Performance analysis of Tohoku-Shinkansen viaducts affected by the 2011 Great East Japan earthquake

Abstract

Tohoku-Shinkansen viaducts in eastern Japan were designed in accordance with specifications published in the 1970s. They have less shear reinforcement than required by current design specifications. Consequently, the No. 5 Inohana viaducts of Tohoku-Shinkansen failed in shear during the 2003 Sanriku-Minami earthquake. The viaducts were retrofitted by means of steel jacketing so that they had sufficient shear capacity. The retrofitted columns of the viaducts performed well during the 2011 Great East Japan earthquake. However, there is a lack of understanding of the impact of these retrofitting interventions on the vulnerability of the viaduct. It is important to recognise the relationship between the damage to the Shinkansen viaduct with retrofitted reinforced concrete columns and the ground motion intensity. After a brief review of the history of the performance of Shinkansen viaducts to several earthquakes prior to the 2011 Great East Japan earthquake, this paper presents fragility curves of the retrofitted and non-retrofitted Tohoku-Shinkansen viaducts based on nonlinear dynamic analyses and Monte Carlo simulation. It was found that the median of the fragility curve associated with the ultimate limit state for retrofitted viaduct is at least five times larger than that for as-built viaduct.

Keywords::

• bridges
• concrete structures
• reliability
• retrofitting
• seismic engineering

Acknowledgements

The first author acknowledges the support provided by the J-RAPID programme of the Japan Science and Technology Agency (project leader: Prof. Kazuhiko Kawashima, Tokyo Institute of Technology). The author thank the National Research Institute for Earth Science and Disaster Prevention, Japan, for providing the strong-motion data recorded by the K-NET. The opinions and conclusions presented in this paper are those of the authors and do not necessarily reflect the views of the sponsoring organisation.

Notes

^1. Email: [email protected]

^2. Email: [email protected]