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Offshore Wind Turbines
Published in Srinivasan Chandrasekaran, Faisal Khan, Rouzbeh Abbassi, Wave Energy Devices, 2022
Srinivasan Chandrasekaran, Faisal Khan, Rouzbeh Abbassi
The TLP is tethered to the seafloor using a taut-leg mooring system known as vertical tendons, which restrain the heave motion of the platform (Atcheson et al., 2016; Henderson and Witcher, 2010). The primary benefit of the TLP is that the substructure is smaller and lighter than other types of floating platforms, resulting in cheaper material costs. Its ability to be commissioned at the deeper water depth depends on the seabed state and geology. A TLP-supported wind turbine has a relatively less dynamic response to wave excitation than other floating structures, such as barges, SPARs, and semi-submersibles. TLPs possess desirable heave and pitch/roll motion but have an expensive and complex mooring system installation. The GICON-SOF Pilot by GICON and Blue H, a prototype TLP platform with a small wind turbine installed in a water depth of 113 m, are two experimental studies that used a TLP structure (Kolios et al., 2016; Musial et al., 2004).
Introduction
Published in Charles Aubeny, Geomechanics of Marine Anchors, 2017
A tension leg platform (TLP) consists of a semisubmersible vessel moored by vertical tendons connected to the seafloor, as illustrated in Figure 1.3. The excess buoyancy of the structure—typically on the order of 15%–25% of the platform displacement—maintains the tendons in tension even under the worst storm loading conditions. Conoco constructed the first TLP in the British sector of the North Sea in the early 1980s in approximately 150 m of water. This structure was selected for relatively shallow water as a test of the concept prior to use in deep waters. Since then, several deep water TLPs (>450 m) have been installed. The foundations for TLPs usually consist of large diameter pipe piles that provide resistance to uplift through skin friction, although suction caissons (Section 1.2.1) can be used. Loading on the foundation consists of a tensile mooring force and cyclic loading owing to wave loading on the superstructure. Loading is predominantly vertical with lateral forces estimated at less than 10% of vertical forces. A critical loading condition most likely occurs when a change in mean sea level owing to a storm surge occurs in conjunction with large wave loading. TLPs can provide a feasible platform alternative to water depths from approximately 450 to at least 1000 m.
Saipem's submerged floating tunnel concept – an industry and University cooperation to drive innovation in civil infrastructures
Published in Joan-Ramon Casas, Dan M. Frangopol, Jose Turmo, Bridge Safety, Maintenance, Management, Life-Cycle, Resilience and Sustainability, 2022
G. Chiesa, B. Faggiano, R. Landolfo, F.M. Mazzolani, L. Martinelli, M.G. Mulas, F. Perotti
The key technologies that support the SSFT Concept mainly relate to the Anchoring System, the Welding and Non-Destructive Testing Processes, as well as the Underwater Monitoring and Inspection.Tendon’s technology has been frequently adopted to moor a Tension Leg Platform (TLP) floating surface facility to seabed piled foundations (Figures 3b, c). The TLP is kept in position by a system of tendons which counteract the buoyancy upthrust of the TLP hull and allow for some horizontal displacement and rotation by means of flexible connectors located at the interface with the foundation and with the hull. Figure 3c show the application of this technology for various hull displacements.
Effects of tendon breakage on the dynamic behaviour of a TLP
Published in Ships and Offshore Structures, 2023
Haitao Wu, Zhiyang Zhang, Weixing Liu, Lin Cui
TLP is one of the main offshore structures for deepwater oil and gas development. This platform generally consists of the hull, tendons, risers, the topsides and foundation piles. It produces much more buoyancy than gravity. In addition to counteracting its own weight, the remaining buoyancy balances the pretension provided by the tendons and risers. With the increase of water depth, the environmental condition will become more severe, so the loads on the tendon increases significantly and the instability of floating system increases. Under the extreme sea conditions, the tendon may break due to overload. Meanwhile, the local structural damage caused by accumulated fatigue, corrosion defects, installation damage and accidental collision may also lead to mooring failure (Ma et al. 2013; Gordon et al. 2014; Prislin and Maroju 2017). Tendon breakage can change the performance of the floating system, which may reduce the survivability of the platform. So the tendon system should have a certain redundancy strength to deal with the negative effects of tendon failure.
Long term response analysis of TLP-type offshore wind turbine
Published in ISH Journal of Hydraulic Engineering, 2020
K. G. Vijay, D. Karmakar, C. Guedes Soares
Tension-leg-platforms gain its stability by the use of tendons at high tension having one end of tendons connected to TLP and the other to seabed. Due to the lower responses, the dynamic loading on to the structure and tower of wind turbine is greatly reduced. So, detailed long-term response analysis studies has to be carried out before venturing into construction and installation of the structures, to estimate the maximum response of the structure during its service life (Bagbanci et al. 2015). In order to quantify the influence of the transfer function uncertainty on the short-term response variance, Guedes Soares and Moan (1991) performed the uncertainty of the long-term distribution of wave-induced bending moments for fatigue design of ship structures. The influence of the directionality of waves on the loads generated on a ship, is analyzed by Guedes Soares (1995). Based on the maximum responses, the floater configuration and the associated ancillary equipment’s could be redesigned. The design optimization of different configurations of TLP is carried out in detail by Bachynski and Moan (2012). Further, the comparison of spar and semi-submersible floater concepts using long-term analysis is presented by Bagbanci et al. (2015).
The hydrodynamic performance of a tension leg platform with one-tendon failure
Published in Ships and Offshore Structures, 2019
Yinghe Qi, Xinliang Tian, Xiaoxian Guo, Haining Lu, Lei Liu
The parameters of the TLP selected for this investigation are based on a design for an actual TLP project located in the South China Sea. The TLP Hull has a square arrangement and consists of four columns connected underwater by four pontoons. Eight tendons hold the TLP in place, two tendons per TLP hull column and connected to the TLP hull near the column bottom, approximately 4.0 m above the keel. The TLP is symmetrical about x-axis and y-axis, with respect to both the TLP hull and tendons. The general arrangement of the TLP Hull is shown in Figures 2 and 3. The details and weight distribution of the TLP Hull are presented in Table 1.