Hurricane Design in the Standards

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1 Hurricane Design in the Standards IEC Hurricane Classes and API Hazard Curves Rudy Hall Keystone Engineering Inc.

2 Codes and Standards Hierarchy Extra-Tropical Storm Regions IEC IEC ISO Wind Turbines- Part 1: Design Requirements Wind Turbines- Part 3: Design Requirements for Offshore Wind Turbines

3 Unique Site Conditions in US Waters Gulf and Atlantic Coasts Exposed to Tropical Cyclones Hurricane Katrina 2005 Central Gulf of Mexico 400 Year Return Conditions Hurricane Sandy 2012 New Jersey Coast <100 Year Return Conditions

AWEA Codes and Standards Hierarchy The Order of Document Priority US OCS and US State Waters IEC 61400-1 Wind Turbine Class S for Sites Exposes to

4 AWEA Codes and Standards Hierarchy The Order of Document Priority US OCS and US State Waters IEC Wind Turbine Class S for Sites Exposes to Severe Tropical Cyclones Potentially Exceed Extreme Conditions Class 1A AWEA OCRP IEC ISO API RP2A ROADMAP LOADS RESISTANCE US UNIQUE

Recent Proposal IEC 61400-1 Add Class T to cover significant

5 Recent Proposal IEC Add Class T to cover significant percentage of sites in China, Japan, Korea, Taiwan, US and other Regions

6 Recent Proposal IEC Annex I (Applies to Support Structures Only) Suggest Robustness Level Criteria to Verify Structural Integrity of the Substructure and Foundation Similar to API Design situation DLC Wind condition Waves Wind and wave directionalit y Sea currents Water level Other conditions Type of analysi s Partial safety factors on loads and strength 6) Parked (standing still or idling) 6.1 EWM Turbulent wind model Vhub = k1 V10min, EWM Turbulent wind model Vhub = k1 V10min,75 ESS Hs = k2 Hs500 ESS Hs = k2 Hs75 MIS, MUL ECM EWLR U 1.0* MIS, MUL ECM EWLR Loss of electrical network U 1.0* DLC 6.2 requires 75 year Return Period which assumes a Conditional Reliability of the Yaw System with Backup Power of 85% for 48 hours during persistence of Extreme Conditions

7 Unique Site Conditions North & Mid Atlantic Atlantic OCS Wind Energy Areas Hurricane Hazard NA Nantucket Sound RI Block Island NJ Atlantic City VA VOWTAP

8 Hurricane Hazard Atlantic Coast - Historic Hurricane Tracks

9 Hurricane Hazard US Gulf & Atlantic Coast - Historic Hurricane Strikes

RP 2A MET ISO 19902 RP 2A EQ RP 2A GEO RP

10 What is the History of US Platform Design? RP 2A 22 nd Ed. RP 2A MET ISO RP 2A EQ RP 2A GEO RP 2A SIM RP 2A LRFD From Presentation to API Sub Committee 2

11 Hazard (Probability ) - Exceeding Design Conditions DESIGN CONDITIONS ARE LIKELY TO BE EXCEEDED DURING SERVICE LIFE. RESERVE STRENGTH IS IMPORTANT!

12 API RP 2A (22 nd Ed) Exposure Category Matrix Consequence Category Life Safety Category C 1, High Consequence C 2, Medium Consequence C 3, Low Consequence S 1 manned nonevacuated L 1a L 1a L 1a S 2 manned evacuated L 1 L 2 L 2 S 3 unmanned L 1 L 2 L 3 a Manned nonevacuated platforms are presently not applicable to the U.S. GoM waters where platforms are normally evacuated ahead of hurricane events. The metocean design criteria in Section 5 have not been verified as adequate for manned nonevacuated in the U.S. GoM. However, the winter storm, sudden hurricane and earthquake criteria for the U.S. GoM have been verified as adequate for the manned nonevacuated situation occurring during those events when platforms in the U.S. GoM waters are not normally evacuated. RECOMMENDED BY AWEA OCRP FOR OFFSHORE WIND SUPPORT STRUCTURES

13 Latest API Requirements Hurricane Hazard L1 Structures L2 Structures Coastal Regions Structure Types Deck Clearance 1000 Year Return Robustness Check 500 Year Return Robustness Check Site Specific Conditions - API 2MET Robust and Non-Robust 1000 Year Return Crest Elevation

14 API Design Level & Robustness Criteria Exposure Category L 1a Design Level Criteria Use the 100 year full population and associated conditions from API 2MET or site specific data developed in accordance with API 2MET Robustness Level Ultimate Strength Analysis Use the 1,000 year full population wave and associated conditions from API 2MET or sitespecific data developed in accordance with API 2MET L 2 Use the 50 year full population and associated conditions from API 2MET or site specific data developed in accordance with AP 2MET Not required if L 2 exposure category platform has a robust configuration For non robust configurations Use the 500 year full population wave and associated conditions from API 2MET or site specific data developed in accordance with API 2MET L 3 Use the 25 year full population and associated conditions from API 2MET or site specific data developed in accordance with API 2MET Not required

15 What is Robustness? Robustness is Reserve Strength. Reserve Strength Ratio (RSR) RSR = Ultimate Structure Resistance Design Load

16 Design (LRFD) & Robustness Check LRFD DESIGN FORMAT MEAN SAFETY MARGIN NOMINAL SAFETY MARGIN = Ƴ/ф Ƴ = PARTIAL LOAD FACTOR (IEC) RANDOM LOAD ф = RESISTANCE FACTOR (ISO) LOAD BIAS NOMINAL SAFETY MARGIN RESISTANCE BIAS UNCERTAIN RESISTANCE COV L COV R NOTIONAL PROBILITY OF FAILURE MEAN LOAD NOMINAL LOAD (DESIGN LOAD) MEAN RESISTANCE NOMINAL RESISTANCE (ULTIMATE STRUCTURE RESISTANCE) ILLUSTRATION OF MEANS, BIASES AND SAFETY MARGINS OF LOAD AND RESISTANCE

17 Hazard (Probability ) Design Conditions Exceeded ROBUSTNESS CHECK CONDITIONS ARE MUCH LESS LIKELY TO BE EXCEEDED DURING SERVICE LIVE.

18 Support Structures have Unique Characteristics:

19 Will the Robustness Check control the Design? Yes - for some Regions because the Hazard can be different! RSR 3.0 Region B Hazard Curve Design Capacity (IEC/ISO FACTORS) Region A Hazard Curve Jacket (50% Gravity Load) Monopile Typical L-2 Jacket Support Structure RSR Design Point 1.0 Region B Robustness Check - Controls ,000 Load Return Period (Years) From Presentation to API Sub Committee 2 Region A Robustness Check - Satisfied

20 Hazard Curves Atlantic WEAs L-1 Structure

21 Hazard Curves Atlantic WEAs L-2 Structure

22 Potential Design Controlling ULS DLCs Substructure & Foundation DLC 1.6 Power Production (Normal) DLC 6.1 Parked (Normal) DLC 6.2 Parked (Abnormal) DLC 6.1 Parked (Robust) DLC 6.2 Parked (Robust)

23 THANK YOU

RECOMMENDED PRACTICE FOR SITE SPECIFIC ASSESSMENT OF MOBILE JACK-UP UNITS

RECOMMENDED PRACTICE FOR SITE SPECIFIC ASSESSMENT OF MOBILE JACK-UP UNITS GULF OF MEXICO ANNEX Revision 0 September 2007 Rev Issue Date Details 0 September 2007 Submitted to SNAME OC7 for Adoption Introduction: