Design of Dynamic High Voltage Cables for Floating Substation

2020 ◽  
Author(s):  
Lucie Guignier ◽  
Riccardo Mariani ◽  
Arthur Cottet-Emard ◽  
Stéphane Toumit ◽  
Thomas Choisnet
Keyword(s):  
Fatigue Limit ◽  
Limit State ◽  
Time Domain Analysis ◽  
Fatigue Properties ◽  
Design Verification ◽  
Coupled Models ◽  
Limit State Design ◽  
Pacific Coast Of Japan ◽  
And Performance ◽  
Fatigue Limit State

Abstract This paper presents the design and performance assessment of 220kV dynamic export cables for a floating substation characterized by a ring-shaped floater known as Damping Pool. The main originality of the design presented is that the cables considered have dry conductors. They are shielded from the water by a longitudinally welded corrugated copper sheath. Similar cables have been operating at lower voltage levels and thus with thinner insulation thicknesses. The export cable configuration has been designed considering environmental conditions representative of both the Central North Sea, Pacific Coast of Japan or the US, in 100m water depth. Ultimate and fatigue limit-state design verification of the configuration are made through nonlinear time-domain analysis using coupled models comprising the floating substation hull, the mooring system and dynamic export cables. Fatigue limit-state design verification is based on the fatigue properties of the cable section, combined with appropriate S-N curves of the armour layers and metallic screen-sheath. Design verifications show that the dynamic export cable configuration proposed could satisfactorily meet the performance requirements for a service life over 25 years, considering proven cable equipment such as a bend stiffener remaining within today’s manufacturer molding capacities.

Fatigue Limit-State Design

2009 ◽  
pp. 217-256
Author(s):  
Jeom Kee Paik ◽  
Anil Kumar Thayamballi
Keyword(s):  
Fatigue Limit ◽  
Limit State ◽  
Limit State Design ◽  
Fatigue Limit State

Fatigue limit state design of fast boats

2017 ◽  
Vol 55 ◽  
pp. 17-36 ◽  
Author(s):  
Or Neuberg ◽  
Nitai Drimer
Keyword(s):  
Fatigue Limit ◽  
Limit State ◽  
Limit State Design ◽  
Fatigue Limit State

Applications of Probabilistic Fracture Mechanics to Offshore Structures

1988 ◽  
Vol 41 (2) ◽  
pp. 61-84 ◽  
Author(s):  
Finn Kirkemo
Keyword(s):  
Fracture Mechanics ◽  
Model Updating ◽  
Fatigue Cracks ◽  
Limit State ◽  
Steel Structures ◽  
Local Stress ◽  
Offshore Structures ◽  
And Performance ◽  
Fatigue Limit State ◽  
Life Predictions

For offshore structures the fatigue limit state is governing the structural dimensions of several members and joint connections. Safety against fatigue failure is achieved through a combination of design requirements and performance of in-service inspections with repair of detected fatigue cracks. A review of uncertainties involved in fatigue life predictions by fracture mechanics is presented with particular reference to steel structures. Sources of uncertainties considered are: environmental conditions, hydrodynamic loading, global structural analysis, local stress calculation at fatigue sensitive points, and fatigue crack growth modeling by fracture mechanics. A probabilistic model using the fracture mechanics in probabilistic form is presented. This model accounts for uncertainties in loading, initial and critical defect sizes, material parameters, and in the uncertainty related to computation of the stress intensity factor. Failure probabilities are computed by first-order reliability methods and sensitivity factors are determined. Model updating based on in-service inspection results is formulated. Uncertainties with respect to detecting a crack and to correctly sizing a crack are included. Experience on application of the analysis method is presented.

Preliminary Design of Bottom-Fixed Lattice Offshore Wind Turbine Towers in the Fatigue Limit State by the Frequency Domain Method

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Haiyan Long ◽  
Geir Moe
Keyword(s):  
Frequency Domain ◽  
Fatigue Limit ◽  
Limit State ◽  
Offshore Wind ◽  
Design Stage ◽  
Frequency Domain Method ◽  
Preliminary Design ◽  
Early Design Stage ◽  
Lattice Towers ◽  
Fatigue Limit State

The fatigue assessment of support structures is one of the most significant challenges in the design of offshore wind turbines (OWT). Fatigue analysis can be conducted in either the time-domain or the frequency-domain. The advantage of frequency-domain analysis is its time efficiency. This paper shows how the frequency domain method can be used to dimension lattice-type OWT towers such that they meet the fatigue criteria in the preliminary design stage. Two types of lattice towers, a three-legged and four-legged version, were redesigned in the fatigue limit state for the NREL 5 MW baseline wind turbine sited at a water depth of 35 m. The wall thickness of the members was chosen as the only variable and varied during the design process until the towers could survive for at least 20 years. In comparison with designs based upon ultimate strength, the mass of both types of towers increased no more than 30% when the fatigue limit state was considered. It is concluded that the lattice type structure requires only half as much material as its tubular counterpart. The three-legged tower is promising because of its simple geometry, even though it displayed a lower torsional stiffness than the four-legged tower. All the analyses in this paper were performed by an in-house FE code, intended for the early design stage of lattice towers. Once the optimum configuration is found in the early design stage, integrated time-domain analyses for the entire OWT system might be required to refine the design, taking all the nonlinear parameters into account.

Fatigue Evaluation of Steel and Concrete Bridges

2000 ◽  
Vol 1696 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Maria M. Szerszen ◽  
Andrzej S. Nowak
Keyword(s):  
Fatigue Limit ◽  
Concrete Beams ◽  
Limit State ◽  
Concrete Bridges ◽  
Reinforced Concrete Beams ◽  
State Function ◽  
Bridge Superstructure ◽  
Degradation Of Materials ◽  
Fatigue Evaluation ◽  
Fatigue Limit State

The fatigue limit state is one of the important considerations in the design of bridges. Accumulated load cycles can cause cracking or even failure. An approach to evaluation of steel and concrete bridges with regard to fatigue is presented. The method for prediction of the remaining life of a bridge superstructure is based on the load model and the procedure to estimate fatigue degradation of materials. In the case of steel girders, degradation of material is considered using S-N curves. For reinforced concrete beams, degradation of concrete in the compressive zone is described by the rheological fatigue model. Reliability analysis is performed for the fatigue limit state function of flexure. Prediction of the remaining fatigue life for steel and concrete beams is illustrated on examples of existing bridge girders.

Evaluation of methods for calculating reinforced concrete structural members for the fatigue limit state

2020 ◽  
pp. 148-159
Author(s):  
Ravil Sharipov ◽  
◽  
Sergey Zenin ◽  
Sergey Krylov ◽  
Yuri Volkov ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Fatigue Limit ◽  
Limit State ◽  
Structural Members ◽  
Fatigue Limit State ◽  
Evaluation Of Methods

В нормах по проектированию железобетонных конструкций зданий и сооружений (начиная с 1962 г. и по настоящее время) содержится методика расчета на выносливость, которая была составлена с учетом обобщения и анализа данных многочисленных экспериментально-теоретических исследований. Последующее использование данной методики в практике проектирования железобетонных конструкций показало, что при эксплуатации конструкций, рассчитанных с учетом требований по выносливости, разрушений не происходило. Вместе с тем, анализ показал отличие отечественной методики от подходов иностранных норм в части расчета по растянутой арматуре. Дальнейшие исследования показали некоторые неcовершенства нормативной методики расчета по растянутой арматуре (как ненапрягаемой, так и предварительно напряженной). С учетом данных проведенных расчет-но-теоретических исследований, а также в целях гармонизации с основными положениями расчета на усталость, принятого в нормах проектирования ряда ведущих стран, представляется полезным в расчете на усталость по растянутой арматуре наряду с максимальным напряжением в пределах цикла нагрузки учитывать и предельную амплитуду напряжений. В этой связи предполагается проведение актуализации существующей методики расчета на выносливость, которая будет дополнена новыми положениями расчета по растянутой арматуре. При актуализации методики наиболее правильным будет максимально учесть другие положения существующей методики. В частности, будет сохранен прежний подход к определению действующих напряжений в бетоне и арматуре, а также расчет на усталость по сжатому бетону.

Sign in / Sign up

Export Citation Format

Share Document