Special Session 24.4 Great East Japan Earthquake
15th World Conference on Earthquake Engineering
Lisbon, Portugal, September 24, 2012

A Great Success and Future Challenges
for Mitigating Damage of Bridges

Kazuhiko Kawashima
Tokyo Institute of Technology

2011 Great East Japan earthquake was a good
opportunity to learn whether damage ofbridges was mitigated as a consequence ofcode upgrading since 1990
North Miyagi-ken andsouth Iwate-ken where
damage was evaluatedbetween two earthquakes
Damaged region

1978 MJMA7.4
Miyagi-ken-okiearthquake

The Pacific Ocean0550km

2011 Mw 9.0 GreatEast Japan earthquake

Ground acceleration was slightly stronger
during the 2011 event the 1978 event
2011 Great East Japan

2015TRUDLGTRLG

105UD

0012
Period (s)3Response Acceleration (m/s2)

Response Acceleration (m/s2)

1978 Miyagi-ken-oki

2015LG
TR
UDTR

10LG
5UD

0012
Period (s)31978 Miyagi-ken-oki Earthquake (MJMA7.4)
Damage concentrated to RC columns at lap
splice of longitudinal bars
Sendai Bridge
National Road 6

Extensive Damage of Steel Bearings Almost all side stoppers suffered damage
Pin and roller bearings were vulnerable todamage

Damaged side stoppers

Failure of pier at bearing

Pull-out of anchor bolts Pull-out of rollers

Ruptureof pin1978 Miyagi-ken-oki earthquake-An Important Turning Point of Design
If we look back the past design,……
Stage 1: Days when seismic design was notconducted or it was insufficient（1868-1945）
Overturning, sliding or
settlement of foundations--- Collapse

Stage 2: Days when we were not aware ofliquefaction and unseating prevention devices
were not yet developed (1964 Niigata EQ)
Excessive response offoundations & piers---- Collapse1978 Miyagi-ken-oki earthquake-An Important Turning Point in Design (2)Stage 3: Days when we were not aware of
the importance of ductility capacity of piers

Enhancing the past weak links led to damage in thenext weak link. This became apparent during 1978
Miyagi-ken-oki EQ and 1982 Urakawa-oki EQ;
 Piers & columns
 Bearings
Bearing damage

Shear failure at cut-off

Shear failure

Flexural failureThis type of damage extensively occurred
during 1995 Kobe earthquake

Extensive Shear
Failure at Cut-off ofLongitudinal Rebars

1995 Kobe earthquakeCourtesy of Prof. H. Kameda

Shear Failure at Cut-off of Longitudinal
RebarsA mandate Practice for saving cost prior to 1980
Bending Moment
Distribution
Singlereinforcement

doublereinforcement

Mmax

300mm
Cut-off ofinnerlongitudinalbars

Full Scale
Experiment for a
Shear Failure
Dominant
Column: C1-2

E-Defense, NIEDSeismic Design was Extensively Enhanced
since 1970
Pre-1990 Design Codes

Post-1990 Design Codes

Static elastic
analysis

Static inelastic
analysis0.2-0.3g design response
acceleration (L1)

0.7-2.0 g design response
acceleration (L2)

Allowable stress designLinear & nonlinear
dynamic analysis

Linear dynamicanalysis
Steel bearings

Elastomeric bearings
including LRB andHDRType I GM (1990-)
M8 Subduction events atmiddle-fieldLong duration
Typical GMs in Tokyo
during the 1923 Kanto EQType II GMs (1995-)
Near-field GM by M7
EventsShort duration with HighIntensity
Typical GMs in Kobe during
the 1995 Kobe EQ

Response acceleration (m/s2)

Departure from Elastic Static Analysis toInelastic Static Analysis (Post-1990 Codes)
25Type II GM
20ⅠStiff
ⅡMediumⅢSoft

15

Type I GM

10500

Elastic Static123

Period (s)42Seismic Retrofit
 RC jacket (standard for columns in water) Steel jacket (standard for column on land) Carbon fiber wrapping Prestressed jacket
 Aramid fiber jacket
 ………
 Implement of seismic isolation/ structural control
Some 30,000 piers & columns were retrofitted
since 1995

Implementation of Steel Jacketing wasinitiated since 1989, prior to the 1995
Kobe Earthquake

2.4m x 2.4m x9mtall column withsteel jacketing

Metropolitan Expressway

During the 2011 Great East Japan
earthquake, shear failure at cut-off still
occurred at RC columns which have not yet
been retrofitted
Fuji Bridge, Iwate-ken

Dr. Jyunichi Hoshikuma

Bridges which were retrofitted inaccordance with the post-1990 code
suffered virtually no damage
Steel jacketing was effective

Replacement ofvulnerable steel bearings
with elastomeric bearings
was effective

Elastomeric bearings
Retrofitted by steel jacketing

Iinogawa Bridge, Route 45

Steel bearings and their support which suffereddamage during 1978 Miyagi-ken-oki earthquake
suffered damage again
Tennoh Bridge, National Road 45
1978 Miyagi-ken-oki

2011 Great East Japan

Roller bearingBridge was about tocollapse if an aftershock
was stronger

Bridges designed based on the post-1990
design code suffered no damage
Higashi Matsuyama Bridge (National Toad 45)

Shin-Tenno Bridge (Sanriku Expressway)

No single word about “Tsunami” hadbeen described in the codes
Extensive damage occurred due to tsunami
Utazu Bridge
National Road 45, Minami-Sanriku
S8
S5 S6 S7S3S2P2S9

S10 P10S4

P3 P4P5

P6 P7

A2Kesennuma
S12
S11 P11 Location

P8P9

where a local
resident tookvideoSendai
P1Irimae BayVideo showing submerging of Utatsu Bridge

Before Tsunami Attack

Tsunami rose up to thebottom of the bridge

Center of Utatsu Town

Sea sideUtatsu
BridgeNearly 4 m tall
Embankment
Still peoples werechatting &watching see

Houses are being floated
Courtesy of Mr. Katsuya Oikawa

Rising Up of Tsunami
A cloud of dust
resulted from failureof houses
A 6 m tall polehanging nameplate of thebridge

Tsunamiflowed fromthe back of apeninsula
The bridge
was almost
Water
was risingup to 6m
under water

Two small fishingboats were colliding

Top of a poleTsunami
wasrising up
to 3 mUtatsu HighUtasu Town was disappearing
Schoolby 14 m tall tsunami
Utatsu JuniorHigh School

Center of Utatsu Town

Utatsu Bridge

Courtesy of Mr. Katsuya Oikawa

PC girder decks floated by tsunami
Utazu Bridge, Route 45, Rikuzen-Takada CityP10 P9P8P7P6Spans overturned up side down

Short span decks were simply draggedby tsunami
Stoppers for preventing
P2

excessive deck displacement in
the longitudinal direction

A Possible Failure Mechanism of Shortspan Decks due to Tsunami
Tsunami ForceSteel stoppers were provided, but they
were ineffective for preventing transverse
deck movement & uplift by tsunami
3 stoppers for preventing
excessive deck longitudinal
response

4 Seat extenders

Most Probable Failure Mechanism ofMedium-span decks due to Tsunami
Tsunami Force

Uplifted before floatedUplift Force5

Uplift due to Air Trapped under a PC Deck
End diaphragmMid-span diaphragm

1.75m

0.4m

Tsunami

8.3m
7.5m

0.4m

Trapped Air5

Many bridges survived whereas they werecompletely submerged by tsunami
Minami-Sanriku-Town

Sunday MainichiVol. 90, No. 15, 2011

Yanoura Bridge,Kamaishi
Kamaishi City
National Road 45

3:20

3:22

3:22

3:31
After Kozo Sawada, Sunday Maichi, Special Issue for E-J EQ, No.2

Yano-ura Bridge after the earthquake

No residual displacement

Conclusions
 It was a great success that groundmotion- induced damage of bridges which
had been designed or retrofitted inaccordance with the post-1990 designcodes was generally limited. This wasresulted from the recent advancement ofseismic design practice and implementationof seismic retrofit.
 New challenges which were identified aresecuring seismic performance under morestronger ground motions and mitigatingtsunami-induced-damage.

Thank you for your kind attention
A young pine tree which survived tsunami