[S07-9] Strong motion and seismic sources II

[S07-9-03] Features of long-period spectrum of SMART-1 array strong motion records

^○Haiying Yu^{1, 2}, Baofeng Zhou^{1, 2}, Xuan Xu^1,2, Ruizhi Wen^1,2, Dongwang Tao^1,2 (1.Institute of Engineering Mechanics, China Earthquake Administration, harbin, China, 2.Key Laboratory of Earthquake Engineering and Engineering Vibration, harbin, China)

Long period features of strong motion on the same kind of sites are analysed using the records of digital accelerographs deployed in SMART-1 array of Taiwan. Although the differences of epicentral distances for different stations are small for the same earthquake, the short period spectral components of accelerograms are different obviously, while the long period spectral components are same mainly. The effects of magnitude and epicentral distance on long period spectral components are not so stronger as for short period components. Finally, the average spectrum for SMART-1 array of Taiwan is compared with the design spectra of the new seismic design code of buildings. Some useful conclusions are summarized as follows.
(1)For accelerogram of the same class site at the same epicentral distance of one earthquake, there is some significant difference between the acceleration response spectra in the short period parts, but little difference in long period parts. The effects of exiguous difference of the local site and other random factors can be neglected in the long period parts.
(2)For accelerogram at the same place from difference earthquakes, there is some significant difference between the periods at which the peak values the acceleration response spectra, and values of spectra are also different in long period parts. That is to say, it is maybe not proper that the characteristic period of design spectra is adjusted only according to the site conditions.
(3)From the shape of average spectra for soil sites, it is obviously that the declined speed of long period parts is slower than that of short period parts. It shows that it is reasonable that the declined segment of design spectra is divided into two parts in the revision of Seismic Design Code of Buildings. and on the other hand, the characteristic period of design spectra should be extended further.