Junichiro Niwa, Prof., Dr. Eng. Department of Civil Engineering Tokyo Institute of Technology

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

2. Great East Japan Earthquake, March 11. 2011 (1) The Great East Japan Earthquake occurred at 2:46 PM, March 11, 2011. (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. (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. 2

3. Great East Japan Earthquake, March 11. 2011 ■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) Distribution of Main Shock and Aftershocks (Magnitude > 5.0) 3

4. Characteristics of Earthquake Motion Great East Japan Earthquake, March 11. 2011 Observed in Urayasu Duration of Earthquake Motion is very long. Example of Kobe Earthquake, 1995 ■Very long duration might be a reason to increase the disaster of severe liquefaction. 4

5. Damages of Railway Structures • Surveyed Targets: • Shin-kansen structures • (2) Bridges and piers of local • JR linesin the coastal regions 5

6. Damages of Railway Structures, Shin-kansen Structures 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. Iwate-Numakunai Morioka Sendai Distribution of Damages of Shin-kansen Structures 【 Legend 】 Ohmiya Civil Electricity Tokyo 50 places 10 places 6 1 place

7. Damages of Railway Structures, Shin-kansen Structures 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. 7

8. Damages of Railway Structures, Shin-kansen Structures 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. 8

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

10. Damages of Railway Structures, Shin-kansen Structures Shin-kansen Line Conventional Line 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.) 10

11. Damages of Railway Structures, Shin-kansen Structures 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. 11

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

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

14. Damages of Railway Structures, Local JR Lines in the Coastal Regions 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

15. 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. Abutment still remained. Completely collapsed pier. 15

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

17. Damages of Railway Structures, Local JR Lines in the Coastal Regions Pretensioned T-Shaped Girder Since the girder height is not high, the location of gravity center is not so high. 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. 17

18. Damages of Railway Structures, Local JR Lines in the Coastal Regions 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. One of RC piers was failed with the break of longitudinal reinforcement. However, RC girders still remained. 18

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

20. Damages of Railway Structures, Local JR Lines in the Coastal Regions Tsuyagawa bridge (JR Kesen-numa line, Kesen-numa city, Miyagi Pref.) 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. 20

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

22. Damages of Railway Structures, Local JR Lines in the Coastal Regions Tsuyagawa bridge (JR Kesen-numa line, Kesen-numa city, Miyagi Pref.) 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. 22

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

24. 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

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

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

27. Damages of Road Bridges, Steel Bridges 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. 27

28. Damages of Road Bridges, Steel Bridges 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. 28

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

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

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

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

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

34. 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

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

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

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

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

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

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

41. Damages of Road Bridges, Concrete Bridges Numata bridge over railway (Road bridge, Rikuzen-takada city, Iwate Pref.) Anchor bar 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. 41

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

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

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

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

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

47. Damages of Other Structures, Port Structures 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. 47

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

49. Damages of Other Structures, Floodgate Failure of concrete slabs of a floodgate by Tsunami (Fudai-hama port, Fudai village, Iwate Pref.) PC curtain wall Floodgate of Fuda-hama port PC curtain wall structure Design Tsunami Height: T.P.+15.5 m (1896 Great Sanriku Tsunami was supposed.) Actual Tsunami Height 2011：around 17 m 49

50. Damages of Other Structures, Floodgate 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. 50