Advancement of Design Standards for Infrastructures after the Kobe Earthquake

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Advancement of Design Standards for
Infrastructuresafter the Kobe Earthquake
Technical Workshop Rebuilding Bam learning from
past reconstruction programmes 25-26 February
2004 Tehran, Islamic Republic of Iran

• Tetsushi KURITA
• Senior Researcher
• Asian Disaster Reduction Center

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Collapse of the Myth of Safety
- Collapse of elevated bridges -
Upside-down expressway
635 m
Fall down of bullet-train bridge
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Collapse of the Myth of Safety
- Collapse of bank protection structures-
Slumped dike
sea
river
Slumped quay
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Fundamental Policy on New Seismic Design for
Infrastructures

• Performance verification design against
  earthquake loads
• Considering two levels of input earthquake motion
  for seismic design

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Performance Verification Design
Three levels of performance required for
structures

• Structures keep functioning without repair after
  earthquake.
• Structures which could restore function shortly
  after repair.
• Structures do not collapse in the earthquake.

Strict
Lowest
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Two Levels of Input Earthquake Motion
- Definition -

• Level 1 It covers motions which occur one or
  two times during the in-service period of the
  facility. It is same as the previous seismic load
  in the design code.
• Level 2 Though infrequent motions, intensity
  of the motion is extremely high. e.g. The
  strong motion experienced in Kobe city during the
  Kobe earthquake.

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Two Levels of Input Earthquake Motion

• Level 1 The motion which is comparable to the
  seismic loadings traditionally used in Japanese
  seismic codes for which structures are to remain
  within their elastic limits.
• Level 2 Structures those allowed to undergo
  plastic deformations as long as collapse and
  loss of life are prevented.

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Building Damage in Kobe City
Cracks on facade of apartment house
First story collapse
Story collapse at 5th floor
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Characteristics of Building Damage in Kobe City
18.0
16.0
22.7
18.0
16.7
7.9
4.9
24.9
32.2
20.5
10.7
6.8
Construction Year
3.3
36.0
38.7
11.3
5.3
5.3
Component Ratio
Amendment of Building Standard Law
(Based on the observations of Chuo ward, Kobe
city by the structural damage evaluation
committee)
Amendment of Aseismic Provision in Building
Standard Law
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History of Japanese Building Design Codes
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Case of Tokachi-oki Earthquake
May 16, 1968 Magnitude 7.9 Focal Depth
shallow Max JMA seismic intensity 5 Death
49 Disappearances 3 Injures
330 Collapsed houses
673 Half-collapsed houses
3,004 Partly-damaged houses 15,697
March 4, 1952 Magnitude 8.2 Focal Depth
shallow Max JMA seismic intensity
6 Death 28 Disappearances
5 Injures 287 Collapsed houses
815 Half-collapsed
houses 1,324 Partly-damaged houses
6,395
September 26, 2003 Magnitude 8.0 Focal Depth
42km Max JMA seismic intensity 6 lower Death
0 Disappearances 2 Injures
844 Collapsed houses
60 Half-collapsed houses
81 Partly-damaged houses 1,292
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Case of Tokachi-oki Earthquake, 1952
Collapsed school
Train derailment
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Case of Tokachi-oki Earthquake, 1968
Collapsed buildings
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Case of Tokachi-oki Earthquake, 2003
Cracked road
Collapsed house
Oil storage fire
Tsunami inundation
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Why People Concern about the Building Standards ?
Government
Local Government
Capital Injection
Low Interest Home Loan
Inspection
Government Housing Loan Corporation
Construction
Citizen
Residences
GHLC
Inspection of the Building under Construction
(2-3 times)
Contract
Building Inspection Organizations
lt Options gt
If lenders accept higher standards, GHLC can
secure

• high amount of loan.
• low rate of interest.

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Damage to Housing Units in Kobe Earthquake
( Source GHLC )
16.3
6.4
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Conclusions

• After the 1995 Kobe earthquake, design standards
  for infrastructures are improved.
• Amendment of building standard law has been
  effective to reduce the building damage.
• Inspection by the subsidy company is effective to
  make people paying attention the building
  standards.

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THANK YOU