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A platform for research: civil engineering, architecture and urbanism
Fatigue behaviour of submerged axially loaded grouted connections ; Ermüdungsverhalten unter Wasser liegender axial beanspruchter Grout-Verbindungen
With conversion of the German supply system for electrical energy towards renewable resources, the demand for offshore wind farms significantly increases. For installation of wind turbines in the German North Sea, lattice substructures such as jackets are a possible design choice. These structures are usually fixed to their steel foundation piles via grouted connections, a structural detail consisting of one steel tube inserted into a second steel tube with larger diameter. The steel surfaces located inside the resulting annulus are equipped with shear keys and the annulus is filled with a grout material. The connection is located at mudline level in submerged conditions and is manufactured without sealing against water ingress. Due to the load bearing behaviour of the substructure, these grouted connections are predominantly axially loaded. All currently available design approaches for the Fatigue Limit State of grouted connections are based on experimental tests which were carried out in dry ambient conditions. However, experimental investigations on the fatigue behaviour of concrete specimens in submerged conditions show an obvious reduction of fatigue capacity caused by interactions between specimens and the surrounding water. Corresponding degradation phenomena were also observed at foundations of onshore wind turbines. Objective of this thesis is to investigate the influence of water on the fatigue behaviour of predominantly axially loaded grouted connections. In a first step, a set-up of tests on small-scale grouted connections in both, dry and wet ambient conditions, was realised. Besides the ambient condition, the influences of different grout layer thicknesses, different grout materials, the loading level as well as varied loading frequencies were investigated. In total, results from 78 small-scale specimens were evaluated. The tests showed a significant reduction of fatigue capacity caused by the interaction between connection and sur-rounding water. This effect was also influenced by the loading ...
Fatigue behaviour of submerged axially loaded grouted connections ; Ermüdungsverhalten unter Wasser liegender axial beanspruchter Grout-Verbindungen
With conversion of the German supply system for electrical energy towards renewable resources, the demand for offshore wind farms significantly increases. For installation of wind turbines in the German North Sea, lattice substructures such as jackets are a possible design choice. These structures are usually fixed to their steel foundation piles via grouted connections, a structural detail consisting of one steel tube inserted into a second steel tube with larger diameter. The steel surfaces located inside the resulting annulus are equipped with shear keys and the annulus is filled with a grout material. The connection is located at mudline level in submerged conditions and is manufactured without sealing against water ingress. Due to the load bearing behaviour of the substructure, these grouted connections are predominantly axially loaded. All currently available design approaches for the Fatigue Limit State of grouted connections are based on experimental tests which were carried out in dry ambient conditions. However, experimental investigations on the fatigue behaviour of concrete specimens in submerged conditions show an obvious reduction of fatigue capacity caused by interactions between specimens and the surrounding water. Corresponding degradation phenomena were also observed at foundations of onshore wind turbines. Objective of this thesis is to investigate the influence of water on the fatigue behaviour of predominantly axially loaded grouted connections. In a first step, a set-up of tests on small-scale grouted connections in both, dry and wet ambient conditions, was realised. Besides the ambient condition, the influences of different grout layer thicknesses, different grout materials, the loading level as well as varied loading frequencies were investigated. In total, results from 78 small-scale specimens were evaluated. The tests showed a significant reduction of fatigue capacity caused by the interaction between connection and sur-rounding water. This effect was also influenced by the loading ...
Fatigue behaviour of submerged axially loaded grouted connections ; Ermüdungsverhalten unter Wasser liegender axial beanspruchter Grout-Verbindungen
Raba, Alexander (author)
2018-01-01
Theses
Electronic Resource
English
Fatigue behaviour of axially loaded grouted connections in jacket structures
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