Development of Site Classification System and Modification of Design Response Spectra considering Geotechnical Site Characteristics in Korea (II) - Development of Site Classification System

국내 지반특성에 적합한 지반분류 방법 및 설계응답스펙트럼 개선에 대한 연구 (II) - 지반분류 개선방법

  • 윤종구 (한국유지관리(주) 지반설계사업부) ;
  • 김동수 (한국과학기술원 건설및환경공학과) ;
  • 방은석 (한국과학기술원 건설및환경공학과)
  • Published : 2006.04.30


In the companion paper (I-Problem Statements of the Current Seismic Design Code), the current Korean seismic design code is required to be modified considering site characteristics in Korea for the reliable estimation of site amplification. In this paper, three site classification methods based on the mean shear wave velocity of the top 30m $V_{S30}$, fundamental site periods $(T_G)$ and bedrock depth were investigated and compared with each other to determine the best classification system. Not enough of a difference in the standard deviation of site coefficients $(F_a\;and\;F_v)$ to determine the best system, and neither is the difference between the average spectral accelerations and the design response spectrum of each system. However, the amplification range of RRS values based on $T_G$ were definitely concentrated on a narrow band than other classification system. It means that sites which have a similar behavior during earthquake will be classified as the same site category at the site classification system based on $T_G$. The regression curves between site coefficients and $T_G$ described the effect of soil non linearity well as the rock shaking intensity increases than the current method based on $V_{S30}$. Furthermore, it is unambiguous to determine sue category based on $T_G$ when the site investigation is performed to shallower depth less than 30m, whereas the current $V_{S30}$ is usually calculated fallaciously by extrapolating the $V_s$ of bedrock to 30m. From the results of this study, new site classification system based on $T_G$ was recommended for legions of shallow bedrock depth in Korea.


site classification;site period;bedrock depth;response spectrum;site response analysis;site coefficient;ratio of response spectrum;RRS


  1. 윤종구, 김동수, 방은석 '국내 지반특성에 적합한 지반 분류 방법 및 설계응답스펙트럼 개선에 대한 연구(I) - 국내 내진설계기준의 문제점 분석', 한국지진공학회 논문집, 제10권 2호(통권 제48호), 2006, pp. 39-50
  2. MCEER-99-00l0, Site Factors and Site Categories in Seismic Codes, Ricardo Dobry, Ricardo Ramos and Maurice S, Power. July 19, 1999
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  4. Dobry, R. and Martin G. 'Development of Site Dependent Ratio of Elastic Response Spectra(RRS)', Proceeding of the Workshop on Earthquake Site Response and Seismic Code Provisions, 1999
  5. Idriss, 1. M., and Sun, J. I., User's manual for SHAKE91 : A computer program for conducting equivalent linear seismic response analysis of horizontally layered soil deposits, University of California, Davis, 1992, 13 pp
  6. Kramer, S. L. Geotechnical Earthquake Engineering, Prentice Hall, Englewood Cliffs, New Jersey, 1996

Cited by

  1. Site Classification System and Site Coefficients for Shallow Bedrock Sites in Korea pp.1559-808X, 2017,