Volkmar Zabel

Volkmar Zabel
Bauhaus-Universität Weimar ·  Institut für Strukturmechanik

About

93
Publications
14,757
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
694
Citations
Citations since 2016
44 Research Items
524 Citations
2016201720182019202020212022020406080100
2016201720182019202020212022020406080100
2016201720182019202020212022020406080100
2016201720182019202020212022020406080100

Publications

Publications (93)
Article
Full-text available
In this paper, the formulation of Generalized Beam Theory (GBT) for the geometrically nonlinear analysis of thin-walled circular pipes is presented. GBT is a computationally efficient numerical method which is especially formulated for thin-walled members with a capacity of determining the cross-sectional deformation through a combination of a set...
Article
Progressive updating strategies are commonly used for the calibration of numerical models such as those of a track-bridge system. These strategies involve, first, updating the track model based on dedicated dynamic tests, and second, the calibration of the bridge model based on ambient vibration tests considering the updated track parameters. This...
Conference Paper
Full-text available
This paper presents alternative complementary shear and transversal elongation modes of Generalized Beam Theory (GBT) for thin-walled hollow circular cross-sections and compares them to the recent developments concerning membrane's shear and transversal elongation. The main features of the alternative complementary modes are: i) despite of Poisson'...
Article
Full-text available
This paper presents the dynamic analysis extension of the Generalized Beam Theory (GBT) formulation developed in [1] for curved thin-walled pipes. The new proposed dynamic curved GBT element formulation goes beyond the current GBT’s analysis of straight pipes, not only concerning the coupling and behavior of pipe bends or toroidal shells, but also...
Article
Full-text available
In this paper, the linear Generalized Beam Theory (GBT) is formulated for stress and deformation analysis of curved thin-walled circular pipes. In comparison to the analysis of straight pipes, the analysis of pipe bends is a complex problem due to the strong coupling effect of the longitudinal bending, warping and the cross-sectional ovalization. G...
Chapter
Full-text available
Pipelines in earthquake-prone regions can be susceptible to damage through different failure mechanisms. For above ground pipeline systems, investigating these failures requires a numerical method that appropriately describes the pipe, the support system, their interaction and failure modes characterized by local cross-sectional deformations. Commo...
Thesis
Full-text available
In recent years the demand on dynamic analyses of existing structures in civil engineering has remarkably increased. These analyses are mainly based on numerical models. Accordingly, the generated results depend on the quality of the used models. Therefore it is very important that the models describe the considered systems such that the behaviour...
Conference Paper
Während eines Erdbebens können Rohrleitungen, die eine tektonische Verwerfung kreuzen, durch Relativverschiebungen der Lager zu beiden Seiten der Verwerfung großen Verformungen unterworfen werden. Dadurch entstehen im Rohr sehr hohe Zwangsspannungen, die bis zum Versagen, beispielsweise durch lokales Beulen, führen können. Die Simulation solcher Ve...
Conference Paper
Full-text available
In this study the formulation of fully geometrically nonlinear GBT analysis is developed for thin-walled circular pipes. This formulation uses the Sanders definition of kinematic relations for circular cylindrical shells which satisfies the Love-Kirchhoff assumption. Here, the nonlinearity is only considered for the membrane strains since for thin-...
Article
de Die Tragfähigkeitsbeurteilung einer bestehenden fachwerkartigen Eisen‐ und Stahlkonstruktion ist wesentlich von den vorhandenen Stabnormalkräften und den daraus resultierenden Spannungen abhängig. Liegen ausreichend Informationen zum Tragwerk und den äußeren Einwirkungen vor, können die Stabnormalkräfte im Fachwerk in Form einer statischen Berec...
Article
Warping and distortion are relevant kinematic features of thin-walled beam structures, which have a non-trivial analysis. On this basis, this paper not only evaluates the possible kinematic transmissions involving high-order warping and distortion, but also presents a procedure to analyze structures using mixed models based on shell and Generalized...
Conference Paper
Full-text available
In structural monitoring a structure's response to loads and environmental influences is continuously observed to reduce the uncertainties in the assessment of the actual structural condition, justify an extension of service life or to detect possible damage. In this study, a monitoring system using accelerometers and fibre bragg gratings was insta...
Article
Full-text available
This paper presents the formulation of exact stiffness matrices applied in linear generalized beam theory (GBT) under constant and/or linear loading distribution in the longitudinal direction. Also, the assortment of the correct exact stiffness matrix and the corresponding shape function are presented based on main transversal deformation mode, whi...
Conference Paper
This work presents a procedure to couple shell and Generalized Beam Theory, GBT, elements. The main focus of this procedure is the possibility to model mixed beam frame structures, which the traditional shell elements are applied at the joints and GBT elements are used to model the beams/columns. Such modeling technique can use the benefits of both...
Article
Full-text available
Demolition of guyed masts is usually carried out by cutting down some of the supporting guy cables using an explosive in such a way that the mast can fall into the desired direction. Without the cable supports, guyed tubular masts are very slender structures which are susceptible to local buckling based on the internal force distribution. If this l...
Conference Paper
Full-text available
The dynamic behavior of slender structures, such as tower structures, is frequently characterized by unfavorable responses resulting in resonant phenomena between the dynamic actions and the structures, such as the "lock-in" effect. For counteracting unfavorable vibrations of slender structures, tuned mass dampers are frequently employed. Tuned mas...
Conference Paper
Full-text available
Historically, a number of major catastrophic earthquakes have resulted in a real loss of life and property worldwide. During the last decades, in particular, the overall exposure to seismic risk has increased not only due to the higher population density but also due to the more challenging construction methods and the multilayered connection betwe...
Article
Full-text available
Slender structures, such as towers and masts, frequently exhibit unfavourable responses when subjected to dynamic loads, characterized by the non-negligible contribution of higher modes of vibration as well as resonant phenomena between the loads and the structure. To mitigate such responses, tuned mass dampers (TMDs) have been employed in several...
Data
German version of the following paper, published in the journal "Bautechnik", 95(6), pp. 401-409: https://www.researchgate.net/publication/324479325_Monitoring-based_performance_analysis_of_tuned_mass_dampers_in_tower_structures
Conference Paper
Full-text available
Kurzfassung In den letzten Jahren wurde in mehreren Veröffentlichungen über die Anwendung von Methoden der Operational Modal Analysis auf gemessene Dehnungszeitreihen berichtet. Im Fokus standen dabei oft Dehnungsmessungen mit Faser-Bragg-Gitter-Sensoren. Im vorliegenden Beitrag wird über ein Langzeitmonitoring an einem Sendeturm berichtet. Für di...
Article
Full-text available
Im Rahmen des DFG Graduiertenkollegs 1462 wurde an einem ca. 200 m hohen Sendeturm mit rotationssymmetrischem Querschnitt ein Monitoringsystem zur Erfassung von Schwingbeschleunigungen, Temperaturen und Windeinwirkungen installiert, welches über einen Zeitraum von zwei Jahren betrieben wurde. Die Auswertung der Schwingungsdaten erfolgte mithilfe ei...
Article
A Bayesian framework is presented for finding the optimal locations of strain sensors in a plate with a crack with the goal of identifying the crack properties, such as crack location, size, and orientation. Sensor grids of different type and size are considered. The Bayesian optimal sensor placement framework is rooted in information theory, and t...
Conference Paper
This paper describes the experimental calibration of an existing Wiegmann–Polonceau roof truss based on modal parameters. Dynamic tests allowed the determination of the natural frequencies and mode shapes of the global truss and of individual truss members. The global and local modal configurations as well as coupled vibration of truss members are...
Article
Full-text available
This paper is concerned with the inverse identification of the stress state in axially loaded slender members of iron and steel truss structures using measured dynamic data. A methodology is proposed based on the finite element model updating coupled with nature-inspired optimization techniques, in particular the particle swarm optimization. The nu...
Article
Optimal reference sensor positions for applications in model updating using output-only vibration test data based on random excitation: Part 1 - objective function and numerical benchmark study
Article
Optimal reference sensor positions for applications in model updating using output-only vibration test data based on random excitation: Part 2 - improved search strategy and experimental case study
Article
Das dynamische Verhalten von Eisenbahnbrücken mit kurzer Spannweite - numerische und experimentelle Untersuchungen
Article
Full-text available
The final publication is available at http://link.springer.com The use of scanning laser doppler vibrometers (SLDV) is common practice in the context with experimental modal analysis. In recent years, commercial 3D SLDV have been developed, where three laser heads simultaneously point to the same measuring point and an input reference signal is us...
Chapter
The natural frequencies of the Metsovo bridge during construction are identified both in actual scale and in 1:100 scale. Finite element models of increasing modeling complexity are developed in order to investigate their efficiency in representing the measured dynamic stiffness of the bridge-foundation-soil system. The results highlight the import...
Conference Paper
Full-text available
The presented study is a contribution towards the assessment of uncertainties in operational modal analysis. It is well known, that the quality of the identified modal parameters depends on the quality of the measured vibration data and further sources of uncertainty. It is sought to enhance the process of an operational modal analysis by identifyi...
Article
Full-text available
Safety assessment of existing iron and steel truss structures requires the determination of the axial forces and corresponding stresses in truss structural members. The results of the axial force determination can be integrated as part of a structural health monitoring scheme for existing trusses. In this work, a methodology is proposed to identify...
Conference Paper
Full-text available
Zusammenfassung: Im vorliegenden Beitrag wird die Auswertung von Langzeitmonito-ringdaten eines Sendeturms vorgestellt. Der Turm hat eine Höhe von ca. 200 m, und ist an seiner Turmspitze mit einem Schwingungsdämpfer ausgestattet. Das im Rahmen eines Forschungsvorhabens installierte Monitoringsystem erfasst im Wesentlichen Schwingbe-schleunigungen,...
Conference Paper
Structures under repetitive or cyclic loading are prone to have damages or cracks due to fatigue. Crack identification of such structures while under operational loading is a challenging task in the field of structural health monitoring (SHM). Fatigue state or fatigue life cycle assessment (LCA) of a structure is therefore updated by monitoring str...
Article
Tragfähigkeits‐ und Gebrauchstauglichkeitsnachweise von Eisenbahnbrücken für den Hochgeschwindigkeitsverkehr erfordern in der Regel einen Vergleich zwischen relevanten Eigenfrequenzen des Überbaus und Frequenzen aus der periodischen Belastung durch überfahrende Radsätze. Werden die Eigenfrequenzen des Bauwerks rechnerisch bestimmt, hängt die Qualit...
Article
Despite the major advances in finite-element (FE) modeling and system identification (SI) of extended infrastructures, soil compliance and damping at the soil–foundation interface are not often accurately accounted for due to the associated computational demand and the inherent uncertainty in defining the dynamic stiffness. This paper aims to scrut...
Chapter
Even if the development of several software packages has facilitated the performance of experimental and operational modal analysis in recent years, modal identification is still a complex task which requires experience and a solid theoretical background of the analyst since the results are influenced by several factors. One of these factors that m...
Chapter
Full-text available
The use of Scanning Laser Doppler Vibrometers (SLDV) is a common practice in the context with modal analysis. 3D SLDV have been used with classical experimental modal analysis for several years. In this case, three laser heads, which simultaneously point to the same location, are used and an additional input reference signal is required to combine...
Conference Paper
Full-text available
Guyed antenna masts which are no longer used for their initially intended purpose due to various reason are usually demolished. The simplest way of demolishment is to cut some guy-cables such that the mast can fall into one direction. Due to the fact that guyed masts are extremely slender structures, they are prone to bending failure if the horizon...
Conference Paper
Full-text available
In Structural Health Monitoring (SHM) applications, observed discrepancies between identified and numerically calculated dynamic characteristics of structures have to be carefully interpreted and evaluated. Structural damage is not always responsible for those discrepancies, which can also be attributed to the initial assumptions adopted for the nu...
Chapter
Before starting an experiment it is wise to make close investigations on the structure to be examined and the possible designs of the experiment. The optimal design of the measurement setups is acquired by using mathematical optimization methods which are supported by numerical simulations of the structure and its behavior. The numerical model can...
Article
Full-text available
To reduce the resonant response of high-speed railway bridges, semi-active magnetorheological dampers are proposed in this study. The elements are connected to the structure in a double beam configuration. An H∞ control algorithm to drive magnetorheological damping forces of MR dampers is derived. Feasible solutions for an uncertain time-delay mode...
Chapter
Dieses Kapitel fasst die wesentlichen Grundlagen der Baudynamik hinsichtlich Modellbildung und Analyseverfahren zusammen. Generell können Tragwerke hinsichtlich der Erdbebenbeanspruchung nur unter Anwendung dynamischer Modellbildung und Analyse sicher und wirtschaftlich ausgelegt werden. Grundsätzlich werden die Gleichungen für das dynamische Verha...
Chapter
The increasing speed of railway traffic sets not only higher safety and serviceability requirements to the rolling stock but also to the civil engineering infrastructure. An important criterion that has to be satisfied for bridges is, that resonances between moving axle loads and the structure’s natural frequencies should be avoided. This has usual...
Article
In the context of finite element model updating, experimentally obtained features are used to improve the quality of an initial finite element model. Using vibration tests, features like natural frequency, mode shapes, and modal damping ratios can be extracted from measured data. One possibility to perform such tests is a roving setup configuration...
Chapter
Full-text available
During the Weimar Summer School course “Model Validation and Simulation” the project “System Identification, Model Updating and Simulation” has been performed. The project was about modal analysis of civil structures. As an example a down scaled “tower” was given. This tower was made of PVC water pipes, with a basement of concrete. Four acceleratio...
Article
Full-text available
This article describes the experimental calibration of a three-dimensional numerical model of an Alfa Pendular train vehicle based on modal parameters. The dynamic tests of the carbody and bogie of the vehicle allowed the determination of the frequencies and modal configurations of 13 vibration modes, by applying the data-driven stochastic subspace...
Article
Fatigue is an important failure mode for bridges under dynamic loadings. The major concern of this paper is to estimate the remaining fatigue life of each structural member of a severely corroded historical riveted steel railway bridge, which was in service for more than 100 years. A numerical model of the structure in its current condition was use...
Article
Full-text available
This article describes the calibration of the numerical model of a bowstring-arch railway bridge based on modal parameters. An ambient vibration test allowed the identification of the natural frequencies, mode shapes and damping coefficients of several global and local modes of vibration of the bridge by the application of an output-only technique...
Article
This paper deals with the optimization of TMD systems to suppress multi-resonant dynamic structural response of high-speed railway bridges. Unlike the previous methods, the presented method chooses the objective function based on the H2 norm along with the constraints on all the peaks which are at the same heights over the frequency ranges of inter...
Article
The process of analysis and design in structural engineering requires the consideration of different partial models of loading, structural material, structural elements and analysis type, among others. All of these, need an adequate modelling as individuals and as coupled sets to catch a behaviour of interest. This paper proposes an innovative algo...
Conference Paper
Full-text available
Vibration induced settlements are one of the major issues in vibration analysis. The realistic determination of the right amplitudes is still a very complex task with many uncertainties. The presented study analyses several theories of cyclic accumulation of settlements at an existing building with considerable settlements, road traffic close to th...
Article
In the context of finite element model updating using output-only vibration test data, natural frequencies and mode shapes are used as validation criteria. Consequently, the correct pairing of experimentally obtained and numerically derived natural frequencies and mode shapes is important. In many cases, only limited spatial information is availabl...
Article
In previous years numerous research projects were focused on the detection of structural damage based on vibration measurements. There are two groups of approaches which can be distinguished in this context, model-based methods and algorithms that only use the measured vibration response of the structure. The damage indicator applied in this study...
Article
The present work concentrates on stochastic model updating for finite element models using uncertain data from measurements. One model updating technique, based on the perturbation method, has been proposed by Khodaparast et al [6] [7]. The method gives accurate results, but the numerical effort is not acceptable, especially for real-scale structur...
Article
The process of model updating incorporates several aspects that have an influence on both computational performance and the results of the process. Generally the objective of model updating is to modify the system parameters of a theoretical model such that the model describes the structural behaviour of a considered mechanical system as good as po...
Article
Full-text available
In the context of the enhancement of high-speed railway lines, existing railway bridges need to be investigated and assessed. To predict the structural response due to train passages with sufficient reliability, a numerical model is required to simulate the dynamic behaviour of the bridge. The establishment of a realistic numerical model is a diffi...
Article
Full-text available
In the context of the project DETAILS (Design for optimal life cycle costs of high-speed rail-way bridges by enhanced monitoring systems), sponsored by the European Research Fund for Coal and Steel, the Erfttal Bridge near Aachen in Germany was subject of both, an experi-mental as well as an analytical investigation into its dynamic characteristics...
Article
Global monitoring systems are frequently used to monitor structures with the intention to assess the structure and support the maintenance. In most cases the indicators are not only sensitive to a structural damage, but also to environmental changes (e.g., temperature, humidity) or applied excitation. In this study, modal and wavelet-based indicato...
Article
The German Federal Garden Exhibition BUGA will be held in 2007 in the Thuringian towns Gera and Ronneburg. The most outstanding structure on the exhibition area is a 225 m long footbridge, the “Erlebnisbrücke“. This structure is a three span stress ribbon bridge with a timber superstructure. Several resonances in the range of typical step frequenci...
Conference Paper
p>The German Federal Garden Exhibition BUGA will be held in 2007 in the Thuringian towns Gera and Ronneburg. The most outstanding structure on the exhibition area is a 225 m long footbridge, the “Erlebnisbrücke”. This structure is a three span stress ribbon bridge with a timber superstructure. Several resonances in the range of typical step frequen...
Article
This paper reports about a study concerning the dynamic behaviour of the Nordbrücke in the exhibition area of the IGA Rostock. This study includes the experimental identification of modal parameters by means of vibration tests, investigations with respect to the modal properties of a numerical model of the bridge as well as computations of the stru...
Article
As existing facilities / structures are modi.ed, as engineering knowledge advances and as the requirements to extend life increase, industries must demonstrate that operations can continue safely and economically. This is one objective of the Thematic Network SAFERELNET [1], where reassessment strategies are covered. One possibility to enhance the...
Article
Most system identification methods are based on a time or frequency domain analysis of data that were measured in dynamic tests. In this article, an algorithm for the identification of a finite element model's parameters is presented that utilizes wavelet coefficients of the measured data and their integrals or derivatives, respectively. How the wa...
Article
A great variety of wavelet-based engineering applications were developed in the past decades. One of these techniques is based on signals' wavelet decompositions' energy components in the context with structural damage detection. This approach is described and applied to data from dynamic bridge tests. Both, relations between response and excitatio...
Article
In recent years various wavelet-based approaches for structural damage detection were developed by several researchers. Some of these methodologies use energy components of measured response signals' wavelet decompositions. This paper describes a study with respect to the development of a damage detection indicator for civil engineering structures...
Article
Die meisten traditionellen Methoden der Systemidentifikation beruhen auf der Abbildung der Meßwerte entweder im Zeit- oder im Frequenzbereich. In jüngerer Zeit wurden im Zusammenhang mit der Systemidentifikation Verfahren entwicklet, die auf der Anwendung der Wavelet-Transformation beruhen. Das Ziel dieser Arbeit war, einen Algorithmus zu entwickel...
Article
The wavelet analysis has been applied to several problems of system identification for the last decade. In this paper a wavelet based approach for the identification of system stiffness, damping and mass parameters is proposed. It is based on the transformation of the equation of motion into the time-scale domain. The choice of appropriate analyzin...
Article
Structural damage causes a decrease of the stiffness of a structure which leads to changes of the dynamic behaviour of the considered system. In this study the change of dynamic structural properties of two precast concrete slabs which were reinforced by glass fibre composite bars due to progressive damage was investigated. Free-vibration laborator...