seismic resistant repair and reconstruction - critical...

Government of China & the World Bank GroupEarthquake Recovery and Reconstruction: International Experience and Best Practice

June 12, 2008, Beijing

Seismic Resistant Reconstruction – Critical Issues 1 Scawthorn



Seismic Resistant Repair and Reconstruction - Critical Issues

Charles Scawthorn, S.E., D.EngProfessor, Kyoto University




Critical Issues

• Who• What• Where – siting issues• When• Why• How to rebuild - maps, materials, codes

• Who• What• Where • When• Why• How




Siting Issues

• Faulting• Landslide• Liquefaction Undamaged Buildings next to fault, M7.4

Turkey, 1999

Faults not the biggest issueFaults not the biggest issue

Adapazari, heavily damaged by Liquefaction, M7.4 Turkey 1999

Landslide / Liquefaction – limits sites for rebuilding adds time and cost

Landslide / Liquefaction – limits sites for rebuilding adds time and cost




Reconstruction?URM / PreCast Collapse

Photos: K. Miyamoto




Seismicity of China 2300 BC present, M>5




China Seismicity Record, by Era and Magnitude

75% recorded since 1900M > 7

75% recorded since 1900M > 7




PGA, 10% probability of exceedance in 50 years (Units are in g)

2001 National Seismic Zoning map of China

Substantial uncertainty in zoning map

Wenchuan zoning needs to be increased (a lot)

Substantial uncertainty in zoning map

Wenchuan zoning needs to be increased (a lot)




Earthquake “Performance”Chinese Building Code philosophylike US, Japanese European codes:

1. Minor earthquake: no damage2. Design level earthquake: damage but no loss of life3. Strongest earthquake expected at the site without

total collapse, but potentially with extreme damage

Codes protect life, not damageDamage accepted in the design, to dissipate energy

With Vision 2000, codes shifting to Performance Basis




China Building Code – Earthquake Design

<1957 Soviet code, but not much used1974 TJ11-74

1978 Revised (Tangshan earthquake) TJ11-78.

1989 Seismic Design Code for Buildings. GBJ- 11-89

1991 Tall Bldgs: Regulation on the Design and Construction of Tall Reinforced Concrete Buildings JGJ-3-91

2001 National Standards of the People's Republic of China, Code for Seismic Design of Buildings (GB50011-2001)

2008 Current code? Zonation? Compliance?

(Shuping 1993)




Engineered Building Reconstruction

PreCast combined with URM

NON-Ductile Reinforced Concrete

Photos: K. Miyamoto




NON-ductile

DUCTILE




Engineered Building Reconstruction

Assuming modern standards are to be met, many damaged buildings are going to be uneconomical to repair.

Photo: XIAO

YanNon-Ductile detailing, 2008 Wenchuan Earthquake




SchoolsCalifornia

• 1933 Earthquake Field Actschools special design review

• last 75 years, no school collapse or loss of life.

• State-wide review in 2000 14% vulnerable:

Assumed OK




Seismic Rehabilitation Costs

Seismic Rehabilitation cost approximately $620,000 / building (C¥ 780,000 / building based on PPP ratio)

Seismic Rehabilitation cost approximately $620,000 / building (C¥ 780,000 / building based on PPP ratio)

Retrofitted schoolNiigata, Japan




Non-Engineered Buildings

Earth or stone rubble walls, Earth roof

Brick (or stone) wallsRCC roof

Brick walls, Tin roofRCC Frame, Tin Roof

Figs. © C. Scawtorn, 2004




Earth or stone rubble walls, Earth roof

Brick (or stone) wallsRCC roof

Brick walls, Tin roofRCC FrameFigs. © C. Scawtorn, 2004




Confined MasonryTechnology




Non-engineered BuildingsNon-engineered buildings will be built back the same unless:

• Owners are educated

• Builders and Craftsman are trained

• Achieve Code complianceby institutions for Code enforcement




Non-engineered Buildings – Improving Quality

World Bank sponsored project




All ChinaDue to underzoning… parts of China … many high riskbuildings / infrastructure.

Need: Major program to:

• New seismic zonation

• Identify hazardous buildings

• Long-term retrofitting program




SummaryIF 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 Programneeds to be developed, to address Earthquake, Flood, Typhoon…




Thank you

Charles Scawthorn

[email protected]

mailto:[email protected]

seismic resistant repair and reconstruction - critical...

Documents