TY - THES A1 - Stein, Peter T1 - Procedurally generated models for Isogeometric Analysis N2 - Increasingly powerful hard- and software allows for the numerical simulation of complex physical phenomena with high levels of detail. In light of this development the definition of numerical models for the Finite Element Method (FEM) has become the bottleneck in the simulation process. Characteristic features of the model generation are large manual efforts and a de-coupling of geometric and numerical model. In the highly probable case of design revisions all steps of model preprocessing and mesh generation have to be repeated. This includes the idealization and approximation of a geometric model as well as the definition of boundary conditions and model parameters. Design variants leading to more resource-efficient structures might hence be disregarded due to limited budgets and constrained time frames. A potential solution to above problem is given with the concept of Isogeometric Analysis (IGA). Core idea of this method is to directly employ a geometric model for numerical simulations, which allows to circumvent model transformations and the accompanying data losses. Basis for this method are geometric models described in terms of Non-uniform rational B-Splines (NURBS). This class of piecewise continuous rational polynomial functions is ubiquitous in computer graphics and Computer-Aided Design (CAD). It allows the description of a wide range of geometries using a compact mathematical representation. The shape of an object thereby results from the interpolation of a set of control points by means of the NURBS functions, allowing efficient representations for curves, surfaces and solid bodies alike. Existing software applications, however, only support the modeling and manipulation of the former two. The description of three-dimensional solid bodies consequently requires significant manual effort, thus essentially forbidding the setup of complex models. This thesis proposes a procedural approach for the generation of volumetric NURBS models. That is, a model is not described in terms of its data structures but as a sequence of modeling operations applied to a simple initial shape. In a sense this describes the "evolution" of the geometric model under the sequence of operations. In order to adapt this concept to NURBS geometries, only a compact set of commands is necessary which, in turn, can be adapted from existing algorithms. A model then can be treated in terms of interpretable model parameters. This leads to an abstraction from its data structures and model variants can be set up by variation of the governing parameters. The proposed concept complements existing template modeling approaches: templates can not only be defined in terms of modeling commands but can also serve as input geometry for said operations. Such templates, arranged in a nested hierarchy, provide an elegant model representation. They offer adaptivity on each tier of the model hierarchy and allow to create complex models from only few model parameters. This is demonstrated for volumetric fluid domains used in the simulation of vertical-axis wind turbines. Starting from a template representation of airfoil cross-sections, the complete "negative space" around the rotor blades can be described by a small set of model parameters, and model variants can be set up in a fraction of a second. NURBS models offer a high geometric flexibility, allowing to represent a given shape in different ways. Different model instances can exhibit varying suitability for numerical analyses. For their assessment, Finite Element mesh quality metrics are regarded. The considered metrics are based on purely geometric criteria and allow to identify model degenerations commonly used to achieve certain geometric features. They can be used to decide upon model adaptions and provide a measure for their efficacy. Unfortunately, they do not reveal a relation between mesh distortion and ill-conditioning of the equation systems resulting from the numerical model. T3 - Schriftenreihe des DFG Graduiertenkollegs 1462 Modellqualitäten // Graduiertenkolleg Modellqualitäten - 7 KW - NURBS KW - Isogeometric Analysis KW - Procedural modeling KW - Templates KW - Mesh quality Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20130212-18483 SN - 978-3-86068-488-7 PB - Universitätsverlag CY - Weimar ER - TY - THES A1 - Nikulla, Susanne T1 - Quality assessment of kinematical models by means of global and goal-oriented error estimation techniques T1 - Anwendung globaler und zielorientierter Fehlerschätzer zur Beurteilung der Notwendigkeit einer geometrisch nicht-linearen Berechnung N2 - Methods for model quality assessment are aiming to find the most appropriate model with respect to accuracy and computational effort for a structural system under investigation. Model error estimation techniques can be applied for this purpose when kinematical models are investigated. They are counted among the class of white box models, which means that the model hierarchy and therewith the best model is known. This thesis gives an overview of discretisation error estimators. Deduced from these, methods for model error estimation are presented. Their general goal is to make a prediction of the inaccuracies that are introduced using the simpler model without knowing the solution of a more complex model. This information can be used to steer an adaptive process. Techniques for linear and non-linear problems as well as global and goal-oriented errors are introduced. The estimation of the error in local quantities is realised by solving a dual problem, which serves as a weight for the primal error. So far, such techniques have mainly been applied in material modelling and for dimensional adaptivity. Within the scope of this thesis, available model error estimators are adapted for an application to kinematical models. Their applicability is tested regarding the question of whether a geometrical non-linear calculation is necessary or not. The analysis is limited to non-linear estimators due to the structure of the underlying differential equations. These methods often involve simplification, e.g linearisations. It is investigated to which extent such assumptions lead to meaningful results, when applied to kinematical models. N2 - Die verschiedenen Methoden zur Bewertung der Modellqualität haben ein Ziel: Das passende Modell in Bezug auf Genauigkeit und Berechnungsaufwand für eine konkrete Struktur zu finden. Steht dabei die Untersuchung eines Kinematik-Modells im Vordergrund, können Modellfehlerschätzer zur Modellbewertung verwendet werden. Dieser Zusammenhang gilt, solange es sich um mechanisch motivierte Modelle handelt, bei denen die Modellhierarchie und damit das beste Modell bekannt sind. Die vorliegende Arbeit beschreibt den Weg von den einfachen Fehlerschätzern für Diskretisierungsfehler bis zu den daraus abgeleiteten Modellfehlerschätzern. Das Ziel der letztgenannten besteht in der Vorhersage von Ungenauigkeit, die durch die Verwendung eines vereinfachten anstatt des komplexen Modells entstehen. Aus den gewonnenen Informationen wird eine adaptive Modellanpassung entwickelt. Die Methoden lassen sich dabei nach verschiedenen Kriterien unterscheiden. Diese diffenzieren zwischen den verschiedenen Anwendungsbereichen, zwischen linearen und nicht-linearen Modellen sowie zwischen globalen und ziel-orientierten Fehlern. Die bislang in der Literatur hauptsächlich zu findenden Anwendungsgebiete sind die Materialmodellierung und die Dimensionsadaptivität. Im Rahmen dieser Arbeit werden nun die bekannten Methoden zur Abschätzung des Modellfehlers auf kinematische Modelle erweitert. Zudem wird die Frage, ob eine geometrisch nicht-lineare Berechnung notwendig ist oder nicht, untersucht. Aufgrund der Struktur der zugrunde liegenden Differentialgleichungen beschränken sich die Analysen auf nicht-lineare Fehlerschätzer. Da diese Methoden oft auf Vereinfachungen wie z.B. die Linearisierung der Grundgleichungen zurückgreifen, wird in der vorliegenden Arbeit untersucht, inwieweit diese Annahmen zu verwertbaren Ergebnissen führen. T3 - Schriftenreihe des DFG Graduiertenkollegs 1462 Modellqualitäten // Graduiertenkolleg Modellqualitäten - 4 KW - Model quality, Model error estimation, Kinematical model, Geometric non-linearity, Finite Element method KW - Modellqualität, Modellfehlerschätzer, Geometrisch nicht-lineare Berechnung, Kinematik Modell, Finite Elemente Methode Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20120419-16161 PB - Verlag der Bauhaus-Universität Weimar CY - Weimar ER - TY - THES A1 - Nasser, Mourad T1 - Quality Assessment of Dynamic Soil-Structure Interaction Models Using Energy Measures N2 - In this research work, an energy approach is employed for assessing quality in dynamic soil-structure interaction (SSI) models, and energy measures are introduced and investigated as general indicators of structural response. Dynamic SSI models with various abstraction levels are then investigated according to different coupling scenarios for soil and structure models. The hypothesis of increasing model uncertainty with decreasing complexity is investigated and a mathematical framework is provided for the treatment of model uncertainty. This framework is applied to a case study involving alternative models for incorporating dynamic SSI effects. In the evaluation process, energy measures are used within the framework of the \textit{adjustment factor} approach in order to quantitatively assess the uncertainty associated with SSI models. Two primary types of uncertainty are considered, namely the uncertainty in the model framework and the uncertainty in the model input parameters. Investigations on model framework uncertainty show that the more complex three-dimensional FE model has the best quality of the models investigated, whereas the Wolf SSI model produces the lowest model uncertainty of the simpler models. The fixed-base model produces the highest estimated uncertainty and accordingly the worst quality of all models investigated. These results confirm the hypothesis of increasing model uncertainty with decreasing complexity only when the assessment is based on the ratio of structural hysteretic energy to input energy as a response indicator. T3 - Schriftenreihe des DFG Graduiertenkollegs 1462 Modellqualitäten // Graduiertenkolleg Modellqualitäten - 8 KW - soil-structure interaction KW - model assessment KW - structural energy KW - Boden-Bauwerk-Wechselwirkung Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20130220-18542 SN - 978-3-86068-494-8 PB - Verlag der Bauhaus-Universität CY - Weimar ER - TY - THES A1 - Keitel, Holger T1 - Bewertungsmethoden für die Prognosequalität von Kriechmodellen des Betons T1 - Evaluation Methods for Prediction Quality of Concrete Creep Models N2 - Ziel dieser Arbeit ist die Entwicklung von Methoden, mit denen die Prognosequalität von Kriechmodellen des Betons bestimmt werden kann. Die Methoden werden in zwei Ausgangsszenarien unterschieden: die Bewertung ohne und die Bewertung mit Verwendung von spezifischen Versuchsdaten zum Kriechverhalten des Betons. Die Modellqualität wird anhand der Gesamtunsicherheit der prognostizierten Kriechnachgiebigkeit quantifiziert. Die Unsicherheit wird für die Kriechprognose ohne Versuchsdaten über eine Unsicherheitsanalyse unter Berücksichtigung korrelierter Eingangsparameter ermittelt. Bei der Verwendung experimenteller Daten werden die stochastischen Eigenschaften der Modellparameter mittels Bayesian Updating bestimmt. Die Bewertung erfolgt erneut basierend auf einer Unsicherheitsanalyse sowie alternativ mittels Modellselektion nach Bayes. Weiterhin wird eine auf Graphentheorie und Sensitivitätsanalysen basierende Methode zur Bewertung von gekoppelten Partialmodellen entwickelt. Damit wird der Einfluss eines Partialmodells auf das Verhalten einer globalen Tragstruktur quantifiziert, Interaktionen von Partialmodellen festgestellt und ein Maß für die Qualität eines Gesamtmodells ermittelt. N2 - The goal of this doctoral thesis is the development of methods for the evaluation of the prediction quality of concrete creep models. The methods are distinguished into two scenarios: the evaluation with and without experimental data about the creep behavior of concrete. The model quality is quantified by the total uncertainty of the predicted creep compliance. The uncertainty of the creep prognosis without using measurement data is quantified by an uncertainty analysis taking into account the parameter correlation. When experimental data is considered the stochastic properties of the creep model parameters are found by means of Bayesian Updating. The evaluation is once more based on an uncertainty analysis or, alternatively, applying Bayesian model selection. Further, an assessment method of coupled partial models based on graph theory and sensitivity analysis is developed. Therewith, the influence of classes of partial models on the global model response is quantified, interactions of partial models are detected, and a measure for the quality of the global model is derived. T3 - Schriftenreihe des DFG Graduiertenkollegs 1462 Modellqualitäten // Graduiertenkolleg Modellqualitäten - 2 KW - Kriechen KW - Bewertung KW - Prognosequalität KW - Bayes-Inferenz KW - Unsicherheitsanalyse KW - Gekoppelte Modelle KW - Coupled models KW - Bewertungsmethode KW - Evaluation methods Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20120207-15569 SN - 978-3-86068-466-5 PB - Verlag der Bauhaus-Universität Weimar CY - Weimar ER - TY - THES A1 - Kavrakov, Igor T1 - Synergistic Framework for Analysis and Model Assessment in Bridge Aerodynamics and Aeroelasticity N2 - Wind-induced vibrations often represent a major design criterion for long-span bridges. This work deals with the assessment and development of models for aerodynamic and aeroelastic analyses of long-span bridges. Computational Fluid Dynamics (CFD) and semi-analytical aerodynamic models are employed to compute the bridge response due to both turbulent and laminar free-stream. For the assessment of these models, a comparative methodology is developed that consists of two steps, a qualitative and a quantitative one. The first, qualitative, step involves an extension of an existing approach based on Category Theory and its application to the field of bridge aerodynamics. Initially, the approach is extended to consider model comparability and completeness. Then, the complexity of the CFD and twelve semi-analytical models are evaluated based on their mathematical constructions, yielding a diagrammatic representation of model quality. In the second, quantitative, step of the comparative methodology, the discrepancy of a system response quantity for time-dependent aerodynamic models is quantified using comparison metrics for time-histories. Nine metrics are established on a uniform basis to quantify the discrepancies in local and global signal features that are of interest in bridge aerodynamics. These signal features involve quantities such as phase, time-varying frequency and magnitude content, probability density, non-stationarity, and nonlinearity. The two-dimensional (2D) Vortex Particle Method is used for the discretization of the Navier-Stokes equations including a Pseudo-three dimensional (Pseudo-3D) extension within an existing CFD solver. The Pseudo-3D Vortex Method considers the 3D structural behavior for aeroelastic analyses by positioning 2D fluid strips along a line-like structure. A novel turbulent Pseudo-3D Vortex Method is developed by combining the laminar Pseudo-3D VPM and a previously developed 2D method for the generation of free-stream turbulence. Using analytical derivations, it is shown that the fluid velocity correlation is maintained between the CFD strips. Furthermore, a new method is presented for the determination of the complex aerodynamic admittance under deterministic sinusoidal gusts using the Vortex Particle Method. The sinusoidal gusts are simulated by modeling the wakes of flapping airfoils in the CFD domain with inflow vortex particles. Positioning a section downstream yields sinusoidal forces that are used for determining all six components of the complex aerodynamic admittance. A closed-form analytical relation is derived, based on an existing analytical model. With this relation, the inflow particles’ strength can be related with the target gust amplitudes a priori. The developed methodologies are combined in a synergistic framework, which is applied to both fundamental examples and practical case studies. Where possible, the results are verified and validated. The outcome of this work is intended to shed some light on the complex wind–bridge interaction and suggest appropriate modeling strategies for an enhanced design. T3 - Schriftenreihe des DFG Graduiertenkollegs 1462 Modellqualitäten // Graduiertenkolleg Modellqualitäten - 21 KW - Brücke KW - Bridge KW - Computational Fluid Dynamics KW - Aerodynamics KW - Aeroelasticity KW - Category Theory KW - Aerodynamik KW - Aeroelastizität Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20200316-41099 UR - https://asw-verlage.de/katalog/?id=2255 SN - 978-3-95773-284-2 PB - Bauhaus-Universitätsverlag CY - Weimar ER - TY - THES A1 - Karaki, Ghada T1 - Assessment of coupled models of bridges considering time-dependent vehicular loading N2 - Bridge vibration due to traffic loading has been a subject of extensive research in the last decades. The focus of such research has been to develop solution algorithms and investigate responses or behaviors of interest. However, proving the quality and reliability of the model output in structural engineering has become a topic of increasing importance. Therefore, this study is an attempt to extend concepts of uncertainty and sensitivity analyses to assess the dynamic response of a coupled model in bridge engineering considering time-dependent vehicular loading. A setting for the sensitivity analysis is proposed, which enables performing the sensitivity analysis considering random stochastic processes. The classical and proposed sensitivity settings are used to identify the relevant input parameters and models that have the most influence on the variance of the dynamic response. The sensitivity analysis exercises the model itself and extracts results without the need for measurements or reference solutions; however, it does not offer a means of ranking the coupled models studied. Therefore, concepts of total uncertainty are employed to rank the coupled models studied according to their fitness in describing the dynamic problem. The proposed procedures are applied in two examples to assess the output of coupled subsystems and coupled partial models in bridge engineering considering the passage of a heavy vehicle at various speeds. N2 - Brückenschwingungen infolge von Verkehrslasten sind seit mehreren Jahrzehnten Gegenstand intensiver Forschung. Im Fokus stand hierbei im Besonderen die Entwicklung von Lösungsalgorithmen zur Ermittlung des dynamischen Bauwerkverhaltens. Begleitet ist diese Entwicklung von der Frage nach der Qualität und Zuverlässigkeit dieser Modelle für den Gebrauch im konstruktiven Ingenieurbau. In diesem Zusammenhang werden in der vorliegenden Arbeit Konzepte der Unsicherheits- und Sensitivitätsanalyse erweitert, um das dynamische Bauwerkverhalten unter Berücksichtigung transienter Fahrzeuglasten bei gekoppelten Modellen des Brückenbaus zu bewerten. Bestehende Sensitivitätsanalysen werden ergänzt, um diese auch unter Berücksichtigung von stochastischen Prozessen durchführen zu können. Die klassische und die erweiterte Methode werden angewandt, um relevante Eingangsparameter sowie Partialmodelle mit wesentlichem Einfluss auf die Varianz der dynamischen Strukturantwort zu identifizieren. Die mit Hilfe der Sensitivitätsanalyse ermittelbaren Kennzahlen können ohne Bezug zu einer Referenzlösung in die Modellbewertung einfließen, allerdings ist es nicht möglich, die Modelle hinsichtlich der realitätsnahen Abbildung des dynamischen Problems zu bewerten. Um dies zu ermöglichen, wurden Konzepte der Gesamtunsicherheit verwendet. Die vorgestellten Methoden wurden auf zwei Beispiele angewandt, um die Ergebnisse von gekoppelten Subsystemen und gekoppelten Partialmodellen des Brückenbaus zu evaluieren. Hierbei handelt es sich um die Überfahrt von schweren Fahrzeugen mit verschiedenen Geschwindigkeiten. T3 - Schriftenreihe des DFG Graduiertenkollegs 1462 Modellqualitäten // Graduiertenkolleg Modellqualitäten - 5 KW - Ingenieurbau KW - bridge-vehicle interaction KW - random vibrations KW - sensitivity and uncertainty analysis Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20120402-15894 ER - TY - THES A1 - Göbel, Luise T1 - Experimental and semi-analytical multiscale approaches for the characterization of the elastic and viscoelastic behavior of polymer-modified cement-based materials T1 - Experimentelle und semi-analytische Multiskalenmethoden für die Charakterisierung des elastischen und viskoelastischen Verhaltens polymermodifizierter zementgebundener Materialien N2 - Polymer-modified cement concrete (PCC) is a heterogeneous building material with a hierarchically organized microstructure. Therefore, continuum micromechanics-based multiscale models represent a promising method to estimate the mechanical properties. By means of a bottom-up approach, homogenized properties at the macroscopic scale are derived considering microstructural characteristics. The extension of existing multiscale models for the application to PCC is the main objective of this work. For that, cross-scale experimental studies are required. Both macroscopic and microscopic mechanical tests are performed to characterize the elastic and viscoelastic properties of different PCC. The comparison between experiment and model prediction illustrates the success of the modeling approach. N2 - Polymermodifizierter Beton (PCC) ist ein heterogener Baustoff mit einer hierarchisch organisierten Mikrostruktur. Deshalb sind Multiskalenmodelle, die auf Prinzipien der Kontinuumsmikromechanik beruhen, sehr gut für die Abschätzung mechanischer Eigenschaften geeignet. Mit Hilfe eines Bottom-Up-Ansatzes werden unter Berücksichtigung mikrostruktureller Charakteristika homogenisierte Eigenschaften auf der makroskopischen Materialebene erhalten. Die Erweiterung bestehender Multiskalenmodelle für die Anwendung auf PCC ist das Hauptziel dieser Arbeit. Dafür werden skalenübergreifende Experimente herangezogen. Sowohl makroskopische als auch mikroskopische mechanische Tests werden durchgeführt, um das elastische und viskoelastische Verhalten verschiedener PCC zu charakterisieren. Ein Vergleich zwischen experimentellen Ergebnissen und der entsprechenden Modellvorhersage verdeutlicht den Erfolg des Modellierungsansatzes. T3 - Schriftenreihe des DFG Graduiertenkollegs 1462 Modellqualitäten // Graduiertenkolleg Modellqualitäten - 19 KW - Elastizitätsmodul KW - Zementstein KW - Kunststoffadditiv KW - Modellierung KW - Mehrphasensystem KW - Multiskalenmodellierung KW - Multiscale modeling KW - Mikrostruktur KW - Polymermodifizierung KW - Kriechen KW - Elastizitätsmodul KW - Microstructure KW - Polymer modification KW - Creep KW - Young's modulus Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20181211-38279 SN - 978-3-95773-269-9 PB - Bauhaus-Universitätsverlag CY - Weimar ER - TY - THES A1 - Fröbel, Toni T1 - Data coupled civil engineering applications: Modeling and quality assessment methods T1 - Datenkopplung für Anwendungen im Bauingenieurwesen: Methoden zur Modellierung und Qualitätsbewertung N2 - The planning process in civil engineering is highly complex and not manageable in its entirety. The state of the art decomposes complex tasks into smaller, manageable sub-tasks. Due to the close interrelatedness of the sub-tasks, it is essential to couple them. However, from a software engineering point of view, this is quite challenging to do because of the numerous incompatible software applications on the market. This study is concerned with two main objectives: The first is the generic formulation of coupling strategies in order to support engineers in the implementation and selection of adequate coupling strategies. This has been achieved by the use of a coupling pattern language combined with a four-layered, metamodel architecture, whose applicability has been performed on a real coupling scenario. The second one is the quality assessment of coupled software. This has been developed based on the evaluated schema mapping. This approach has been described using mathematical expressions derived from the set theory and graph theory by taking the various mapping patterns into account. Moreover, the coupling quality has been evaluated within the formalization process by considering the uncertainties that arise during mapping and has resulted in global quality values, which can be used by the user to assess the exchange. Finally, the applicability of the proposed approach has been shown using an engineering case study. N2 - Der Planungsprozess im Bauwesen ist hochkomplex und daher in seiner Gesamtheit nicht zu erfassen. Deshalb wird dieser in kleinere und beherrschbarere Teilaufgaben zerlegt. Auf Grund ihrer starken Wechselwirkungen ist deren Kopplung unabdingbar. Aus Sicht der Informatik wird dies jedoch durch eine große Anzahl inkompatibler Softwareanwendungen erschwert. Die Arbeit beschäftigt sich daher mit zwei wesentlichen Aufgabenfeldern im Bereich der Softwarekopplung. Als erstes werden Kopplungskonzepte unabhängig von spezifischen Hardware- oder Softwareeigenschaften beschrieben, um den Ingenieur bei der Durchführung und Auswahl von entsprechenden Kopplungsstrategien zu unterstützen. Dies wird durch eine Kopplungs-Mustersprache in Verbindung mit einer Meta-Modell-Architektur erreicht. Seine Anwendbarkeit wird an einem Kopplungsszenario gezeigt. Das zweite Aufgabenfeld beschäftigt sich mit der Qualität von gekoppelten Softwaresystemen. Eine Qualitätsbewertung erfolgt hierbei auf Basis von bewertetem Schema-Mapping. Der Ansatz ist auf Grundlage der Mengen- und Graphentheorie mathematisch beschrieben. Er berücksichtigt die gängigen Mapping-Muster und Unsicherheiten, die während des Mappingprozesses auftreten können. Der Bewertungsprozess liefert einen globalen Qualitätswert, der vom Ingenieur direkt verwendet werden kann, um den Austausch zu bewerten. Die Anwendbarkeit wird an einem Beispiel gezeigt. T3 - Schriftenreihe des DFG Graduiertenkollegs 1462 Modellqualitäten // Graduiertenkolleg Modellqualitäten - 6 KW - Data exchange, Schema mapping, Quality assessment, Uncertainty, Coupling, BIM, Design patterns, Metamodel architecture KW - Data exchange, Schema mapping, Quality assessment, Uncertainty, Coupling, BIM, Design patterns, Metamodel architecture Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20130128-18366 SN - 978-3-86068-486-3 PB - Verlag der Bauhaus-Universität Weimar 2013 CY - Weimar ER - TY - THES A1 - Abbas, Tajammal T1 - Assessment of Numerical Prediction Models for Aeroelastic Instabilities of Bridges N2 - The phenomenon of aerodynamic instability caused by the wind is usually a major design criterion for long-span cable-supported bridges. If the wind speed exceeds the critical flutter speed of the bridge, this constitutes an Ultimate Limit State. The prediction of the flutter boundary, therefore, requires accurate and robust models. The complexity and uncertainty of models for such engineering problems demand strategies for model assessment. This study is an attempt to use the concepts of sensitivity and uncertainty analyses to assess the aeroelastic instability prediction models for long-span bridges. The state-of-the-art theory concerning the determination of the flutter stability limit is presented. Since flutter is a coupling of aerodynamic forcing with a structural dynamics problem, different types and classes of structural and aerodynamic models can be combined to study the interaction. Here, both numerical approaches and analytical models are utilised and coupled in different ways to assess the prediction quality of the coupled model. T3 - Schriftenreihe des DFG Graduiertenkollegs 1462 Modellqualitäten // Graduiertenkolleg Modellqualitäten - 16 KW - Brücke KW - Flattern KW - Unsicherheit KW - Flutter KW - Bridges KW - Sensitivity KW - Uncertainty KW - Model assessment Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20180515-27161 UR - https://asw-verlage.de/katalog/assessment_of_numerical_prediction_models_for_aeroelastic_instabilities_of_bridges-1897.html PB - Jonas Verlag CY - Weimar ER -