In this paper, using the general purpose software ABAQUS, a three dimensional (3-D) finite element model was built to simulate semi-rigid composite connection with precast hollowcore slabs. 3D continuum elements are used for all parts of the composite connections and the contact conditions between all the components are explicitly modelled. The model also incorporates nonlinear material characteristics and non-linear geometric behaviour. A simplified method to simulate the bolted end plate connection is introduced and validated. The proposed simulation method of the longitudinal shear transmission can accurately simulate the plastic state of the longitudinal rebars after cracking. Different materials are chosen by the authors to simulate the concrete slab, and the elastic¿plastic material property is adopted which can accurately simulate the moment¿rotation response of the connections. Numerical results are presented and compared with the experimental data and good agreement is obtained.

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A novel, general, numerical model is described that is capable of predicting the load-displacement relationship up to and at failure of multiple-bolt joints in timber of various configurations. The model is not tied to a single input function and bolt holes are permitted to be drilled oversize resulting in a slack system. The model consists of five parts. A new mathematical hysteresis model describes the stiffness of the individual bolt at each time step increment and accounts for non-linear and slack behavior; a mechanically-based structural stiffness model explains the interaction of one bolt with another bolt within a joint; an analytically-based failure model computes the stresses at each time step and initiates failure if crack length equals fastener spacing; a stochastic routine accounts for material property variation; and a heuristic optimization routine estimates the parameters needed. The core model is a modified array of differential equations whose solution describes accurate hysteresis shapes for slack systems. Hysteresis parameter identification is carried out by a genetic algorithm routine that searches for the best-fit parameters following evolutionary principles (survival of the fittest). The structural model is a linear spring model. Failure is predicted based on a newly developed 'Displaced-Volume-Method' in conjunction with beam on elastic foundation theory, elastic theory, and a modified Tsai-Wu Failure criterion. The devised computer model enhances the understanding of the mechanics of multiple-bolt joints in timber, and yields valid predictions of joint response of two-member multiple-bolt joints. This research represents a significant step towards the simulation of structural wood components. / Ph. D.

This dissertation presents the results of testing to determine the load-slip characteristics of single-shear single lag screw connections subjected to monotonic lateral loading parallel to grain. Of particular importance was the comparison of experimental capacity and 5% offset yield load resistances to load resistances as predicted by the American Forest & Paper Association's (AF&PA) publication General Dowel Equations for Calculating Lateral Connection Values, Technical Report 12 (TR-12). Additionally some other tests were conducted, including fracture, tension strength perpendicular-to-grain, lag screw connection inking, dowel embedment, specific gravity and moisture content. The results for the testing program are presented. Four hundred and forty eight lateral tests were conducted on lag screw connections. Each connection was comprised of a 2 x 6 x 14 in. long wood main member, 1/4 in. thick steel side plate, and a single lag screw. The parameters of interest were specific gravity, lag screw diameter, and pilot hole diameter. Two species of wood, Douglas-fir and spruce-pine-fir, three lag screws diameters, and three pilot hole diameters for each species of wood were implemented. Models were developed to predict lag screw connection capacity and 5% offset yield and are contained herein. Models were based on results from connection and inking tests and mechanical analysis. Recommendation for ASD and LRFD design values were derived from connection test results for connections that used AF&PA's National Design Specification for Wood Construction (NDSb) specified pilot holes. Using fracture mechanics results, work was performed to determine the effective load required to crack and separate fracture surfaces of wood main members due to the installation of lag screws with varying pilot hole diameters. / Ph. D.

An analytical and experimental investigation was conducted to study the six bolt flush moment end-plate connection configuration which is used in steel frame construction. The limit states of plate yielding and bolt fracture were analyzed using yield-line theory to predict endplate thicknesses and a split-tee analogy to develop a method to predict bolt forces. Five experimental tests were conducted on four configurations within a matrix of geometric parameters. The predicted ultimate moment showed good . correlation to the yield moment obtained from the experimental deflection plots. The experimental bolt forces correlated well with the predicted bolt forces when plotted versus the applied moment. Additionally, an equation to model the moment-rotation relationship was developed from a regression analysis to determine the construction type suitable for a given connection configuration. Finally, a method of designing the six-bolt flush end-plate configuration is presented and an example given. / Master of Science

An experimental investigation was conducted to study the behavior of snug tight ASTM A325 bolts in moment end-plate connections for use in single story buildings. Wind loading was deemed to be the critical loading on snug tight bolt, moment end-plate connections. A test loading sequence was established based on a statistical analysis of the 50-year wind loading on low rise buildings. Eleven specimens, representing six end-plate configurations, were tested under cyclic loading covering expected wind loads in the range of 33 to 100 percent of the connection design (allowable stress design) moment. Following the cyclic loading, the specimens were statically loaded to failure, and the experimental strengths were compared with predicted strengths for connections with fully tightened A325 bolts. Additionally, the effect of snug tight bolts on connection stiffness are considered. Finally, recommendations for the use of snug tight bolts in moment end-plate connections were provided. / Master of Science

Os pontos com maior fragilidade em estruturas de madeira são as ligações, pois nelas ocorrem as maiores concentrações de tensões. Dentre os tipos de conectores mais utilizados nas ligações temos os pinos metálicos, no quais se enquadra o parafuso comum. Para o dimensionamento de ligações por pinos metálicos, dois parâmetros são utilizados: a resistência ao escoamento do aço e a resistência da madeira ao embutimento. O objetivo deste trabalho foi comparar os métodos de ensaio de documentos normativos (ABNT NBR 7190:1997, EN 383:2007, ASTM D5764:2007, EUROCODE 5:2004, NDS:2001 e LRFD:1996) com a finalidade de estabelecer uma proposta de método de ensaio para a determinação da resistência da madeira ao embutimento. Foram realizados ensaios na direção paralela e na direção normal às fibras para seis espécies de madeira (Paricá, Pinus elliottii, Pinus oocarpa, Jatobá, Lyptus e Cupiúba), utilizando vários diâmetros (8 mm, 10 mm, 12 mm e 16 mm) para os pinos metálicos. Baseado na análise dos resultados obtidos foi proposta a adoção do método de ensaio baseado na EN 383:2007. Os resultados experimentais para a resistência ao embutimento tem maior aprovação com o parâmetro resistência à compressão paralela às fibras, atualmente adotado pela ABNT NBR 7190:1997. Além disso, esse método recomenda dimensões que facilitam a confecção dos corpos de prova, principalmente na direção normal às fibras. / Main fragility in timber structures occurs in the connections, because to stress concentrations. Most of connections use bolts laterally loaded, a metal dowel-type fastener. Two parameters are used for design of the connections with metal dowel-type in timber structures: yield strength of metal dowel and embedment strength of wood. The aim of this study was to compare the test methods of Codes (ABNT NBR 7190:1997, EN 383:2007, ASTM D5764:2007, EUROCODE 5:2004, NDS:2001 and LRFD:1996) in order to establish a proposed test method for the determination of the embedment strength of wood. The tests were performed applying load in the direction parallel and in the direction perpendicular to the grain for six species of wood (Paricá, Pinus elliottii, Pinus oocarpa, Jatobá, Lyptus and Cupiúba) using several diameters (8 mm, 10 mm, 12 mm and 16 mm) for the metal dowels. Based on the analysis of the results, is proposed adopting the test method based on EN 383:2007. The experimental results for the embedment strength has better fit with the strength parameter currently used by ABNT NBR 7190:1997, compression parallel to the grain. In addition, this method recommends dimensions that facilitate the specimens preparation, mainly in the direction perpendicular to the grain.

A presente dissertação versa sobre a determinação do parâmetro de adesão entre nata de cimento e rocha. Este parâmetro é de fundamental importância no dimensionamento de grampos e tirantes ancorados, sistemas de contenção frequentemente executados que utilizam da técnica de ancoragem. Ensaios de arrancamento in loco são comumente realizados para avaliar essa tensão de aderência, no entanto, muitas vezes, apenas se tornam viáveis financeiramente durante a etapa de execução das obras. A metodologia Composite Cylinder Bond Test (CCBT) permite a determinação da adesão de maneira mais simples e com menor custo, por meio de ensaios de laboratório utilizando corpos de prova mistos de rocha e nata de cimento, sendo, por isto, uma interessante alternativa para a etapa de definição paramétrica de projetos. Neste contexto, foram estudadas três litologias sedimentares do município de Caçapava do Sul/RS – aqui chamadas de conglomerado, arenito muito fino e arenito médio – pertencentes à Formação Varzinha. A caracterização dessas litologias foi realizada por meio de lâminas delgadas e outros ensaios de caracterização de laboratório A classificação textural do conglomerado é de conglomerado arenoso, o arenito muito fino é classificado como arenito lamoso e o arenito médio é classificado como arenito. Do ponto de vista composicional, o arenito muito fino é classificado como arcóseo, enquanto o arenito médio é classificado como arcóseo lítico. Noventa ensaios CCBT, além de ensaios de resistência à compressão simples das rochas e da nata de cimento foram realizados. As tensões de adesão médias obtidas dos ensaios de laboratório foram de 2,52 MPa para o conglomerado, 1,84 MPa para o arenito muito fino e 1,43 MPa para o arenito médio. Foi realizada uma avaliação de intervalos de confiança de valores de tensão de adesão, conforme a distribuição t-student. Concluiu-se que não apenas a resistência das rochas influencia nessa capacidade de adesão, mas também a capacidade de absorção d’água e a porosidade. Maiores valores dessas duas propriedades na rocha favorecem a adesão entre os dois materiais. Os valores encontrados em laboratório são compatíveis com dados de literatura de campo em rochas similares. / This dissertation evaluates the determination of the adhesion parameter between cement grout and rock. This parameter is of great importance on design of two systems frequently executed that use the technique of anchoring: rock anchors and bolts. Pull out field tests are commonly carried out to evaluate this bond strength, however, they are normally only economically feasible during the construction stage. The Composite Cylinder Bond Test (CCBT) methodology allows the adhesion determination in a simpler and cheaper way, by laboratory tests using mixed samples of rock and cement grout. Therefore, the CCBT is an interesting alternative to project definition of adhesion values. In this context, three different sedimentary lithologies from Caçapava do Sul/RS, Southern Brazil, were studied. The lithologies – called here as conglomerate, fine sandstone and medium sandstone – belong to Varzinha Formation. The characterization of these lithologies were made by thin sections and characterization laboratory tests The textural classification of the conglomerate was sandy conglomerate, the fine sandstone was classified as muddy sandstone, and the medium sandstone was classified as sandstone. In the view of their composition, the fine sandstone was classified as arkose, while the medium sandstone was classified as lithic arkose. Ninety CCBT tests, besides unconfined compression tests on rock and cement grout specimens were carried out. The average adhesion values obtained from laboratory tests were 2,52 MPa for the conglomerate, 1,84 MPa for the fine sandstone and 1,43 MPa for the medium sandstone. An evaluation of confidence intervals of adhesion was also carried out, according to t-student distribution. It was concluded that the adhesion strength was influenced not only by the unconfined compressive strength of the rocks, but also by their water absorption and porosity. Larger values of these two properties increased the adhesion between the two materials. The values obtained from laboratory tests are compatible with literature field data in similar rocks.