Seismic Resistant Repair and Reconstruction - Critical Issues

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1 Government of China the World Bank Group Earthquake Government Recovery and Reconstruction: of China & International the World Experience Bank and Group Best Practice Seismic Resistant Repair and Reconstruction - Critical Issues Charles Scawthorn, S.E., D.Eng Professor, Kyoto University 1 Scawthorn

2 Who What What Where siting issues Where When When Why Why Critical Issues How to rebuild - maps, materials, codes How 2 Scawthorn

3 Siting Issues Faulting Landslide Faults not the biggest issue Liquefaction Undamaged Buildings next to fault, M7.4 Turkey, 1999 Landslide / Liquefaction limits sites for rebuilding adds time and cost Adapazari, heavily damaged by Liquefaction, M7.4 Turkey Scawthorn

4 Reconstruction? URM / PreCast Collapse Photos: K. Miyamoto 4 Scawthorn

5 Seismicity of China 2300 BC present, M>5 5 Scawthorn

6 China Seismicity Record, by Era and Magnitude 75% recorded since 1900 M > 7 6 Scawthorn

7 2001 National Seismic Zoning map of China Government of China & the World Bank Group Substantial uncertainty in in zoning map Wenchuan zoning needs to to be be increased (a (a lot) PGA, 10% probability of exceedance in 50 years (Units are in g) 7 Scawthorn

8 Earthquake Performance Chinese Building Code philosophy like US, Japanese European codes: 1. Minor earthquake: no damage 2. Design level earthquake: damage but no loss of life 3. Strongest earthquake expected at the site without total collapse, but potentially with extreme damage Codes protect life, not damage Damage accepted in the design, to dissipate energy With Vision 2000, codes shifting to Performance Basis 8 Scawthorn

9 China Building Code Earthquake Design <1957 Soviet code, but not much used 1974 TJ Revised (Tangshan earthquake) TJ Seismic Design Code for Buildings. GBJ Tall Bldgs: Regulation on the Design and Construction of Tall Reinforced Concrete Buildings JGJ National Standards of the People's Republic of China, Code for Seismic Design of Buildings (GB ) 2008 Current code? Zonation? Compliance? (Shuping 1993) 9 Scawthorn

10 Engineered Building Reconstruction PreCast combined with URM NON-Ductile Reinforced Concrete Photos: K. Miyamoto 10 Scawthorn

11 DUCTILE NON-ductile 11 Scawthorn

12 Engineered Building Reconstruction Assuming modern standards are to be met, many damaged buildings are going to be uneconomical to repair. Photo: XIAO Yan Non-Ductile detailing, 2008 Wenchuan Earthquake 12 Scawthorn

13 Schools California Government of China & the World Bank Group 1933 Earthquake Field Act schools special design review last 75 years, no school collapse or loss of life. State-wide review in % vulnerable: Assumed OK 13 Scawthorn

14 Seismic Rehabilitation Costs Seismic Rehabilitation cost approximately $620,000 // building (C 780,000 // building based on on PPP ratio) Retrofitted school Niigata, Japan 14 Scawthorn

15 Non-Engineered Buildings Earth or stone rubble walls, Earth roof Brick (or stone) walls RCC roof Brick RCC Frame, walls, Tin roof Roof Figs. C. Scawtorn, Scawthorn

16 Earth or stone rubble walls, Earth roof Brick (or stone) walls RCC roof Figs. C. Scawtorn, 2004 Brick RCC walls, Frame Tin roof 16 Scawthorn

17 Confined Masonry Technology 17 Scawthorn

18 Non-engineered Buildings Non-engineered buildings will be built back the same unless: Owners are educated Builders and Craftsman are trained Achieve Code compliance by institutions for Code enforcement 18 Scawthorn

19 Non-engineered Buildings Improving Quality World Bank sponsored project 19 Scawthorn

20 Government of China & the World Bank Group All China Due to underzoning parts of China many high risk buildings / infrastructure. Need: Major program to: New seismic zonation Identify hazardous buildings Long-term retrofitting program 20 Scawthorn

21 Summary IF we re not to rebuild the next disaster that is, if we seek to meet modern standards, then: Siting in the steep terrain areas is going to be a major, time consuming problem, requiring detailed geotechnical investigations Repair: many damaged buildings will be found to be uneconomical to reconstruct the losses will be higher than currently estimated. Reconstruction: Engineered structures will be rebuilt at a significantly higher standard than what they replaced. This will add 5-30% to cost Document engineering and scientific lessons to be learned Non-engineered structures, especially rural housing, will need special education, training and advisory programs (such as in Pakistan) Longer-Term: a National Earthquake (Natural Hazards!) Mitigation Program needs to be developed, to address Earthquake, Flood, Typhoon 21 Scawthorn

22 Thank you Charles Scawthorn 22 Scawthorn