Final report for WP4.3: Enhancement of design methods ... - Upwind
Final report for WP4.3: Enhancement of design methods ... - Upwind
Final report for WP4.3: Enhancement of design methods ... - Upwind
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
UPWIND WP4: Offshore Support Structures and Foundations<br />
SLS<br />
ALS<br />
Parked / standstill due to availability reasons DLC 6.4, 7.2<br />
Hydrodynamic stability all DLCs<br />
Motions all DLCs<br />
Floatability all DLCs<br />
Leakage, water on deck, openings<br />
Limitation <strong>of</strong> the movement (blade deflection)<br />
Loss <strong>of</strong> station keeping (free drifting)<br />
Ship impact<br />
Safety Factors<br />
Table 9.2 gives a comparison <strong>of</strong> the current safety factors adopted in the existing standards GL Guidelines <strong>for</strong><br />
Offshore Wind Turbines [31] and IEC 61400-3 [69]. Table 9.3 summarises the limit states and safety factors <strong>of</strong><br />
different standards, together with the associated return periods. Table 9.4 gives assumptions <strong>for</strong> environmental<br />
conditions (return periods) associated with different <strong>design</strong> conditions.<br />
Table 9.2: Safety Factors: Guidelines GL Offshore Wind Turbines 2005 and IEC 61400-3<br />
Limit State Design Condition<br />
137<br />
GL 2005<br />
Offshore Wind Turbines<br />
Normal operation plus occurrence<br />
<strong>of</strong> fault<br />
1,10 / 1,20 1,10 / 1,35<br />
ULS Emergency stop procedures<br />
Extreme environmental con-<br />
1,20 1,35<br />
ditions (wind, wave, sea ice,<br />
temperatures)<br />
1,35 1,35<br />
Parked / standstill 1,35 1,35<br />
Parked / standstill after occurrence<br />
<strong>of</strong> fault<br />
1,10 1,10<br />
Normal operation 1,00 1,00<br />
FLS Start / Normal stop procedures<br />
1,00 1,00<br />
Parked / standstill due to<br />
availability reasons<br />
1,00 1,00<br />
SLS Elastic deflections 1,00 n/a<br />
ALS n/a n/a n/a<br />
IEC 61400-3<br />
Offshore Wind Turbines,<br />
Edition 1<br />
It should be emphasized that safety factors <strong>for</strong> floating wind turbines should be assessed based on existing<br />
experience from various <strong>of</strong>fshore standards, combined with consideration <strong>of</strong>:<br />
• Reliability level required<br />
• Uncertainties in loads, resistances and models used to calculate characteristic load effects and load<br />
bearing capacities<br />
• Computational models required / recommended <strong>for</strong> calculation <strong>of</strong> loads and load bearing capacities