| Summary: | 碩士 === 逢甲大學 === 土木及水利工程所 === 92 === As a consequence of 921 Chi-Chi Earthquake, the seismic codes in Taiwan were revised or adjusted. Especially, for the near fault region, bigger acceleration design spectra were adopted, reflecting the characteristics of near-fault earthquakes. It is known that the current seismic codes were established by making use of the elastic/inelastic response spectra of SDOF systems. Therefore, the design base shear of a MDOF building determined by the current seismic codes is considered biased and need modification. This study proposes to do a series of inelastic dynamic analysis for moment-resisting steel frames (2~30 stories) subjected to 7 distant and 7 near fault earthquakes. Based on the inelastic dynamic analysis results and the limitation of the ductility demand in seismic code, the modification factors for the design base shear, distant and near fault, are estimated. In the distant fault region, the code-design base shear is conservative for nearly all buildings; however, in the near fault region, it is obviously insufficient, especially for the 10- and 20-story buildings. No matter for safety or economy considerations, the modification factors estimated in this paper can provide useful information for the building design.
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