DOI QR코드

DOI QR Code

Deformation Based Seismic Design of Asymmetric Wall Structures

변형에 기초한 비대칭 벽식 주초의 내진설계

  • Published : 2002.02.01

Abstract

Current torsional provisions focus n restricting torsional effect of asymmetric wall structures by proportioning strength of wall based on the traditional assumption that stiffness and strength are independent. Recent studies have pointed out that stiffness of structural wall is dependent on the strength. This implies that actual stiffness of walls can be determined only after torsional design is finished and current torsional provisions may result in significant errors. To overcome this shortcoming, this paper proposes deformation based torsional design for asymmetric wall structures. Contrary to the current torsional provisions, deformation-based torsional design uses displacement and rotation angle as design parameters and calculates base shear for inelastic torsional response directly. Main purpose of deformation based torsional design is not to restrict torsional response but to ensure intended torsional mechanism according to the capacity design concept. Because displacement and rotation angle can be used as performance criteria indicating performance level of asymmetric structures, this method can be applied to the performance based seismic design effectively.

기존의 비틀림 설계법은 구조 벽체의 강성은 강도에 무관하게 결정된다는 기본 가정하에 강성을 설계 변수로 비대칭 벽식 구조의 비틀림 효과를 최소화 하기 위한 각 부재의 강도를 결정한다. 이와는 달리 최근의 연구에 의하면 구조 벽체의 강성과 강도는 상호 연관성을 갖는 것으로 알려졌다. 이 경우 벽체의 실제 강성은 비틀림설계를 모두 마친 후에야 결정되므로 강성에 기초하여 비틀림 설계를 수행한다는 것은 모순이다. 이와 같은 문제점을 해결하기 위해 본 논문은 강성이 아닌 변형에 기초한 비대칭 벽식 구조의 비틀림 설계법을 제안한다. 기존의 비틀림 설계법은 탄성 비틀림 응답과 반응수정계수를 이용하여 비탄성 응답에 대한 설계 하중을 간접적으로 계산하지만 변형에 기초한 비틀림 설계법은 변위와 비틀림 회전각을 설계 변수로 비탄성 응답에 대한 설계 하중을 직접적으로 계산한다. 기존의 비틀림 설계법이 비틀림 효과를 최소화하는 것을 목적으로 하는 데 비하여, 변형에 기초한 비틀림 설계법은 내진역량설계법의 기본 개념에 의거하여 설계자가 의도한 비틀림 미케니즘을 발휘하는 데 그 목적을 둔다. 변위와 회전각은 비대칭 구조의 성능수준을 직접적으로 나타내는 성능 지표이므로 본 설계법은 성능기초 내진설계에 효과적으로 사용될 수 있다.

Keywords

References

  1. Uniform Building Code, International Conference of Building Officials, Whittier, California, 1997.
  2. CEN Techn. Comm. 250/SC8, Eurocode 8: Earthquake-Resistant Design of Structures, CEN, Berlin, 1995.
  3. SANZ(Standards Association of New Zealand), NZS 4203 : General Structural Design and Design Loadings for Buildings, Wellington, 1992.
  4. Chandler, A. M. and Duan, X. N., “Performance of asymmetric code-designed buildings for serviceability and ultimate limit states,” Earthquake Engng. Struct. Dyn., Vol. 26, 1997, pp. 717-735. https://doi.org/10.1002/(SICI)1096-9845(199707)26:7<717::AID-EQE672>3.0.CO;2-X
  5. Tso, W. K. and Smith, R. S. H., “Re-evaluation of seismic torsional provisions,” Earthquake Engng. Struct. Dyn., Vol. 28, 1999, pp. 899-917. https://doi.org/10.1002/(SICI)1096-9845(199908)28:8<899::AID-EQE846>3.0.CO;2-Q
  6. Humar, J. L. and Kumar, P., “Effect of orthogonal inplane structural elements on inelastic torsional response,” Earthquake Engng. Struct. Dyn., Vol. 28, 1999, pp. 1071-1097. https://doi.org/10.1002/(SICI)1096-9845(199910)28:10<1071::AID-EQE855>3.0.CO;2-V
  7. Priestley, M. J. N. and Paulay, T., Seismic Design of Reinforced Concrete and Masonry.
  8. Priestley, M. J. N. and Kowalsky, M. J., “Direct displacement-based seismic design of concrete buildings,” Bulletin, New Zealand National Society for Earthquake Engineering, Vol. 33, 2000, pp. 421-444.
  9. Priestley, M. J. N. and Kowalsky, M. J., “Aspects of drift and ductility capacity of rectangular cantilever structural walls,” Bulletin, New Zealand National Society for Earthquake Engineering, Vol. 31, 1998, pp.73-85.
  10. Paulay, T., “Torsional mechanisms in ductile building systems,” Earthquake Engng. Struct. Dyn., Vol. 27, 1998, pp. 1101-1121. https://doi.org/10.1002/(SICI)1096-9845(199810)27:10<1101::AID-EQE773>3.0.CO;2-9
  11. Paulay, T., “A simple displacement compatibility-based seismic design strategy for reinforced concrete buildings,” 12th World Conference on Earthquake Engineering, Paper 0062, 2000.
  12. Bluebook SEAOC, “Guidelines for performance-based seismic engineering,” SEAOC Blue Book-draft of Appendix I, 1999.
  13. Panagiotakos, T. B. and Fardis, M. N., “Deformations of reinforced concrete members at yielding and ultimate,” ACI Structural Journal, Vol. 98, No. 2, 2001, pp. 135-148.
  14. Wallace, J. W. and Thomsen IV, J. H., “Seismic design of RC structural walls; Part I: New code format, Part II: Application,” Journal of Structural Engineering, ASCE, Vol. 120, No. 3, 1995.
  15. ATC, “NEHRP guidelines for the seismic rehabilitation of buildings,” FEMA Report 273, Applied Technology Council for the Building Seismic Safety Council, Washington, D.C, 1997.
  16. Cho, B. H. and Hong, S. G., “Displacement based seismic design of aymmetric-plan buildings,” KEERCMAE Joint Seminar on Risk Mitigation for Regions of Moderate Seismicity, University of Illinois at Urbana-Champaign, 2001, pp. 361-370.