Junichiro Niwa, Prof., Dr. Eng. Department of Civil Engineering Tokyo Institute of Technology DISASTERS AND LESSONS OF CIVIL ENGINEERING STRUCTURES BY THE GREAT EAST JAPAN EARTHQUAKE

2 (1) The Great East Japan Earthquake occurred at 2:46 PM, March 11, (2) The epicenter was 24 km in depth from the seabed at 130 km east by southeast from Oshika peninsula. (3) The magnitude was 9.0, which is the highest magnitude ever recorded in Japan. (4) The epicentral area was very huge, about 500 km from Iwate Pref. to Ibaraki Pref. in a north-south direction, and about 200 km in a east-west direction. Great East Japan Earthquake, March (5) By the earthquake, huge Tsunami, which average height was near 10 m, (the maximum height was around 40 m) occurred, and the devastating disaster was caused.

Distribution of Main Shock and Aftershocks (Magnitude > 5.0) ■ Very active aftershocks ■ Wide range of after- shocks (from Iwate pref. to Ibaraki pref., 500km in N-S direction, 200 km in E-W direction) Great East Japan Earthquake, March

Characteristics of Earthquake Motion ■ Very long duration might be a reason to increase the disaster of severe liquefaction. Duration of Earthquake Motion is very long. Observed in Urayasu Example of Kobe Earthquake, Great East Japan Earthquake, March

Damages of Railway Structures Surveyed Targets: (1) Shin-kansen structures (2) Bridges and piers of local JR lines in the coastal regions 5

Damages of Railway Structures, Shin-kansen Structures 6 Damages due to Earthquake Motion In Tohoku Shin-kansen, damages happened in very wide range from Ohmiya to Iwate- Numakunai. In addition to civil engineering structures, many structures of electricity were damaged. Distribution of Damages of Shin-kansen Structures Morioka Sendai Tokyo 【 Legend 】 Civil Electricity 50 places 10 places 1 place Ohmiya Iwate-Numakunai

Damages of RC Piers of Tohoku Shin-kansen Line: RC piers were damaged by the earthquake. This damage was very similar to that of 1995 Kobe earthquake. Damages of Railway Structures, Shin-kansen Structures 7

Since these piers are supposed to fail in flexure, sufficient shear reinforcement was not provided. However, within two weeks after the earthquake, sufficient shear reinforcement has been provided to these piers. Damages of Railway Structures, Shin-kansen Structures 8

Damages of Railway Structures, Shin-kansen Structures 9 Damage of RC pier Damage of RC pier at the cut-off point of longitudinal bars. Damage of PC girder The end of PC girder was damaged near the support.

Left: Conventional Railway Viaduct (No damage at all because the newly developed seismic strengthening method after 1995 Kobe earthquake has been applied.) Right: Tohoku Shin-kansen Viaduct (Small damage was observed because only traditional seismic strengthening was provided.) Damages of Railway Structures, Shin-kansen Structures 10 Shin-kansen Line Conventional Line

The collapse of PC electric poles occurred in wide area (around 800 poles). It delayed the recovery of Shin-kansen line. Example of a PC electric pole with cracks by the earthquake. Damages of Railway Structures, Shin-kansen Structures 11

The concrete cover of a PC electric pole was completely peeled off. A PC electric pole was replaced by a steel electric pole after the earthquake. Damages of Railway Structures, Shin-kansen Structures 12

Falling of ceiling boards of Shin-kansen platform at Sendai station by the earthquake. Emergency stop of Shin- kansen train. No derailing at all. Damages of Railway Structures, Shin-kansen Structures 13

Completely destroyed Shin-chi station by Tsunami (Soma county, Fukushima Pref.). Main girders were swept away by Tsunami (Tsuyagawa Bridge, JR Kesen-numa line). 14 Damages of Railway Structures, Local JR Lines in the Coastal Regions

Isato-maegawa bridge (JR Kesen-numa line, Minami- sanriku town, Miyagi Pref.) PC simple girder bridge. Piers were collapsed and girders were fallen down and swept away. Completely collapsed pier. Abutment still remained. 15 Damages of Railway Structures, Local JR Lines in the Coastal Regions

PC girders were completely swept away in the upstream of the river. One of the girder was completely turned upside down. Isato-maegawa bridge (JR Kesen-numa line, Minami- sanriku town, Miyagi Pref.) 16 Damages of Railway Structures, Local JR Lines in the Coastal Regions

Damages of Railway Structures, Local JR Lines in the Coastal Regions 17 Since the girder height is not high, the location of gravity center is not so high. Pretensioned T-Shaped Girder Post-tensioned T-Shaped Girder Since the girder height is high, the location of gravity center is also high. After the flow of the girder, it may turn upside-down.

Tsuyagawa bridge (JR Kesen-numa line, Kesen-numa city, Miyagi Pref.) PC and RC simple girder bridge. Some of piers were already collapsed and girders were fallen and swept away. However, RC girders still remained. One of RC piers was failed with the break of longitudinal reinforcement. 18 Damages of Railway Structures, Local JR Lines in the Coastal Regions

The top of a RC pier was failed with the break of longitudinal reinforcement and the lateral beam was fallen down. Tsuyagawa bridge (JR Kesen-numa line, Kesen-numa city, Miyagi Pref.) 19 Damages of Railway Structures, Local JR Lines in the Coastal Regions

Several piers in the river were inclined. After 1978 Miyagiken-oki earthquake, girders and piers were strongly connected to prevent the falling down of girders. This time it worked negatively to increase the applying moment to piers due to Tsunami. Tsuyagawa bridge (JR Kesen-numa line, Kesen-numa city, Miyagi Pref.) 20 Damages of Railway Structures, Local JR Lines in the Coastal Regions

Tsuyagawa bridge (JR Kesen-numa line, Kesen-numa city, Miyagi Pref.) 21 Damages of Railway Structures, Local JR Lines in the Coastal Regions Inclined RC piers still remained untouched in JR Tsuyagawa bridge.

Damages of Railway Structures, Local JR Lines in the Coastal Regions 22 Main PC girder of Tsuyagawa bridge was swept away by Tsunami. Although it was a post-tensioned PC girder, it did not barely turn upside-down. Tsuyagawa bridge (JR Kesen-numa line, Kesen-numa city, Miyagi Pref.)

Damages of Road Bridges Surveyed Targets: (1) Steel bridges (2) Concrete bridges 23

Damages of Road Bridges, Steel Bridges Shin-kitakami bridge (Road bridge, Ishinomaki city, Miyagi Pref.) Steel truss girder bridge. Two spans of main girders were swept away by Tsunami. 24

Damages of Road Bridges, Steel Bridges 25 Structural members make a triangle. Normally it does not block the water flow of the river. Truss Girder Plate Girder Steel plate is provided at the web. Mechanism is very clear. However, it will block the water flow of the river.

Two spans of main truss girders were swept away in the upstream of the river (around 500 m). Damages of Road Bridges, Steel Bridges Shin-kitakami bridge (Road bridge, Ishinomaki city, Miyagi Pref.) 26

Damages of Road Bridges, Steel Bridges 27 Shin-kitakami bridge (Road bridge, Ishinomaki city, Miyagi Pref.) Floated pavement slab of the bridge and other debris may block the water flow of the river. This is the reason why two spans of main truss girders were swept away.

Damages of Road Bridges, Steel Bridges 28 Shin-kitakami bridge (Road bridge, Ishinomaki city, Miyagi Pref.) Two-span steel truss girders were completely swept away. On the other hand, RC piers remained without any serious damage.

Damages of Road Bridges, Steel Bridges 29 Shin-kitakami bridge (Road bridge, Ishinomaki city, Miyagi Pref.) Steel truss girders were found at around 500 m in the upstream of the river.

Damages of Road Bridges, Steel Bridges 30 Shin-kitakami bridge (Road bridge, Ishinomaki city, Miyagi Pref.) Temporary steel girders have been erected to restore Shin-kitakami bridge to the normal state.

Koizumi bridge (Road bridge, Kesen-numa city, Miyagi Pref.) Six-span steel plate girder bridge. Main steel plate girders were completely swept away. Damages of Road Bridges, Steel Bridges 31

The device to prevent the falling of a girder remained. However, the device was not able to prevent the falling of a girder. Damages of Road Bridges, Steel Bridges Koizumi bridge (Road bridge, Kesen-numa city, Miyagi Pref.) The steel plate girders were found at around 350 m in the upstream of the river. 32

Shishi-ori viaduct (Road bridge, Kesen-numa city, Miyagi Pref.) This viaduct was submerged in Tsunami water. Since girders were connected each other and piers were already strengthened, no serious damage was caused at all. Damages of Road Bridges, Concrete Bridges 33

Damages of Road Bridges, Concrete Bridges Matsukawa-ura bridge, PC Cable-stayed bridge (Road bridge, Soma city, Fukushima Pref.) This bridge was attacked by Tsunami. Wave-dissipating blocks in the sea are found on the bridge deck after Tsunami. In spite of Tsunami attack, the bridge was sound and strong enough. 34

Utazu bridge (Road bridge, Minami-sanriku town, Miyagi Pref.) 35 Damages of Road Bridges, Concrete Bridges A1 A2 P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 To Sendai To Kesen-numa Pretensioned 5 girders Post-tensioned 5 girders 国土地理院ホームページより 12-span PC girders Pretensioned 5 girders Post-tensioned 3 girders were fallen down Post-tensioned 2 girders Fallen girders of Utazu bridge

Utazu bridge (Road bridge, Minami-sanriku town, Miyagi Pref.) 36 Damages of Road Bridges, Concrete Bridges Post-tensioned PC girder turned upside-down. Pretensioned PC girder was fallen down without turning.

Utazu bridge (Road bridge, Minami-sanriku town, Miyagi Pref.) 37 Damages of Road Bridges, Concrete Bridges The device to prevent the falling of a girder was broken. It was not able to prevent the falling of a girder. The main girder and concrete slab were fallen down together near the RC piers.

Since a RC pier was already strengthened, the damage was very slight. Utazu bridge (Road bridge, Minami-sanriku town, Miyagi Pref.) From the damage of the pier, the direction of applying moment by Tsunami can be predicted. 38 Damages of Road Bridges, Concrete Bridges

Utazu bridge (Road bridge, Minami-sanriku town, Miyagi Pref.) 39 Damages of Road Bridges, Concrete Bridges Fallen PC girders in the sea still remained untouched near the RC pier in Utazu bridge.

Numata bridge over railway (Road bridge, Rikuzen- takada city, Iwate Pref.) Simply supported post- tensioned PC T-shaped girders were fallen down. Situation of a fallen girder. 40 Damages of Road Bridges, Concrete Bridges

The device to prevent the falling of a girder was not seriously damaged. Since the anchor bars remained straight, the main girder was supposed to be floating and then falling. Anchor bar Numata bridge over railway (Road bridge, Rikuzen- takada city, Iwate Pref.) 41 Damages of Road Bridges, Concrete Bridges

Other Structures Surveyed Targets: (1)Disaster of Onagawa Town (2)Port structures (3) Floodgate (4) PC tank (5) Airport 42

Damages of Other Structures, Disaster of Onagawa Town by Tsunami 43 Most of the town was damaged by Tsunami. RC building was turned over by Tsunami.

Damages of Other Structures, Disaster of Onagawa Town by Tsunami 44 Many wooden buildings were completely swept away by Tsunami. Even RC buildings were turned over by Tsunami.

Damages of Other Structures, Disaster of Onagawa Town by Tsunami 45 Trains were swept away and collapsed by Tsunami. Another train car was shifted on the hill by Tsunami.

Damages of Other Structures, Port Structures Damages of breakwater and embankment by Tsunami (Tarou port, Tarou town, Iwate Pref.) Breakwater and embankment were completely collapsed. Breakwater of Tarou port was collapsed. 46

Failure of huge concrete blocks of embankment (Soma port, Soma city, Fukushima Pref.) Huge concrete blocks of embankment were collapsed and moved up on the apron deck of the port by Tsunami. Damages of Other Structures, Port Structures 47

Damage of port structures by Tsunami (Soma port, Soma city, Fukushima Pref.) Collapsed quays in Soma port. Damages of Other Structures, Port Structures 48

Floodgate of Fuda-hama port PC curtain wall structure Design Tsunami Height: T.P m (1896 Great Sanriku Tsunami was supposed.) Actual Tsunami Height 2011 ： around 17 m Damages of Other Structures, Floodgate Failure of concrete slabs of a floodgate by Tsunami (Fudai-hama port, Fudai village, Iwate Pref.) PC curtain wall 49

Failure of concrete slabs of a floodgate by Tsunami (Fudai-hama port, Fudai village, Iwate Pref.) Tsunami over the floodgate suddenly dropped on the concrete slabs and destroyed the bridge. Damages of Other Structures, Floodgate 50

Damages of Other Structures, Floodgate Failure of concrete slabs of a floodgate by Tsunami (Fudai-hama port, Fudai village, Iwate Pref.) The bridge was completely collapsed by the overflow of Tsunami. 51

Damages of Other Structures, PC tank 52 PC water tank and RC high pier (Iwate Pref.) A RC high pier was damaged. Shear cracks were initiated in a RC high pier after the earthquake, March 11.

53 Damages of Other Structures, PC tank A PC water tank was fallen down from the top, but it did not crush. PC water tank and RC high pier (Iwate Pref.) A RC high pier was damaged by the earthquake, March 11. Shear cracks were initiated. Due to the aftershock of April 7, a RC high pier was completely failed.

Damages of Other Structures, Airport 54 Damage of Sendai airport by Tsunami (Natori city, Miyagi Pref.) Sendai Airport Sendai plain field was occupied by water caused by Tsunami. Natori River

Damage of Sendai airport by Tsunami (Natori city, Miyagi Pref.) Mud water accumulated on Sendai airport. However, Sendai airport has re-opened at July 25, Damages of Other Structures, Airport 55

Summary (1)Major damages of civil engineering structures were caused by Tsunami, not from the strong earthquake motion itself. (2)Except the electric poles and another attachments, the damage of Shin-kansen was relatively slight. (3)The damages of local JR line bridges and several road bridges were very serious. Many girders were fallen down or swept away by Tsunami. Several piers were also damaged by Tsunami. 56

Thank you very much for your attention. 57 DISASTERS AND LESSONS OF CIVIL ENGINEERING STRUCTURES BY THE GREAT EAST JAPAN EARTHQUAKE