Evaluation of Seismic Performance of Wooden Houses during the Northern Miyagi Earthquakes of July 26, 2003

Abstract

2003年宮城県北部の地震で被害を受けた木造建物の被災調査を実施し、耐震性能評価を行った。先ず、震源域の地震動強さの考察を実施し、墓石転倒率、墓石滑動移動量から推定される最大地動速度は90cm/s以上である事を示した。次に、平屋建ての建物が2階建てより被害率が高かった事を、等価1自由度系の解析から考察した。そして、被災建物の耐震性能を限界耐力計算手法から評価し、耐震性能は比較的高く、背の高い小壁が重要な耐震要素である事を示した。

This paper presents the results of our investigation on wooden house damages during the earthquakes in Northern Miyagi, Japan. First, earthquake observation records are summarized. Next, the peak ground velocities in the area of severe damages are estimated from the toppling ratios or displacements of tombstones. Then, from a survey of the damages in three towns, it is found that the damage ratio of one-story houses is much higher than that of two-story houses. This damage trend is analyzed and explained by using the method of equivalent-performance response spectrum. Finally, seismic performances of 21 typical houses are compared based on the response limit strength design method.