Effect of the Soft Soil Layer on the Vertical Response of a Structure Excited with the Vertical Component of Earthquakes

연약지반이 수직방향 지진하중을 받는 구조물의 수직방향 반응에 미치는 영향

  • Published : 1999.03.01

Abstract

The importance of the vertical response of a structure was well recognized after the Hyogoken-Nanbu earthquake of Japan. However, most of the seismic design codes does not specified the site sail profiles, and the sail and foundations conditions were mostly neglected in the vertical seismic analyses of a structure. In this paper, the effects of foundation size, sail layer depth under the foundation, foundation embedment and pile foundation on the vertical seismic response spectra for both surface and embedded mat foundation were studied to investigate the effects of the soft soil layer on the vertical response of a structure excited with the vertical components of Taft and El Centro earthquakes, considering the sail profile types of $S_A,S_C,S_E$ in UBC-97, the medium and large size foundations, the soil layer depth under the foundation of 30 and 60m, the foundation embedment of 0 and 15m, and the precast reinforced concrete bearing piles installed in the soft soil deposit. According to the study results, the foundation size has a little effect on the vertical seismic response, However, the soil layer depth under the foundation of 60m has to be considered for the vertical seismic analysis of a structure as for the horizontal one. The embedded pile foundations as well as the surface ones built on the soft soil layer amplified the vertical seismic response of a structure very much.

일본 고베지진후 구조물 수직방향 내진거동의 중요성은 잘 인식되었으나 대부분의 내진설계규준에서는 지반조건을 규정하지 않아 수직방향 구조물 내진해석시 대개 토질과 기초조건을 무시하고 수행하였다 이 논문에서는 연약지반이 Taft 지진과 El Centro 지진의 수직방향 지진하중을 받는 구조물의 수직방향 반응에 미치는 영향을 알아보기 위해 기초크기, 기초 및 지반깊이 , 기초근입깊이 및 말뚝기초가 수직방향 내진반응스펙트럼에 미치는 영향에 대해 연구하였는데 지반은 UBC-97에서 분류한 Sa. Sc. SE를 기초크기는 중 대형 기초를. 기초 및 지반깊이는 30m 와 60m를 기초근입깊이를 0m와 15m를 고려하였으며 연약지반에 설치한 말뚝은 기성제 콘크리트 선단지지말뚝을 고려하였다 연구결과에 의하면 기초크기는 구조물의 수직방향 내진반응에 별 영향이 없지만 지반깊이는 수평방향 내진해석에서처럼 기초 및 60m까지 고려해야 하며 연약지반위에 설치된 묻힌기초와 얕은 말뚝기초는 구조물의 수직방향 내진거동을 크기 증폭시켰다.

Keywords

References

  1. Preliminary Reconnaisance Report The Hyogoken-Nanbu earthquake great Han-shin earthquake disaster january 17,1995 Earthquake Engineering Research Institute
  2. Uniform Building Code International Conference of Building Officals
  3. M.S Thesis, The University of Texas at Austin Effect of Embedment on Seismic Motions of Buildings Kim, Y. S.
  4. Ph. D. Dissertation, The University of Texas at Austin Dynamic Response of St-ructures on Pild Foundations Kim, Y. S.
  5. Journal of the Earthquake Engineering Society of Korea v.1 no.1 Seismic response of structure on flexible foundation Kim, Y. S.
  6. Analysis and Design of Pile Foundations,ASCE Dynamic stiffness of pile groups Roesset, J. M.
  7. Research Report R83-07 Dynamic analysis of axisymmetric pile groups Tyson, T. R.;Kausel, E.
  8. Earthquake Engineering Wiegel, R. L.
  9. Proceedings of Structural Engineers World Congress, Re-ference T108-3 Study on the effects of the characteristics of a soil layer on the seismic response of a high-rise building Kim, Y. S.