PRACTICAL APPLICATION OF SEISMIC RISK EVALUATION FOR BUILDINGS

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Elwin Ford
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1 Session: Engineering for Natural Disaster Resiliency, Understanding Natural Hazards and Predicting Associated Risk, 2012 JAFOE, 28 Oct. PRACTICAL APPLICATION OF SEISMIC RISK EVALUATION FOR BUILDINGS Yuko Murachi Swiss Re International SE, Japan Branch

2 Contents 1. Damage of The 3.11Tohoku Earthquake at a Glance Seismic Wave Physical Damage Financial Damage Lessons from 3.11 Earthquake 2. Why "Seismic Risk Evaluation" is important? 3. Evaluation Methodology 4. Practical Application for Governmental Buildings p2

3 1. Damage of The 3.11 Tohoku Earthquake at a Glance - What was new features of Seismic Wave Pre-event: Long-term evaluation of occurrence probability At 3.11 Earthquake: Seismic sources Ground Motion: Comparison in Tohoku and Kanto Tsukidate (JMA 7):PGA 2933gal NS EW UD Shinjuku (JMA 5-) 200s Source : The Headquarters for Earthquake Research Promotion, National Research Institute for Earth Science and Disaster Prevention 2011 p3 600s

4 1. Damage of The 3.11 Tohoku Earthquake at a Glance - Physical Impact and Financial Impact Physical Impact Tohoku People House Building Fire Dead Disappeared Injured Collapse Half Collapse Partially Destroyed Public Building Others 16,278 2,994 6, , , ,192 35,465 17, Financial Impact of 3,543 listed companies as of 31 March 2012 Range of Extraordinary Loss Due to Disaster (JPY billion) # of Company % for total # of company Accumulated Loss (JPY million) % for total amount of loss 50 or more % 527, % 10 or more and less than % 457, % 5 or more and less than % 230, % 3 or more and less than % 153, % 2 or more and less than % 106, % 1 or more and less than % 137, % less than 1 1, % 188, % Total 1,354 1,800,819 Source : Tokyo Shoko Research p4

Osaka Prefecture Super high scraper 55 stories, 256m in height

770km Seismic intensity at ground surface was observed 3 (JMA) Damage

5 1. Damage of The 3.11 Tohoku Earthquake at a Glance - Seismic Wave (2) Public Building of Osaka Prefecture Super high scraper 55 stories, 256m in height Distance from hypocenter is approx. 770km Seismic intensity at ground surface was observed 3 (JMA) Damage due to long-period ground motion Trapped in stopped elevator Damage of some fireproof doors Falling or cracked ceiling panels (more than 100 panels) 52F 38F 18F 1F p5

1. Damage of The 3.11 Tohoku Earthquake at a Glance - Lessons from 3.

is recognized that ground motion wasn't increased proportionally in magnitude.

- Unpredicted Tsunami height, e.g. observed Tsunami height at Tokyo Bay was T.P. + 1.

- Damage due to ground liquefaction. (Especially in reclaimed area within 50 years.

6 1. Damage of The 3.11 Tohoku Earthquake at a Glance - Lessons from 3.11 Earthquake (1) - The first time to observe the M9 class earthquake around Japan, and it is recognized that ground motion wasn't increased proportionally in magnitude. - Effect of baseisolated buildings. Damage in room is extremely reduced. - Unpredicted Tsunami height, e.g. observed Tsunami height at Tokyo Bay was T.P m compared with pre-event evaluated height which is up to +1.0m. - Damage due to ground liquefaction. (Especially in reclaimed area within 50 years.) - Damage in room due to long-period ground motion. - Lifeline outage spread in huge area, and significantly influenced on the business continuity of companies. Source : Si (2011) p6

7 1. Damage of The 3.11 Tohoku Earthquake at a Glance - Lessons from 3.11 Earthquake (2) People and Japanese Companies start to think that disaster mitigation countermeasures based on public information might not be enough For instance, Lots of people were extremely frightened because buildings were shaken widely. Is our office building is still healthy/secured even if the next big earthquake happened under the Great Tokyo area? Give me specific information, not talking about general building based on structural design standard. A Building owner of our office always says "This building is designed based on old structural designed code (enforced before 1981), however result of seismic diagnosis indicates this building has adequate seismic capacity equivalent to buildings designed by new code. What dose it mean "adequate"? It may be for evacuating people. We want know effects on business continuity in more detail. Governmental building should be a key station in a time of disaster, however budgets is not unlimited. Benefit-cost analysis is necessary for possible alternatives. p7

2. Why "Seismic Risk Evaluation" is important?

Important Facilities 1. Seismic capacity of building itself, 2.

Is amplification of surface ground relatively high?, and 4. Where and how important facilities installed?

8 2. Why "Seismic Risk Evaluation" is important? When think about "Seismic Risk" from the view points of business continuity, it varies by many parameters, such as; Important Facilities 1. Seismic capacity of building itself, 2. Is it located near active faults, and is occurrence probability of the fault high?, 3. Is amplification of surface ground relatively high?, and 4. Where and how important facilities installed? Namely, it is important that we need to know potential risk before thinking about countermeasures to mitigate/translate/avoid the risk. Avoid (Alternative) Current condition Risk Evaluation Shift (Insurance) Gap Mitigate (retrofitting etc.) Objectives Business Impact Analysis p8

Deterministic Approach Based on individual scenarios etc. Ex.

Index/result of evaluation PML Probable Maximum Loss Direct Damage (Physical /

9 3. Evaluation Methodology Ex. of methodology Probabilistic Approach Monte Carlo Simulation Hazard Curve etc. Deterministic Approach Based on individual scenarios etc. Ex. of application Real Estate Securitization Damage Prediction of Governments Index/result of evaluation PML Probable Maximum Loss Direct Damage (Physical / Human Suffering) Indirect Damage (Economical) Problem to use for organizations Hard to image countermeasures practically Unexpected Scenarios Contain Engineering Judgments p9

10 3. Evaluation Methodology (cont.) Seismic Risks are evaluated utilizing simulation technologies on each specific fields. Probability Statistics Ground surface Socioeconomics Safety of people Structural Engin. Active faults Earthquake Engin. Geotechnique p10

4. Practical Application for Governmental Buildings - Evaluation Process GL Target

Create building model -Current Condition -After retrofitted -Rebuild 7.

Expected damage accumulated during its use Surface Layer Amplified due to surface layer

Attenuation Property of each source Magnitude Location Occurrence probability 2.

11 4. Practical Application for Governmental Buildings - Evaluation Process GL Target buildings Seismic Intensity (JMA) 4. Cost setting 3. Create building model -Current Condition -After retrofitted -Rebuild 7. Benefit-cost analysis 5. Expected damage under scenario EQ 6. Expected damage accumulated during its use Surface Layer Amplified due to surface layer 1.Soil Conditions Bed Rock Seismic Basement Active Faults or Focal Areas Distance Attenuation Property of each source Magnitude Location Occurrence probability 2. Seismic risk evaluation of target site *This practical application had conducted by KOZO KEIKAKU Engineering Inc. as a consulting service requested by Yotsukaido City in Chiba Prefecture. p11

12 4. Practical Application for Governmental Buildings - Target Buildings 2 nd Building (2stories) Fire Station (3stories) Main Building (3stories) Other site Gallery Main Building (1story) Annex (5stories) Branch p12

Amplification Factor due to Surface layer 4. Practical Application for Governmental Buildings - 1. Soil Conditions 4.0 3.

13 Amplification Factor due to Surface layer 4. Practical Application for Governmental Buildings - 1. Soil Conditions Amplification Factor of Acceleration spectrum Natural Period (1 st ) of Buildings (Average) Period (sec) 100gal( 平均 ) 100gal(-σ) 100gal(+σ) (Average) 200gal( 平均 ) 200gal(-σ) 200gal(+σ) (Average) 300gal( 平均 ) 300gal(-σ) 300gal(+σ) p13

4. Practical Application for Governmental Buildings - 2.

6- JMA 6+ JMA 7 likelihood Return Period 30yrs 64% 100yrs 26% 500yrs 6% 1000 yrs 3000

people are considerably frightened and find it difficult to move.

96%) EQ along Philippine Sea Plate Miura Peninsula Fault Zone (Main Part)

Off-Sanriku to Off-Bousou 1% Kanto-Heiya Hokuseien Fault Zone (Main Part) Difficult to

14 4. Practical Application for Governmental Buildings - 2. Seismic Risk Evaluation of Target Site Seismic Intensity at the Site JMA 5- JMA 5+ JMA 6- JMA 6+ JMA 7 likelihood Return Period 30yrs 64% 100yrs 26% 500yrs 6% 1000 yrs 3000 yrs Occurrence Probability In the next 30yrs 3% Most people try to escape from a danger. Some people find it difficult to move. Tokai EQ EQ along Pacific Plate EQ along Philippine Sea Plate South Kanto EQ Many people are considerably frightened and find it difficult to move. South Kanto EQ EQ along Pacific Plate EQ along Nankai Trough(5.1/9.96%) EQ along Philippine Sea Plate Miura Peninsula Fault Zone (Main Part) Kinugasa/Kitatake Fault Zone Near-field EQ Near-filed EQ Tachikawa fault zone EQ along Off-Sanriku to Off-Bousou 1% Kanto-Heiya Hokuseien Fault Zone (Main Part) Difficult to keep standing. Most Urgent Scenario South Kanto EQ Great Kanto EQ Near-filed EQ Impossible to keep standing and to move without crawling. Near-filed (6.0/0.005%) Thrown by the shaking and impossible to move at will. Max. Exposure p14

Share Force (ton) Share Force (ton) Share

Simulation Model Simulation Model Building

capacity by push-over analysis p15 Lateral

square meter JPY 204,000~249,000 Cost per

15 Share Force (ton) Share Force (ton) Share Force (ton) 4. Practical Application for Governmental Buildings - 3. Create Building Models + 4. Cost Setting Current Condition After Retrofitted Rebuilt Simulation Model Simulation Model Simulation Model Building capacity by push-over analysis Building capacity by push-over analysis Building capacity by push-over analysis p15 Lateral Displacement (cm) Lateral Displacement (cm) Lateral Displacement (cm) Cost per square meter JPY 197,000~242,000 Cost per square meter JPY 204,000~249,000 Cost per square meter JPY 315,000 (*considering seismic design grade)

16 4. Practical Application for Governmental Buildings - 5. Expected damage under scenario EQ Near-filed EQ (JMA 6+) Repurchase Cost (JPY kilo) Probability of damage suffering major or more RED:75% or more ORANGE:50% or more YELLOW:25% or more Expected cost(jpy) RED:0.3bn or more ORANGE:0.2bn or more YELLOW:0.1bn or more Recovery time (Operational) RED:1yr or more ORANGE:6 mo. or more YELLOW:2 mo. or more Current Condition Main Building (3 stories) Main Building (1 story) 479, ,500 Extremely High Extremely High % 0.48bn (100.0%) 16.0 mo. 92.0% 0.106bn (79.4%) 14.4 mo. Annex 765,330 High 63.6% 0.39bn (51.8%) 12.1 mo. 2 nd building 199,620 Low 3.6% 0.017bn (8.3%) 2.4 mo. Fire Station 193,270 Medium 35.2% 0.051bn (26.4%) 6.7 mo. After Retrofitted Main Building (3 stories) 773,400 Low 21.3% 0.195bn (25.2%) 6.4 mo. Annex 970,750 Medium 37.8% 0.260bn (26.8%) 6.8 mo. Rebuilt Main Building 2,205,000 Low 12.3% 0.124bn (5.6%) 1.5 mo. Fire Station 218,420 Medium 25.2% 0.026bn (11.7%) 3.4 mo. p16

17 4. Practical Application for Governmental Buildings - 6. Expected damage accumulated during its use Probability of damage suffering major or more during 20~60yrs With in the next 20 yrs (by 2032) With in the next 40 yrs (by 2052) With in the next 60 yrs (by 2072) Current Condition Main Building (3 stories) Main Building (1 story) 0.59times 1.10times 1.56times 0.69times 1.32times 1.86times Annex 0.01times 0.02times 0.04times 2 nd building Nil Nil Fire Station 0.01times 0.01times After Retrofitted Main Building (3 stories) Nil Nil Nil Annex 0.01times 0.01times Rebuilt Main Building Fire Station Nil Nil 0.01times p17

18 4. Practical Application for Governmental Buildings - 7. Benefit-cost analysis (1) # Pattern for benefit-cost analysis Name of Plan Remarks *according to the evaluation results 0 Continue to use current buildings --- Basis model 1 Rebuilt main building (3stories only) A Not realistic * 2 Rebuilt main building (both of 3stories and 1story) B 3 Rebuilt main building (both of 3stories and 1story) and branch C Need to retrofit annex too * 4 Rebuilt main building and 2 nd building D-1 Not realistic * 5 Rebuilt main building (both of 3stories and 1story) and second building D-2 6 Rebuilt main building (both of 3stories and 1story), branch and second building D-3 Need to retrofit annex too * 7 Rebuilt main building (both of 3stories and 1story), branch, second building and fire station D-3 + fire station p18

19 Life-cycle costs including maintenance/operation costs and costs due to EQ damage (JPY mn) 4. Practical Application for Governmental Buildings - 7. Benefit-cost analysis (2) 9,000 8,000 7,000 6,000 5,000 No. 0 (1.19bn) No. 2 (0.44bn) No. 3 (0.44bn) No. 5 (0.45bn) No. 6 (0.45bn) No. 7 (0.43bn) 1: 現状 21: 本館平屋改築新館庁舎補強案 23: 本館平屋第二庁舎改築新館庁舎補強案 25: 本館平屋分館改築新館庁舎補強案 27: 本館平屋分館第二庁舎改築新館庁舎補強案 28: 本館平屋分館第二庁舎改築新館庁舎補強消防改築案 * () shows expected costs due to EQ damage with in the next 60yrs. unit: JPY No. 2 (rebuilt main buildings and annex) is the plan which marks the highest benefit-cost, except No.0. 4,000 3,000 2,000 No. 0 (continue to use current buildings) cannot say a realistic if consider expected damage once earthquake happened. 1,000 p Elapsed years from 2012

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