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Nonlinear Lateral Behavior and Cross-Sectional Stress Distribution of Concrete Rocking Columns

콘크리트 회전형 기둥의 비선형 횡방향 거동 및 단면응력 분포 분석

  • Roh, Hwa-Sung (Dept. of Civil and Environmental Engineering, Hanyang University) ;
  • Hwang, Woong-Ik (Dept. of Civil and Environmental Engineering, Hanyang University) ;
  • Lee, Hu-Seok (Dept. of Civil and Environmental Engineering, Hanyang University) ;
  • Lee, Jong-Seh (Dept. of Civil and Environmental Engineering, Hanyang University)
  • 노화성 (한양대학교 건설환경공학과) ;
  • 황웅익 (한양대학교 건설환경공학과) ;
  • 이후석 (한양대학교 건설환경공학과) ;
  • 이종세 (한양대학교 건설환경공학과)
  • Received : 2012.01.11
  • Accepted : 2012.04.12
  • Published : 2012.06.30

Abstract

Fixed connection is generally used for beam and column connections of concrete structures, but significant damages at the connection due to severe earthquakes have been reported. In order to reduce damages of the connection and improve seismic performance of the connection, several innovative connections have been suggested. One newly proposed connection type allows a rotation of the connection for applications in rotating or rocking beams, columns, and shear walls. Such structural elements would provide a nonlinear lateral force-displacement response since their contact depth developed during rotation is gradually reduced and the stress across the sections of the elements is non-linearly distributed around a contact area, which is called an elastic hinge region in the present study. The purpose of the present study is to define the elastic hinge region or length for the rocking columns, through investigating the cross-sectional stress distribution during their lateral behavior. Performing a finite element analysis (FEA), several parameters are considered including axial load levels (5% and 10% of nominal strength), different boundary conditions (confined-ends and cantilever types), and slenderness ratios (length/depth = 5, 7, 10). The FEA results showed that the elastic hinge length does not directly depend on the parameters considered, but it is governed by a contact depth only. The elastic hinge length started to develop after an opening state and increased non-linearly until a rocking point(pre-rocking). However, the length did not increase any more after the rocking point (post-rocking) and remained as a constant value. Half space model predicting the elastic hinge length is adapted and the results are compared with the numerical results.

일반적으로 콘크리트 구조물은 보와 기둥이 서로 강결되어 있으며, 이러한 경우 강진에 의해 연결부에서 심각한 손상이 발생할 수 있다. 이를 저감시키면서 내진성능을 향상시키기 위한 다양한 연결 형태가 연구되어지고 있다. 그 한 예로 연결부에서의 회전을 허용하는 연결형식이 있으며 보나 기둥, 그리고 전단벽에 응용되고 있다. 이러한 회전형 구조요소들은 횡방향 거동시 비선형 힘-변위 관계를 나타내는데, 그 원인은 연결부의 회전으로 인한 접촉면의 깊이(contact depth)가 줄어듦과 동시에 요소의 각 단면에서의 응력이 비선형적으로 분포되는 탄성힌지 구간이 존재하기 때문이다. 이 연구에서는 축방향 하중(공칭강도의 5%와 10%)과 경계조건(양단구속 형식, 캔틸레버 형식), 세장비(L/d = 5, 7, 10) 등의 변수를 고려한 유한요소해석을 통해 회전형 기둥의 탄성힌지 구간 또는 길이를 분석하였다. 그 결과 이 세가지 변수는 탄성힌지길이 변화에는 직접적인 영향을 주지 않았으며 다만 접촉면의 깊이에 의해 지배됨을 알 수 있었다. 이 탄성힌지길이는 opening state부터 발생하기 시작하여 rocking point까지(pre-rocking 구간) 증가하였으나 그 이후(post-rocking 구간)에서는 일정한 값을 보였다. 탄성힌지길이에 대한 유한요소해석 결과를 이론적 예측식인 반무한모델(half space model)의 결과와 비교하였다.

Keywords

References

  1. Priestley, M. J. N., Seible, F., and Uang, C. M., "The Northridge Earthquake of January 17. 1994: Damage Analysis of Selected Freeway Bridges," Report No. SSRP-94/06, Structural Systems Research Project at the University of California, San Diego, California, 1994, 266 pp.
  2. Stanton, J. F., Stone, W. C., and Cheok, G. S. "Hybrid Reinforced Frame for Seismic Regions," PCI Journal, Vol. 42, No. 2, 1997, pp. 20-32.
  3. Cheok, G. S. and Lew, H. S., "Performance of Precast Concrete Beam-to-Column Connections Subject to Cyclic Loading," PCI Journal, Vol. 36, No. 3, 1999, pp. 56-67.
  4. Priestley, M. J. N., Seible, F., and Calvi, G. M. Seismic Design and Retrofit of Bridge, John Wiley & Sons, INC., New York, 1996, 686 pp.
  5. Priestley, M. J. N. and Tao, J. R., "Seismic Response of Precast Prestressed Concrete Frame with Partially Debonded Tendons," PCI Journal, Vol. 38, No. 1, 1993, pp. 58-67.
  6. Priestley, M. J. N. and MacRae, G. A., "Seismic Tests of Precast Beam-to-Column Joint Subassemblage with Unbonded Tendons," PCI Journal, Vol. 41, No. 1, 1996, pp. 64-81.
  7. Costley, A. C. and Abrams, D. P., "Response of Building Systems with Rocking Piers and Flexible Diaphragms," Worldwide Advances in Structural Concrete and Masonry, Proc. Of the CCMS Symposium Held in Conjunction with Structures Congress XIV, ASCE, 1996, pp. 135-140.
  8. Toranzo, L., Restrepo, J. I., Mander, J. B., and Carr, A. J., "Shake-Table Tests of Confined-Masonry Rocking Walls with Supplementary Hysteretic Damping," Journal of Earthquake Engineering, Vol. 13, No. 6, 2009, pp. 882-898. https://doi.org/10.1080/13632460802715040
  9. Ajrab, J. J., Pekcan, G., and Mander, J. B., "Rocking Wall- Frame Structures with Supplemental Tendon Systems," Journal of Structural Engineering, Vol. 130, No. 6, 2004, pp. 895-903. https://doi.org/10.1061/(ASCE)0733-9445(2004)130:6(895)
  10. Mander, J. B. and Cheng, C. T., "Seismic Resistance of Bridge Pier based on Damage Avoidance Design," Technical Rep. No. NCEER-97-0014, University of New York, Buffalo, NY, 1997.
  11. Cheng, C. T., "Energy Dissipation in Rocking Bridge Piers under Free Vibration Tests," Earthquake Engineering and Structural Dynamics, Vol. 36, No. 4, 2007, pp. 503-518. https://doi.org/10.1002/eqe.640
  12. Christiopoulos, C., Filiatrault, A., Uang, C. M., and Folz, B., "Post-Tensioned Energy Dissipating Connection for MRFs," Journal of Structural Engineering, Vol. 128, No. 9, 2002, pp. 1111-1120. https://doi.org/10.1061/(ASCE)0733-9445(2002)128:9(1111)
  13. Kurama, Y. C. and Shen, Q., "Postensoined Hybrid Coupled Walls under Lateral Loads," Journal of Structural Engineering, Vol. 130, No. 2, 2004, pp. 297-309. https://doi.org/10.1061/(ASCE)0733-9445(2004)130:2(297)
  14. Pampanin S., "Emerging Solutions for High Seismic Performance of Precast/Prestressed Concrete Buildings," Journal of Advanced Concrete Technology, Vol. 3, No. 2, 2005, pp. 207-223. https://doi.org/10.3151/jact.3.207
  15. Palermo A., Pampanin S., and Calvi G. M., "Concept and Development of Hybrid Solutions for Seismic Resistant Bridge Systems," Journal of Earthquake Engineering, Vol. 9, No. 6, 2005, pp. 899-921.
  16. Pinochet J., Llera, J. C., and Luders, C., "Analysis of a Kinematic Self-Centering Seismic Isolator," Earthquake Engineering and Structural Dynamics, Vol. 35, No. 12, 2006, pp. 1533-1561. https://doi.org/10.1002/eqe.601
  17. Roh, H., Seismic Behavior of Structures using Rocking Columns and Viscous Dampers, Ph. D. Dissertation, State University of New York at Buffalo, 2007, 264 pp.
  18. Roh, H. and Reinhorn, A. M., "Analytical Modeling of Rocking Elements," Engineering Structures, Vol. 31, No. 5, 2009, pp. 1179-1189. https://doi.org/10.1016/j.engstruct.2009.01.014
  19. Roh, H. and Reinhorn, A. M., "Nonlinear Static Analysis of Structures with Rocking Columns," Journal of Structural Engineering, Vol. 136, No. 8, 2010, pp. 532-542. https://doi.org/10.1061/(ASCE)ST.1943-541X.0000154
  20. ABAQUS Users Manual, Version 6.8-1, Dassault Systems Simulia Corp., 2008, pp. 27.2.10-4.
  21. Mander, J. B., Priestley, M. J. N., and Park, R., "Theoretical Stress-Strain Model for Confined Concrete," Journal of Structural Engineering, Vol. 114, No. 8, 1988, pp. 1804-1826. https://doi.org/10.1061/(ASCE)0733-9445(1988)114:8(1804)
  22. Park, R. and Paulay, T., Reinforced Concrete Structures, John Wiley & Sons, NY, USA, 1975, 800 pp.
  23. Johnson, K. L., Contact Mechanics, Cambridge University Press, 1985, 464 pp.