The shoulder joint is a multi-axis synovial ball and socket joint, by having a loose connection it provides a wide degree of freedom; however this means the joint lacks robustness and is prone to damage most commonly from shoulder dislocations. A rotator cuff tear causes major problems in allowing the arm to be lifted beyond a 90˚ abduction position. It is common that this insufficiency aggravates arthritis problems that may have occurred due the rotator cuff tear problem. The study focuses on investigating, describing and quantifying the implant geometric properties to evaluate the joint contact characteristics and use the outcome in redesign the implant. The investigation presents results of finite element analysis on a heavy loading condition on a Verso (reverse) shoulder implant which is validated using experimental data on the same prosthesis. The results are validated within a 5% error margin. A Verso implant is modelled using MIMICS (materialise) and imported into ABAQUS (Simulia, Providence, USA) to analyse the distribution of stress, strain and displacement across the Humerus and Scapula. Details of interaction, boundary conditions, loads and material properties are all obtained from research and applied to the model to portray realistic behaviour. The resulting stress, strain and displacement from this simulation are indicated to show the magnitude and distribution across the entire bone region. This validates the benefits of a Verso implant compared to conventional and long stemmed reverse shoulder implants, as well as provide a basis from which improved designs can be built upon and allow further accurate methods to be developed in analysing shoulder implants effectively.

Caribbean-style hybrid concrete-masonry structures consist of a reinforced concrete frame with partially grouted and reinforced infill masonry walls. The infill walls are typically connected to the RC frame with cast-in-place dowel reinforcement along one or more edges of the wall. There is limited guidance in masonry codes to design these types of structures, and their seismic performance has not been characterized with experimental tests. In this work, an experimental program characterized the seismic behavior of hybrid concrete-masonry frames and showed they do not exhibit the typical strut mechanism observed in unreinforced masonry infill structures. In addition, a detailed finite element modeling scheme and calibration methodology was developed for modeling partially grouted masonry. This model includes a novel calibration method to account for the difference in the shear and tensile behavior of bed joints with grouted and ungrouted cells, and a method to account for the contribution of vertical reinforcement to the shear capacity of the bed joints with grouted cells. Finally, simplified models were proposed for use in engineering design. A modification of the TMS 402 strut model for hybrid concrete-masonry was suggested to incorporate the effects of the masonry infill and connections in large models.

This thesis investigates the flexural behavior of interlocking compressed earth block (ICEB) shear walls. In-plane cyclic tests were conducted to evaluate the performance of three flexure dominant large scale ICEB specimens: a slim wall with a 2:1 height to width aspect ratio, a flanged wall, and a wall with an opening at the center. Following the experimental investigation, two types of analyses were conducted for calculating the ultimate strength of flexure dominant ICEB walls: a nonlinear static analysis model assuming lumped plasticity and a plastic analysis model. In addition, incremental dynamic analysis was conducted to address the seismic performance of flexure dominant ICEB buildings. Based on the database from the incremental dynamic analysis, the collapse potential of demonstration ICEB buildings were compared for the countries of interest.

Abstract: Highway bridges have great values in a country because in case of any natural disaster they may serve as lines to save people’s lives. Being vulnerable under significant seismic loads, different methods can be considered to design resistant highway bridges and rehabilitate the existing ones. In this study, base isolation has been considered as one efficient method in this regards which in some cases reduces significantly the seismic load effects on the structure. By reducing the ductility demand on the structure without a notable increase of strength, the structure is designed to remain elastic under seismic loads. The problem associated with the isolated bridges, especially with elastomeric bearings, can be their excessive displacements under service and seismic loads. This can defy the purpose of using elastomeric bearings for small to medium span typical bridges where expansion joints and clearances may result in significant increase of initial and maintenance cost. Thus, supplementing the structure with dampers with some stiffness can serve as a solution which in turn, however, may increase the structure base shear. The main objective of this thesis is to provide a simplified method for the evaluation of optimal parameters for dampers in isolated bridges. Firstly, performing a parametric study, some directions are given for the use of simple isolation devices such as elastomeric bearings to rehabilitate existing bridges with high importance. Parameters like geometry of the bridge, code provisions and the type of soil on which the structure is constructed have been introduced to a typical two span bridge. It is concluded that the stiffness of the substructure, soil type and special provisions in the code can determine the employment of base isolation for retrofitting of bridges. Secondly, based on the elastic response coefficient of isolated bridges, a simplified design method of dampers for seismically isolated regular highway bridges has been presented in this study. By setting objectives for reduction of displacement and base shear variation, the required stiffness and damping of a hysteretic damper can be determined. By modelling a typical two span bridge, numerical analyses have followed to verify the effectiveness of the method. The method has been used to identify equivalent linear parameters and subsequently, nonlinear parameters of hysteretic damper for various designated scenarios of displacement and base shear requirements. Comparison of the results of the nonlinear numerical model without damper and with damper has shown that the method is sufficiently accurate. Finally, an innovative and simple hysteretic steel damper was designed. Five specimens were fabricated from two steel grades and were tested accompanying a real scale elastomeric isolator in the structural laboratory of the Université de Sherbrooke. The test procedure was to characterize the specimens by cyclic displacement controlled tests and subsequently to test them by real-time dynamic substructuring (RTDS) method. The test results were then used to establish a numerical model of the system which went through nonlinear time history analyses under several earthquakes. The outcome of the experimental and numerical showed an acceptable conformity with the simplified method. / Résumé: Les ponts routiers ont une grande valeur dans un pays parce qu’en cas de catastrophe naturelle, ils peuvent servir comme des lignes pour sauver des vies. Étant vulnérable sous des charges sismiques importantes, on peut considérer différentes méthodes pour concevoir des ponts routiers résistants et également pour réhabiliter des ponts existants. Dans cette étude, l'isolation de la base a été considérée comme une méthode efficace qui peut réduire significativement les effets des charges sismiques sur la structure. En réduisant la demande en ductilité sur la structure sans une augmentation notable de force, la structure est conçue pour rester élastique sous des charges sismiques. Le problème associé aux ponts isolés, particulièrement avec des appuis en élastomère, peut être leurs déplacements excessifs sous les charges de service et de séisme. Ceci peut défier l’objectif d'utiliser des appuis en élastomère pour les ponts typiques de petite portée où les joints de dilatation et les dégagements peuvent aboutir à une augmentation significative des frais d'exploitation et de maintenance. Ainsi, supplémenter la structure avec des amortisseurs d’une certaine rigidité peut servir de solution, ce qui peut cependant augmenter l’effort tranchant transmis à la sous-structure. Cette étude a pour but de fournir une méthode simplifiée afin d’évaluer les paramètres optimaux des amortisseurs dans les ponts isolés. Dans cette thèse, premièrement, basé sur une étude paramétrique, quelques directions sont données pour l'utilisation de dispositifs d'isolation simples, dont les appuis en élastomère, afin de réhabiliter des ponts existant avec une haute importance. Les paramètres comme la géométrie du pont, les clauses des normes et le type de sol sur lequel la structure est construite ont été appliqués sur un pont typique de deux portées. Il est conclu que les paramètres mentionnés peuvent déterminer l'emploi d'isolement de la base des ponts routiers. À la deuxième phase, basé sur le coefficient de réponse élastique des ponts isolés, une méthode de conception simplifiée d’amortisseur pour des ponts routiers réguliers isolés à la base a été présentée dans cette étude. En sélectionnant des objectifs pour la réduction du déplacement et la variation de l’effort tranchant, la rigidité et l'amortissement exigés d'un amortisseur hystérétique peuvent être déterminés. L’étude s’est poursuivie par une modélisation numérique d’un pont à deux portées pour vérifier l'efficacité de la méthode. Pour un modèle numérique d'un pont isolé typique, la méthode a été utilisée pour identifier des paramètres linéaires équivalents pour un certain déplacement et effort tranchant désigné. Par la suite, assumant un amortisseur de type hystérétique, les paramètres non linéaires de l’amortisseur ont été calculés et utilisés. La comparaison des résultats du modèle numérique sans amortisseur et avec l'amortisseur a démontré que la méthode proposée est suffisamment précise. Par la suite, un nouvel amortisseur hystérétique simple en acier a été conçu. Cinq spécimens ont été fabriqués de deux différents grades d’acier et ont été testés en combinaison avec un isolateur à l’échelle réelle dans le laboratoire de structures de l'Université de Sherbrooke. La procédure comprenait la caractérisation des spécimens par des tests cycliques en contrôle de déplacement et par la suite la réalisation d’essais par la méthode de sous-structuration dynamique en temps réel. Les résultats des essais ont été utilisés pour établir un modèle numérique du système qui a subi des analyses temporelles non linéaires sous plusieurs séismes. Le résultat des essais expérimentaux et numériques montrent une conformité acceptable avec la méthode simplifiée.

This thesis focuses on the effect of microstructural variation on the mechanical properties and deformation behavior of ductile iron. To research and determine these effects, two grades of ductile iron, (i) GJS-500-7 and (ii) high silicon GJS-500-14, were cast in a geometry containing several plates with different section thicknesses in order to produce microstructural variation. Microstructural investigations as well as tensile and hardness tests were performed on the casting plates. The results revealed higher ferrite fraction, graphite particle count, and yield strength in the high silicon GJS-500-14 grade compared to the GJS-500-7 grade. To study the relationship between the microstructural variation and tensile behavior on macroscale, tensile stress-strain response was characterized using the Ludwigson equation. The obtained tensile properties were modeled, based on the microstructural characteristics, using multiple linear regression and analysis of variance (ANOVA). The models showed that silicon content, graphite particle count, ferrite fraction, and fraction of porosity are the major contributing factors that influence tensile behavior. The models were entered into a casting process simulation software, and the simulated microstructure and tensile properties were validated using the experimental data. This enabled the opportunity to predict tensile properties of cast components with similar microstructural characteristics. To investigate deformation behavior on micro-scale, a method was developed to quantitatively measure strain in the microstructure, utilizing the digital image correlation (DIC) technique together with in-situ tensile testing. In this method, a pit-etching procedure was developed to generate a random speckle pattern, enabling DIC strain measurement to be conducted in the matrix and the area between the graphite particles. The method was validated by benchmarking the measured yield strength with the material’s standard yield strength. The microstructural deformation behavior under tensile loading was characterized. During elastic deformation, strain mapping revealed a heterogeneous strain distribution in the microstructure, as well as shear bands that formed between graphite particles. The crack was initiated at the stress ranges in which a kink occurred in the tensile curve, indicating the dissipation of energy during both plastic deformation and crack initiation. A large amount of strain localization was measured at the onset of the micro-cracks on the strain maps. The micro-cracks were initiated at local strain levels higher than 2%, suggesting a threshold level of strain required for micro-crack initiation. A continuum Finite Element (FE) model containing a physical length scale was developed to predict strain on the microstructure of ductile iron. The material parameters for this model were calculated by optimization, utilizing the Ramberg-Osgood equation. The predicted strain maps were compared to the strain maps measured by DIC, both qualitatively and quantitatively. To a large extent, the strain maps were in agreement, resulting in the validation of the model on micro-scale. In order to perform a micro-scale characterization of dynamic deformation behavior, local strain distribution on the microstructure was studied by performing in-situ cyclic tests using a scanning electron microscope (SEM). A novel method, based on the focused ion beam (FIB) milling, was developed to generate a speckle pattern on the microstructure of the ferritic ductile iron (GJS-500-14 grade) to enable quantitative DIC strain measurement to be performed. The results showed that the maximum strain concentration occurred in the vicinity of the micro-cracks, particularly ahead of the micro-crack tip. / Denna avhandling fokuserar på effekten av variationer i mikrostrukturen på mekaniska egenskaper och deformationsbeteende hos segjärn. För att undersöka dessa effekter, två olika sorter av segjärn, (i) GJS-500-7 och (ii) högkisellegerad GJS-500-14, gjutits till plattor av olika tjocklekar för att generera mikrostrukturvariationen. Mikrostrukturundersökning, samt drag- och hårdhetsprov gjordes på de gjutna plattorna. Resultaten visade att en högre ferritfraktion, grafitpartikelantal och sträckgräns i den högkisellegerade GJS-500-14-sorten jämfört med GJS-500-7. För att studera förhållandet mellan mikrostrukturell variation och spännings-töjningsbeteendet på makroskala, modellerades detta med hjälp av Ludwigson-ekvationen. De erhållna spännings-töjningsegenskaperna modellerades baserat på mikrostrukturell karaktäristika genom multipel linjärregression och variansanalys (ANOVA). Modellerna visade att kiselhalt, grafitpartikelantal, ferritfraktion och porfraktion var de viktigaste bidragande faktorerna. Modellerna implementerades i ett simuleringsprogram för gjutningsprocessen. Resultatet från simuleringen validerades med hjälp av experimentella data som inte ingick i underlaget för regressionsanalysen. Detta möjliggjorde att prediktera spännings-töjningsbeteendet och dess variation hos gjutna segjärns komponenter med liknande sammansättning och gjutna tjocklekar som användes i denna studie. För att kunna undersöka deformationsbeteendet på mikroskala utvecklades en metod för kvantitativ mätning av töjning i mikrostrukturen, genom DIC-tekniken (digital image correlation) tillsammans med in-situ dragprovning. I denna metod utvecklades en grop-etsningsprocess för att generera ett slumpvis prickmönster, vilket möjliggjorde DIC-töjningsmätning i matrisen och i området mellan grafitpartiklarna med tillräcklig upplösning. Metoden validerades genom benchmarking av den uppmätta sträckgränsen mot materialets makroskopiska sträckgräns mätt med konventionell dragprovning. Det mikrostrukturella deformationsbeteendet under dragbelastning karakteriserades. Under elastisk deformation avslöjade töjningsmönstret en heterogen töjningsfördelning i mikrostrukturen, och bildandet av skjuvband mellan grafitpartiklar. Sprickbildning initierades vid låg spänning och redan vid de spänningsnivåer som ligger vis ”knät” på dragprovningskurvan, vilket indikerar energidissipering genom både begynnande plastisk deformation och sprickbildning. Den lokala töjningen vis sprickinitiering skedde då den lokala töjningen översteg 2%, vilket indikerar att detta skulle kunna vara en tröskelnivå för den töjning som erfordras för initiering av mikro-sprickor. En kontinuum Finita Element (FE) modell utvecklades för att prediktera töjningen hos ett segjärn och dess fördelning i segjärns mikrostruktur. Materialparametrarna för denna modell optimerades genom att anpassa parametrarna i Ramberg-Osgood ekvationen. De predikterade töjningsfördelningarna jämfördes med de experimentell uppmätta töjningsmönstren uppmätta med DIC, både kvalitativt och kvantitativt. Töjningsmönstren överensstämde i stor utsträckning, vilket resulterade i att modellerna kunde anses vara validerade på mikronivå. För att kunna mäta töjningsmönster under dynamiska förlopp på mikronivå utvecklades en metod för att skapa prickmönster och att utföra in-situ CT provning i ett svepeletronmikroskop (SEM). Prickmönstret skapades genom avverkning med en fokuserad jonstråle (FIB), och provades på det ferritiska segjärnet (GJS-500-14 grad). Resultaten visade att maximal töjningskoncentration fanns i närheten av mikrosprickorna, framförallt framför sprickspetsen.