The objective of the present study is the computational and analytical modelling of a stress and strain state of the composite laminated structures. The exact three dimensional solution is derived for laminated anisotropic thick cylinders with both constant and variable material properties through the thickness of a layer. The governing differential equations are derived in a such form that to satisfy the stress functions and are given for layered cylindrical shell with open ends. The solution then extended to the laminated cylindrical shells with closed ends, that is to pressure vessels. Based on the accurate three-dimensional stress analysis an approach for the optimal design of the thick pressure vessels is formulated. Cylindrical pressure vessels are optimised taking the fibre angle as a design variable to maximise the burst pressure. The effect of the axial force on the optimal design is investigated. Numerical results are given for both single and laminated (up to five layers) cylindrical shells. The maximum burst pressure is computed using the three-dimensional interactive Tsai-: Wu failure criterion, which takes into account the influence of all stress components to the failure. Design optimisation of multilayered composite pressure vessels are based on the use of robust multidimensional methods which give fast convergence. Transverse shear and normal deformation higher-order theory for the solution of dynamic problems of laminated plates and shells is studied. The theory developed is based on the kinematic hypotheses which are derived using iterative technique. Dynamic effects, such as forces of inertia and the direct influence of external loading on the stress and strain components are included at the initial stage of derivation where kinematic hypotheses are formulated. The proposed theory and solution methods provide a basis for theoretical and applied studies in the field of dynamics and statics of the laminated shells, plates and their systems, particularly for investigation of dynamic processes related to the highest vibration forms and wave propagation, for optimal design etc. Geometrically nonlinear higher-order theory of laminated plates and shells with shear and normal deformation is derived. The theory takes into account both transverse shear and normal deformations. The number of numerical results are obtained based on the nonlinear theory developed. The results illustrate importance of the influence of geometrical nonlinearity, especially, at high levels of loading and in case when the laminae exhibit significant differences in their elastic properties. / Thesis (Ph.D.)-University of Natal, Durban, 1995.

Spanwise nonuniformity effects are modeled in the cross-sectional analysis of beam theory. This modeling adheres to an established numerical framework on cross-sectional analysis of uniform beams with arbitrary cross-sections. This framework is based on two concepts: decomposition of the rotation tensor and the variational-asymptotic method. Allowance of arbitrary materials and geometries in the cross-section is from discretization of the warping field by finite elements. By this approach, dimensional reduction from three-dimensional elasticity is performed rigorously and the sectional strain energy is derived to be asymptotically-correct. Elastic stiffness matrices are derived for inputs into the global beam analysis. Recovery relations for the displacement, stress, and strain fields are also derived with care to be consistent with the energy. Spanwise nonuniformity effects appear in the form of pointwise and sectionwise derivatives, which are approximated by finite differences. The formulation also accounts for the effects of spanwise variations in initial twist and/or curvature. A linearly tapered isotropic strip is analyzed to demonstrate spanwise nonuniformity effects on the cross-sectional analysis. The analysis is performed analytically by the variational-asymptotic method. Results from beam theory are validated against solutions from plane stress elasticity. These results demonstrate that spanwise nonuniformity effects become significant as the rate at which the cross-sections vary increases. The modeling of transverse shear modes of deformation is accomplished by transforming the strain energy into generalized Timoshenko form. Approximations in this transformation procedure from previous works, when applied to uniform beams, are identified. The approximations are not used in the present work so as to retain more accuracy. Comparison of present results with those previously published shows that these approximations sometimes change the results measurably and thus are inappropriate. Static and dynamic results, from the global beam analysis, are calculated to show the differences between using stiffness constants from previous works and the present work. As a form of validation of the transformation procedure, calculations from the global beam analysis of initially twisted isotropic beams from using curvilinear coordinate axes featuring twist are shown to be equivalent to calculations using Cartesian coordinates.

Bibliography: leaves 140-144. / xix, 156 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Determines the effect of partial-interaction and interfacial friction on the fatigue behaviour of composite bridge beams and develops a set of design rules for the assessment of the residual strength and performance of composite bridge beams. / Thesis (Ph.D.)--University of Adelaide, Dept. of Civil and Environmental Engineering, 1999

Orientador: Leandro Palermo Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-12T00:34:01Z (GMT). No. of bitstreams: 1 Gaiga_Flavio_M.pdf: 4138952 bytes, checksum: a8e6c34a3ba774087ac02c45444601ca (MD5) Previous issue date: 2008 / Resumo: Na construção civil, o uso racional do aço e concreto na composição de seções estruturais é uma forma economicamente e estruturalmente viável, principalmente em edifícios de múltiplos andares. Dentre o vasto campo denominado "estruturas mistas aço concreto", podemos caracterizar os pilares mistos parcialmente revestidos como um perfil de aço estrutural do tipo "I" ou "H" revestido com concreto, armadura longitudinal e transversal, e conectores de cisalhamento nas mesas e alma. Na determinação da resistência dos pilares mistos, parte-se da hipótese básica de que há interação completa entre os dois materiais, e que não haja escorregamento relativo entre as duas superfícies. Tendo em vista estes aspectos, neste trabalho são apresentados modelos numéricos tridimensionais de pilares mistos com o objetivo de simular o seu comportamento estrutural. As simulações foram feitas utilizando o programa ANSYS versão 9.0, com base no Método dos Elementos Finitos (MEF). Com o objetivo de validar a estratégia de análise foram construídos modelos numéricos comparando os resultados obtidos com os provenientes de análise experimental, extraídos de trabalhos apresentados por outros pesquisadores. A partir desta análise numérica foi aplicado o método simplificado proposto pela ABNT/NBR:14323/99 no dimensionamento de um pilar misto parcialmente revestido, comparando os resultados analíticos com os provenientes da análise numérica via MEF, e identificando as regiões de aplicação de cargas e transferência de esforços na interface aço concreto. / Abstract: The rational use of the steel and concrete in buildings, in the composition of structural sections is a economically form and structural viable, mainly in multi storey buildings. Among the vast field called "steel-concrete composite structures", we can characterize the composite columns encased like a profile of structural steel of the type "I" or "H" covered with concrete, longitudinal and transversal bars, and shear connectors in flange and web. For determination of the strength of the composite columns, it starts of the basic hypothesis that there is complete interaction among the two materials, and that there is not relative relationship among the two surfaces. Despite these aspects, this work presents three-dimensional numeric models of composite columns with the goal of simulating shearing structural behavior. The simulations were made using the software ANSYS version 9.0, based on the Finite Element Method (FEM). With the purpose of validating the analysis strategy numeric models it were built comparing the results obtained with the coming of experimental analysis, extracted from works presented by other researchers. From this numerical analysis it was applied the simplified method proposed by ABNT/NBR:14323/99 for the design of a partially encased composite column, comparing the analytical results with the coming of numerical analysis using FEM, and identifying the regions of loads application and transfer in the interface steel-concrete. / Mestrado / Estruturas / Mestre em Engenharia Civil

Mit der Entwicklung von Bewertungssystemen für das Nachhaltige Bauen und der Zertifizierung von Gebäuden gewinnen Kriterien ergänzend zur Funktionalität, Wirtschaftlichkeit und Standsicherheit zunehmend an Bedeutung. Neben der Aufarbeitung wesentlicher Hintergründe dieser Systeme bedarf es Verfahren für die Praxis, Gebäude nach Nachhaltigkeitskriterien zu planen und zu bauen. Im Rahmen der vorliegenden Dissertation „Nachhaltige Bürogebäude in Stahl- und Stahlverbundbauweise“ werden Methoden zur Optimierung von Tragkonstruktionen in Stahl- und Verbundbauweise nach ökologischen und ökonomischen Kriterien vorgestellt. Auf der Basis umfangreicher Parameterstudien werden Empfehlungen zur Konstruktion und Bemessung nachhaltiger Decken- und Stützensysteme für Bürogebäude abgeleitet. Ausgehend von den deutschen Bewertungssystemen DGNB und BNB werden die Grundlagen und Methoden zur Bewertung der ökologischen und ökonomischen Nachhaltigkeit von Tragkonstruktionen abgeleitet. Als Basis der Parameterstudien werden Ökobilanzdaten von Baumaterialien und -produkte, Herstellungsprozesse und Transporte aus generischen Daten, Datenbanken und Umweltproduktdeklarationen mit dem Ziel einer möglichst vollständigen Lebenszyklusanalyse zusammengestellt. Ergänzend hierzu werden Kosten für Baumaterialien und -prozesse auf der Basis von Baukostenkatalogen und Expertenbefragungen ermittelt. Es folgen Parameterstudien zu Unterzugs- und Flachdecken, Stützen und Anschlüssen, bevor die Decken-Stützen-Systemen von Geschossbauten in ihrer Gesamtheit untersucht werden. Dabei werden die Bauweisen, Rastermaße, Materialgüten, Konstruktionsformen und Nutzlasten variiert, um den Einfluss der jeweiligen Parameter isoliert und in Kombination zu verdeutlichen. Zusammenfassend werden aus den Ergebnissen Empfehlungen zur nachhaltigen Gestaltung der Tragkonstruktionen für Bürogebäude in Stahl- und Stahlverbundbauweise abgeleitet.:Inhaltsverzeichnis 1 Einleitung 1.1 Problemstellung und Zielsetzung 1.2 Aufbau der Arbeit 2 Bürogebäude 2.1 Allgemein 2.2 Büroorganisationsformen 2.3 Grundriss und Höhenentwicklung 2.3.1 Grundrissgestaltung 2.3.2 Höhenentwicklung 3 Bausysteme in Stahl- und Stahlverbundbauweise 3.1 Allgemeines 3.2 Deckensysteme 3.3 Stützen 3.4 Anschlüsse 3.5 Systemwahl und Rastermaße 4 Technische Anforderungen 4.1 Lastannahmen 4.2 Korrosionsschutz 4.3 Brandschutz 4.4 Schallschutz 4.5 Technische Gebäudeausrüstung 5 Nachhaltigkeit von Bürogebäuden 5.1 Begriff Nachhaltigkeit 5.2 Richtlinien und Gesetze 5.3 Normative Grundlagen 5.4 Bewertungssysteme für Bürogebäude 5.5 Ökologische Nachhaltigkeit 5.5.1 Methodik zur Ökobilanzierung 5.5.2 Auswahl der Bewertungskriterien 5.5.3 Datengrundlagen 5.5.4 Bewertungssystem für Tragkonstruktionen 5.6 Ökonomische Nachhaltigkeit 6 Bemessung 6.1 Allgemeines 6.2 Grenzzustand der Tragfähigkeit 6.2.1 Decken 6.2.2 Unterzugsträger als Verbundträger 6.2.3 Schweißprofile 6.2.4 Slim-Floor-Träger 6.2.5 Stützen 6.2.6 Anschlüsse 6.3 Grenzzustand der Gebrauchstauglichkeit 6.3.1 Begrenzung der Verformungen 6.3.2 Verformungen von Decken 6.3.3 Verbundträger 6.3.4 Slim-Floor-Träger 6.3.5 Rissbreitenbegrenzung 6.3.6 Schwingungen 6.4 Bemessung im Brandfall 6.4.1 Normative Grundlagen 6.4.2 Brandschutzprodukte 6.4.3 Decken 6.4.4 Unterzugsträger 6.4.5 Slim-Floor-Träger 6.4.6 Stützen 6.4.7 Anschlüsse 7 Programmdokumentation 7.1 Überblick 7.2 Programmstruktur im Allgemeinen 7.3 Decken 7.3.1 Stahlbetondecken und Spannbetonhohldielen 7.3.2 Verbunddecken 7.4 Deckensystem 7.4.1 Unterzugsdecken mit Walzprofilen 7.4.2 Unterzugsdecken mit Schweißprofilen 7.4.3 Slim-Floor-Konstruktionen 7.5 Stützen 8 Nachhaltige Material- und Konstruktionswahl 8.1 Erläuterungen zu den Parameterstudien 8.2 Decken 8.2.1 Stahlbetondecken aus Ortbeton 8.2.2 Verbunddecken 8.2.3 Decken im Vergleich 8.3 Unterzugsdecken 8.3.1 Variation der Trägerabstände 8.3.2 Variation der Nutzlasten 8.3.3 Vergleich Ein- und Zweifeldträger 8.3.4 Variation der Stahlgüte und der Durchbiegungsbegrenzung 8.3.5 Variation der Betongüte 8.3.6 Schweißprofile 8.4 Slim-Floor-Konstruktionen 8.4.1 Variation der Trägerabstände und des Deckentyps 8.4.2 Variation der Querschnittstypen 8.4.3 Untersuchung von Deckensystemen mit Einfeldträgern 8.4.4 Variation der Nutzlast 8.5 Vergleich von Unterzugsdecken und Slim-Floor-Konstruktionen 8.6 Stützen 8.6.1 Querschnittswahl 8.6.2 Materialgüten 8.6.3 Einfluss der Stützenhöhe 8.6.4 Berücksichtigung von Maßnahmen zum Brandschutz 8.7 Anschlüsse 8.8 Tragkonstruktion 8.8.1 Tragkonstruktionen mit Unterzugsdecken 8.8.2 Tragkonstruktionen mit Slim-Floor-Systemen 8.8.3 Vergleich der Tragsysteme mit Unterzugsdecken und Slim-Floor 9 Zusammenfassung und Ausblick 9.1 Allgemeines 9.2 Unterzugsdecken 9.3 Slim-Floor-Konstruktionen 9.4 Stützen 9.5 Anschlüsse 9.6 Ausblick 10 Quellenverzeichnis 11 Anhang Anhang A Büroorganisationsformen Anhang B Schallschutz Anhang C Datengrundlagen Anhang D Bemessung und Produktdaten Anhang E Anschlüsse

The design of composite laminated panels is a combinatorial problem when the orientation of the fibers in each layer is restricted to a discrete pool of angles. Additionally, composite laminates often have many optimal and near-optimal designs, and the designer may benefit by knowing many of those designs. Genetic algorithms are well suited for laminate design because they can handle the combinatorial nature of the problem and they permit the designer to obtain many near-optimal designs. However, their computational cost is high for most structural optimization problems. This work describes several attempts to reduce the cost of optimizing composite laminates using genetic algorithms. First, the use of a genetic algorithm to maximize the buckling load of a fixed thickness composite laminate is studied. Various genetic parameters, including population size, probability of mutation, and probability of crossover are optimized by numerical experiments. A new genetic operator - stack swap - is proposed and shown to be effective in reducing the cost of the optimization. Second, the genetic algorithm is revised and improved for minimum thickness design of composite laminated plates. The influence on the genetic search of the penalty functions enforcing failure constraints is studied. Combining fixed and proportional penalty functions is found to be the most efficient strategy. Improved selection, mutation, and stack swap operators are proposed. The use of an operator called scaling mutation that projects designs towards the feasible domain is investigated. The improvements in the genetic algorithm are shown to reduce the average price of the search by more than 50%. Next, the improved genetic algorithm for minimum thickness laminate design is applied to a more complex wing box-beam optimization problem. Tuning the genetic algorithm on this problem shows that, because the maximum length of a search is limited, the optimal population size does not grow with the size of the design space. If the probability of applying stack swap is reduced with the number of independent laminates in the wing box, stack swap enhances the performance of the genetic search on the wing box -beam problem. Finally, the possibility of running many searches is investigated. It is empirically shown that several short searches can be more efficient than a long one, especially when high levels of reliability are required. An example is given where a genetic algorithm is specifically modified for better efficiency in the context of repeated short runs. A procedure is studied that enables predicting reliability at later stages of the search. / Ph. D.

Este trabalho aborda o estudo da aderência aço-concreto em pilares mistos preenchidos através de revisão bibliográfica e de investigação experimental. De modo esquemático, a aderência é dividida em três parcelas: adesão, aderência mecânica e atrito, que em conjunto compõem a aderência natural. Adicionalmente, podem ser empregados conectores de cisalhamento, que são dispositivos mecânicos fixados nas superfícies internas dos tubos, como meio de ampliar a resistência ao escorregamento. Foram realizados ensaios do tipo pushout em alguns tipos de modelos de pilar preenchido: modelos simples, com adição de conectores tipo pino com cabeça, com cantoneiras na interface aço-concreto e semelhantes aos anteriores mais elementos de ligação. Com os resultados obtidos traçaram-se comportamentos força x escorregamento do concreto, força x deformações axiais nos materiais e curvas de distribuição de força ao longo do comprimento dos modelos. Concluiu-se que conectores tipo pino com cabeça e cantoneiras são uma excelente alternativa como dispositivos auxiliares na transferência de tensões de cisalhamento na interface aço-concreto. Entretanto, é necessário garantir resistência à ligação para que esses mecanismos sejam mobilizados / This research presents a study of influence of bond on concrete-filled steel tubes by means of a bibliography review and an experimental investigation. The bond strength counts on three mechanisms: adhesion of the concrete to the steel surface, friction and wedging of the concrete core. In order to improve the shear resistance of the steel-concrete interface, shear connectors can be used. A series of push-out tests of rectangular concrete-filled steel tubes was conducted in the specimens without mechanical shear connectors, specimens with stud bolt shear connectors and specimens with angles. They were also tested the corresponding beam-column connections. The results are shown in curves force x slip of concrete, force x axial strain of materials and distribution of axial load to the steel and to the concrete. The results of the tests permitted identify the mechanisms of natural bond and indicated that the stud bolts and the angles are excellent alternatives as auxiliary mechanisms to transfer shear between the concrete and steel in the concrete filled composite column. However, it is necessary to guarantee the connection enough strength in order to permit these resistance be developed

La thèse comprend 8 chapitres, 3 annexes, 191 figures, 43 tableaux, 13 photos et 181 références bibliographiques. Le corps du texte totalise 135 pages et les annexes 120 pages. Le chapitre 1 constitue lintroduction dans laquelle le contexte et les objectifs de la recherche sont définis. Le chapitre 2 présente létat de la question concernant les colonnes faites de tubes en acier remplis de béton (CFSHS columns - concrete filled steel hollow section columns). Leur comportement à température ordinaire et sous conditions dincendie est analysé ainsi que les paramètres significatifs qui guident leur comportement. Les propriétés du béton auto-plaçant sont aussi examinées dans ce chapitre. Le chapitre 3 est consacré à la présentation du code de calcul SAFIR développé à lUniversité de Liège pour la simulation du comportement structural à température ordinaire et sous conditions dincendie. Le logiciel a été utilisé pour simuler des résultats dessais expérimentaux présentés dans la littérature, et quelques calibrations sont proposées. En utilisant le modèle décrit au chapitre 3, la charge ultime à température ordinaire des colonnes CFSHS est calculée en considérant différents paramètres. On considère essentiellement des tubes de petites dimensions avec un pourcentage élevé darmatures ou contenant un autre profilé métallique. Ce type délément nest pas couvert par les Eurocodes. Des simulations ont été réalisées en vue dexaminer si les méthodes classiques de lEurocode 4 (EN1994-1-1) sont applicables à ce type de section et de voir quelle courbe de flambement est la plus appropriée. Le chapitre 5 décrit la recherche expérimentale réalisée à lUniversité de Liège relative au comportement au feu des colonnes CFSHS. Les essais expérimentaux ont été simulés par SAFIR, tant en ce qui concerne la répartition de la température à lintérieur des éléments que le comportement structural. Un des objectifs de ces calculs était de vérifier si les propriétés thermiques et mécaniques du béton auto-plaçant sont proches de celles du béton ordinaire. En vue de fournir aux bureaux détudes des outils pratiques de dimensionnement, une formule permettant dévaluer la résistance au feu des colonnes CFSHS est proposée dans le chapitre 6. Le domaine dapplicabilité a été étendu par rapport aux études précédentes. Une formule pour colonnes courtes de section carrée a dabord été établie sur base de simulations effectuées à laide de SAFIR en considérant linfluence des paramètres principaux. On examine ensuite si cette formule est aussi applicable à dautres types de profilés. La formule a été étendue en cas des colonnes élancées et à celui des colonnes chargées excentriquement. Létude expérimentale du chapitre 5 est limitée à des sections dassez petites dimensions (< 300 mm), essentiellement pour des problèmes de capacité de mise en charge des laboratoires. En vue de recueillir des informations pratiques pour des profilés de plus grandes dimensions pour lesquels on peut atteindre des résistances au feu de 2 heures et plus, des simulations numériques additionnelles sont présentées dans le chapitre 7, avec des résultats utilisables en bureau détudes. Le chapitre 8 donne les conclusions de létude et présente des suggestions pour des recherches futures.

SectionBuilder is an innovative finite element based tool, developed for analysis and design of composite beam cross-sections. The tool can handle the cross-sections with parametric shapes and arbitrary configurations. It can also handle arbitrary lay-ups for predefined beam cross-section geometries in a consistent manner. The material properties for each layer of the cross-section can be defined on the basis of the design requirements. This tool is capable of dealing with multi-cell composite cross-sections with arbitrary lay-ups. It has also the benefit of handling the variation of thickness of skin and D-spars for beams such as rotor blades. A typical cross-section is considered as a collection of interconnected walls. Walls with arbitrary lay-ups based on predefined geometries and material properties are generated first. The complex composite beam cross-sections are developed by connecting the walls using various types of connectors. These connectors are compatible with the walls, i.e., the thickness of the layers of the walls must match with those of the connectors at the place of connection. Cross-sections are often reinforced by core material for constructing realistic rotor blade cross-sections. The tool has the ability to integrate core materials into the cross-sections. A mapped mesh is considered for meshing parametric shapes, walls and various connectors, whereas a free mesh is considered for meshing the core materials. A new algorithm based on the Delaunay refinement algorithm is developed for creating the best possible free mesh for core materials. After meshing the cross-section, the tool determines the sectional properties using finite element analysis. This tool computes sectional properties including stiffness matrix, compliance matrix, mass matrix, and principal axes. A visualization environment is integrated with the tool for visualizing the stress and strain distributions over the cross-section.

Este trabalho aborda o estudo da aderência aço-concreto em pilares mistos preenchidos através de revisão bibliográfica e de investigação experimental. De modo esquemático, a aderência é dividida em três parcelas: adesão, aderência mecânica e atrito, que em conjunto compõem a aderência natural. Adicionalmente, podem ser empregados conectores de cisalhamento, que são dispositivos mecânicos fixados nas superfícies internas dos tubos, como meio de ampliar a resistência ao escorregamento. Foram realizados ensaios do tipo pushout em alguns tipos de modelos de pilar preenchido: modelos simples, com adição de conectores tipo pino com cabeça, com cantoneiras na interface aço-concreto e semelhantes aos anteriores mais elementos de ligação. Com os resultados obtidos traçaram-se comportamentos força x escorregamento do concreto, força x deformações axiais nos materiais e curvas de distribuição de força ao longo do comprimento dos modelos. Concluiu-se que conectores tipo pino com cabeça e cantoneiras são uma excelente alternativa como dispositivos auxiliares na transferência de tensões de cisalhamento na interface aço-concreto. Entretanto, é necessário garantir resistência à ligação para que esses mecanismos sejam mobilizados / This research presents a study of influence of bond on concrete-filled steel tubes by means of a bibliography review and an experimental investigation. The bond strength counts on three mechanisms: adhesion of the concrete to the steel surface, friction and wedging of the concrete core. In order to improve the shear resistance of the steel-concrete interface, shear connectors can be used. A series of push-out tests of rectangular concrete-filled steel tubes was conducted in the specimens without mechanical shear connectors, specimens with stud bolt shear connectors and specimens with angles. They were also tested the corresponding beam-column connections. The results are shown in curves force x slip of concrete, force x axial strain of materials and distribution of axial load to the steel and to the concrete. The results of the tests permitted identify the mechanisms of natural bond and indicated that the stud bolts and the angles are excellent alternatives as auxiliary mechanisms to transfer shear between the concrete and steel in the concrete filled composite column. However, it is necessary to guarantee the connection enough strength in order to permit these resistance be developed