Abstract
In general, peak ground acceleration (PGA), peak ground velocity (PGV), seismic intensity and spectral intensity (SI) have been used as the indices of destructive power on earthquake motion. However, it is quite important to consider the number of earthquake response cycles in the vicinity of the maximum response and natural period of structures for predicting damage to structures. Especially, destruction of the wooden structure was expanded by aftershock after the main shock in 2004 Niigata-ken Chuetsu earthquake. In this study, the influence by accumulation of the earthquake motion on wooden structure destruction is considered. The fatigue response spectral intensity (FSI) of having taken the repetition of earthquake motion into consideration is applied, and a relation with wooden structure damage is considered. This index, which is called as FSI, is defined as integrated value on tripartite coordinates: natural period of wooden structures, pseudo-response velocity spectra and number of seismic response cycles. FSI was calculated by using the response to recent earthquakes in Japan such as the 2004 Niigata-ken Chuetsu Earthquake and so on. As a result, it was clarified that accumulation of an earthquake motion influences structure damage and the earthquake motion destructive power index proposed by this research that accumulation of the earthquake motion by aftershock can be taken into consideration is effective. Based on this study it is concluded that FSI value demonstrate the damage ratio more accurately than alternative indices such as seismic intensity, PGV, and SI value.
