TY - THES A1 - Wuttke, Frank T1 - Beitrag zur Standortidentifizierung mit Oberflächenwellen T1 - Site identification using surface waves N2 - In der Dissertation wurden unterschiedliche Methoden zur Standortidentifizierung mit Oberflächenwellen analysiert. Es wurden neue Methoden zur Parameteridentifikation unter Nutzung von Oberflächenwellen vorgeschlagen. Die Ziele der Arbeit können wie folgt definiert werden: a) Die Entwicklung eines geeigneten theoretischen Modells als Grundlage zur Untersuchung des Standortes hinsichtlich vorhandener Bodensteifigkeiten. b) Die Entwicklung einer neuen Inversionsmethodik unter Berücksichtigung aller auftretenden Moden im Oberflächenwellenfeld. Die Erstellung eines Modells des vertikal heterogenen Untergrundes erfolgte im Frequenz-bereichs für beliebig geschichtete Böden, aufbereitet durch weitestgehend analytische Formulierungen. Durch Nutzung beliebiger horizontaler, elastisch-isotroper Schichten konnte die vertikale Heterogenität approximiert werden. Die Definition der Green'schen Funktionen wurde in Form der Reflexions- und Transmissionskoeffizienten durchgeführt. Die Lösung des formulierten Halbraumproblems erfolgte unter Verwendung der Konturintegration. Dazu wurde die Vorgehensweise der bestehenden Lösung des homogenen Halbraums auf das Problem des geschichteten Mediums übertragen. Die daraus sich ergebende Lösung ist in ein Körperwellen- und ein Oberflächenwellenfeld separiert. Der Vorteil dieser analytischen Betrachtungsweise liegt in der eindeutigen Zuordnungsmöglichkeit der erhaltenen Lösungen zu Wellentypen und in der klaren Dispersionscharakteristik der berechneten Modelle. Im Gegensatz dazu liefern numerische Lösungen, wie FEM, immer ein Wellenfeld, in dem die Wellentypen zugeordnet bzw. interpretiert werden müssen. Mit Hilfe der synthetischen Bodenmodellierung wird das Verhalten von geschichteten Böden bei durchlaufenden Oberflächenwellenfeldern simuliert und untersucht. Für die Untersuchung der Profile wurde hauptsächlich die Modale Superposition von Oberflächenwellen und die Wellenzahl-Integration verwendet. Bei der Analyse von Oberflächenwellenfeldern in vorhandenen Medien sind abweichend von den üblichen seismischen Methoden spezielle Untersuchungsmethoden zur Ermittlung der vorhandenen Dispersion notwendig. Zur Durchführung der Dispersionsanalyse wird in geotechnischen Untersuchungen in der Regel das Phasen-Differenzen-Verfahren (SASW) genutzt. Aufgrund der beschränkten Aussagefähigkeit dieses Verfahrens zu auftretenden höheren Moden werden verbesserte Analysemethoden zur experimentellen Auswertung hinzugezogen. Diese Methoden nutzen zur Informationsgewinnung das räumlich ausgedehnte Wellenfeld. Ausgehend von dem Dispersionsverhalten kann die Bodenstruktur mittels inverser Methoden bestimmt werden. Für die gemeinsame Inversion der in den Messungen vorhandenen Moden wurde ein entsprechendes Inversionsverfahren abgeleitet. Als Grundlage der Inversion wurde ein Verfahren des kleinsten Fehlerquadrates gewählt. Der Vorteil hinsichtlich einer effizienten und stabilen Inversion unter Nutzung dieser Methodik überwiegt den Nachteil der lokalen Suche nach dem Fehlerminimum. Zum Erreichen der stabilen und zielgerichteten Inversion wird der Levenberg-Marquardt Algorithmus, zusammen mit der Wichtung der Dispersionsäste entsprechend ihres Anregungsverhaltens in den Dispersionsspektren, eingesetzt. Von Vorteil hat sich innerhalb der Arbeit die gleichzeitige Behandlung von theoretischen und experimentellen Parameterstudien erwiesen, da sich Ergebnisse und Erkenntnisse beider Seiten ergänzten. Eine Interpretation von Felddaten kann damit weitaus sicherer durchgeführt werden. Zusätzlich konnten die erarbeiteten experimentellen und theoretischen Verfahren gegenseitig überprüft werden. N2 - In this thesis various available methods for the site identification with surface waves were analyzed. Some new methods are proposed for the site identification using surface wave characteristics. The objectives of the thesis are as follows: a) To develop an appropriate theoretical model that can work in conjunction with the results obtained from the site inverstigations to precisely identify the actual in situ stiffness profiles. b) To develop a new inversion procedure that enables to inverse all the appearing modes in a wave field. An appropriate model should be able to define the vertical heterogeniety of the subsoil. In this study, the existing solution for the homogeneous half space was extended to the stratified medium. An analytical formulation in the frequency domain was used for this purpose by considering arbitrary horizontal, elastic isotropic layers. The Green’s functions were defined in the matrix formulation in the form of reflection- and transmission coefficients. In this way the analytical considerations could be carried out in a strong mathematical procedure. The solution for the forced excited layered half space was obtained following the contour integration. The solution could be separated in to the body wave and the surface wave fields. The advantage of such an analytical approach lies in the definite allocation of the preserved solutions for wave types and the straight dispersion characteristic of the calculated models. The difference between the analytical and the numerical solutions, such as using FEM, is that the interpretation of the calculated wave field is not required in the former, whereas it is necessary in the latter case. With the help of an analytic wave field calculation the behavior of the propagate surface wave fields in the stratified media could be better simulated and examined. For the investigation of the stiffness profiles primarily the modal superposition by surface waves and the wave number-integration were used. Special surface wave field investigation methods were necessary for the determination of the available dispersion characterisic. For the realization of the dispersion analysis in geoengineering investigations the phase difference method (SASW) is a widely used tool. Since the information on the higher modes are limited, an improved method is proposed to separate the different modes from the experimental data. The proposed method used the spatially spread wave field for the dispersion information. The soil structure can be determined by using various inverse methods. For the joint inversion of all the available modes in the measurements, a suitable inversion procedure was derived. For the stabilization of the inversion procedure, a least square method was chosen. The disadvantage of this efficient method is a local minimum search of the objective function. To achieve a stable and focused inversion procedure the Levenberg-Marquardt algorithm was used. The different dispersion branches multiplied by weighting factors corresponds to the excitation behavior in the dispersion spectra. One particularly advantage in the work is the concurrent treatment of theoretical and experimental parameter studies. According this treatment, the results and cognitions of both sides were complementary. An interpretation of field data could be carried out reliably. In addition, the compiled experimental and theoretical procedures could be checked mutually. KW - Inversionsalgorithmus KW - Inversionstheorie KW - Wellenausbreitung KW - Anomale Dispersion KW - Dispersion KW - Energieübertragung KW - wave propagation KW - inversion procedure KW - inversion theorie KW - wave field dispersion Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20050708-6874 ER - TY - CHAP A1 - Schanz, Tom A1 - Wuttke, Frank A1 - Dineva, Petia ED - Gürlebeck, Klaus ED - Könke, Carsten T1 - HYBRID APPROACH OF WAVE NUMBER INTEGRATION-BOUNDARY INTEGRAL EQUATION METHOD FOR SITE EFFECT ESTIMATION OF A LATERALLY VARYING SEISMIC REGION N2 - In this paper we evaluate 2D models for soil-water characteristic curve (SWCC), that incorporate the hysteretic nature of the relationship between volumetric water content Θ and suction Ψ. The models are based on nonlinear least squares estimation of the experimental data for sand. To estimate the dependent variable Θ the proposed models include two independent variables, suction and sensors reading position (depth d in the column test). The variable d represents not only the position where suction and water content are measured but also the initial suction distribution before each of the hydraulic loading test phases. Due to this the proposed 2D regression models acquire the advantage that they: (a) can be applied for prediction of Θ for any position along the column and (b) give the functional form for the scanning curves. KW - Architektur KW - CAD KW - Computerunterstütztes Verfahren Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170327-29132 UR - http://euklid.bauing.uni-weimar.de/ikm2006/index.php_lang=de&what=papers.html ER - TY - CHAP A1 - Stutz, Henning A1 - Wuttke, Frank ED - Gürlebeck, Klaus ED - Lahmer, Tom ED - Werner, Frank T1 - EVALUATION OF SOIL-STRUCTURE INTERACTION MODELS USING DIFFERENT MODEL-ROBUSTNESS APPROACHES T2 - Digital Proceedings, International Conference on the Applications of Computer Science and Mathematics in Architecture and Civil Engineering : July 04 - 06 2012, Bauhaus-University Weimar N2 - The aim of this study is to show an application of model robustness measures for soilstructure interaction (henceforth written as SSI) models. Model robustness defines a measure for the ability of a model to provide useful model answers for input parameters which typically have a wide range in geotechnical engineering. The calculation of SSI is a major problem in geotechnical engineering. Several different models exist for the estimation of SSI. These can be separated into analytical, semi-analytical and numerical methods. This paper focuses on the numerical models of SSI specific macro-element type models and more advanced finite element method models using contact description as continuum or interface elements. A brief description of the models used is given in the paper. Following this description, the applied SSI problem is introduced. The observed event is a static loaded shallow foundation with an inclined load. The different partial models to consider the SSI effects are assessed using different robustness measures during numerical application. The paper shows the investigation of the capability to use these measures for the assessment of the model quality of SSI partial models. A variance based robustness and a mathematical robustness approaches are applied. These different robustness measures are used in a framework which allows also the investigation of computational time consuming models. Finally the result shows that the concept of using robustness approaches combined with other model–quality indicators (e.g. model sensitivity or model reliability) can lead to unique model–quality assessment for SSI models. KW - Angewandte Informatik KW - Angewandte Mathematik KW - Computerunterstütztes Verfahren Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170314-27878 UR - http://euklid.bauing.uni-weimar.de/ikm2012 SN - 1611-4086 ER - TY - CHAP A1 - Alalade, Muyiwa A1 - Kafle, Binod A1 - Wuttke, Frank A1 - Lahmer, Tom ED - Gürlebeck, Klaus ED - Lahmer, Tom T1 - CALIBRATION OF CYCLIC CONSTITUTIVE MODELS FOR SOILS BY OSCILLATING FUNCTIONS T2 - Digital Proceedings, International Conference on the Applications of Computer Science and Mathematics in Architecture and Civil Engineering : July 20 - 22 2015, Bauhaus-University Weimar N2 - In order to minimize the probability of foundation failure resulting from cyclic action on structures, researchers have developed various constitutive models to simulate the foundation response and soil interaction as a result of these complex cyclic loads. The efficiency and effectiveness of these model is majorly influenced by the cyclic constitutive parameters. Although a lot of research is being carried out on these relatively new models, little or no details exist in literature about the model based identification of the cyclic constitutive parameters. This could be attributed to the difficulties and complexities of the inverse modeling of such complex phenomena. A variety of optimization strategies are available for the solution of the sum of least-squares problems as usually done in the field of model calibration. However for the back analysis (calibration) of the soil response to oscillatory load functions, this paper gives insight into the model calibration challenges and also puts forward a method for the inverse modeling of cyclic loaded foundation response such that high quality solutions are obtained with minimum computational effort. Therefore model responses are produced which adequately describes what would otherwise be experienced in the laboratory or field. KW - Angewandte Informatik KW - Angewandte Mathematik KW - Building Information Modeling KW - Computerunterstütztes Verfahren KW - Data, information and knowledge modeling in civil engineering; Function theoretic methods and PDE in engineering sciences; Mathematical methods for (robotics and) computer vision; Numerical modeling in engineering; Optimization in engineering applications Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170314-27932 SN - 1611-4086 ER - TY - CHAP A1 - Khosravian, Reza A1 - Wuttke, Frank ED - Gürlebeck, Klaus ED - Lahmer, Tom T1 - QUALITATIVE INVESTIGATION OF THE EFFECT OF SOIL MODELING APPROACH ON DYNAMIC BEHAVIOR OF A SMALL-SCALE 2-DOF STRUCTURE WITH PILE FOUNDATION T2 - Digital Proceedings, International Conference on the Applications of Computer Science and Mathematics in Architecture and Civil Engineering : July 20 - 22 2015, Bauhaus-University Weimar N2 - Known as a sophisticated phenomenon in civil engineering problems, soil structure interaction has been under deep investigations in the field of Geotechnics. On the other hand, advent of powerful computers has led to development of numerous numerical methods to deal with this phenomenon, resulting in a wide variety of methods trying to simulate the behavior of the soil stratum. This survey studies two common approaches to model the soil’s behavior in a system consisting of a structure with two degrees of freedom, representing a two-storey frame structure made of steel, with the column resting on a pile embedded into sand in laboratory scale. The effect of soil simulation technique on the dynamic behavior of the structure is of major interest in the study. Utilized modeling approaches are the so-called Holistic method, and substitution of soil with respective impedance functions. KW - Angewandte Informatik KW - Angewandte Mathematik KW - Building Information Modeling KW - Computerunterstütztes Verfahren KW - Data, information and knowledge modeling in civil engineering; Function theoretic methods and PDE in engineering sciences; Mathematical methods for (robotics and) computer vision; Numerical modeling in engineering; Optimization in engineering applications Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170314-28080 SN - 1611-4086 ER - TY - JOUR A1 - Alalade, Muyiwa A1 - Reichert, Ina A1 - Köhn, Daniel A1 - Wuttke, Frank A1 - Lahmer, Tom ED - Qu, Chunxu ED - Gao, Chunxu ED - Zhang, Rui ED - Jia, Ziguang ED - Li, Jiaxiang T1 - A Cyclic Multi-Stage Implementation of the Full-Waveform Inversion for the Identification of Anomalies in Dams JF - Infrastructures N2 - For the safe and efficient operation of dams, frequent monitoring and maintenance are required. These are usually expensive, time consuming, and cumbersome. To alleviate these issues, we propose applying a wave-based scheme for the location and quantification of damages in dams. To obtain high-resolution “interpretable” images of the damaged regions, we drew inspiration from non-linear full-multigrid methods for inverse problems and applied a new cyclic multi-stage full-waveform inversion (FWI) scheme. Our approach is less susceptible to the stability issues faced by the standard FWI scheme when dealing with ill-posed problems. In this paper, we first selected an optimal acquisition setup and then applied synthetic data to demonstrate the capability of our approach in identifying a series of anomalies in dams by a mixture of reflection and transmission tomography. The results had sufficient robustness, showing the prospects of application in the field of non-destructive testing of dams. KW - Damm KW - Defekt KW - inverse analysis KW - damage identification KW - full-waveform inversion KW - dams KW - wave propagation KW - OA-Publikationsfonds2022 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20221201-48396 UR - https://www.mdpi.com/2412-3811/7/12/161 VL - 2022 IS - Volume 7, issue 12, article 161 PB - MDPI CY - Basel ER -