Jun Iyama

Application of wavelets to analysis and simulation of earthquake motions

A method of applying wavelet transform to earthquake motion analysis is developed from the viewpoint of energy input structures, in which relationships between wavelet coefficients and energy input, namely energy principles in wavelet analysis are derived. By using the principles, time–frequency characteristics of the 1995 Hyogoken-Nanbu earthquake ground motions are analysed and time histories of energy input for various ranges of frequencies and epicentral distances are identified. Furthermore, a technique to simulate earthquake ground accelerations by wavelet inverse transform is developed on the condition that target time-frequency characteristics are specified. Structural responses to the simulated accelerations are compared with the target time–frequency characteristics, which shows satisfactory correlations between wavelet coefficients and energy responses in both time and frequency domains. Copyright

STRUCTURAL DAMAGE ON SCHOOL GYMNASIUMS DUE TO THE 2011 TOHOKU EARTHQUAKE

In order to clarify structural damage on school gymnasiums due to the 2011 Tohoku Earthquake, total 1611 of school gymnasiums in Iwate Prefecture, Miyagi Prefecture, Fukushima Prefecture, Ibaraki Prefecture, and Tochigi Prefecture were investigated. More than 70% of investigated school gymnasium were slightly damaged or not damaged. On the other hand, about 6% of school gymnasium built in or after 1982 were seriously damaged. Moreover, in this paper, structural elements damaged seriously in the school gymnasiums built in 1982 or afterwards were examined.

RECONNAISSANCE OF DAMAGED STEEL SCHOOL BUILDINGS DUE TO THE 2011 TOHOKU EARTHQUAKE

An outline of a reconnaissance of steel school buildings damaged by the 2011 Tohoku earthquake is presented. In this reconnaissance, a total of 216 facilities have been investigated by the Steel Structure Working Group of the Subcommittee on Seismic Performance of School Buildings, Architectural Institute of Japan. The damage to structural elements, connections, non-structural elements, foundation and surrounding soil, as well as the details including building history and seismic retrofit have been recorded and the overall damage has been evaluated based on the “Standard for Post-earthquake Damage Evaluation of Damaged Buildings” published by the Japan Building Disaster Prevention Association. Not only seismic damage but damage caused by the devastating tsunami are also covered. Detailed analysis of the damage to individual structural and non-structural components are presented in following papers.