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Dynamic Loading on Structures and Structural Response
Published in Suhasini Madhekar, Vasant Matsagar, Passive Vibration Control of Structures, 2022
Suhasini Madhekar, Vasant Matsagar
Wave loading is considered to be one of the most important environmental loads acting on offshore structures. The loads due to waves very often dominate and dictate the design of offshore structures and bridges located in the coastal zones. Figure 2.9 shows marine structures with mobile and fixed configurations. The type of structure depends upon the purpose and depth of water at a particular location.
The undrained behaviour of over-consolidated clay subjected to pure rotation of principal stress directions
Published in Marine Georesources & Geotechnology, 2022
Zhixuan Liang, Ying Liu, Zhiyong Liu
The subsoil of offshore structures may be subjected to various non-proportional cyclic loadings, such as wave loading, tide loading and earthquake. Under those cyclic loadings, strain and excess pore water pressure (EPWP) accumulate in soil (Xiao et al. 2014, 2017; Qian et al. 2016; Shi et al. 2018; Miura, Miura, and Toki 1986; Ishihara and Towhata 1983; Price, DeJong, and Boulanger 2017; Pan et al. 2019, 2020). Large soil deformation would introduce great settlement and/or differential settlement and threaten the safety and serviceability of geotechnical structures. To reduce the deformation of soil, surcharge preloading is widely used to improve the deformation resistance of soft clay. After applying surcharge, the soil is over consolidated and its deformation behaviour is different from normally consolidated soil (Liu and Xue 2022; Shi et al. 2018; Zapata-Medina, Finno, and Vega-Posada 2014; Atkinson, Richardson, and Stallebrass 1990; Santagata and Germaine 2005). Understanding the undrained deformation of over-consolidated clay subjected to non-proportional cyclic loadings is critical to analyzing the safety and serviceability of geotechnical structures.
A review on the behavior of helical piles as a potential offshore foundation system
Published in Marine Georesources & Geotechnology, 2020
Giovanni Spagnoli, Cristina de Hollanda Cavalcanti Tsuha
The four above-mentioned aspects are important in general but particularly for offshore applications, because, loads in offshore environments are high (e.g. from 6 MN for a wind turbine with a capacity of 3.5 MW to up to 40MN for oil & gas fixed platforms, Byrne and Houlsby 2003; Kraft and Lyons 1974; De Mello, Beim, and Coelho 1983), therefore in order to achieve the necessary axial pile capacity, large embedment depths are required (see Young and Sullivan 1978). However, large embedment depths mean higher torque installation values, which are in turn affected by pile geometry and soil properties (e.g. Spagnoli, de Hollanda Cavalcanti Tsuha, et al. 2018; Spagnoli et al. 2019). For offshore wind turbines, the wave loading forces acting on the structure are greater than the wind loading. However, in terms of the overturning bending moments generated, the wave loading generally has only a minor role, compared with the rotor–thrust reaction to the wind loads (e.g. O’Kelly and Arshad 2016).