Scaling of spectral displacement ordinates with damping ratios

The next generation of seismic design codes, especially those adopting the framework of performance-based design, will include the option of design based on displacements rather than forces. For direct displacement-based design using the substitute structure approach, the spectral ordinates of displacement need to be specified for a wide range of response periods and for several levels of damping. The code displacement spectra for damping values higher than the nominal value of 5% of critical will generally be obtained, as is the case in Eurocode 8 and other design codes, by applying scaling factors to the 5% damped ordinates. These scaling factors are defined as functions of the damping ratio and, in some cases, the response period, but are independent of the nature of the expected ground shaking. Using both predictive equations for spectral ordinates at several damping levels and stochastic simulations, it is shown that the scaling factors for different damping levels vary with magnitude and distance, reflecting a dependence of the scaling on the duration of shaking that increases with the damping ratio. The options for incorporating the influence of this factor into design code specifications of displacement response spectra are discussed. Copyright © 2004 John Wiley & Sons, Ltd.

[1]  Thomas H. Jordan,et al.  Predominance of Unilateral Rupture for a Global Catalog of Large Earthquakes , 2002 .

[2]  P. Somerville.  Magnitude scaling of the near fault rupture directivity pulse , 2003 .

[3]  Robert D. Hanson,et al.  STUDY OF INELASTIC SPECTRA WITH HIGH DAMPING , 1989 .

[4]  E. Faccioli,et al.  DISPLACEMENT DESIGN SPECTRA , 1999 .

[5]  N. Abrahamson,et al.  Modification of Empirical Strong Ground Motion Attenuation Relations to Include the Amplitude and Duration Effects of Rupture Directivity , 1997 .

[6]  V. W. Lee,et al.  Empirical models for scaling pseudo relative velocity spectra of strong earthquake accelerations in terms of magnitude, distance, site intensity and recording site conditions , 1989 .

[7]  Yu-Yuan Lin,et al.  Study on Damping Reduction Factor for Buildings under Earthquake Ground Motions , 2003 .

[8]  David M. Boore,et al.  Simulation of Ground Motion Using the Stochastic Method , 2003 .

[9]  E. Faccioli,et al.  Displacement Spectra for Long Periods , 2004 .

[10]  F. Cotton,et al.  NEW EMPIRICAL RESPONSE SPECTRAL ATTENUATION LAWS FOR MODERATE EUROPEAN EARTHQUAKES , 2003 .

[11]  A. G. Brady,et al.  A STUDY ON THE DURATION OF STRONG EARTHQUAKE GROUND MOTION , 1975 .

[12]  Jonathan P. Stewart,et al.  EQUIVALENT NUMBER OF UNIFORM STRESS CYCLES FOR SOIL LIQUEFACTION ANALYSIS , 2001 .

[13]  W. J. Hall,et al.  Earthquake spectra and design , 1982 .

[14]  J. Bommer,et al.  THE EFFECTIVE DURATION OF EARTHQUAKE STRONG MOTION , 1999 .

[15]  W. B. Joyner,et al.  ESTIMATION OF RESPONSE SPECTRA AND PEAK ACCELERATIONS FROM WESTERN NORTH AMERICAN EARTHQUAKES: AN INTERIM REPORT PART 2 , 1993 .

[16]  J. Bommer,et al.  DISPLACEMENT SPECTRA FOR SEISMIC DESIGN , 1999 .

[17]  Mete A. Sozen,et al.  SUBSTITUTE-STRUCTURE METHOD FOR SEISMIC DESIGN IN R/C , 1976 .

[18]  Hong Hao,et al.  Generation of probabilistic displacement response spectra for displacement-based design , 2004 .

[19]  Eduardo Miranda,et al.  Evaluation of approximate methods to estimate maximum inelastic displacement demands , 2002 .

[20]  Kazuhiko Kawashima,et al.  MODIFICATION OF EARTHQUAKE RESPONSE SPECTRA WITH RESPECT TO DAMPING , 1984 .