Keiko Morita

Lessons learned from the 2016 Kumamoto earthquake: Building damages and behavior of seismically isolated buildings

Powerful earthquakes stuck Kumamoto and Oita Prefectures in Kyushu, Japan. It began with the Magnitude 6.5 foreshock at 21:26 JST 14 April, followed by the Magnitude 7.3 mainshock at 1:25 JST 16 April, 2016. The sequence earthquakes also involved more than 1700 perceptible earthquakes as of 13 June. The entire sequence was named the 2016 Kumamoto earthquake by the Japan Meteorological Agency. Thousands of buildings and many roads were damaged, and landslides occurred. The Japanese building standard law is revised in 1981. Structural damages were concentrated on buildings constructed prior to 1981. The area of Mashiki and Southern Aso were most badly affected, especially wooden houses extremely damaged. In Japan, Prof. Hideyuki Tada (title at the time) undertook research on laminated rubber bearings in 1978, and put it into practical use in 1981. The single family house at Yachiyodai, Chiba Prefecture is completed in 1983, it’s the first seismically isolated building which is installed laminated rubber bea...

Problems in the identification of base isolation systems from earthquake records

This work extends some recently obtained results on the identification of base isolation systems from earthquake response records. The identification is carried out by means of the Covariance Matrix Adaptation - Evolution Strategy (CMA-ES). By extending the number of iterations in each run and the number of runs it is shown that the obtained results have engineering significance. The design of a fictitious problem on the basis of a real seismic isolation system has allowed for the evaluation of the error on the individual system parameters. Some information on the completeness of the data used for the identification has also been provided. The work is concluded by the description of some open problems that the authors are facing and are determined to solve using the recent advances in computer science and technology.