MICROTREMOR MEASUREMENT AND POSSIBILITY OF ITS APPLICATION TO SEISMIC DIAGNOSIS : Study on seismic diagnosis for wooden structures Part 2

Abstract

In order to study the natural period and the damping factor of conventional wooden-framed houses, and to consider the possibility of applying microtremor measurement to seismic diagnosis, we investigated 238 two-storied houses, and analyzed the results based on shaking table tests using9 full-scale models. Major findings are as follows: 1) As the housing becomes newer, the natural period becomes shorter, and the damping factor and the evaluation of seismic diagnosis become higher. 2) The natural period becomes shorter in accordance with construction stage, and the stiffness of completed house is about four times greater than that of the framework with bracing members and bearing walls. 3) The elastic period obtained by the sweep vibration tests, whose input acceleration values are from 25 to 30 gals, has a relation to the natural period. 4) The natural period based on microtremor measurement is not sufficient to estimate the evaluation of seismic diagnosis. 5) As the stiffness obtained by seismic diagnosis does not correlate closely with that obtained by microtremor measurement, it would be difficult to estimate the stiffness of seismic diagnosis from microtremor measurement.