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Vienna, Austria

Urban S.,Strabag AG | Strauss A.,University of Vienna | MacHo W.,University of Vienna | Bergmeister K.,University of Vienna | And 2 more authors.
Bautechnik | Year: 2012

Concrete structures under cyclic loading - robustness and redundancy considerations for residual lifetime optimization Concerning fatigue analysis of concrete structures, especially in offshore areas, the continuous degradation of material parameters is not taken into account. One effect of the damaged material structure in parts of the concrete cross section is the stress redistribution from highly loaded (damaged) areas to low loaded (undamaged) areas and therefore an elongation of the theoretical residual service life. Concrete is described by the use of material parameters. A very important parameter is the E-modulus, also called the modulus of elasticity. A possibility to consider the degradation process within the material concrete is the gradual adaption and minimization of the E-modulus. In order to analyze and dimension a structure, to predict the internal stress distribution and deflection behavior, it is very important to specify this parameter and to know the variation according loading history and time. In addition to robustness and redundancy definition given in this article, a life time calculation of the Strabag gravity base test foundation in Cuxhaven according Model Code 1990 for the planned fatigue tests with realistic reduction of E-Modulus is performed. Concerning the case study "Cuxhaven" the use of system robustness in order to extend the residual service life is been demonstrated by means of a linear iterative modeling process. Copyright © 2012 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Source

Friedl H.,AIT Austrian Institute of Technology | Reiterer M.,RED Bernard GmbH | Kari H.,OBB Infrastruktur AG
Civil-Comp Proceedings | Year: 2013

Structures such as noise-barrier walls along high-speed railway lines are subject to aerodynamic excitations caused by alternating overpressure and underpressure loads induced by passing trains. This paper presents the results from holistic investigations during in-situ measurements at a new train high speed track in Austria. Trains moving quickly create an aerodynamic bow wave, comprised of a rapid alternation of overpressures and underpressures, as well as an aerodynamic stern wave, comprised of a rapid alternation of underpressures and overpressures. The amplitude of these waves depends on various factors, including the shape of the front and the back of the train and its velocity. A passing train thus causes cycles of overpressure and underpressure to act on any structures near the track, such as noise-barrier walls. The intensity of the load also depends on various factors, including the distance of the wall from the track. These effects cause cyclical stresses at a frequency of several per second. Due to the significant influence of the trains' aerodynamic shape, in-situ measurements for the determination of the aerodynamic impact of different train types were carried out. The test bed area was located between Vienna and St. Pölten, maximum speed drives were operated by ICE trains with a measured train velocity of 336km/h. In this paper the functional correlation between the dynamic excitation and the dynamic characteristics of noise barrier walls are discussed. © Civil-Comp Press, 2013. Source

Strauss A.,University of Vienna | Wendner R.,University of Vienna | Bergmeister K.,University of Vienna | Reiterer M.,RED Bernard GmbH | Horvatits J.,Asfinag Bau Management GmbH
Beton- und Stahlbetonbau | Year: 2011

Monitoring is of most practical significance for the design and assessment of new as well as of existing engineering structures. Practical experience and observations show that monitoring can provide the basis for new code specifications or efficient maintenance programs. Moreover, monitoring systems can avoid considerable costs of repairs and inconvenience to the public due to interruptions. This gives rise to the need for a thorough investigation to achieve an effective implementation of recorded monitoring data in numerical or analytical structural models that allow the detection of a deviant behavior from the proposed and the detection of initial deterioration processes. This study attempts to derive a concept for the effective incorporation of monitoring information in numerical models based on the concept of model correction factors. In particular, these studies are performed on the abutment free bridge structure S33.24 that has been proof loaded in February 2010 and monitored since December 2008. A merit of models derived based on monitoring data is that they are directly related to performance indicators which can be used for the assessment of the existing structural capacity and for an efficient life cycle analysis. Copyright © 2011 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG. Source

Engineering structures are subjected to continuous and increasing static and dynamic loads from artificial and natural environmental conditions (e.g. wind, traffic loads or wave loading on offshore wind turbine structures). Dynamic Loads can result in fatigue phenomena within the material concrete which are not totally explored even in their beginnings. Especially in the fields of Foundations for wind energy plants on- and offshore fatigue is a big problem. The Fatigue associated load combinations are mostly the decisive ones for design and dimensioning of the structure. The targets of the research are the development of a monitoring system for detecting the initiation or the early stage of a fatigue process in concrete and for the identification of the degree of deterioration in the concrete structure. The full scale model of a new type of gravity base foundation for offshore wind turbines in Cuxhaven projected by the Ed. Züblin AG is an optimal possibility to test the monitoring system within a concrete structure of real dimensions. The objective of this contribution is to provide a short review of concrete fatigue properties, to discuss, demonstrate and portray preliminary analyses results which are decisive for the final fatigue test layout at the Strabag gravity base foundation in Cuxhaven. The conduction of the fatigue tests at the gravity base foundation are planned in the beginning of the year 2013. Copyright © 2012 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Source

Urban S.,Strabag AG | Wagner R.,RED Bernard GmbH | Strauss A.,University of Vienna | Reiterer M.,RED Bernard GmbH | And 2 more authors.
Beton- und Stahlbetonbau | Year: 2013

In order to use structures up to their real end of lifetime it is of great importance to know the degree of damage of the structure. By using the actual Codes and Specifications (e.g. CEB-FIP Model Code 2010) it is not possible to define the real degree of deterioration. A practicable way of determining the degree on-site is the employment of non-destructive testing methods (monitoring). This field until now is not finally explored. The constant monitoring from the erection of a structure up to the end of its lifetime is seen as a very promising possibility to assess the residual lifetime. In this article fatigue tests on concrete specimens, accompanied with ultrasonic and acoustic emission measurements will be investigated closer and a possible way for the determination of the degree of damage and lifetime assessment will be proposed. Copyright © 2013 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Source

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