subjected to pulse-type motions in the near-fault region
HAO An-min1; ZHOU De-yuan1; LI Ya-ming2; ZHANG Hui2
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1．School of Civil Engineering, Tongji University, Shanghai 200092, China;2．Shanghai Institute of Architectural Design & Research Co．Ltd, Shanghai 200092, China
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History+
Received
Revised
Published
2010-08-05
2010-11-01
2011-12-25
Issue Date
2011-12-25
Abstract
Damping modification factors (DMF) are used in modern seismic codes to adjust elastic response spectral values corresponding to 5% of viscous damping to other damping levels. However, codes have the disadvantage of neglecting the impact of pulse-type motions. This study examined the influence of moment magnitude, site classes and distance on pulse periods by representative forward-directivity ground motion records with distinct velocity pulses. Furthermore, Pulse periods were confirmed to possess better linear relationship with periods corresponding to the peak values of pseudo-velocity spectral. Finally, Nonlinear regression analyses were conducted with the Levenberg–Marquardt method. The resulting equations, as a function of both normalized periods and damping ratios, for DMF successfully represented data distribution. The results show that，with the decrease of pulse periods, periods corresponding to DMF peak values reduce and DMF approach 1.0 at middle and long period range. In contrast to the considerations of current seismic codes, DMF are strongly dependent on pulse periods, the periods of structural vibration and damping ratios, and that in comparison with the DMF proposed by the authors, current DMF are shown to be either too low or too high, depending on pulse periods, period range, damping ratios.
HAO An-min;ZHOU De-yuan;LI Ya-ming;ZHANG Hui.
subjected to pulse-type motions in the near-fault region[J]. Journal of Vibration and Shock, 2011, 30(12): 108-113,
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