Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-31142 Beitrag zu einem Tagungsband Baeßler, Matthias; Bronsert, Jeffrey; Cuéllar, Pablo; Rücker, Werner Chen, A.; Frangopol, D.M.; Ruan, X. Evaluating the degradation of ballasted track at bridges for high-speed railways The bridge design for railway bridges is far more dependent on the interaction with the traffic and the carriageway than for road bridges. This is especially true for the specific demands of the track in highspeed railways. Both maintenance and safety of the track have to be considered. The most relevant sections for the design criteria can be located at the bridge transition zones. Based on experimental investigations it is shown that bridge joint displacements, changes in stiffness and uplifting of the sleeper are causes for an increased degradation and loss in strength of the ballasted track. With respect to high speed vibrations of the bridge deck can have an even more decisive impact. Bridge deck vibrations can lead to destabilization of the bailast. In a numerical study the behavior of the track at the bridge is illustrated. CRC Press 2014 IABMAS 2014 - 7th International conference of bridge maintenance, safety and management (Proceedings) 978-1-138-00103-9 IABMAS 2014 - 7th International conference of bridge maintenance, safety and management Shanghai, China 07.07.2014 11.07.2014 1 8 2016-02-20 OPUS4-31144 Beitrag zu einem Tagungsband Bronsert, Jeffrey; Baeßler, Matthias; Cuéllar, Pablo; Rücker, Werner Cunha, A.; Caetano, E.; Ribeiro, P.; Müller, G. Assessment and optimisation of bridge transition zones on the basis of a numerical model for train-track-bridge interaction The main degradation process at bridge transition zones due to traffic loads is the appearance of differential settlements. Abrupt stiffness changes, repeating traffic loads and relative displacements of the superstructure ends on bridges often aggravate this problem. In this contribution, a 3D finite element (FE) model extended with a boundary formulation in the frame of the scaled-boundary finite element method (SBFEM) for a transient analysis of train-track-bridge interaction is presented. This numerical model permits an assessment of bridge transition zone with respect to permanent deformations of the track. The main focus lies on the modeling strategies for the vehicle and their impact on suitable assessment criteria for bridge transition zones. For this purpose, two different modeling strategies for the vehicle, a moving load model and a multibody model, have been compared and discussed on the basis of the assessment criteria. The results indicate that the model of the vehicle has a minor effect for an assessment on the embankment, but that the assessment on the bridge may show significant differences depending on whether the inertial components of the vehicle (multibody model) are considered. 2014 EURODYN 2014 - 9th International conference on structural dynamics (Proceedings) 978-972-752-165-4 EURODYN 2014 - 9th International conference on structural dynamics Porto, Portugal 30.06.2014 02.07.2014 799 804 2016-02-20 OPUS4-48444 Beitrag zu einem Tagungsband Kullolli, Borana; Baeßler, Matthias; Cuéllar, Pablo; Rica, S.; Rackwitz, F. An enhanced interface model for friction fatigue problems of axially loaded piles The shaft bearing capacity often plays a dominant role for the overall structural behaviour of axially loaded piles in offshore deep foundations. Under cyclic loading, a narrow zone of soil at the pile-soil interface is subject to cyclic shearing solicitations. Thereby, the soil may densify and lead to a decrease of confining stress around the pile due to microphenomena such as particle crushing, migration and rearrangement. This reduction of radial stress has a direct impact on the shaft capacity, potentially leading in extreme cases to pile failure. An adequate interface model is needed in order to model this behaviour numerically. Different authors have proposed models that take typical Interface phenomena in account such as densification, grain breakage, normal pressure effect and roughness. However, as the models become more complex, a great number of material parameters need to be defined and calibrated. This paper proposes the adoption and transformation of an existing soil bulk model (Pastor- Zienkiewicz) into an interface model. To calibrate the new interface model, the results of an experimental campaign with the ring shear device under cyclic loading conditions are here presented. The constitutive model shows a good capability to reproduce typical features of sand behaviour such as cyclic compaction and dilatancy, which in saturated partially-drained conditions may lead to liquefaction and cyclic mobility phenomena. Glasgow, Scotland ASME 2019 OMAE 2019 2019 Conference: OMAE Glasgow, Scotland, UK 09.06.2019 14.06.2019 Article Number: UNSP V001T10A013 2019-07-15 OPUS4-30490 Zeitschriftenartikel Cuéllar, Pablo; Mira, P.; Pastor, M.; Merodo, J.A.F.; Baeßler, Matthias; Rücker, Werner A numerical model for the transient analysis of offshore foundations under cyclic loading A comprehensive numerical model for the analysis of offshore foundations under a general transient loading is presented here. The theoretical basis of the model lies on the Swansea formulation of Biot's equations of dynamic poroelasticity combined with a constitutive model that reproduces key aspects of cyclic soil behaviour in the frame of the theory of generalised plasticity. On the practical side, the adoption of appropriate finite element formulations may prevent the appearance of spurious numerical instabilities of the pore pressure field. In this respect, the use of a coupled enhanced-strain element is here proposed. On the other hand, the practicality of the presented model depends ultimately on its computational efficiency. Some practical recommendations concerning the solution strategies, the matrix storage/handling procedures and the parallel multi-processor computation are here provided. Finally, the performance of the model with a benchmark study case and its practical application to analyse the soil-structure interaction of an offshore monopile under a realistic transient storm loading are discussed. Barking Elsevier Ltd. 2014 Computers and geotechnics 59 75 86 10.1016/j.compgeo.2014.02.005 2016-02-20 OPUS4-30453 Zeitschriftenartikel Karabeliov, Krassimire; Baeßler, Matthias; Cuéllar, Pablo; Rücker, Werner A method for system identification of a structure supported by nonlinear springs using evolutionary computing A mechanical structure supported by nonlinear springs subjected to an external load is considered. If all mechanical parameters of the system were known, the displacement of the system subjected to this load could be easily calculated. If not all of the parameters are known, but the load and the displacement are measured at one location, an inverse problem exists. In the presented problem the nonlinear springs are unknown and have to be determined. At first glance a problem needs to be solved, which is underdetermined due to the number of unknown variables. However, evolutionary computing can be applied to solve this inverse, nonlinear and multimodal problem. Sometimes a prior knowledge exists on certain system properties, which is difficult to implement into analytical or numerical solver. This knowledge can play a decisive role in identifying the system properties and it can be easily included as boundary condition when applying evolutionary algorithm. This article examines how and under what conditions the spring resistances can be identified. The procedure is exemplified at a mechanical system of a pile foundation. Bristol, UK IOP Publ. 2014 Journal of physics / Conference series 490 2nd International conference on mathematical modeling in physical sciences 2013 Prague, Czech Republic 01.09.2013 05.09.2013 012095 1 4 urn:nbn:de:kobv:b43-304531 10.1088/1742-6596/490/1/012095 http://creativecommons.org/licenses/by/3.0/de/deed.de 2016-02-20