Timber-concrete composite (TCC) floor systems consist of a bottom layer of wood that is connected to a top layer of concrete using shear connectors. The shear connectors resist slip between the layers, thus allowing wood and concrete develop composite action when subjected to flexure. The objective of this study is to determine the flexural strength and behavior of TCC floor systems that consist of a cross laminated timber wood layer connected to a concrete top layer using hexagonally headed self-tapping screw shear connectors. To accomplish the objective, coupon specimens and full-scale TCC floor panels were tested, and a finite element modelling approach was developed. The coupon tests were used to determine the stiffness of the shear connection and to determine the effect of the screw configuration. The results from the coupon tests indicated that the inclined screw configuration provided the largest shear strength compared to the normal, crossed, and nested screw configurations. Based on the results from the coupon tests, bending and vibration (heel drop) tests were conducted on full-scale panel specimens with an inclined screw configuration and with a strong-axis panel orientation. The results from the full-scale panel tests showed that the flexural stiffness and strength of the TCC floor system was consistent and that the composite floor panels have adequate stiffness to minimize transient floor vibrations that are caused by walking for typical span lengths and typical loading. A finite element model of TCC floor systems was developed to simulate TCC floor systems and calibrated with the test data. The simulated response matched the test response fairly well for partially composite single-span and double-span panels. Additional refinement of the model is needed to better match fully composite panels. The research demonstrated that hexagonal-headed self-tapping screws may be effectively used to connect wood and concrete layers in TCC floor systems.

The results of sixty-five double-sided pushout tests utilizing the Elco grade 8, 5/16 in. diameter, standoff screw functioning as a mechanical shear connector are presented. In all tests, the base material, through which the screw was fastened, was fabricated out of back to back angle to simulate the top chord of an open web steel joist. Varied test parameters include: steel deck profile, base angle thickness, screw embedment depth, slab thickness, and slab width. The objectives of the testing were (1) to provide an understanding of the strength of the standoff screw in various test geometries and (2) to provide an understanding of the slip characteristics, or ductility, of the connector. A review of literature presents several applicable existing welded stud strength models based on post-test observations of failure mechanisms. Modeled failure mechanisms include: concrete splitting, concrete pullout, rib shear, and stud shear. After applying the existing models to the pushout test data, the following conclusions are drawn: (1) the concrete splitting model developed by Oehlers (1989) can be used to predict the strength of the standoff screw in flat slab geometries and (2) no existing model adequately predicts the strength of the standoff screw in geometries utilizing profiled steel deck. An equation, based on a rederivation of a wedged shaped shear-cone pullout model (Lloyd & Wright 1990), is presented which predicts the strength of the standoff screw in geometries with steel deck with acceptable accuracy. / Master of Science

The objective of the research reported herein is to present a comprehensive evaluation of all available experimental data from push-out tests utilizing the ELCO Grade 8 standoff screws. The goal is to develop a strength prediction equation and determine reliability parameters compatible with the Load Factor Resistance Design (LRFD) procedure that would allow the use of this shear connector in design of composite floor systems. The study considers results from push-out tests using this type of screw reported by Hankins et al. (1994), Alander et al. (1998), Webler et al. (2000), and Mujagic et al. (2000). Further, this study identifies the limitations in earlier approaches aimed at predicting the strength of standoff screws. An improved strength prediction model is developed that considers all applicable limit states and determines maximum strength of a connector. A reliability study was also conducted to derive strength reduction factors to be used in design. Parameters considered in the model include deck type and geometry, screw height, concrete compressive strength, top chord angle yield strength, and stand-off screw rupture strength. Results from strength prediction model were compared with results from composite joist tests. / Master of Science

L’analyse de tolérances par des ensembles de contraintes repose sur la détermination de l’accumulation de variations géométriques par des sommes et intersections d’ensembles opérandes 6d. Les degrés de liberté des liaisons et les degrés d’invariance des surfaces génèrent des opérandes non-bornés (polyèdres), posant des problèmes de simulation. En 2014, L. Homria proposé une méthode pour résoudre ce problème, consistant à ajouter des limites artificielles(contraintes bouchon) sur les déplacements non-bornés. Même si cette méthode permet la manipulation d’objets bornés (polytopes), les contraintes bouchon augmentent la complexité des simulations. En réponse à cette difficulté, une méthode dérivée est proposée dans cette thèse.Cette méthode consiste à tracer et simplifier les contraintes bouchon au travers des opérations.Puis une seconde stratégie basée sur la décomposition d’un polyèdre en une somme d’un polytope et de lignes droites (associées aux déplacements non-bornés). Cette stratégie consiste à simuler d’une part les sommes de droites, et d’autre part, à déterminer la somme de polytopes dans un sous-espace de dimension inférieur à 6. Ces trois stratégies sont comparées au travers d’une application industrielle. Cela montre que la traçabilité des contraintes bouchons est un aspect fondamental pour contrôler leur propagation et pour réduire le temps de calcul des simulations. Toutefois, cette méthode exige encore de déterminer les limites des déplacements non-bornés. La deuxième méthode, adaptant systématiquement la dimension de l’espace de calcul, elle permet de diminuer davantage le temps de calcul. Ce travail permet d’envisager la mise en oeuvre de cette méthode selon des formulations statistiques avec la prise en compte des défauts de forme des surfaces. / The cumulative stack-up of geometric variations in mechanical systems can be modelled summing and intersecting sets of constraints. These constraints derive from tolerance zones or from contact restrictions between parts. The degrees of freedom (DOF) of jointsgenerate unbounded sets (i.e. polyhedra) which are difficult to deal with. L. Homri presented in 2014 a solution based on the setting of fictitious limits (called cap constraints) to each DOFto obtain bounded 6D sets (i.e. polytopes). These additional constraints, however, increase the complexity of the models, and therefore, of the computations. In response to this situation,we defined a derived strategy to control the effects of the propagation of the fictitious limits by tracing and simplifying the generated, new cap constraints. We proposed a second strategy based on the decomposition of polyhedra into the sum of a polytope and a set of straight lines.The strategy consists in isolating the straight lines (associated to the DOF) and summing the polytopes in the smallest sub-space. After solving an industrial case, we concluded that tracing caps constraints during the operations allows reducing the models complexity and,consequently, the computational time; however, it still involves working in 6d even in caseswhere this is not necessary. In contrast, the strategy based on the operands decompositionis more efficient due to the dimension reduction. This study allowed us to conclude that the management of mechanisms’ mobility is a crucial aspect in tolerance simulations. The gain on efficiency resulting from the developed strategies opens up the possibility for doing statistical treatment of tolerances and tolerance synthesis.

A alta frequência das fraturas da extremidade distal do rádio estimula o contínuo estudo e desenvolvimento dos métodos de tratamento, buscando melhor qualidade de vida com menos sequelas e limitações. A placa volar bloqueada tem se tornado o método de escolha no tratamento nos últimos anos. Menos morbidade e a reabilitação mais precoce têm aumentado muito a utilização dessas placas. Esse método, contudo, não é isento de complicações. As mais frequentes estão relacionadas aos tendões extensores. Tendinites e rupturas têm sido relatadas. Com o objetivo de se proteger os tendões extensores, estudos têm sugerido a utilização de parafusos unicorticais na parte distal da placa e recomendam que os mesmos tenham pelo menos 75% do comprimento do parafuso bicortical. Esses estudos são restritos a fraturas extra-articulares. Esta pesquisa objetivou estudar e comparar as propriedades mecânicas dos modelos fixados com placas volares utilizando parafusos unicorticais e bicorticais em fraturas intra-articulares da extremidade distal do rádio classificadas como AO 23C3 sob cargas fisiológicas e a possibilidade de recomendar o parafuso unicortical na prática clínica. Objetivou também comparar, pelo método dos elementos finitos, as tensões geradas nos modelos após diferentes carregamentos com validações realizadas com os resultados dos ensaios mecânicos. Foram avaliados 42 modelos divididos em seis grupos de sete modelos, três com parafusos unicorticais e três com parafusos bicorticais. Cada grupo foi submetido a um único tipo de ensaio: compressão axial, flexão dorsal e flexão volar. Foram feitos dois ensaios estáticos intercalados por um carregamento cíclico e por último um ensaio até a falência. Os resultados demonstraram similaridade entre os respectivos grupos e confirmaram nossas hipóteses de que: a) o comportamento mecânico do modelo utilizando parafusos unicorticais é equivalente ao modelo usando parafusos bicorticais; b) o carregamento cíclico afeta o comportamento mecânico dos modelos das fixações das placas volares bloqueadas na extremidade distal do rádio. A análise por elementos finitos mostrou que as fixações unicortical e bicortical não resultaram em qualquer região de concentração de tensão crítica, sendo as duas indicadas para a estabilização de fraturas do rádio. / The high frequency of distal radius fractures stimulates the continuous study and development of treatment methods seeking a better quality of life and fewer sequels and limitations. The volar locking plate has become the chosen method for the treatment in recent years. The lower morbidity and earlier rehabilitation have greatly increased the use of these plates. This method, however, is not free from complications, the most common being related to extensor tendons. Tendinitis and rupture have been reported. In order to protect the extensor tendons, studies have suggested the use of unicortical screws in the distal part of the plate, and recommended that they be at least 75% of the length of the bicortical screw. These studies are restricted to extra articular fractures. This study aimed at studying and comparing the mechanical properties of the models fixed with volar plates using unicortical and bicortical screws in intra-articular fractures of the distal radius classified as AO 23C3 under physiological loads and the possibility of recommending the unicortical screw in clinical practice. The tensions generated in the models after different loads with validations performed with the results of the mechanical tests were also compared. We studied 42 models divided into six groups of seven models, three with unicortical screws and three with bicortical screws. Each group underwent a single type of test: axial compression, dorsiflexion and volar flexion. Two static tests were performed, intercalated by a cyclic loading, and finally a test until bankruptcy. Our results demonstrated a similarity between the respective groups and confirmed both our hypotheses that: a) the mechanical behavior of the model using unicortical screws is equivalent to the model using bicortical screws, and b) that the cyclic loading affects the mechanical behavior of the models of the fixations of the volar locked plates in the distal radius. The finite element analysis showed that the unicortical and bicortical fixations did not result in any regions of critical stress concentration, so they are both indicated for the stabilization of radius fractures.

A alta frequência das fraturas da extremidade distal do rádio estimula o contínuo estudo e desenvolvimento dos métodos de tratamento, buscando melhor qualidade de vida com menos sequelas e limitações. A placa volar bloqueada tem se tornado o método de escolha no tratamento nos últimos anos. Menos morbidade e a reabilitação mais precoce têm aumentado muito a utilização dessas placas. Esse método, contudo, não é isento de complicações. As mais frequentes estão relacionadas aos tendões extensores. Tendinites e rupturas têm sido relatadas. Com o objetivo de se proteger os tendões extensores, estudos têm sugerido a utilização de parafusos unicorticais na parte distal da placa e recomendam que os mesmos tenham pelo menos 75% do comprimento do parafuso bicortical. Esses estudos são restritos a fraturas extra-articulares. Esta pesquisa objetivou estudar e comparar as propriedades mecânicas dos modelos fixados com placas volares utilizando parafusos unicorticais e bicorticais em fraturas intra-articulares da extremidade distal do rádio classificadas como AO 23C3 sob cargas fisiológicas e a possibilidade de recomendar o parafuso unicortical na prática clínica. Objetivou também comparar, pelo método dos elementos finitos, as tensões geradas nos modelos após diferentes carregamentos com validações realizadas com os resultados dos ensaios mecânicos. Foram avaliados 42 modelos divididos em seis grupos de sete modelos, três com parafusos unicorticais e três com parafusos bicorticais. Cada grupo foi submetido a um único tipo de ensaio: compressão axial, flexão dorsal e flexão volar. Foram feitos dois ensaios estáticos intercalados por um carregamento cíclico e por último um ensaio até a falência. Os resultados demonstraram similaridade entre os respectivos grupos e confirmaram nossas hipóteses de que: a) o comportamento mecânico do modelo utilizando parafusos unicorticais é equivalente ao modelo usando parafusos bicorticais; b) o carregamento cíclico afeta o comportamento mecânico dos modelos das fixações das placas volares bloqueadas na extremidade distal do rádio. A análise por elementos finitos mostrou que as fixações unicortical e bicortical não resultaram em qualquer região de concentração de tensão crítica, sendo as duas indicadas para a estabilização de fraturas do rádio. / The high frequency of distal radius fractures stimulates the continuous study and development of treatment methods seeking a better quality of life and fewer sequels and limitations. The volar locking plate has become the chosen method for the treatment in recent years. The lower morbidity and earlier rehabilitation have greatly increased the use of these plates. This method, however, is not free from complications, the most common being related to extensor tendons. Tendinitis and rupture have been reported. In order to protect the extensor tendons, studies have suggested the use of unicortical screws in the distal part of the plate, and recommended that they be at least 75% of the length of the bicortical screw. These studies are restricted to extra articular fractures. This study aimed at studying and comparing the mechanical properties of the models fixed with volar plates using unicortical and bicortical screws in intra-articular fractures of the distal radius classified as AO 23C3 under physiological loads and the possibility of recommending the unicortical screw in clinical practice. The tensions generated in the models after different loads with validations performed with the results of the mechanical tests were also compared. We studied 42 models divided into six groups of seven models, three with unicortical screws and three with bicortical screws. Each group underwent a single type of test: axial compression, dorsiflexion and volar flexion. Two static tests were performed, intercalated by a cyclic loading, and finally a test until bankruptcy. Our results demonstrated a similarity between the respective groups and confirmed both our hypotheses that: a) the mechanical behavior of the model using unicortical screws is equivalent to the model using bicortical screws, and b) that the cyclic loading affects the mechanical behavior of the models of the fixations of the volar locked plates in the distal radius. The finite element analysis showed that the unicortical and bicortical fixations did not result in any regions of critical stress concentration, so they are both indicated for the stabilization of radius fractures.

In dieser Arbeit wird das Revisionsverhalten kanülierter, fenestrierter Pedikelschrauben evaluiert. Dies erfolgt zum einen anhand von Messungen des Drehmoments bei dem Entfernen von Pedikelschrauben aus osteoporotischen Wirbelkörpern eines Kadermodells. Hierbei werden Werte nicht zementierter und zementierter, kanülierter Pedikelschrauben erhoben, verglichen und ausgewertet. Während der Schraubenexplantation werden etwaig auftretende Rotationsbewegungen des Zements im Wirbelkörper radiografisch detektiert. Darüber hinaus wird das Revisionsverhalten kanülierter, fenestrierter Pedikelschrauben nach Zementaugmentation in vivo anhand monozentrisch, retrospektiv erhobener Patientenbeispiele aus dem klinischen Alltag beurteilt. Im Rahmen der Drehmomentmessungen bei Entfernung der kanülierten, fenestrierten Pedikelschrauben nach vorangeganger Zementierung konnte keine Destruktion des Wirbelkörpers beobachtet werden. Auch in den untersuchten Fallbeispielen des klinischen Alltags konnten die zementaugmentierten Pedikelschrauben komplikationslos entfernt werden.

O emprego de parafusos auto-atarraxantes em ligações metálicas, nos últimos anos, têm aumentado de forma significativa, principalmente como dispositivo de ligação entre componentes leves da construção metálica, como por exemplo, nas ligações entre telhas metálicas e terças. Tais ligações apresentam modos de falha diferentes dos observados para as ligações parafusadas convencionais, em função do tipo de parafuso e das reduzidas espessuras dos elementos conectados, definidos como \"pull-out\" e \"pull-over\". No Brasil, a carência de estudos específicos nesse tema foi uma das razões da omissão da recente norma brasileira de dimensionamento de estruturas de aço constituídas por perfis formados a frio - NBR 14762:2001, quanto a procedimentos específicos para o projeto de ligações com parafusos auto-atarraxantes. Nesse trabalho foi desenvolvido um estudo abrangente sobre as ligações metálicas com parafusos auto-atarraxantes, com ênfase na ligação telha-terça, onde são apresentados os procedimentos e as recomendações das principais normas estrangeiras, bem como os ensaios padronizados para caracterização dos parafusos e avaliação do comportamento estrutural e resistência de ligações. São apresentados também os resultados de uma investigação experimental, com base no ensaio padrão do AISI (1996) (American Iron and Steel Institute), em 27 corpos-de-prova com variação no diâmetro do parafuso e espessura dos componentes da ligação (terça e telha), com o objetivo principal de avaliar as expressões das AISI (2001b e 1996) para dimensionamento. Como conclusão, são relatadas as dificuldades associadas ao ensaio padrão, que apesar de sua concepção simples, conduz à elevada variabilidade nos resultados, indicando a necessidade da adoção de ensaios mais representativos e confiáveis. / The use of screws in steel connections has increased significantly in recent years, mainly as connecting devices between light-gage components in steel construction, as, for example, in joints between metal roofing and purlins. These connections exhibit different failure modes from those displayed by conventional bolted connections, due to the type of fastener and the reduced thicknesses of the connected elements, defined as pull-out and pull-over. In Brazil, the lack of specific studies of this theme was one of the reasons for the omission of specific procedures for the design of screw connections from the new edition of the brazilian code for cold-formed steel members - NBR 14762:2001. The work reported here involved a comprehensive study of steel connections using screws, with emphasis on the sheating-purlin connection. A presentation is made of the procedures and recommendations of the main foreign codes, as well as of standardized tests for characterizing screws and evaluating the structural behavior and strength of connections. Also presented are the results of an experimental investigation based on the standard test of the AISI (1996) (American Iron and Steel Institute) applied to 27 test specimens with varying screw diameters and connector component thicknesses (purlin and sheeting), whose main purpose was to evaluate the AISI\'s design equations (2001b e 1996). To conclude, a report is made of the difficulties associated with the standard test, which, despite its simple conception, leads to considerably variable results, indicating the need for the adoption of more representative and reliable tests.

As fraturas do ângulo mandibular são muito frequentes dentre as fraturas mandibulares e um das formas de tratamento é a utilização de fixação interna com placas e parafusos. Neste estudo o objetivo foi avaliar comparativamente a resistência de três tipos de fixação em réplicas de mandíbula de poliuretano. Foram utilizadas 63 mandíbulas dentadas, submetidas a seccionamento simulando uma fratura linear e desfavorável de ângulo mandibular esquerdo. As fixações foram realizadas com placas do sistema 2,0 mm, dispostas da seguinte forma: uma placa reta de quatro furos, uma placa reta de quatro furos com extensão (ponte) e uma placa 3D 4 furos. Cada grupo (n = 21) foi submetido ao teste de resistência linear com aplicação de carga no sentido súpero-inferior em três pontos distintos da mandíbula, de modo não simultâneo (região do primeiro molar ipsilateral à secção, primeiro molar contralateral e incisivos centrais) em máquina de ensaio universal EMIC DL 2000. Foram mensurados valores de carga no deslocamento de 1 mm, 2 mm e 5mm. Os resultados obtidos foram submetidos à análise estatística, utilizando a análise de variância (ANOVA), nível de significância de 5%. Os valores obtidos, não apresentaram diferença estatisticamente significante entre as placas. Os resultados mostraram que as placas 3D produzem escores similares às placas usadas convencionalmente. Com base nos resultados obtidos, pode-se concluir que os três tipos de fixação se comportam de forma similar. / Mandibular angle fractures are very frequent among the mandibular fractures and a form of treatment is the use of internal fixation with plates and screws. In this study, the objective was to evaluate the resistance of three types of fixation in mandibular replicas of polyurethane. Sixty three toothed mandibles were used, subject to sectioning simulating a linear and unfavorable fracture of left mandibular angle. The fixations were performed with straight plates system 2.0 mm, prepared as follows: one plate with 4-holes, one 4-holes and extension (bridge) and one plate 3D 4-holes .Each set was submitted for loading test with load application towards in three distinct points of the mandible, so do not simultaneously (molar region on the side ipsilateral of section, the central incisors and contralateral molar) in universal testing machine EMIC DL 2000. Load values were measured at offset 1 mm, 2 mm and 5mm and was noted the final dislocation. The results were submitted to statistical analysis, using analysis of variance (ANOVA), a significance level of 5%. the values obtained showed no statistically significant difference between the plates. The results show that the 3D plate can reproduce similar mechanical scores to the plates used conventionally. It can be concluded that the three types of fasteners behaved similarly.

As claudicações são a principal causa de encaminhamento de equinos aos médicos veterinários e uma das maiores causas de encaminhamento destes animais aos hospitais de referência; sendo as fraturas, especialmente aquelas de ossos longos e articulares, as que têm menor índice de sucesso devido ao prognóstico reservado e alto custo do tratamento; entendendo como sucesso o retorno do animal à função ou manutenção da qualidade de vida. A articulação interfalangeana proximal (AIP) dos equinos é clinicamente importante devido à apresentação frequente de claudicação, com lesões que comprometem a vida esportiva e função do equino. O objetivo desta pesquisa foi comparar biomecanicamente as características de duas técnicas de artrodese da AIP em equinos, utilizando-se placa de compressão dinâmica (DCP) de 4.5mm e três orifícios em combinação com dois parafusos corticais transarticulares de 5.5mm oblíquos inseridos pela técnica de tração (lag screw) e placa em "Y\" de compressão bloqueada (LCP) de 5,0mm e sete orifícios, com parafusos bloquados unicorticais e um parafuso cortical de 4.5mm oblíquo transarticular inserido no orifício central da placa, pela técnica de parafuso de tração. Foram utilizadas doze peças anatômicas de membros anteriores de equinos, das quais foi isolada a porção distal do membro desde a primeira falange até o casco. Uma vez preparadas as peças, cada par foi sorteado randomicamente para cada um dos dois grupos. Os modelos experimentais foram submetidos a ensaios biomecânicos de compressão axial em ciclo único até a sua falha. O tipo de falha ocorrida na placa, nos parafusos ou nos ossos foi avaliado, assim como a força à qual ocorreram estas falhas. Não houve diferença estatística significativa entre os grupos DCP e Y-LCP, nas variáveis rigidez e força máxima, quando submetidas a compressão axial até sua falha. Mesmo não havendo diferença entre as duas técnicas cirúrgicas na variável rigidez, a técnica Y-LCP possibilitou um procedimento menos invasivo e com menor tempo cirúrgico. Conclui-se que, as propriedades biomecânicas das duas técnicas de fixação (DCP e Y-LCP) são semelhantes nas condições testadas. / Lameness is the main cause of sport horses\' owners consulting equine veterinarians and one of the highest cause to send these animals to the reference hospitals. Long bones and joint fractures have the lesser rate of success, consequence of the hight cost of the treatment and poor prognosis. Understanding as success the return of the horse to previous athletic performance or at least to have useful life. The proximal interphalangeal joint (PIPJ) is clinically important because the injuries that involve it may threaten the horses sport life or its usefulness. The objective of this study was to compare the biomechanical properties of two PIPJ arthrodesis techniques using 4.5mm dynamic compression plate (DCP) in conjunction with two oblique abaxial transarticular 5.5mm cortical screws inserted in lag fashion and 5.0mm Y locking compression plate (Y-LCP) with unicortical locking screws and one axial transarticular 4.5mm cortex screw inserted in lag fashion through the midle plate hole. It was used twelve cadaveric adult equine forelimbs from the first phalanx to the foot. After full-limb preparations, each forelimb pair was randomly assigned to one of two treatment groups. Constructs were submited to axial compression single cycle to failure biomechanical testing. The failure of the screws, plate or bone, and the force at wich it happened was evaluated. There were no significant differences in construct stiffness or max force when loaded to failure, between the DCP and Y-LCP treatment groups. Even though there was no construct stiffness diffrences between the two techniques, the Y-LCP technique provided the possibility of a less invasive procedure with a shorter surgical time. In conclusion, the biomechanical properties of both fixation techniques (DCP and Y-LCP) are equivalent under the test conditions used.