<p>This thesis reports on shake table tests on fully-grouted reinforced masonry (RM) shear walls. The test walls covers a range of design parameters to facilitate benchmarking, a thorough performance investigation, and calibration of numerical models as well as development of fragility curves within the context of Performance Based Seismic Design (PBSD). The details of the experimental program undertaken, including general observations in terms of cracking patterns and failure modes of the tested walls and the results on the lateral strength, hysteretic response, dynamic properties, and the contribution of different displacement components to the response of the walls, are presented. More detailed analyses include seismic performance quantification of the walls in terms of inelastic behaviour characteristics, various energy components, and the effective dynamic properties of the tested walls. The analysis is concluded with development of simplified nonlinear response history analytical models and seismic fragility assessment tools for the tested walls. In general, the study results indicated that the displacement ductility capacity of the RM walls and their capability to dissipate energy through plastic hinging are higher than what is currently recognized by the National Building Code of Canada (NBCC). The fragility assessment study further indicated that similar walls are expected to conform to the current drift limits of the NBCC even at high seismic regions in Canada. The results of this study are expected to contribute to the growing Seismic Performance Database (SPD) of RM Seismic Force Resisting System (SFRS), and to the understanding of the lightly reinforced masonry wall system behaviour.</p> / Master of Applied Science (MASc)

Recent research has identified that current code level seismic demands used for diaphragm design are considerably lower than demands in real structures during a seismic event. However, historical data has shown that steel deck diaphragms, common to steel framed buildings, perform exceptionally well during earthquake events. A new alternative diaphragm design procedure in ASCE 7-16 increases diaphragm seismic demand to better represent expected demands. The resulting elastic design forces from this method are reduced by a diaphragm design force reduction factor, Rs, to account for the ductility of the diaphragm system. Currently, there exist no provisions for Rs factors for steel deck diaphragms. This research was therefore initiated to understand inelastic steel deck diaphragm behavior and calculate Rs factors. A review of the literature showed that a large number of experimental programs have been performed to obtain the in-plane load-deformation behavior of steel deck diaphragms. To unify review of these diaphragm tests and their relevant results, a database of over 750 tested specimens was created. A subset of 108 specimens with post-peak, inelastic behavior was identified for the characterization of diaphragm behavior and ductility. A new recommended method for predicting shear strength and stiffness for steel deck diaphragms with structural concrete fill is proposed along with an appropriate resistance factor. Diaphragm system level ductility and overstrength are estimated based on subassemblage test results and Rs factors are then calculated based on these parameters. The effects of certain variables such as deck thickness and fastener spacing on diaphragm ductility are explored. / Master of Science / A building’s floor and roof systems active in the resistance of in-plane loads, known as diaphragms, can be a critical component of a structure. In the past, the majority of diaphragm systems have demonstrated exceptional performance during earthquake events. Diaphragms must be designed in compliance with building codes. ASCE 7 is a widely recognized document in structural engineering used to prescribe building loads and outline design methodologies. Recent research has identified that code level seismic demands in ASCE 7-10 used for diaphragm design are considerably lower than demands in real structures during a seismic event. However, historical data has shown that steel deck diaphragms, common to steel framed buildings, perform exceptionally well during earthquake events. A new alternative diaphragm design procedure in ASCE 7-16 increases diaphragm seismic demand to better represent expected demands. The resulting design forces from this method are reduced by a diaphragm design force reduction factor, R_s, to account for the diaphragm system’s ability to permanently deform without undergoing catastrophic failures – an engineering concept known as ductility. Currently, there exist no provisions for R_s factors for steel deck diaphragms. This research was therefore initiated to understand steel deck diaphragm behavior and calculate R_s factors. A review of the literature showed that a large number of experimental programs have been performed to obtain the in-plane load-deformation behavior of steel deck diaphragms. To unify review of these diaphragm tests and their relevant results, a database of over 750 tested specimens was created. A subset of 108 specimens with complete, inelastic behavior was identified for the characterization of diaphragm behavior and ductility. A new recommended method for predicting the in-plane strength and stiffness for steel deck diaphragms with overlaying structural concrete fill is proposed along with an appropriate resistance factor. Valuable information is extracted from previously tested steel deck diaphragms and R_s factors are then calculated based on these parameters. The effects of certain variables such as deck thickness and fastener spacing on diaphragm ductility are also explored.

Yes / This paper reports the testing of 11 reinforced concrete (RC) two-span beams strengthened in flexure with externally bonded carbon fiber-reinforced polymer (CFRP) sheets. The beams were classified into two groups according to the arrangement of the internal steel reinforcement. Each group included one unstrengthened control beam. The main parameters studied were the position, length, and number of CFRP layers. External strengthening using CFRP sheets was found to increase the beam load capacity. All strengthened beams exhibited less ductility compared with the unstrengthened control beams, however, and showed undesirable sudden failure modes. There was an optimum number of CFRP layers beyond which there was no further enhancement in the beam capacity. Extending the CFRP sheet length to cover the entire hogging or sagging zones did not prevent peeling failure of the CFRP sheets, which was the dominant failure mode of beams tested.

Résumé : Plusieurs tremblements de terre passés ont montré que face aux séismes, les ponts peuvent être les points faibles d’un réseau de transport. Néanmoins, les retours des expériences postsismiques ainsi que les études théoriques et expérimentales effectuées par les chercheurs et les ingénieurs de la pratique ont permis de faire évoluer les règles de l'art relatives au comportement sismique des ponts. Un des résultats de cette évolution est le dimensionnement basé sur la performance sismique (DBPS). En bref, le DBPS tente de concevoir des structures qui atteindront un état limite de performance déterminé lorsqu’ils sont soumis à un séisme d’une intensité donné. Toutefois, dans l'optique du DBPS, il est primordial de situer les états limites des composantes principales des ponts, principalement des piliers, de manière mesurable plutôt que phénoménologique. Lors du développement de courbes de fragilité des ponts au Québec, il est apparu que les états limites des piliers de ponts n'étaient pas clairement définis. Un programme de recherche expérimental a donc été conçu pour déterminer les états limites des piliers de pont en béton armé. Le projet comprend l’essai d’un poteau en béton armé à échelle réelle soumis à des cycles de chargement latéral en plus d’une charge axiale constante représentative du niveau de chargement réel. Le poteau reproduit les propriétés exactes des piliers du pont Chemin des Dalles (Trois-Rivières, Québec). Ce projet de recherche vise à améliorer l’évaluation de la fragilité sismique des ponts actuels du réseau routier québécois et à optimiser le dimensionnement sismique des futures structures selon l’approche basée sur la performance sismique. En particulier, le projet cherche à répondre aux incertitudes importantes qui subsistent sur la description quantitative des états limites des piliers de ponts en béton armé, particulièrement au niveau des déformations associées. / Abstract : Several past earthquakes have shown that bridges can be the weak points of a transport network. Nevertheless, returns of the post-seismic experiences as well as theoretical and experimental studies made by researchers and practice engineers allowed the art rules evolution related to the seismic behavior of bridges. One result of this evolution is the seismic performance based design (DBPS). In brief, the DBPS tries to design structures which will reach a certain limit state of performance when they are submitted to an earthquake of a given intensity. However, in the optics of the DBPS, it is essential to define the limit states of the main components of bridges, mainly for columns, in a measurable way rather than phenomenological. During the development of the fragility curves of bridges in Québec, it seemed that the limit states of the bridges columns were not clearly defined. An experimental research program was thus designed to determine the limit states of the reinforced concrete bridge columns. The project includes the testing of a large-scale reinforced concrete bridge column submitted to lateral cycles load in addition to a constant axial load which represented the real dead load level. The column reproduces the exact properties of the Chemin des Dalles bridge columns (Trois-Rivières, Québec). This research project aims to improve the evaluation of the seismic fragility of existing bridges of Québec road network and optimize the seismic design for future structures according to the performance based seismic approach. In particular, the project seeks to address the significant uncertainties which remain on the quantitative description of the limit states of the reinforced concrete bridge columns, particularly at the associated deformations level.

A new methodology is proposed to perform nonlinear time domain analysis on three-dimensional reinforced concrete bridge structures subjected to spatially varying seismic ground motions. A stochastic algorithm is implemented to generate unique and correlated time history records under each bridge support to model the spatial variability effects of seismic wave components traveling in the longitudinal and transverse direction of the bridge. Three-dimensional finite element models of highway bridges with variable geometry are considered where the nonlinear response is concentrated at bidirectional plastic hinges located at the pier end zones. The ductility demand at each pier is determined from the bidirectional rotations occurring at the plastic hinges during the seismic response evaluation of the bridge models. Variability of the soil characteristics along the length of the bridge is addressed by enforcing soil response spectrum compatibility of the generated time history records and of the dynamic stiffness properties of the spring sets modeling soil rigidity at the soil-foundation interface at each support location. The results on pier ductility demand values show that their magnitude depends on the type of soil under the pier supports, the pier location and the overall length and geometry of the bridge structure. Maximum ductility demand values were found to occur in piers supported on soft soils and located around the mid span of long multi-span bridges. The results also show that pier ductility demand values in the transverse direction of the bridge can be significantly different than the values in the longitudinal direction and in some instances, the maximum value occurs in the transverse direction. Moreover, results also show that ignoring the effects of spatial variability of the seismic excitation, the pier ductility demand can be severely underestimated. Finally, results show that increasing the vertical acceleration component in the seismic wave will generate an increase in the pier axial loads, which will reduce the ductility range of the pier plastic zones. As result, even though the increase in pier ductility demand associated with the increase in the vertical acceleration component was found to be relatively small, the number piers exhibiting significant structural damage increased.

Neste estudo foram analisados experimentalmente o comportamento de 24 pilares curtos de Concreto de Ultra Alta Resistência - CUAR, confinados por armaduras helicoidais, avaliando especificamente os acréscimos de resistência e ductilidade obtidos com diferentes níveis de pressão lateral de confinamento. Na etapa experimental foram realizados ensaios de pilares curtos de CUAR com as seguintes características: - seção circular de 7,2 cm de diâmetro e comprimento de 23 cm, e quatro níveis de resistência à compressão do concreto sendo eles, 165, 175, 200 e 229 MPa, dosados sem e com adição de fibras metálicas; - diferentes espaçamentos das armaduras helicoidais, de modo que fossem obtidas situações com baixo, médio e alto índice de confinamento e taxa de armadura longitudinal fixa. Os ensaios de compressão centrada foram realizados com controle de deslocamento, de modo que foram obtidas as curvas força x deslocamento completas. Constatou-se que a seção resistente dos pilares de CUAR é a formada pelo núcleo de concreto confinado, área delimitada pelo eixo da armadura transversal. Observou-se que o CUAR com fibras metálicas apresenta maior deformação do núcleo de concreto confinado em relação ao núcleo de concreto confinado de CUAR sem adição de fibras metálicas, indicando dessa forma, que os pilares de CUAR com fibras metálicas apresentam comportamento mais dúctil. Para as situações de alto confinamento foram gerados ao concreto do núcleo confinado significativos acréscimos de resistência e deformação axial, aumentando a resistência do concreto confinado em relação a resistência do concreto não confinado em: 82,26%, 75,34%, 90,46% e 70,51%, respectivamente, e as deformações axiais do concreto confinado em relação a deformação axial do concreto não confinado em: 433%, 474%, 647% e 550%. Finalmente, acredita-se que os resultados obtidos poderão trazer subsídios para aplicações futuras desta técnica de confinamento na construção de novos elementos estruturais e no reforço de pilares submetidos a elevados níveis de solicitação axial. / This study evaluated experimentally the behavior of 24 short columns of Ultra High Strength Concrete - UHSC confined by helical transverse reinforcement, specifically evaluating strength increases and ductility obtained with different levels of lateral pressure of confinement. In the experimental phase short UHSC columns with the following characteristics were tested: - circular cross section of 7.2 cm diameter and 23 cm length, four levels of concrete strength (165, 175, 200 and 229 MPa), with and without addition of metallic fibers; - different spacing of transverse reinforcement, so that situations were obtained with low, medium and high level of confinement, while the longitudinal reinforcement ratio was fixed. The centered compression tests were conducted with displacement control, so that complete force x displacement curves were obtained. It was found that the resistant section of UHSC columns is formed by the confined concrete core delimited by the axis of the transverse reinforcement. It was observed that the axial displacement reached in columns with steel fibers was higher than without fibers, indicating that columns with steel fibers exhibit more ductile behavior. For high confinement levels significant axial strength and displacement increases were observed. Increases of axial strength of confined concrete in comparison to unconfined concrete were 82.26%, 75.34%, 90, 46% and 70.51%. Axial displacements were increased by 433%, 474%, 647% and 550%. Finally, it is believed that the results could provide information for future applications of this technique in construction of a new type of columns or in strengthening of columns subjected to high levels of axial force.

O emprego de pilares mistos formados por tubos de aço preenchidos com concreto de alta resistência, sobretudo em edifícios altos, é uma tendência em diversos países europeus, americanos e asiáticos. A tais elementos são atribuídas vantagens como: alta resistência e ductilidade, economia de materiais e mão-de-obra, redução das dimensões da seção transversal e melhoria no comportamento dos materiais aço e concreto, devido ao efeito de confinamento. Buscando suprir algumas carências de conhecimento, procura-se obter dados experimentais sobre o comportamento de pilares mistos axialmente comprimidos, possibilitando desta forma avaliar parâmetros como influência da forma da seção transversal e da espessura do perfil tubular no seu comportamento. Foram analisadas seções quadradas, circulares e retangulares, preenchidas por concreto com resistência média de 50MPa. A ruína destes elementos caracterizou-se pelo esmagamento do concreto, ocorrendo posteriormente a flambagem local do perfil em diversos pontos. A capacidade resistente prevista por diversas normas resultou em valores muito próximos dos experimentais, embora várias destas normas não considerem o efeito de confinamento. Os ensaios mostraram que o efeito de confinamento contribui de forma decisiva na melhoria do comportamento dos materiais, sobretudo ductilizando o concreto de alta resistência, entretanto seus efeitos não são significativos no aumento da capacidade resistente da seção mista. Alguns critérios para avaliação da ductilidade à compressão foram adaptados e mostraram bons resultados, possibilitando o cálculo do índice de ductilidade. / The use of concrete filled steel tubes especially in tall buildings is a tendency in several european, american and asian countries. The use of these members has several advantages: high resistance and ductility, saving of materials and labour, reduction of cross section dimensions and improvement in behaviour of the materials steel and concrete due the confinement. The main purpose of this study is provide some experimental results of the behaviour of concrete filled steel tubes concentrically loaded. The main experimental parameters considered were the influence of the cross-section shape and thickness of steel tube. Square, circular and rectangular cross-section shapes infilling with concrete of the 50MPa of strength were analyzed. The failure was characterized for crushing of the concrete and later local buckling of the steel section in several points. The strength capacity predicted for several standards showed good agreement with the experimental failure values although this does not consider the confinement of the concrete. The results of tests showed that the confinement effect contributes for improvement behaviour of materials, especially increasing the ductility of the high strength concrete. However the results showed that the triaxial confinement does not increase the axial capacity of the concrete filled steel tubes. Some methods to estimate the ductility of axially compressed concrete columns were adapted and showed good results permitting the calculation of the ductility index of short columns.

O efeito de confinamento do concreto em pilares submetidos à compressão axial traz diversos benefícios ao seu comportamento estrutural, dentre os quais destacam-se o aumento na resistência à compressão axial do concreto pela ação das pressões laterais, e a melhoria da ductilidade do elemento estrutural. Em função destas vantagens, o confinamento é uma das principais técnicas de reforço de pilares de concreto. Porém, dependendo da forma da seção transversal, a eficiência do reforço pode ficar comprometida em função da distribuição da pressão de confinamento. No caso de pilares de seção circular, esta distribuição é uniforme. Já em pilares de seção quadrada e retangular, existe concentração de tensão nos cantos da seção transversal, o que, no caso de reforço por encamisamento com PRFC, pode causar a ruptura prematura da camisa, resultando num reforço ineficiente. Com o intuito de considerar as diferentes configurações da distribuição da pressão de confinamento, utiliza-se um coeficiente de forma, que em seções diferentes da circular (para a qual este coeficiente é igual à unidade), minora o valor da pressão de confinamento, o qual é utilizado na previsão da carga de ruptura do pilar reforçado. Este trabalho tem como objetivo central o estudo de vários tipos de seção transversal com o intuito de avaliar a sua influência na eficiência do reforço e da ductilidade do elemento estrutural. Para tal, foram realizadas simulações experimentais com pilares de seção transversal circular, quadrada e retangular com os cantos arredondados, elíptica e uma seção composta por semicírculos. Os resultados demonstram que uma forma de seção transversal adequada é essencial para um bom desempenho do pilar reforçado, sendo assim, as seções transversais que apresentaram os melhores resultados foram a circular, a elíptica e a composta por semicírculos / The effect of the concrete confinement in columns submitted to the axial compression brings many benefits to its structural behavior, amongst them the increase of the axial compressive strength due to the action of the lateral pressures and the improvement of the ductility. In function of these advantages, the confinement is one of the main techniques for strengthening of concrete columns. However, depending on the shape of the cross section, the efficiency of the reinforcement can be impaired by the non-uniformity of the confinement pressure distribution. In the case of circular cross section columns, this distribution is uniform. Otherwise, in square and rectangular cross section columns, there is a pressure concentration at the cross section corners. In case of CFRP jackets, the pressure concentration leads to a premature rupture of the jacket, resulting in an inefficient reinforcement. Intending to consider the different confinement pressure distributions, a shape coefficient is applied to cross sections with distinguished shape from the circular one (for which this coefficient is equal to the unit), to correct the confinement pressure value. The corrected pressure is applied in theoretical evaluations of the column’s load carrying capacity. The main objective of work is to analyze the structural behavior of strengthened concrete columns with different shape cross-sections, evaluating the influences in the efficiency of the jacketing and in the ductility of the structural element. Experimental simulations were made in columns with the following cross section shapes: circular, square and rectangular with rounded corners, elliptical and a section composed by semicircles. The results demonstrated that an adequate shape of the cross-section is essential for a good performance of the strengthened columns. The cross sections that presented the best results were the circular, the elliptical and the one composed by semicircles

Foi estudado, através de ensaio de tração, o Nb policristalino com teor de hidrogênio de 0 a 50 partes por milhão em peso (ppm-p) nas temperaturas de 223, 273 e 293 K. Os ensaios de tração a velocidades constantes foram realizados com taxas iniciais de deformaçao de 4,2 X 10-5 e 42 X 10-5 s-1 , e os parâmetros de ductilidade e resistência mecânica foram analisados em função da concentração de hidrogênio. Foram também obtidos o coeficiente de sensitividade a taxa de deformação (m) e o volume de ativação (V) através de ensaios de tração, alternando-se abruptamente a taxa de deformação entre os valores acima mencionados, em sucessivos pontos da curva tensão-deformação. Para o cálculo destes dois últimos parâmetros foi proposta uma análise detalhada, considerando-se os efeitos elásticos e o encruamento durante a deformação plástica uniforme. Todo o estudo foi acompanhado por análise fratográfica Que permitiu verificar três comportamentos de ruptura da liga Nb-H, dependendo do teor de hidrogênio e da temperatura. A 223K foi observado que há uma forte redução de ductilidade do Nb para teores de hidrogênio até 10 ppm-p, sendo que para este teor o seu comportamento foi totalmente frágil / Tensile testing at 223, 273 and 293 K was carried out on polycrystalline Nb dopped from 0 to 50 parts per million in weight (ppm-wt) of Hydrogen. The tensile testing at constant velocity was done at 4,2 X 10 -5 and 42 X 10-5 s-1 of initial strain rate, and the ductility and strength parameters was analysed as a function of the hydrogen content. It was also obtained the strain rate sensitivity (m) and the activation volume (V), from tensile testing, cycling between the two above specified strain rates, at several points of the stress-strain curve. For the calculation of this two last parameters it was proposed a detailed analysis, considering the elastic effect and the work hardening during the uniform plastic deformation. All these studies was followed by fratographic analysis that alowed the identification of three rupture behavior for the Nb-H alloy, depending of the temperature and the hydrogen content. At 223 K, it was observed that there is a strong embrittlement of Nb for hydrogen content up to 10 ppm-wt, and for this value the behavior was completely brittle

The future of the aerospace industry in large part relies on two factors: (i) development of advanced damage tolerant materials and (ii) development of advanced smart sensors with the ability to detect and evaluate defects at very early stages of component service life. Laminated composite materials, such as carbon fibre reinforced plastics (CFRP), have emerged as the materials of choice for increasing the performance and reducing the cost and weight of aircrafts, which leads to less fuel consumption and therefore lower CO2 emissions. However, it is well known that these materials exhibit fragile behaviour, poor resistance to impact damage caused by foreign objects and require a relatively slow and labour intensive manufacturing process. These factors prevent the rapid expansion of composite materials in several industrial sectors at the current time. Inspired by the use of rope throughout history and driven by the necessity of creating a lean manufacturing process for composites and enhancing their impact properties, the first part of this work has shown that enhanced damage tolerance and pseudo-ductile behaviour can be achieved with standard CFRP by creatively arranging the fibres into a 3D twisted helical configuration. Through an extensive experimental campaign a new method to arrange fibre reinforcement was presented and its effect investigated. The second part of this PhD work focused on developing a new smart sensor. A spiral passive electromagnetic sensor (SPES) for damage detection on CFRP and glass fibre reinforced plastics (GFRP) is presented in this work. A range of defect types in glass and carbon composite has been considered, such as delamination, perforated holes and cracks. Furthermore, throughout this work, the SPES has been exploited as a multi-sensing device allowing the ability to detect temperature and humidity variation, presence of ice and act as an anti/de-icing device.