REGIONAL VARIATION AND AGE DEPENDENCY IN VIBRATION CHARACTERISTICS OF CONVENTIONAL WOODEN HOUSES BASED ON MICROTREMOR MEASUREMENTS

We collect resonance periods of 163 two-storied, detached wooden houses with traditional construction method by using in-situ microtremor measurements in various regions of Japan. We grasped their averaged vibration characteristics from samples in different regions with different construction ages. A difference of regional design seismic coefficient did not emerge as a difference in averaged resonance periods. Except for Sapporo region a relatively small regional variation is observed. It is estimated that an older house should have a long resonance period so should have a lower seismic capacity. On the average 30 years of age difference yields about 1.41 times of period ratio. This finding on the age degradation in seismic capacity shows good correlation to the independent results based on the damage statistics in Kobe.