles, aux résultats expérimentaux issus de benchmarks internationaux. / In the context of the building’s protection against seismic risk, the strengthening technique by FRP (Fiber Reinforced Polymers) plating and wrapping provides a relevant solution. The objective of this thesis is to propose a reliable modeling for determining the quasi-static and dynamic responses of a wide variety of structural elements and to draw advantage in design. The modeling strategies make use of 3D elements or finite elements based on simplified kinematics (multilayer shells or multifiber beams), associated with local damage and plasticity laws for the constitutive materials (concrete, rebar and FRP). The perfect bond assumption between steel-concrete and FRP-concrete allows efficiently calculating the quasi-static and dynamic behaviors of short and slender columns, as well as short and slender walls. The mechanical contribution of FRP plating and wrapping is reproduced in the modeling by adding material (bar type elements with FRP characteristics) and by changing the parameters of the concrete model on the basis of the experience and analytical formula issued from the literature. The relevance of the approach is finally highlighted by comparing the time-history response of real braced frame or wall structures with the experimental results.

Abstract : Deterioration of concrete structures reinforced with steel bars can be seen daily in regions with aggressive weather as steel-corrosion problems worsen. Fiber-reinforced-polymers (FRP) reinforcement has proven its feasibility through different civil structural elements. Present guidelines for FRP structures in North-America and Europe have not yet handled axially loaded members, due to the lack of research and experiments. This research takes charge of providing experimental database as well as extensive analyses and design recommendations of circular concrete columns reinforced totally with different FRP bars and spirals/hoops (FRP-RC columns). Full-scale columns were tested under monotonic loading with different levels of eccentricity. Test variables included the eccentricity-to-diameter ratio (e/D); reinforcement type (GFRP and CFRP vs. steel); concrete strength; longitudinal and transverse reinforcement ratio; and confinement configuration. All specimens measured 305 mm diameter and 1500 mm height. Test results indicated that specimens reinforced with glass-FRP (GFRP) or carbon-FRP (CFRP) reached their peak strengths with no damages to GFRP or CFRP rebar on either side of specimens. Specimens with CFRP reinforcement (CFRP-RC) behaved very similarly to their steel counterparts, and achieved almost the same nominal axial forces. Specimens with GFRP reinforcement (GFRP-RC) exhibited, however, reduced stiffness and achieved lower nominal axial forces than their steel or CFRP counterparts. Failure of GFRP-RC and CFRP-RC specimens was dominated by concrete crushing at low levels of eccentricity (e/D ratios of 8.2% and 16.4%). Experimental strain results revealed that GFRP bars developed high levels of strains and stresses on the compression and tension sides and hence the GFRP-RC specimens could sustain constant axial load after peak for some time up to the limit of concrete crushing at higher levels of eccentricity (e/D ratios of 8.2% and 16.4%), which help to delay the full damage. At these levels, flexural–tension failure initiated in the GFRP-RC specimens resulting from large axial and lateral deformations and cracks on the tension side until secondary compression failure occurred due to strain limitations in concrete and degradation of the concrete compressive block. The failure of CFRP-RC specimens at higher levels of eccentricity (e/D ratios of 8.2% and 16.4%) was characterized as flexural–compression in which it took place in a less brittle manner. On the other hand, this research also included different studies to analyze the test results, evaluate rebar efficiency, and provide recommendations for analysis and design. It was, therefore, indicated that the axial and flexural capacities of the tested FRP-RC specimens could be reasonably predicted using plane sectional analysis, utilizing the equivalent rectangular stress block (ERSB) parameters given by the ACI 440.1R-15 or CSA S806-12. All predictions underestimated the actual strength with variable levels of conservatism ranged between 1.05 to 1.25 for the GFRP-RC specimens and between 1.20 to 1.40 for the CFRP-RC specimens. These levels were noticeably reduced to critical limits in specimens with high-strength concretes. An elaborate review was made to the available ERSB parameters in the present steel and FRP design standards and guidelines. Modified expressions of the ERSB given in ACI 440.1R-15 and CSA S806-12 were developed. The results indicated good correlation of predicted and measured strength values with enhanced levels of conservatism. Additionally, sets of axial force–bending moment (P-M) interaction diagrams and indicative bar charts are introduced, and recommendations drawn. The compressive-strength contribution of FRP reinforcement was thoroughly reviewed and discussed. The minimum GFRP and CFRP reinforcement ratios to avoid rebar rupturing were broadly examined. Finally, the flexure stiffness (EI) of the tested specimens was analytically determined and compared with the available expressions using experimental and analytical M-ψ responses. Proposed equations are developed and validated against the experimental results to represent the stiffness of GFRP-RC and CFRP-RC columns at service and ultimate levels. / La détérioration des structures en béton armé avec des barres d’armature d’acier peut être observée quotidiennement dans les régions à climat agressif. Le renforcement interne en polymères renforcés de fibres (PRF) a démontré sa faisabilité grâce à différents éléments structuraux en génie civil. Les lignes directrices actuelles pour les structures en béton armé de PRF en Amérique du Nord et en Europe n'ont pas encore gérées les sections soumises à des efforts axiaux excentrique, en raison du manque de recherches et d'expériences. Cette recherche permet d’augmenter la base de données expérimentales ainsi établir des analyses approfondies et des recommandations de conception pour les colonnes circulaires en béton armé complètement renforcées de PRF (barres et spirales). Des grandeur-nature colonnes ont été testées sous charge monotone avec différents niveaux d'excentricité. Les variables de test comprenaient le rapport excentricité / diamètre (e/D) ; le type de renfort (PRFV et PRFC comparativement à l’acier); la résistance du béton en compression; le taux d’armature longitudinal et transversal; et la configuration de l’armature de confinement. Tous les échantillons mesuraient 305 mm de diamètre et 1500 mm de hauteur. Les résultats des tests ont indiqué que les spécimens renforcés avec des PRF de verre ou des PRF de carbone atteignaient leur résistance maximale sans endommager les barres d’armature. Des deux types de renforcement, les spécimens de PRFCCFRP se comportaient de manière très similaire à leurs homologues en acier et atteignaient presque les mêmes résistances axiales. Cependant, les spécimens avec renforcement en PRFV ont présenté une rigidité réduite et des forces axiales nominales inférieures à celles de leurs homologues en acier ou en PRFC. Le mode de rupture des spécimens de PRFC et de PRFV a été dominé par l’écrasement du béton à de faibles niveaux d'excentricité (rapports e/D de 8,2% et 16,4%). Les résultats ont révélé que les barres de PRFV ont développé des niveaux élevés de déformations et de contraintes sur les faces en compression et en tension et, par conséquent, les spécimens de PRFVC pourraient supporter une charge axiale constante après la résistance ultime pendant un certain temps jusqu'à la limite de la rupture en compression du béton du noyau à des niveaux supérieurs d'excentricité (rapport e/D de 8,2% et 16,4%), ce qui contribue à retarder la dégradation. À ces niveaux, une rupture en tension a été initiée dans les spécimens de PRFV résultant à de grandes déformations axiales et latérales et des fissures du côté de la face en tension jusqu'à ce que la rupture en compression du béton. La rupture des spécimens de PRFC à des niveaux supérieurs d'excentricité (rapport e/D de 8,2% et 16,4%) a été caractérisé comme étant en compression du béton dans laquelle il s'est déroulé de manière moins fragile. D'autre part, cette recherche comprenait également différentes études pour analyser les résultats des tests, évaluer l'efficacité des barres d'armature et fournir des recommandations pour l'analyse et la conception. Il a donc été indiqué que les capacités axiales et de flexion des spécimens en PRF testées pourraient être raisonnablement prédites en utilisant une analyse en section plane, en utilisant les paramètres du bloc de contrainte rectangulaire équivalent (BCRE) donnés par l'ACI 440.1R-15 ou la CSA S806- 12. Toutes les prédictions ont sous-estimé la résistance réelle avec des niveaux de variabilité conservateur entre 1,05 et 1,25 pour les spécimens de PRFC et entre 1,20 et 1,40 pour les spécimens de PRFC. Ces niveaux ont été nettement réduits à des limites critiques dans les spécimens avec des bétons à haute résistance. Un examen approfondi a été effectué sur les paramètres du BCRE disponibles dans les normes et les directives de conception actuelles en acier et en PRF. Les expressions modifiées du BCRE fournies dans ACI 440.1R-15 et CSA S806-12 ont été développées. Les résultats indiquent une bonne corrélation entre les valeurs de résistance prédites et mesurées avec des niveaux accrus de conservatisme. La contribution de la résistance à la compression du renforcement en PRF a été soigneusement examinée et discutée. Le taux d’armature minimum de PRFV et de PRFC pour éviter la rupture de l'armature ont été largement examinés. Enfin, la rigidité en flexion (EI) des spécimens testés a été déterminée de manière analytique et comparée aux expressions disponibles dans la littérature en utilisant les réponses expérimentales et analytiques M-ψ. Les expressions modifiées de la rigidité en flexion EI apportées dans l’ACI 440.1R ont été développées et validées.

Le renforcement de structures ou d'éléments de structure par collage de plats PRF (polymères renforcés de fibres) est une technique actuellement reconnue et utilisée dans le monde entier. Il permet d'augmenter la durée de vie des structures existantes ce qui est très intéressant du point de vue développement durable et est souvent plus intéressant d'un point de vue économique. La première partie de ce travail s'intéresse au renforcement de poutres béton armé par des plats PRF. En effet, ce type de renforcement peut engendrer une rupture prématurée de type peeling-off. Ce mode de ruine très fragile résulte du décollement du béton d'enrobage qui reste collé au matériau de renforcement. Pour une conception optimale d'un renforcement en flexion par collage, il est important d'être en mesure de prévoir ce type de rupture et d'en tenir compte dans le dimensionnement. Pour cela, un modèle numérique fiable de type élasto-plastique est dans un premier temps présenté qui permet de prévoir la rupture de type peeling-off. Ce modèle est validé à l'aide de résultats d'essais expérimentaux. Les paramètres principaux affectant l'efficacité du renforcement sont ensuite mis en évidence dans le cadre d'une étude paramétrique. Les résultats de cette étude sont mis en parallèle avec des résultats d'essais de la littérature prouvant ainsi l'efficacité du modèle proposé. Enfin, plusieurs mesures sont proposées pour améliorer la performance du renforcement et éviter la rupture prématurée de peeling-off. La deuxième partie de ce travail s'attache quant à elle à l'étude de renforcement de tabliers de ponts soumis aux efforts éventuels d'impact d'un véhicule sur une barrière de sécurité. Une campagne expérimentale composée de différentes configurations de dalles est d'abord réalisée. Un modèle numérique s'inspirant du modèle proposé précédemment est ensuite présenté. La confrontation des résultats expérimentaux et numériques montre une concordance encourageante avant la fissuration majeure de la dalle. Enfin, les résultats mettent en relief l'efficacité du renforcement par des plats PRF dans le cas de glissières de sécurité / Strengthening of structures by bonding FRP plates (fiber reinforced polymer) is a technique currently recognized and used worldwide. This method is a viable solution to costly replacement of deteriorating structures and increases the life of reinforced structures. The first part of this doctoral work focuses on the strengthening of reinforced concrete beams with FRP plates and more precisely on a premature failure caused by this type of reinforcement called peeling-off or concrete cover separation. This brittle failure mode which prevents the strengthened RC beams from attaining their ultimate flexural capacity involves the tearing-off of the concrete cover along the level of tension steel reinforcement starting from a plate end. The first step for a successful, safe and economic design of flexural strengthening using FRP composite at the bottom of the beam is then to predict such failure and to take it into account in design. A reliable numerical model analysis which is validated by test results is first presented to predict ultimate loading capacity and the failure mode of RC beams in a four-point bending setup. The main parameters affecting the efficiency of the reinforcement are then highlighted in a parametric study. The results of this study are compared with test results in the literature demonstrating the efficiency of the proposed model. Finally, several measures are proposed to improve the performance of the strengthening and in order to avoid the premature rupture of peeling-off. The second part of this work is concerned with the strengthening study of a bridge deck subject to eventual loads generated by a car crash into a safety barrier. A series of equivalent impact tests is first performed on deck slabs. A numerical model inspired by the previously proposed model for RC beams is then presented. Comparisons between the predictions of the numerical model and test results show a good agreement before the major cracking of the slab. Finally, the results highlight the efficiency of FRP plates in the case of safety guardrails

Masonry structures constitute a significant portion of building stock worldwide. Seismic performance of unreinforced masonry has been far from satisfactory. Masonry is purported to be a major source of hazard during earthquakes by reconnaissance surveys conducted aftermath of an earthquake. Reasons for the poor performance of masonry structures are more than one namely lack of deformational capacity, poor tensile strength & lack of earthquake resistance features coupled with poor quality control and large variation in strength of materials employed. Fibre Reinforced Plastic (FRP) composites have emerged as an efficient strengthening technique for reinforced concrete structures over the past two decades. Present thesis is focused towards analysing the behaviour of Fibre Reinforced Plastic (FRP) strengthened masonry under axial compression and in-plane shear loading. Determination of in-planes hear resistance of large masonry panels requires tremendous effort in terms of cost, labour and time. Masonry assemblages like prisms and triplets that represent the state of stress present in masonry walls and masonry in-fills when under the action of in-planes hear forces present an alternative option for research and analysis purposes. Hence, present research is focused towards analysing the performance of FRP strengthened masonry assemblages and unreinforced masonry assemblages. Chapter1 provides a brief review on the behaviour of masonry shear walls and masonry in-fills under the action of in-plane shear forces in addition to the performance of masonry structures during past earthquakes. Review of available literature on FRP confinement of masonry prisms with bed joints inclined from 00 to 900 to the loading axis under axial compression, analytical models available for FRP confined concrete, shear strength of masonry triplets attached with FRP is presented. Chapter 2 primarily focuses on determining the various properties of the materials involved in this research investigation. Test procedure and results of the tests conducted to determine the mechanical and related properties of the materials involved are presented. Elastic properties and stress-strain response of burnt clay brick, mortar and FRP laminates are presented. Studies conducted on behaviour of GFRP confined masonry prisms under monotonic axial compression are included in Chapter 3. The study comprised of testing masonry prisms, both unconfined and FRP confined masonry prisms under axial compression. Stretcher bond and English bond prisms, with bed joints normal and parallel to loading axis are included in this study. Two grades of GFRP,360g/m2 and 600 g/m2 are employed to confine masonry prisms. The experimental program involved masonry prism types that accounted for variations in masonry bonding pattern, bed joint inclination to the loading axis and grade of GFRP. Review of the available analytical models predicting compressive strength of FRP confined masonry prism is presented. Available models for FRP confinement of masonry are re-calibrated using the present experimental data generating new coefficients for the already existing model to develop new expression for predicting the compressive strength of FRP confined prisms. In addition to the prism types mentioned earlier, behaviour of unconfined and GFRP confined stretcher bond prisms with bed joints inclined at 300, 450 & 600 to the loading axis are further investigated. Chapter 4 primarily deals with the shear strength and deformational capacity of masonry triplets that represent joint shear failure in masonry. An experimental program involving masonry triplets attached with different types of FRP(GFRP and CFRP), grade of FRP, percentage area covered by FRP and reinforcement pattern is executed. This exercise determined the influence of these parameters over the enhancement achieved in terms of shear strength and ultimate displacement. Results of tests conducted on stretcher bond prisms presented in chapter 3 and results of tests on shear triplets presented in this chapter are combined to study the interaction between shear and normal stresses acting along the masonry bed joint at different angles of inclination. The thesis culminated with chapter 5 as concluding remarks highlighting the salient Information pertaining to the behaviour of FRP strengthened masonry under axial compression and in-plane shear loading obtained as an outcome of the research conducted as a part of this thesis.

This master thesis deals with the implementation of variants of cryptographic libraries containing primitives for elliptic curves. By creating custom metering charts to compare each implementation. The main task was not only the implementation of libraries but also the design and implementation of test scenarios together with the creation of measurement methods for different libraries and hardware platforms. As a result, a number of experimental tests were conducted on different curves and their parameters so that the results of the work included complex problems of elliptic curves in cryptography. The main parameters were power, time and memory consumption.