Proceedings of the International Symposium on Engineering Lessons Learned fromthe 2011 Great East Japan Earthquake, March 1-4, 2012, Tokyo, Japan

Summary of the Field Survey on the damage of bridges inthe 2011 off the Pacific Coast of Tohoku Earthquake
Syuhei TAKEDA1, Kenji KOSA2 , Masakatsu MIYAJIMA3 and Hideki SHIMIZU4
1Associate Professor, Department of Civil Engineering, Fukui University of Technology
Fukui, Japan, s-takeda@fukui-ut.ac.jp
2Professor, Department of Civil Engineering, Kyusyu Institute of Technology
Fukuoka, Japan, kosa@civil.kyutech.ac.jp
3Professor, School of Environmental Design, Kanazawa University
Ishikawa, Japan, miyajima@t.kanazawa-u.ac.jp
4Chief Engineer, Nippon Engineering Consultants Co., LTD.
Fukuoka, Japan, shimizu_hideki1124@yahoo.co.jp

ABSTRACT: The 2011 off the Pacific Coast of Tohoku Earthquake occurred in Tohoku
Province on March 11, 2011. JMA seismic intensity 7 was recorded in Kurihara city.
Damage of some bridges which were located on the coast were developed by greattsunami. After the earthquake, the authors conducted investigative research into thetypical bridge damage that occurred. Based on the field investigation, damage of sometypical bridges are presented in this report.
Key Words: Field damage investigation, damage of bridges and buildings, Tsunami

INTRODUCTION
The off the Pacific Coast of Tohoku Earthquake (Mw9.0) occurred in Tohoku Province(including Tokyo Metropolitan area), Japan, at 14:46 on March 11, 2011. The number of victims andmissing people was nearly 20,000. JMA seismic intensity 7 was recorded in Kurihara city. Damage ofsome bridges which were located on the coast were developed by great tsunami. On the Kesen Bridge
which is located in Rikuzentakata city, the superstructure washed-away by tsunami. And the Utatsu
Bridge which is located in Minamisanriku town, the superstructure also washed-away.
After the earthquake, the authors of this paper conducted investigative research into the typicalbridge damage that occurred. And we had three times investigations in the flooding regions. We
conducted first field-damage investigation of bridges and buildings, railway in Iwate and Miyagi
prefecture on March 16-21, 2011. Second field-damage investigations were on March 31-April 5, 2011.
And third field-damage investigations were on October 10-13, 2011.
In the investigation, several individual surveys were conducted. Based on the field investigation,
damage of some typical bridges are presented in this report. It should be noted that since theinvestigation was conducted without prior information on design drawings and analysis, it is highly
possible that the authors made incorrect interpretations of the failure mechanism.

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(Area II)(Area I)

TsunamiFig. 1 Relationship between Epicenter and damage of some typical bridges

Table 1 Schedules of survey
NoDate1

March 15-21

PrefectureIwate
MiyagiIwate

2March30-April 4Miyagi
Iwate

3

Octorber10-13

Miyagi
Fukushima

Site
Typical of City
Rikuzentakata, Ofunato
Iwanuma, Ishinomaki, Kesennuma
Minamisanriku, Onagawa
Kamaishi, Yamada, Miyako
Rikuzentakata
Minamisanriku,Onagawa
Rikuzen-Koizumi
Kamaishi, Ryoishi, Touni
Rikuzentakata
Iwanuma, Ishinomaki, Kesennuma
Minamisanriku, WatariSoma, Shinchi

OUTLINE OF THE OFF THE PACIFIC COAST OF TOHOKU EARTHQUAKEThe earthquake of moment magnitude M9.0 occurred off Sanriku coast at 14:26 JST on March 11,2011 and caused tremendous damage of collapse and washed-away of bridges, buildings, houses andother structure by ground motion and tsunami in the Pacific coast of eastern Japan, including
prefecture of Iwate, Miyagi, Fukushima, Ibaraki and Chiba. The earthquake has recorded the seismic
intensity 7, highest in the Japan Meteorological Agency scale, in north of Kurihara city (Miyagi pref.).
Fig.1 shows relationship between epicenter and typical damage of bridges. After the 2011
Tohoku earthquake, many bridges were damaged and washed-away by tsunami. In the Kesen Bridge
where is located in Rikuzentakata City, superstructure washed-away by tsunami. Koizumi Bridge alsowashed-away.

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OUTLINE OF FIELD SURVEY
After the earthquake, the authors of this paper conducted investigative research into the typicalbridge damage that occurred. And we had three times investigations in the flooding regions. Table 1
shows schedules of survey and investigation area. We conducted first field-damage investigation ofbridges and buildings, railway in Iwate and Miyagi prefecture on March 16-21, 2011. Second
field-damage investigations were on March 31-April 5, 2011. Third field-damage investigations wereon October 10-13, 2011. In the investigation, several individual surveys were conducted.

DAMAGE OF BRIDGES
We investigated damage of bridges in Iwate, Miyagi and Fukushima pref. Only typical damage(as shown in Fig.2) is presented in this chapter. Table 2 shows typical damage of bridges by tsunami.
In this report, damage of nine typical bridges are presented

Photo 3
Photo 2

Photo 1
Tsunami(a) Area-I (Generally coastline, Fukushima and Miyagi)

Photo 6
Photo 4

Photo 8
Photo 7

Photo 5Photo 9Tsunami(b) Area-II (Saw-toothed coastline, Miyagi and Iwate)
Fig. 2 Map of typical bridges1412

Table 2 Typical damage of bridges
NoBridge

PrefectureType1

Tsurishi-minato (pc)

Fukushima

Generally coastline

2Ainokama (steel)

Miyagi

Generally coastline

3

Yuriage (pc)

Miyagi

Generally coastline

4

Shin-kitagami (steel, truss)

Miyagi

Saw-toothed coastline

5

Utatsu (pc)

Miyagi

Saw-toothed coastline

6

Koizumi (steel)

Miyagi

Saw-toothed coastline

7

JR-line Bri. (kesennuma-line, pc)

Miyagi

Saw-toothed coastline

8

Kesen (steel)

Iwate

Saw-toothed coastline

9Numata (pc)

Iwate

Saw-toothed coastline

Washed-away

Tsunami(a)The view of bridge

Right side

Tsurishi-Minato Bri.

(b) Superstructure
Photo 1 Tsurishi-Minato Bridge

Aqueduct(c) Abutment

Left side

1.0m

0.2m

Tsunami(a)The view of bridge(b) Superstructure (left side)
Photo 2 Ainokama Bridge(c) Superstructure (Right side)

crack

Tsunami(a)The view of bridge

bearingbump(b) Joint
Photo 3 Yuriage Bridge

1413(c) Superstructure and bearing

(1) Generally coastline (from Fukushima to Miyagi pref.)Tsurishi-Minato Bridge is located in Shinchi town (Fukushima prefecture). Photo 1 shows
damage of bridge after tsunami. Superstructure was made with PC, and the type was single beam. We
see from the Photo 1 (b) that superstructure washed-away. Aqueduct which was located next to theTsurishi-Minato bridge, also washed-away.

Washed-away
TsunamiLeft bank(a)The view of bridge(b) Superstructure
Photo 4 Shin-kitagami Bridge(c) Pier

Washed-away

Tsunami(a)The view of bridge(b) Superstructure
Photo 5 Utatsu Bridge(c) Pier(b) Superstructure(c) Pier

Washed-away

Tsunami(a)The view of bridge

Koizumi Bridge (R45)

TsunamiDamper system(d) Abutment

JR Kesenmuna-line
Washed-away(e) The view of JR Bridge
Photo 6 Koizumi Bridge

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Ainokama Bridge is located in Iwanuma city (Miyagi prefecture). Photo 2 shows damage ofbridge after tsunami. Superstructure was made with steel, and the type was single beam. We see fromthe Photo 2 that superstructure was moved. Relative displacement of left side was about 1.0m, andother side was about 0.2m.
Yuriage Bridge is located in Natori city (Miyagi prefecture). Photo 3 shows damage of bridge
after tsunami. The structure is 541.7m long and consists of three-span continuous PC-Box type girder
bridge with PC-T type girder approach bridges of seven spans. And the bridge supported by steel
bearings as shown in Photo 3 (c). We see from the Photo 3 (b and c) that joint and girder was damaged
by strong ground motion. But the structure did not wash-away by tsunami.

(2) Saw-toothed coastline (from Miyagi to Iwate pref.)Shin-kitagami Bridge is located in Ishinomaki city (Miyagi prefecture). Photo 4 shows damage ofbridge after tsunami. Superstructure was made with steel, and the type was truss beam. We see fromthe Photo 4 (b) that superstructure (two-spans) washed-away.
Utatsu Bridge is located in Minami-sanriku town (Miyagi prefecture). Photo 5 shows damage ofbridge after tsunami. The structure is about 304m long, and the superstructure was made with PC, andthe type was PC-T beam. We see from the Photo 5 (b) that superstructure (eight-spans) washed-away.
Kozumi Bridge is located in Kesennuma city (Miyagi prefecture). Photo 6 shows damage ofbridge after tsunami. The structure is 182m long, and the superstructure was made with steel, and thetype was continuous girder. We see from the Photo 6 (b) that superstructure (six-spans) washed-away.
And one pier (P3) was collapsed and washed away. The boundary of bearing was movable. This bridge
was retrofitted by damper system as shown in Photo 6 (d). JR-line viaduct that is located next to theKoizumi Bridge, also washed-away by tsunami as shown in Photo 6 (e).
JR-line Bridge is located in Kesennuma city (Miyagi prefecture). Photo 7 shows damage ofbridge after tsunami. The superstructure was made with PC, and the type was single beam. We see
from the Photo 7 (b and c) that superstructure (three-spans) washed-away, and two piers werecollapsed.

Tsunami(a)The view of bridge(b) Superstructure
Photo 7 JR-line Bridge (Kesennuma-line)
Rubber bearing(c) Pier

Damper system

Washed-away

Tsunami(a)The view of bridge(b) Rubber bearing
Photo 8 Kesen Bridge

1415(c) Damper

Washed-away

Washed-away

TsunamiTsunami(a)The view of bridge(b) Pier
Photo 9 Numata Bridge(c) Viaduct

Kesen Bridge is located in Rikuzentakata city (Iwate prefecture). Photo 8 shows damage ofbridge after tsunami. The structure is 181.5m long, and the superstructure was made with steel. And
the bridge supported by rubber bearings as shown in Photo 8 (b).
We see from the Photo 8 that superstructure (all-spans) washed-away. This bridge was retrofitted bydamper system as shown in Photo 8 (c).
Numata Bridge is located in Rikuzentakata city (Iwate prefecture). Photo 9 shows damage ofbridge after tsunami. The structure is about 65m long, and the superstructure was made with PC. We
see from the Photo 9 that superstructure (all-spans) washed-away. Viaduct that is located next to theNumata Bridge, also washed-away by tsunami as shown in Photo 9 (c).

CONCLUSIONS
After the off the Pacific Coast of Tohoku Earthquake, the authors of this paper conductedinvestigative research into the typical bridge damage that occurred. And we had three times
investigations in the flooding regions.
From the field survey, the conclusions have been stated below:(1) In the Tsurishi-minato Bridge, superstructure washed-away. But Abutment was not collapse. And
superstructure of aqueduct also washed-away.
(2) In the Ainokama Bridge, superstructure was moved by tsunami.
(3) In the Yuriage Bridge was damaged superstructure, bearing and joint by strong ground motion.
But it was not washed-away.
(4) Some bridges where are located on saw-toothed coastline, superstructure washed-away by tsunami.
In the Koizumi Bridge, pier (P3) was collapse and washed-away.
Finally, it should be noted that since the investigation was conducted without prior information
on design drawings and analysis, it is highly possible that the authors made incorrect interpretations ofthe failure mechanism.

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