κ0 for soil sites: Observations from KiK-net sites and their use in constraining small-strain damping profiles for site response analysis

Boqin Xu, Ellen M. Rathje, Youssef Hashash, Jonathan Stewart, Kenneth Campbell, Walter J. Silva

Research output: Contribution to journalArticlepeer-review

Abstract

Small-strain damping profiles developed from geotechnical laboratory testing have been observed to be smaller than the damping inferred from the observed site amplification from downhole array recordings. This study investigates the high-frequency spectral decay parameter (κ0) of earthquake motions from soil sites and evaluates the use of κ0 to constrain the small-strain damping profile for one-dimensional site response analysis. Using data from 51 sites from the Kiban-Kyoshin strong motion network (KiK-net) array in Japan and six sites from California, a relationship was developed between κ0 at the surface and both the 30-m time-averaged shear wave velocity (Vs30) and the depth to the 2.5 km/s shear wave velocity horizon (Z2.5). This relationship demonstrates that κ0 increases with decreasing Vs30 and increasing Z2.5. An approach is developed that uses this relationship to establish a target κ0 from which to constrain the small-strain damping profile used in one-dimensional site response analysis. This approach to develop κ0-consistent damping profiles for site response analysis is demonstrated through a recent site amplification study of Central and Eastern North America for the NGA-East project.

Original languageEnglish (US)
Pages (from-to)111-137
Number of pages27
JournalEarthquake Spectra
Volume36
Issue number1
DOIs
StatePublished - Feb 1 2020

Keywords

  • Kappa
  • damping
  • site response analysis

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Geophysics

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