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- 2017 (4) (entfernen)
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- Beitrag zu einem Tagungsband (2)
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- Grouted connection (2)
- Joint capacity (2)
- Offshore wind energy (2)
- Shear keys (2)
- Acoustic emission analysis (1)
- Cracks (1)
- Digital image correlation (1)
- Failure (1)
- Grout-Verbindung (1)
- Grouted connections (1)
Eingeladener Vortrag
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In den vergangenen 10 Jahren hat die Errichtung von Windkraftanlagen zur Deckung des zukünftigen Energiebedarfs stark zugenommen. Dabei bilden vor allem Offshore-Windenergieanlagen (OWEA) den Hauptanteil im Bereich der erneuerbaren Energien. Aufgrund der einfachen Installation werden hierbei Grout-Verbindungen sowohl bei Monopile als auch bei Jacket-Konstruktionen zwischen den gerammten Gründungsrohren und einem Adapterstück (Transition Piece) ausgeführt. Die Bemessung der Grout-Verbindung stellt aktuell im Bereich von OWEA weitgehendes Neuland ohne Langzeiterfahrung dar. Lediglich im Bereich der Offshore Erdöl- und Erdgasindustrie kann man auf über 30 Jahre Erfahrung mit dieser Verbindungstechnologie zurückblicken. Hier wurden jedoch für vergleichbare Strukturen Schädigungen und Setzungen während des Betriebs festgestellt. Gleichzeitig sind die Bedingungen bei der Montage Offshore sehr schwierig und die eingesetzten Materialien sind aufgrund ihrer technischen Merkmale in Verbindung mit den Verarbeitungsbedingungen nicht unproblematisch. Dies betrifft insbesondere den Fall, wenn sich die Verbindung unterhalb des Meerwasserspiegels befindet oder das Grout-Material im jungen Alter dynamisch beansprucht wird.
Vor diesem Hintergrund sollen Strategien zur Instandsetzung schadhaft installierter oder im Betrieb geschädigter Grout-Verbindungen mit Hilfe von zementgebundenen Injektionsstoffen entwickelt werden. Hierzu werden zunächst die grundlegenden Schädigungsmechanismen und deren Auswirkung auf die Rissbildungsprozesse untersucht, da diese entscheidend für die Entwicklung eines geeigneten Instandsetzungskonzeptes sind. In diesem Zusammenhang werden Schädigungsmechanismen im Rahmen eines Modellversuchs anhand einer skalierten Grout-Verbindung untersucht. Des Weiteren werden potenzielle Instandsetzungsmaßnahmen und deren Grenzen diskutiert.
At present, Wind Turbine Generators (WTGs) operating in onshore and offshore wind farms are primary sources of renewable energy around the world. Cylindrical grouted sleeve connections are usually adopted in these WTG structures to connect the upper structure and foundation for ease of installation. These structures including grouted connections experience considerable adverse loading during their lifetimes. Settlements were reported inside similar connections used in energy structures especially oil and gas platforms, which were installed in last three decades. Thus, repair and rehabilitation of such connections in existing wind structures should also be planned ahead to keep them operating in the future. The nature of failure and crack generation in grouted connections are crucial prior to adopt a strengthening strategy. This pilot study is carried out to actualize the failure mechanism in the grouted connection, when subjected to axial loading. A novel reusable scaled cylindrical grouted connection with shear keys was designed and tested for its load bearing behaviour. The mechanical test was accompanied by classical measuring techniques (e.g. displacement transducer) as well as non-destructive measuring techniques (e.g. digital image correlation (DIC), acoustic emission analysis (AE)). The failure mechanism incorporating slippage of the shear keys and cracking of the grout was investigated. The capacity and applicability of such test mould were also discussed. The knowledge is expected to pave way towards repair of deteriorated grouted connections with similar geometry and failure pattern.
Current trend suggests that global energy consumption will increase in the future. This growing energy demand and advancement of technology lead to explore all potential offshore fossil and non-fossil energy sources, necessitating erection of exploration and production structures, rigs, platforms and towers, which are susceptible to adverse environmental conditions along with their maintenances. Cylindrical grouted joints provide suitable connections between steel substructure and foundation in these offshore platforms and wind structures especially monopiles for ease of installation. However, these are composite connections with exterior sleeve, interior pile and infill grout. The capacity of these connections is affected by number of factors. The literature over last four decades by numerous researchers has shown the development of these connections with increasingly higher capacities and influences on these capacities due to various factors. This paper provides a comprehensive review on the factors affecting the connection capacity along with technical challenges for the future. Critical aspects and shortcomings of the current connection systems and potential solutions may be sought after for these issues are also discussed.
Current trend suggests that global energy consumption will increase in the future. This growing energy demand and advancement of technology lead to explore all potential offshore fossil and non-fossil energy sources, necessitating erection of exploration and production structures, rigs, platforms and towers, which are susceptible to adverse environmental conditions along with their maintenances. Cylindrical grouted joints provide suitable connections between steel substructure and foundation in these offshore platforms and wind structures especially monopiles for ease of installation. However, these are composite connections with exterior sleeve, interior pile and infill grout. The capacity of these connections is affected by number of factors. The literature over last four decades by numerous researchers has shown the development of these connections with increasingly higher capacities and influences on these capacities due to various factors. This paper provides a comprehensive review on the factors affecting the connection capacity along with technical challenges for the future. Critical aspects and shortcomings of the current connection systems and potential solutions may be sought after for these issues are also discussed.