Os estudos focando a otimização do reforço dos tubos de concreto para obras de saneamento são importantes por estes componentes estarem vinculados a grandes necessidades sociais que ainda atingem o Brasil e outros países em desenvolvimento bem como pelo fato destes componentes serem produzidos em série, o que gera economia de escala. Neste sentido, a utilização de fibras como reforço dos tubos trás consigo um grande número de vantagens aplicativas e de desempenho. A tendência internacional de busca por um consenso no dimensionamento e controle do concreto reforçado com fibras (CRF) como material estrutural está sendo direcionada para o fib Model Code 2010. Geralmente, para a caracterização do CRF são utilizados os ensaios de flexão de vigas. Porém, a moldagem desses corpos de prova para o controle do CRF dos tubos apresentou resultados inadequados em estudos anteriores. A definição do reforço ótimo de tubos de CRF através da tentativa e erro no ensaio de compressão diametral do componente deve ser evitada pelos elevados gastos (financeiros, de material e tempo) associados a esta metodologia. O projeto deve ser atingido através de modelos confiáveis que possam otimizar o reforço através da previsão adequada do desempenho do componente. Da mesma forma, deve-se obter procedimentos de controle do material que sejam concatenados com os procedimentos de controle do produto. Neste sentido, esta tese propõe uma metodologia para a caracterização e controle do comportamento mecânico do CRF para a produção de tubos, que permita modelar o comportamento do componente no ensaio de compressão diametral e verificar sua adequação a uma aplicação estrutural. O estudo foi dividido em três fases principais. Na primeira houve a avaliação de um método de ensaio alternativo ao de flexão de prismas para o controle do CRF. Na segunda fase experimental houve a incorporação de modificações no método de ensaio de compressão diametral do componente de modo a aproximá-lo à filosofia do fib Model Code 2010. Nesta etapa foram avaliados tubos com reforço de fibras de aço, macrofibras poliméricas e vergalhões para comprovar a pertinência da nova metodologia de ensaio. Na terceira fase do estudo foi realizada uma simulação numérica para previsão de comportamento dos componentes ensaiados utilizando os parâmetros do material caracterizados através do método de ensaio alternativo validado na primeira fase. Os resultados obtidos na modelagem foram comparados com o resultado experimental do ensaio do componente de modo a validar a metodologia proposta. Os resultados demonstraram a adequação do ensaio Barcelona para a caracterização e controle do comportamento mecânico do CRF destinado à produção de tubos. Essa caracterização poderá subsidiar simulações numéricas do comportamento do componente no ensaio de compressão diametral. Com isto, ábacos de projeto de tubos de concreto reforçados com diferentes tipos de fibras poderão ser desenvolvidos, identificando as classes resistentes que serão atendidas dependendo do diâmetro do tubo e do teor de fibras empregados. Esta tese aponta também para a necessidade de uma revisão na normalização vigente, estabelecendo critérios relacionados ao comportamento pós-fissuração que avaliem o estado limite de serviço e o estado limite último. Isto permitirá uma avaliação homogênea do tipo de reforço e tornará mais adequada a comparação entre distintos tipos de reforço (fibras ou convencional). / The international trend for a consensus about the design and control of fibre reinforced concrete (FRC) as a structural material is based on the fib Model Code 2010. Generally, in order to characterize the FRC, bending tests are used. However, the moulding of these control test specimens of the FRC pipes is not quite simple as has been shown by previous studies. The design of FRC pipes through trial and error in the component-crushing test should be avoided. This test shall be limited to the acceptance control or final validation of a new component, designed through reliable models that optimize the reinforcement and the component performance. These models should allow both design and prediction of the component behaviour related to the quality control. In that sense, this thesis proposes a methodology for characterizing and controlling the mechanical behaviour of FRC for the production of pipes. This study allows modelling the component behaviour in crushing test and verifying their suitability for structural application. The methodology considered consisted in three main topics: evaluation of an alternative method of FRC control test; modification of the procedure of the crushing test method in order to approach the fib Model Code 2010 philosophy, and prediction the mechanical behaviour of the components comparing numerical simulation results with experiments results. In this last topic, the characterization of the materials performance by the alternative test method was considered. The results indicated that the Barcelona test is suitable in order to characterize and control the mechanical behaviour of the FRC used for the production of pipes. This characterization is able to support numerical simulations of the component behaviour in crushing test. It allows the development of design tables identifying the pipes resistant classes considering a variety of parameters such as types and contents of fibres and pipes diameters. This thesis also points out the need for a review of the current standards, establishing parameters related to the post-cracking behaviour to assess the serviceability limit state and the ultimate limit state. This allows a homogeneous evaluation of the reinforcement type and makes it more suited to comparing different types of reinforcement (fibre or conventional).

Faserverbundwerkstoffe werden häufiger für Leichbauanwendungen eingesetzt. Thermoplastische Matrixmaterialien gewinnen in der letzten Zeit immer mehr an Bedeutung wegen höherer Produktivität, niedriger Kosten und besserer Umweltfreundlichkeit sowie Recyclingsfähigkeit. Im Rahmen des Projektes SFB 639 werden Spacer-Strukturen aus GF (Glas)- und PP (Polypropylen)-Filamenten verstärkten Textilien hergestellt. Die vorliegende Arbeit beschäftigt sich mit der Montage von textilen Preformen mittels Nähtechnik und den mechanischen Eigenschaften genähter thermoplastischer Faserverbundwerkstoffe. Das Ziel ist, durch Untersuchungen der Festigkeitseigenschaften von genähten thermoplastischen Faserverbundwerkstoffen die Möglichkeiten gezielter Verbesserung der mechanischen Eigenschaften herauszufinden. Als Versuchsmaterial werden Twintex®-Gewebe und Mehrlagengestrick (hergestellt im ITB) aus GF- und PP-Filamenten verwendet. Durch Zug-, Schub-, Biege- und interlaminare Scherfestigkeitsuntersuchungen ist festzustellen, dass das Nähen an mehrschichtigen thermoplastischen faserverstärkten Verbundwerkstoffe positiv wirken kann. Durch Verwenden thermoplastischer Nähfäden wie beispielsweise Polyester-Nähfäden kann die Zugfestigkeit des Verbundes sogar erhöht werden. Ohne Verminderung der Zugfestigkeit kann das Nähen die Schlagzähigkeit thermoplastischer Faserverbundwerkstoffe wesentlich erhöhen. Bei der Schlagbelastung erzeugen die Nähte neue Arten des Bruchs, so dass mehr Energie aufgenommen wird. Durch das Nähen lässt sich die Schlagzähigkeit besonders bei Faserverbundwerkstoffen mit thermoplastischer Matrix bei niedrigen Temperaturen erhöhen. Die Zugfestigkeitsuntersuchungen von genähten überlappenden Faserverbunden zeigen, dass das Nähen die Zugfestigkeit überlappender Bauteile leicht erhöhen kann. Die Erfahrungen mit der Wirkung von Überlappungen der Verstärkungstextilien in Faserverbundbauteilen mit duromerer Matrix sind nicht auf thermoplastische Matrices zu übertragen. Der Konsolidierungsprozess mit thermoplastischer Matrix mittels Presstechnologie erzwingt eine konstante Wandstärke, so dass lokal im Überlappungsbereich ein erhöhter Faservolumenanteil theoretisch zu erwarten und praktisch nachgewiesen ist. Zur Vorbereitung der Montage von Faserverbundbauteilen kann das Einbringen von Löchern zur Aufnahme von Bolzen oder Schrauben erforderlich sein. Ein Konzept für ein maschinelles Verfahren zur Lochverstärkung wird in dieser Arbeit vorgeschlagen. Der Konstrukteur von Faserverbundbauteilen muss außerdem berücksichtigen, dass ein Gewinn an Schlagzähigkeit mit Verlusten bei den In-Plane-Eigenschaften verbunden ist. Durch eine optimale Wahl der Nahtparameter lassen sich gewünschte Eigenschaften des Faserverbundwerkstoffes einstellen. Trotz vielfältiger, auch berechtigter Kritik besitzt das Nähen als Montageverfahren für Preformen eine Perspektive, wenn die Nähte zielführend positioniert und schonende Nähprozessbedingungen gewährleistet werden.

Die Arbeit beschreibt die skalenübergreifende Modellierung und Simulation des Werkstoffverhaltens von Faser-Kunststoff-Verbunden mit textiler Verstärkungsstruktur, die ausgehend von den konstitutiven Eigenschaften der Verbundbestandteile (Mikroskala) und ihrer geometrischen Anordnung im Verbund (Mesoskala) die rechnerische Vorhersage des effektiven Materialverhaltens des Verbundes (Makroskala) ermöglicht. Neben Schädigungsprozessen beeinflusst insbesondere das dehnratenabhängige Materialverhalten der polymeren Matrix das mechanische Verhalten des Verbundes. Dieser Einfluss wird anhand verschiedener Glasfaser-Polypropylen-Verbunde numerisch untersucht. Ein viskoplastisches Materialmodell bildet dabei das nichtlineare Materialverhalten von Polypropylen ab. Die Modellierung der textilen Verstärkungsstruktur erfolgt durch Anwendung der erweiterten Finiten-Elemente-Methode (XFEM). Anhand des Vergleichs von rechnerisch und experimentell gewonnenen Ergebnissen erfolgt schließlich die Verifikation der vorgeschlagenen Modellierungsstrategie. / This contribution covers the trans-scale modelling and simulation of the mechanical behaviour of textile-reinforced polymers. Starting from the material properties of the individual constituents (micro-scale) and their geometrical arrangement (meso-scale), the effective material behaviour of the composite (macro-scale) is numerically predicted. In addition to damage processes, the inelastic deformation behaviour of the composite is influenced by the strain-rate dependent material behaviour of the polymeric matrix. This influence is numerically investigated for different glass-fibre-polypropylene composites. A viscoplastic material model accounts for the nonlinear mechanical behaviour of polypropylene. The complex textile reinforcement is modelled by the eXtended finite element method (XFEM). A comparison of computed and experimental results allows for the verification of the proposed modelling strategy.

The benefits of fibre reinforced concrete (FRC) have been thoroughly investigated. Much of this work has focussed on steel FRC subjected to monotonic loads. Data on the structural behaviour of macro-synthetic FRC or FRC under cyclic loads is scarce. A pilot investigation on the shear behaviour of macro-synthetic FRC and on the behaviour of FRC under reversed cyclic in-plane shear loading was carried out. Five in-plane shear panel tests were performed. The parameters under study were the fibre material type (steel or macrosynthetic) and loading protocol. Additionally, a number of compression, direct tension, and flexural tests were performed to determine the material properties of the concretes for comparison. The material response of 2.0% by volume of macro-synthetic FRC matched closely with 1.0% steel FRC. Finally, building upon an existing steel FRC model, a model for macro-synthetic FRC in tension was proposed and a short verification study was undertaken.

The benefits of fibre reinforced concrete (FRC) have been thoroughly investigated. Much of this work has focussed on steel FRC subjected to monotonic loads. Data on the structural behaviour of macro-synthetic FRC or FRC under cyclic loads is scarce. A pilot investigation on the shear behaviour of macro-synthetic FRC and on the behaviour of FRC under reversed cyclic in-plane shear loading was carried out. Five in-plane shear panel tests were performed. The parameters under study were the fibre material type (steel or macrosynthetic) and loading protocol. Additionally, a number of compression, direct tension, and flexural tests were performed to determine the material properties of the concretes for comparison. The material response of 2.0% by volume of macro-synthetic FRC matched closely with 1.0% steel FRC. Finally, building upon an existing steel FRC model, a model for macro-synthetic FRC in tension was proposed and a short verification study was undertaken.

El uso de barras de materiales compuestos (FRP) se propone como una alternativa efectiva para las tradicionales estructuras de hormigón armadas con acero que sufren corrosión en ambientes agresivos. La aceptación de estos materiales en el mundo de la construcción está condicionada a la compresión de su comportamiento estructural. Este trabajo estudia el comportamiento adherente entre barras de FRP y hormigón mediante dos programas experimentales. El primero incluye la caracterización de la adherencia entre barras de FRP y hormigón mediante ensayos de pull-out y el segundo estudia el proceso de fisuración de tirantes de hormigón reforzados con barras de GFRP mediante ensayo a tracción directa. El trabajo se concluye con el desarrollo de un modelo numérico para la simulación del comportamiento de elementos de hormigón reforzado bajo cargas de tracción. La flexibilidad del modelo lo convierte en una herramienta flexible para la realización de un estudio paramétrico sobre las variables que influyen en el proceso de fisuración. / The use of Fibre Reinforced Polymers (FRP) as reinforcement in concrete structures is considered to be a possible alternative to steel in those situations where corrosion is present. The full acceptance of FRP reinforcement in concrete construction is contingent on a complete study and comprehension of all aspects of their structural performance. This thesis investigates the bond behaviour between Fibre Reinforced Polymer (FRP) reinforcement and concrete. Two experimental programs were conducted. In the first program the role of the variables which affect the bond behaviour was studied through pull-out test. In the second program, GFRP RC members were tested in tension to study their cracking response. To conclude the thesis, a numerical model was developed to simulate the cracking behaviour of RC tensile members. Since the model was flexible enough to include any "user-defined" bond-slip law and variable materials' properties, a parametric study was conducted to analyze which are the variables that influence the cracking behaviour.

Research Doctorate - Doctor of Philosophy (PhD) / Inserting fibre reinforced polymer (FRP) strips into pre-cut grooves in the surface of masonry walls is an emerging technique for the retrofit of unreinforced masonry (URM) structures. This method, known as near surface mounting (NSM), provides significant advantages over externally bonded FRP strips in that it has less of an effect on the aesthetics of a structure and can sustain higher loading before debonding. As this technique is relatively new, few studies into the behaviour of masonry walls strengthened using this technique have been conducted. A combined experimental and numerical program was conducted as part of this research project to study the in-plane shear behaviour of masonry wall panels strengthened with NSM carbon FRP (CFRP) strips. In this project the FRP strips were designed to resist sliding along mortar bed joints and diagonal cracking (through mortar joints and brick units). Both of these failure modes are common to masonry shear walls. Different reinforcement orientations were used, including: vertical; horizontal; and a combination of both. The first stage of the project involved characterising the bond between the FRP and the masonry using experimental pull tests (18 in total). From these tests the bond strength, the critical bond length and the local bond-slip relationship of the debonding interface was determined. The second stage of the project involved conducting diagonal tension/shear tests on masonry panels. A total of four URM wall panels and seven strengthened wall panels were tested. These tests were used to determine: the effectiveness of the reinforcement; the failure modes; the reinforcement mechanisms; and the behaviour of the bond between the masonry and the FRP in the case of a panel. The third stage of the project involved developing a finite element model to help understand the experimental results. The masonry was modelled using the micro-modelling approach, and the FRP was attached to the masonry model using the bond-slip relationships determined from the pull tests. Reinforcement schemes in which vertical FRP strips were used improved the strength and ductility of the masonry wall panels. When only horizontal strips were used to reinforce a wall panel, failure occurred along an un-strengthened bed joint and the increase in strength and ductility was negligible. The vertical reinforcement prevented URM sliding failure by restraining the opening (dilation) of the sliding cracks that developed through the mortar bed joints. The finite element model reproduced the key behaviours observed in the experiments for both the unreinforced and FRP strengthened wall panels. This model would potentially be useful for the development of design equations.

Research Doctorate - Doctor of Philosophy (PhD) / Inserting fibre reinforced polymer (FRP) strips into pre-cut grooves in the surface of masonry walls is an emerging technique for the retrofit of unreinforced masonry (URM) structures. This method, known as near surface mounting (NSM), provides significant advantages over externally bonded FRP strips in that it has less of an effect on the aesthetics of a structure and can sustain higher loading before debonding. As this technique is relatively new, few studies into the behaviour of masonry walls strengthened using this technique have been conducted. A combined experimental and numerical program was conducted as part of this research project to study the in-plane shear behaviour of masonry wall panels strengthened with NSM carbon FRP (CFRP) strips. In this project the FRP strips were designed to resist sliding along mortar bed joints and diagonal cracking (through mortar joints and brick units). Both of these failure modes are common to masonry shear walls. Different reinforcement orientations were used, including: vertical; horizontal; and a combination of both. The first stage of the project involved characterising the bond between the FRP and the masonry using experimental pull tests (18 in total). From these tests the bond strength, the critical bond length and the local bond-slip relationship of the debonding interface was determined. The second stage of the project involved conducting diagonal tension/shear tests on masonry panels. A total of four URM wall panels and seven strengthened wall panels were tested. These tests were used to determine: the effectiveness of the reinforcement; the failure modes; the reinforcement mechanisms; and the behaviour of the bond between the masonry and the FRP in the case of a panel. The third stage of the project involved developing a finite element model to help understand the experimental results. The masonry was modelled using the micro-modelling approach, and the FRP was attached to the masonry model using the bond-slip relationships determined from the pull tests. Reinforcement schemes in which vertical FRP strips were used improved the strength and ductility of the masonry wall panels. When only horizontal strips were used to reinforce a wall panel, failure occurred along an un-strengthened bed joint and the increase in strength and ductility was negligible. The vertical reinforcement prevented URM sliding failure by restraining the opening (dilation) of the sliding cracks that developed through the mortar bed joints. The finite element model reproduced the key behaviours observed in the experiments for both the unreinforced and FRP strengthened wall panels. This model would potentially be useful for the development of design equations.

Flammable solvents contained in liquid electrolytes pose a serious safety risk when used in lithium batteries. Oxide ceramic electrolytes are a safer alternative, but suffer from inadequate mechanical properties and ionic conductivity. Thin electrolyte layers resolve the issue of conductance, but accentuate the detrimental mechanical properties of oxide ceramics. The presented work has investigated oxide ceramic electrolyte reinforcement in composite electrolytes for all-solid-state batteries. Fabricating oxide ceramic electrolytes with engineered microstructure enabled development of a reinforced composite. This approach is based on the formation of 3D- porous ceramics via stereolithography printing of polymer templates from designed cubic, gyroid, diamond and bijel architectures. The microstructural parameters of templates were analysed and modified using computational techniques. Infiltration of the prepared 3D-porous electrolyte with polymeric-fibre reinforcement created the reinforced composite electrolyte. The prepared ceramic composite showed excellent reproduction of the template microstructure, good retention of ionic conductivity and enhanced mechanical properties. The final composite was composed of NASICON-type Li_1.6Al_0.6Ge_1.4(PO₄)₃ oxide ceramic electrolyte and epoxy and aramid fibre reinforcement. The gyroid architecture was computationally determined as having the optimal stress transfer efficiency between two phases. The printed gyroid polymer template gave excellent pore microstructure reproduction in ceramic that had 3D-interconnected porosity, high relative density and the most uniform thickness distribution. The ceramic matrix porosity allowed for complete infiltration of reinforcement by aramid and epoxy forming the fibre-reinforced ceramic matrix composite. The interpenetrating composite microstructure with ceramic and epoxy gave a flexural strength increase of 45.65 MPa compared to the ceramic. Unfortunately, the infiltration procedure of aramid-epoxy reinforcement did not realise the full tensile strength potential of aramid fibres.

End-gated and centre gated mouldings have been assessed with varying thickness and sprue geometries for the centre gate. Alternative image analysis techniques are used to measure the orientation and length of injection moulded short and long fibres composite components. The fibre orientation distribution (FOD) measurements for both geometries have been taken along the flow path. In shear flow the FOD changes along the flow path, however the FOD remains relatively constant during expansion flow. The core width and FOD at the skin within a long glass fibre (LGF) specimen is different in comparison to a short glass fibre (SGF) specimen. Fibre length measurements have been taken from the extrudate, sprue and 2 positions within the centre gate cavity. The size of the sprue has little influence on fibre breakage if the moulding is more than 1 mm thick The SGF FOD prediction models within Autodesk Simulation Moldflow Insight 2014 (ASMI) have been validated against measured SGF data. At present, by default, the models over-predict the < cos2θ > for most geometries. When the coefficients are tailored for each model, drastic improvements are seen in the FOD prediction. The recently developed SGF RSC model accurately predicts the FOD in shear, in a thin geometry, whereas the Folgar-Tucker model predicts the FOD accurately in expansion flow. The measured LGF fibre length distribution (FLD) and FOD have been validated against the LGF prediction models. The LGF models are currently under predicting the breakage and over-predicting < cos2θ >. The breakage prediction improves if measured FLD of the extrudate is input into the model.