Este trabalho apresenta uma análise numérica sobre o comportamento estrutural das ligações parafusadas viga-coluna com chapa de topo. São estudados dois métodos tradicionais de dimensionamento e são apresentados cinco sistemas de classificação propostos para as ligações. Modelos numéricos das ligações estudadas são preparados com a utilização de elementos finitos e os resultados numéricos são comparados com resultados experimentais conhecidos. São abordados aspectos relativos às propostas de dimensionamento, em comparação com os resultados numéricos e experimentais. Em particular, é discutida a rigidez das ligações, verificando-se a influência da variação da espessura da chapa de topo e diâmetro dos parafusos. Com a comparação entre resultados numéricos e experimentais, é analisada a representatividade dos modelos numéricos com relação ao comportamento das ligações estudadas. Finalmente, são apresentadas as conclusões e recomendações para futuras pesquisas / This work presents a numerical analysis on the structural behavior of bolted beam-to-column end plate connection. Two traditional design methods are studied and five proposed classification systems for connections are presented. Numerical models representing the studied connections are prepared using finite elements and numerical results are compared with existing experimental results. The design proposals are compared with numerical and experimental results. In particular, the connection rigidity is discussed by verifying the influence of variations in end plate thickness and bolt diameter. Comparing numerical and experimental results the reliability of F.E.M models is appraised. Finally, conclusions are presented with some suggestions for future researches

As alternativas de reciclagem se apresentam com elevado potencial para acrescentar ganho à capacidade estrutural de um pavimento, simultaneamente, aproveitando os materiais compostos do pavimento existente, acarretando benefícios econômicos e ambientais, quando comparadas às soluções de reconstrução tradicionais. Diversos métodos de reciclagem de pavimentos têm sido aplicados no Brasil, particularmente, a reciclagem com adição de cimento, entretanto, não há um método consolidado para o dimensionamento estrutural dessa solução, o que gera dificuldades e muitas vezes desconfiança no seu emprego. Para se desenvolver um procedimento de dimensionamento que contemple esse tipo de solução, foram estudados métodos presentes na bibliografia internacional. Uma abordagem detalhada sobre cada método é apresentada, denotando seus principais aspectos, resultando em uma proposta de procedimento para o dimensionamento estrutural de pavimentos com camadas recicladas com cimento, de forma a atender a metodologia do Manual de Pavimentação do Departamento Nacional de Infraestrutura de Transportes (DNIT) aplicando conceitos de análise mecanicista. A fim de corroborar os assuntos abordados, foi realizado um estudo paramétrico com o desenvolvimento de equações para correlação entre as deformações críticas esperadas na estrutura reciclada, resultando em modelos de dimensionamento para a camada reciclada com cimento e, por fim, o estudo de caso com o dimensionamento estrutural pelos métodos abordados em segmentos da rodovia SP 270. / Recycling alternatives are presented with a high potential to add gain to the structural capacity of a pavement, making use of the existing pavement composite materials while bringing economic and environmental benefits when compared to traditional reconstruction techniques. Several methods of pavement recycling have been applied in Brazil, particularly the recycling with cement addition; however, there is no consolidated method for the structural design of this solution, which generates difficulties and often distrust regarding its employment. In order to develop a design procedure taking into account this sort of solution, methods described in international bibliography have been examined. A detailed approach to each method denoting its main aspects is presented, resulting in a proposed procedure for the structural design of pavements with cement recycled layers so as to comply with the methodology contained in the Paving Manual of National Department of Transport Infrastructure (DNIT) by applying concepts of mechanistic analysis. In order to corroborate the issues discussed, a parametric study has been carried out with the development of equations to correlate the critical deformations expected in the recycled structure, resulting in design models for the cement recycled layer and finally, the case study of a structural design on segments of Highway SP 270 using the methods discussed.

Este trabalho apresenta uma análise numérica e experimental sobre o comportamento estrutural de ligações parafusadas viga-pilar com chapa de topo estendida. Discute-se, em particular, o comportamento da chapa de topo e dos parafusos na determinação da capacidade resistente dessas ligações. A análise de resultados numéricos é utilizada como base para as discussões neste trabalho e a modelagem numérica, realizada em elementos finitos com o software ANSYS, incluiu modelos tridimensionais de ligações com chapa de topo estendida e de ligações duplo “T". Com os resultados numéricos e experimentais, os mecanismos de transferência dos esforços entre viga e pilar e os mecanismos de plastificação da chapa de topo e dos parafusos são observados, avaliando-se as linhas de plastificação na chapa de topo em confronto com a metodologia proposta pelo Eurocode 3 na determinação dos perfis “T" equivalentes. Para esses fatores, observou-se que os modos de falha indicados pelo Eurocode 3 não representam satisfatoriamente o comportamento das ligações analisadas. A modelagem numérica, por sua vez, mostrou-se generalista e representativa como ferramenta para análises paramétricas e como complemento de análises experimentais / This work presents a numerical and experimental analysis on the structural behavior of bolted beam-column extended end plate connections. The behavior of the end plate and bolts used in the calculations of the end plate strength is specially discussed. Numerical results are used as basis to the discussions presented in this work and the modeling methodology, with FE models built with the ANSYS code, included 3D models of extended end plate and T-stub connections. The beam-to-column load transfer mechanisms and the yielding mechanisms at end plates and bolts are observed using numerical and experimental results. The yielding lines at the end plate are evaluated against the methodology proposed by Eurocode 3 for the calculations on the equivalent T-stub. Regarding the aforementioned factors, it is shown that the collapse modes indicated by Eurocode 3 do not represent satisfactorily the behavior of the analyzed connections. The numerical modeling was found to be general in application and reliable as a tool for parametric analyses and as a complement to experiments

In the analyses of steel framed structures it is customary to assume the beam to column connections as either fully rigid which means that all moments are transferred from beam to column with negligible rotation or ideally pinned that resists negligible moment. This assumption is reasonable for some types of connections. However when considering steel connections such as bolted-bolted double web angle connections it can be seen that the behavior of these connections is in between the two extreme cases. Thus a third connection type, namely semi rigid or partially restrained connection, is introduced. However this type of connection exhibits such a nonlinear behavior that modeling this behavior necessities a substantial effort. Moreover to perform a performance based analyses the true behavior of these connections should be incorporated as part of the modeling effort. Several researches dealing with these two topics have been undertaken in literature. Despite these efforts, modeling of the moment rotation behavior of these connections still requires improvement especially under cyclic loading conditions. In addition to this, performing an analysis with existing elements incorporating semi-rigid connections as a spring attached to beam ends is not practical because of the fact that displacement based formulation increases meshing significantly which requires substantial computational power. In this study a hysteretic (quadra-linear) moment rotation model considering pinching, damage and possibility of residual moment capacity is developed. The behavior is calibrated via experimental data available in the literature. Furthermore a force based macro element considering spread inelastic behavior along the element is presented. With this element several connections located anywhere along the beam could be incorporated in the analysis with less degree of freedom with respect to displacement based elements. Moreover the macro element model can be used in conjunction with corotational formulation for the capture of nonlinear geometric effects.

The purpose of this study is to develop an approach that considers fire as a load in the design of structures. Recent studies of the full-scale fire tests in Cardington, UK and the World Trade Centre collapse have shown that the behaviour of steel structures in fire when assembled into a frame differs from that measured or predicted by fire testing of individual structural elements, revealing the importance of accounting for realistic fire loads in the design of structures and the potential inadequacy of fire testing individual elements as employed by current building codes. Yet, there has been limited basic research and development to allow consideration of fire as a load in the analysis and design of structures. In response to this much needed work, this thesis develops an approach to include fire as a load in the analysis of a 2-bay by 2-storey structure when a semi-rigid connection is exposed to thermal loads typical of those that might be encountered during a real fire. The structural fire analysis is principally based on incorporating moment-rotation-temperature data for the connection, as found in archival literature, into a structural analysis software package developed at the University of Waterloo. The software employs a modified Displacement Method for analyzing structures, which involves the computation of stiffness reduction factors that represent the deterioration of strength of the structural elements as they are subjected to various loads. By modifying the moment-rotation-temperature data for a semi-rigid connection into a form recognized by the software, a fire load is simulated by incrementally elevating the temperature of the affected steel connection. In this way, a fragility analysis of the entire structure under fire load is conducted. A series of example calculations are presented for cases in which the semi-rigid connection is exposed to increasing temperatures of 20°C, 200°C, 400°C and 600°C. The analysis showed that as the connection is heated, it is weakened, and the steel structure undergoes a redistribution of moments from the heated connection to other non-heated elements within the framework, which is essentially a form of fire-resistance of the assembled structure that unassembled members in isolation do not have. The study also demonstrated that the experimental moment-rotation-temperature data reported in archival literature can be incorporated into the structural analysis, and that additional force-deformation data obtained from further experimental work or through finite-element analyses would allow the study to be extended to analyze the effects of fire loading on other structural elements of an assembled framework. To demonstrate the link between the predicted structural response at different temperatures and the development of a compartment fire, a fire modelling analysis is also performed.

The purpose of this study is to develop an approach that considers fire as a load in the design of structures. Recent studies of the full-scale fire tests in Cardington, UK and the World Trade Centre collapse have shown that the behaviour of steel structures in fire when assembled into a frame differs from that measured or predicted by fire testing of individual structural elements, revealing the importance of accounting for realistic fire loads in the design of structures and the potential inadequacy of fire testing individual elements as employed by current building codes. Yet, there has been limited basic research and development to allow consideration of fire as a load in the analysis and design of structures. In response to this much needed work, this thesis develops an approach to include fire as a load in the analysis of a 2-bay by 2-storey structure when a semi-rigid connection is exposed to thermal loads typical of those that might be encountered during a real fire. The structural fire analysis is principally based on incorporating moment-rotation-temperature data for the connection, as found in archival literature, into a structural analysis software package developed at the University of Waterloo. The software employs a modified Displacement Method for analyzing structures, which involves the computation of stiffness reduction factors that represent the deterioration of strength of the structural elements as they are subjected to various loads. By modifying the moment-rotation-temperature data for a semi-rigid connection into a form recognized by the software, a fire load is simulated by incrementally elevating the temperature of the affected steel connection. In this way, a fragility analysis of the entire structure under fire load is conducted. A series of example calculations are presented for cases in which the semi-rigid connection is exposed to increasing temperatures of 20°C, 200°C, 400°C and 600°C. The analysis showed that as the connection is heated, it is weakened, and the steel structure undergoes a redistribution of moments from the heated connection to other non-heated elements within the framework, which is essentially a form of fire-resistance of the assembled structure that unassembled members in isolation do not have. The study also demonstrated that the experimental moment-rotation-temperature data reported in archival literature can be incorporated into the structural analysis, and that additional force-deformation data obtained from further experimental work or through finite-element analyses would allow the study to be extended to analyze the effects of fire loading on other structural elements of an assembled framework. To demonstrate the link between the predicted structural response at different temperatures and the development of a compartment fire, a fire modelling analysis is also performed.

Made available in DSpace on 2014-06-11T19:27:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-04-12Bitstream added on 2014-06-13T20:27:39Z : No. of bitstreams: 1 bertolucci_fs_me_ilha.pdf: 2860301 bytes, checksum: 3f3004f9d02861054ffe5fb10b1b2e7d (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A indústria estruturas de concretos pré-moldados possui como grande preocupação a ligação entre seus elementos, tendo em vista que a mesma exerce grande influência no comportamento da estrutura, sendo responsável pela transmissão e redistribuição dos esforços na estrutura. A grande diferença entre estruturas pré-moldadas e estruturas de concreto moldadas “in loco” em relação ao seu comportamento estrutural está na ligação entre seus elementos. As ligações apresentam certa deformação quando solicitadas, recebendo na literatura técnica a denominação de ligações semi-rígidas. Dessa forma, buscou-se estudar todos os grautes existentes no mercado e desenvolver um compósito cimentício de fácil preparo e de baixo custo, do tipo calda de cimento e argamassa, que apresentasse características mecânicas similares aos grautes. Foram desenvolvidas duas caldas de cimento e uma argamassa, as quais foram submetidas juntamente com os grautes selecionados a ensaios específicos de propriedades adesão e aderência. Dentre as principais conclusões obtidas podem ser ressaltadas que a grande parte dos grautes possui problemas de fluidez dificultando o preenchimento total das ligações e sua aplicação. Em relação à aderência as duas caldas de cimento e a argamassa apresentaram comportamento semelhante indicando que há uma boa condição de aderência e, os grautes, devido à sua grande diferença de composição, tiveram comportamentos distintos / One of the concerns of the precast concrete industry is the connection among their different types of elements, in order that they strongly influence the behavior of the structural group, being responsible for the transmission and redistribution of the efforts in the structure. Among the differences between precast structures and concrete structures shaped “in loco” we have the concern about the structural behavior of the link between its elements. The links have shown some deformation when tested, receiving in the technical literature the name of semi-rigid connections. For that the concrete’s precast structure has the behavior of a monolithic structure it’s necessary the solidarization of the connection which is made by filling the vertical and horizontal niches with the aid of the grout. In this paper, we aimed to study some grouts of the Brazilian market and, at the same time, develop a cimentitius composite of easy prepare and low cost, of the cement paste and mortar types, with similar mechanical characteristics to industrialized grouts to be used in the filling of the precast structures. It was rheologically and mechanically created and evaluated two kinds of cement grout and one mortar composition that were submitted along with the selected grouts to an evaluation of their rheological behavior, and to specific tests of their mechanical properties of adhesion and bond. This study let us conclude that the cement paste and mortar developed showed a similar rheological behavior to the Herschel-Bulkley, besides to a good condition of bond and a good behavior in the structure link when compared to some industrialized grouts. Not all the evaluated grouts showed appropriate behaviors for joints’ filling

Airships provide an eco-friendly and cost-effective means to suit sustained airborne operations. Smaller autonomous airships are highly susceptible to adverse atmospheric conditions owing to their under-actuated, underpowered and bulky size relative to other types of unmanned aerial vehicles (UAVs). To mitigate these limitations, careful considerations of the size and shape must be made at the design stage. This research presents a methodology for obtaining an optimized shape of a semi-rigid airship. Rapid descent of the LTA ship is achieved by means of a moving gondola attached to a rigid keel mounted under the helium envelope from the bow to the mid-section of the hull. The study entails the application of a robust hybrid genetic algorithm (HGA) for the multi-disciplinary design and optimization of an airship capable of rapid descent, with lower drag and optimum surface area. A comprehensive sensitivity analysis was also performed on the basis of algorithmic parameters and atmospheric conditions. With the help of HGA, a semi-rigid airship capable of carrying a payload of 0.25 kg to 1.0 kg and capable of pitching at right angles is conceptually designed. The algorithm is also tested on commercially available vehicles to validate the results. In multi-objective optimization problems (MOOPs), the significance of different objectives is dependent on the user.

Este trabalho aborda ligações semi-rígidas com o objetivo de verificar a influência da flexibilidade na análise de estruturas metálicas, com o propósito de apresentar um modelo que represente o real comportamento das conexões assumindo uma situação intermediária entre totalmente rígida e totalmente flexível. Os procedimentos empregados para determinar as propriedades destas conexões estão embasados nos métodos descritos pelo anexo J do Eurocode 3 e recomendações do BCSA/SCI. Com intuito de automatizar o cálculo das conexões semi-rígidas foi implementado um programa computacional que fornece as propriedades necessárias das ligações entre vigas e pilares através da entrada de dados geométricos e especificações do material empregado. São abordadas ligações soldadas e ligações parafusadas com chapa de extremidade.O trabalho apresenta, ainda, uma avaliação da redistribuição de solicitações nas estruturas de aço. Fazendo a análise de um pórtico plano empregando molas rotacionais nos nós de encontro entre vigas e pilares inserindo a rigidez rotacional obtida através dos procedimentos numéricos apresentados neste trabalho. Esta mesma estrutura foi analisada da maneira tradicional, ou seja, considerando nós rígidos no encontro entre vigas e pilares. Através da analogia entre os resultados obtidos pelas duas análises é possível visualizar a diferença entre a distribuição nas solicitações. Dessa forma, é possível verificar a influência da rigidez das ligações na análise das estruturas metálicas. / This work approaches semi-rigid connections with the purpose to verify the influence of connections in the analysis of steel structures, with the intention to present a model that represents the real behavior of the connections assuming an intermediate situation between totally rigid and totally pinned. The used procedures to determine the properties of these connections are based in the described methods for the Annex J of the Eurocode 3 and BCSA/SCI. With intention to speed the calculations of the semi-rigid connections a computational program was implemented that supplies to the necessary properties of the connections between beams and columns through the geometric data entry and specifications of the employed material. They are boarded welded connections and connections bolted with extend end plate. The work presents, still, an evaluation of the new distribution of loads in the steel structures. Making the analysis of a plain frame using rotational springs between beams and columns inserting the gotten rotational rigidity through the presented numerical procedures in this work. This same structure was analyzed in the traditional way, that is, considering rigid we in the meeting between beams and columns. Through the analogy it enters the results gotten for the two analyses is possible to visualize the difference enters the distribution in the requests. Of this form, it is possible to verify the influence of flexibility in the analysis of the metallic structures.

Este trabalho aborda ligações semi-rígidas com o objetivo de verificar a influência da flexibilidade na análise de estruturas metálicas, com o propósito de apresentar um modelo que represente o real comportamento das conexões assumindo uma situação intermediária entre totalmente rígida e totalmente flexível. Os procedimentos empregados para determinar as propriedades destas conexões estão embasados nos métodos descritos pelo anexo J do Eurocode 3 e recomendações do BCSA/SCI. Com intuito de automatizar o cálculo das conexões semi-rígidas foi implementado um programa computacional que fornece as propriedades necessárias das ligações entre vigas e pilares através da entrada de dados geométricos e especificações do material empregado. São abordadas ligações soldadas e ligações parafusadas com chapa de extremidade.O trabalho apresenta, ainda, uma avaliação da redistribuição de solicitações nas estruturas de aço. Fazendo a análise de um pórtico plano empregando molas rotacionais nos nós de encontro entre vigas e pilares inserindo a rigidez rotacional obtida através dos procedimentos numéricos apresentados neste trabalho. Esta mesma estrutura foi analisada da maneira tradicional, ou seja, considerando nós rígidos no encontro entre vigas e pilares. Através da analogia entre os resultados obtidos pelas duas análises é possível visualizar a diferença entre a distribuição nas solicitações. Dessa forma, é possível verificar a influência da rigidez das ligações na análise das estruturas metálicas. / This work approaches semi-rigid connections with the purpose to verify the influence of connections in the analysis of steel structures, with the intention to present a model that represents the real behavior of the connections assuming an intermediate situation between totally rigid and totally pinned. The used procedures to determine the properties of these connections are based in the described methods for the Annex J of the Eurocode 3 and BCSA/SCI. With intention to speed the calculations of the semi-rigid connections a computational program was implemented that supplies to the necessary properties of the connections between beams and columns through the geometric data entry and specifications of the employed material. They are boarded welded connections and connections bolted with extend end plate. The work presents, still, an evaluation of the new distribution of loads in the steel structures. Making the analysis of a plain frame using rotational springs between beams and columns inserting the gotten rotational rigidity through the presented numerical procedures in this work. This same structure was analyzed in the traditional way, that is, considering rigid we in the meeting between beams and columns. Through the analogy it enters the results gotten for the two analyses is possible to visualize the difference enters the distribution in the requests. Of this form, it is possible to verify the influence of flexibility in the analysis of the metallic structures.