In the past, earthquakes have caused critical damage to bridges built on liquefiable ground, resulting in their collapse or long-term closures. In particular, for existing bridges designed in an age when the liquefaction influence was not considered, appropriate measures should be taken as necessary. However, there are many existing stocks of bridges, which require expensive foundation reinforcement. Therefore, it is crucial to appropriately choose bridge foundations for which anti-seismic measures are a high priority and implement the measures efficiently and successively. The present study aims to develop a seismic-performance assessment method and retrofitting technology for coping with liquefiable ground. For this purpose, a large shaking-table experiment was conducted to determine the effects of the liquefiable ground on bridge-foundation behavior and verify the effect of the retrofitting technology. Based on disaster-case analyses and the results of the shaking-table experiment, a seismic-performance assessment method applicable to practical designing was proposed.

1. [1] K. Wakamatsu, “Liquefaction-induced Damage during Near-field Earthquakes in the Tokyo Metropolitan Area,” J. of Geography, Vol.116, Issues 3-4, doi:10.5026/jgeography.116.3-4_480, 2007.
2. [2] Tokyo Disaster Management Council, “Report on Damage Estimates in Tokyo Due to an Earthquake Directly Hitting Tokyo,” pp. 1-190, 2012 (in Japanese).
3. [3] S. Unjoh, J. Hoshikuma, J. Sakai, and K. Ueda, “A case of falling bridge in past large-scale earthquake and its analysis,” Technical Note of Public Works Research institute, No.4158, 2009.
4. [4] T. Tamakoshi and Y. Yokoi, “Annual Report of Basic Data on Road Structures In FY 2013,” Technical Note of National Institute for Land and Infrastructure Management, No.822, 2015 (in Japanese).
5. [5] “Report on Niigata Earthquake,” Report of Public Works Research institute, No.125, 1965.
6. [6] “Report on the Investigation of Damages Caused by the Earthquake in the Tokachi-oki in 1968,” Report of the Civil Engineering Research Institute, Hokkaido Development Bureau, No.49, 1968.
7. [7] “Report on the Investigation of Damages Caused by the Earthquake in the Offing of the Nemuro Peninsula in 1973,” Report of the Civil Engineering Research Institute, Hokkaido Development Bureau, No.62, 1974.
8. [8] Japan Society of Civil Engineers, “Reconnaissance report on the July 12, 1993 Hokkaido Nansei-oki Earthquake,” 1997 (in Japanese).
9. [9] E. Kuribayashi, F. Tatsuoka, and S. Yoshida, “Ground liquefaction history in Japan after the Meiji era,” Report of Public Works Research institute, No.30, pp. 45-57, 1974.
10. [10] S. Kodera, “Earthquake damage and ground of bridge foundation (Part1),” Soil mechanics and foundation engineering, Vol.12, No.3, pp. 11-18, 1964.
11. [11] “Report on the Disaster Caused by the Nihon-kai-chubu Earthquake of 1983,” Report of Public Works Research institute, No.165, 1985.
12. [12] Japan Society of Civil Engineers, “Report on the 1983 seismic damage survey of the Nihon-kai-chubu Earthquake,” 1985.
13. [13] “Quick Report on Damage to Infrastructures by the 2011 off the Pacific coast of Tohoku Earthquake,” Technical Note of National Institute for Land and Infrastructure Management, No.646, Techcnical Note of Public Works Research Institute, No.4202, 2011 (in Japanese).
14. [14] “Reconnaissance Report on Damage to Road Bridge by the 2011 Great East Japan Earthquake,” Technical Note of National Institute for Land and Infrastructure Management, No.814, Techcnical Note of Public Works Research Institute, No.4295, 2014.
15. [15] Japan Society of Civil Engineers, “Report on the Hanshin-Awaji Earthquake disaster: Damage to civil engineering structures,” 1996.
16. [16] Hanshin Expressway Management Technology Center, “Hanshin Expressway Earthquake Disaster Recovery (Photo collection),” 1997.
17. [17] Japanese Geotechnical Society, “Air photographs of the Niigata city immediately after the earthquake in 1964,” 1999.
18. [18] Japan Road Association, “Structural design guidelines for road bridges Pile foundation design edition,” 1964.
19. [19] Japan Road Association, “Specifications for Highway Bridges, Part V: Seismic Design,” 2012.
20. [20] K. Nagaya, S. Kataoka, T. Kusakabe, and K. Matsumoto, “A Research on Immediate Damage Estimation Technology to Improve Crisis Management for Mega-Earthquakes,” J. of Japan Society of Civil Engineers, Ser.A1 (Structural Engineering & Earthquake Engineering (SE/EE)), Vol.72, No.4 (JSCE J. of Earthquake Engineering, Vol.35), pp. I_966-I_974, doi:10.2208/jscejseee.72.I_966, 2016.
21. [21] Japan Road Association, “Specifications for Highway Bridges, Part V: Seismic Design,” 2017.