TY - CONF A1 - Shamsuddoha, Md A1 - Hüsken, Götz A1 - Pirskawetz, Stephan A1 - Baeßler, Matthias A1 - Kühne, Hans-Carsten A1 - Thiele, Marc T1 - Remediation of Cracks Formed in Grouted Connections of Offshore Energy Structures under Static Loads N2 - The future energy demand necessitates the exploration of all potential energy sources both onshore and offshore. Global trend has shifted towards offshore energy, which can be obtained from either carbon intensive or renewable options, hence requiring structures such as rigs, platforms, and monopiles. Most of these structures adopt easily installable construction techniques, where lower foundation need to be connected with the super structure by mean of grouted composite joints. Generally, these composite connections have exterior sleeve, interior pile and infill grout. Being located in remote offshore conditions, connections can experience considerable adverse loading during their lifetimes. Degradations were reported inside similar connections, which were installed in last three decades. Besides, grouting in the offshore sites may often be proven difficult, which eventually leads to reduced capacity of connections in the long run. Thus, repair and rehabilitation of such connections should be planned ahead to minimize operational delays and costs in the future. This study aims at characterizing the nature of crack generation in grouted connections and thereby identifying the potential of repair using suitable repair material. Scaled grouted joints were manufactured using a novel mold, and connections were loaded under static load to visualize the main failure pattern. The failure mechanism and loading capacity are found compatible to previous results from earlier literature. Grouted connection was then repaired using cementitious injectable grout. The effectiveness of the repair system is also discussed. T2 - Twenty-eighth (2018) International Ocean and Polar Engineering Conference CY - Sapporo, Japan DA - 10.06.218 KW - Offshore KW - Energy KW - Grouted Connection KW - Cracks KW - Repair KW - Rehabilitation PY - 2018 AN - OPUS4-45226 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kühne, Hans-Carsten A1 - Shamsuddoha, Md A1 - Hüsken, Götz T1 - Instandsetzung und Verbesserung von Groutverbindungen: Potentiale-Strategien-Grenzen N2 - 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. T2 - BAM Workshop Groutverbindung in der Betriebsphase CY - Berlin, Germany DA - 22.03.2017 KW - Grout-Verbindung KW - Instandsetzung KW - Offshore-Windenergieanlagen PY - 2017 AN - OPUS4-39635 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shamsuddoha, Md A1 - Hüsken, Götz A1 - Baeßler, Matthias A1 - Kühne, Hans-Carsten A1 - Thiele, Marc T1 - Critical Factors Affecting the Capacity of Cylindrical Grouted Connections in Offshore Energy Structures N2 - 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. T2 - 36th International Conference on. Ocean, Offshore and Arctic Engineering CY - Trondheim, Norway DA - 25.06.2017 KW - Offshore wind energy KW - Grouted connection KW - Joint capacity KW - Shear keys PY - 2017 AN - OPUS4-42389 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shamsuddoha, Md A1 - Hüsken, Götz A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Baeßler, Matthias T1 - Superplasticizer and shrinkage reducing admixture dosages for microfine cement in grout systems N2 - Grouts have numerous applications including crack repair as maintenance in construction industries. Microfine cements are intensively used for high strength mortar and grout products. They are ideal for injection grouting in structural repair. Such grouts should have suitable rheological properties to be injectable, especially those used in repair and rehabilitation. The use of superplasticizers (SP) in these products is thus becoming increasingly crucial to achieve favorable workability and viscosity properties. A difficulty in such grouts is the plastic shrinkage due to finer particles used. It is thus necessary to determine optimum SP and shrinkage reducing admixture (SRA) dosages for a microfine cement based grout. In this study, a saturation dosage was decided from two Polycarboxylate ether (PCE) based SPs in relation to neat cement using slump flow and rheological parameters. A range of grout mixtures was formulated containing micro silica (MS) and fly ash (FA), and tested for suitable rheological and mechanical parameters. Based on the results, a grout mixture with MS and FA was selected to determine optimum SRA content. According to the results, a SP dosage of 3% by weight of neat cement is sufficient to achieve saturation. The grout material including MS and FA can produce comparable properties to neat cement grout. MS is found to improve compressive strength within the range considered, whereas a higher FA content provides favourable rheological properties. Finally, a SRA dosage of 4%, which could reduce the shrinkage by about 43% after 28d days, is determined for the grout system. T2 - 2nd International Conference on Building Materials and Materials Engineering (ICBMM 2018) CY - University of Lisbon, Portugal DA - 26.09.2018 KW - Grout KW - Mix design KW - Shrinkage KW - Crack repair KW - Microfine cement PY - 2018 AN - OPUS4-46155 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -