DOI QR코드

DOI QR Code

비선형거동과 구조물유체상호작용을 고려한 취수탑 내진모델의 보수성평가

Conservation for the Seismic Models of Intake Tower with Nonlinear Behaviors and Fluid Structure Interaction

  • 이계희 (목포해양대학교 해양건설학과) ;
  • 이명규 (전주대학교 토목환경공학과) ;
  • 홍관영 ((주)세일종합기술공사 구조부)
  • 투고 : 2020.08.13
  • 심사 : 2020.10.29
  • 발행 : 2020.12.31

초록

본 연구에서는 물로 둘러싸인 철근콘크리트 취수탑에 대한 비선형내진해석을 수행하였다. 구조물 주변의 유체를 고려하기 위하여 부가질량 및 CEL을 이용한 유체구조물 상호작용 모델을 구성하였다. 이 때 부가질량모델은 음해법을 사용하였고 유체구조물 상호작용 모델은 양해법을 사용하였다. 입력운동은 동일한 인공지진을 재현주기에 따라 500년, 1000년, 2400년에 해당하도록 크기를 조절하였다. 유체를 고려한 모델의 보수성을 평가하기 위하여 유체를 고려하지 않은 모델을 구성하여 참조해로 삼았다. 콘크리트와 철근의 재료모델은 항복후의 비선형 거동을 고려할 수 있도록 선정하였고 ABAQUS를 이용하여 해석을 수행하였다. 해석결과 얻어진 구조물의 가속도응답스펙트럼을 비교한 결과 주변 유체의 영향은 구조물의 기본 진동수에 해당하는 첨두의 진동수와 첨두값의 크기를 감소시키는 것으로 나타났다. 하지만 부가 질량 모델에서는 고차 진동수에 해당하는 첨두값에는 영향을 미치지 못하였다. 유체의 영향을 고려한 단면모멘트는 부가질량모델의 경우 참조 모델의 응답에 비하여 크게 증가하였다. 특히 선형거동이 지배적인 작은 크기의 지진응답에 대해서 이러한 증폭이 크게 발생하였다. 유체구조물 상호작용 모델의 경우 낮은 진동수성분을 가진 단면모멘트는 참조모델의 응답에 비하여 증폭이 발생하나, 높은 진동수 성분을 단면 모멘트는 증폭이 발생하지 않았다. 이러한 결과를 종합하여 볼 때 부가질량모델의 보수성이 유체구조물상호작용 모델이 비해 큰 것으로 평가되었다.

In this study, series of nonlinear seismic analysis were performed on a reinforced concrete intake tower surrounded by water. To consider the fluid effect around the structure, analysis models were composed using an added mass and CEL approach. At this time, the implicit method was used for the added mass model, and the explicit method was used for the fluid structure interaction model. The input motions were scaled to correspond to 500, 1000, and 2400 years return period of the same artificial earthquake. To estimate the counteractivity of the fluid coupled model, models without fluid effect were constructed and used as a reference. The material models of concrete and reinforcement were selected to consider the nonlinear behavior after yielding, and analysis were performed by ABAQUS. As results, in the acceleration response spectrum of the structure, it was found that the influence of the surrounding fluid reducing the peak frequency and magnitude corresponding to the fundamental frequency of the structure. However, the added mass model did not affect the peak value corresponding to the higher mode. The sectional moments were increased significantly in the case of the added mass model than those of the reference model. Especially, this amplification occurred largely for a small-sized earthquake response in which linear behavior is dominant. In the fluid structure interaction model, the sectional moment with a low frequency component amplifies compared to that of the reference model, but the sectional moment with a high requency component was not amplified. Based in these results, it was evaluated that the counteractivity of the additive mass model was greater than that of the fluid structure interaction model.

키워드

참고문헌

  1. Mohammad Alembagher (2016), Dynamics of submerged intake towers including interaction with dam and foundation, Soil Dynamics and Earthquake Engineering, 84, 108-119. https://doi.org/10.1016/j.soildyn.2016.02.004
  2. Zhang, ., Wei, K., Pang, Y., Zhang, M. and Qin, S. (2019), Numerical Investigation into Hydrodynamic Effects on the Seismic Response of Complex Hollow Bridge Pier Submerged in Reservoir: Case Study, Journal of Bridge Engineering, ASCE,, 24(2), 05018016.
  3. Hu, J.W., Kim, Y.C., Cha, Y.W. and Lim, J.S. ( 2016), Prediction for Seismic Damage of Intake Tower through Advanced Finite Element Analysis, Journal of the Korean Society for Advanced Composite Structures, 7(4), 24-29. https://doi.org/10.11004/kosacs.2016.7.4.024
  4. Song, S.G., Min, K.U., Bea, J. and Lee, J. (2018), Application of Hydrodynamic Pressure for Three-dimensional Earthquake Safety Analysis of Dam Intake Towers, Journal of Earthquake Engineering, EESK, 22(3), 139-147.
  5. Bae, J., Kim, Y. Lee, J. and Han, S.H. (2009), Seismic Safety Analysis of Intake Tower with Hollow Inside Section, Journal of the Korean Society of Safety, 24(2), 55-61.
  6. Abaqus/CAE (2011), ABAQUS 6.12 User manual, Dassault Systems Simulia Corp.
  7. Alok Goyal, Anil K. Chopra (1989), Earthquake analysis and response of intake-outlet tower, National Science Foundation, UCB/EERC-89/04, 189-240.
  8. Xangjian Xiao, Zengshun Chen, Jianting Zhou, Yanling Leng and Runchuan Xia (2017), Concrete plastic-damage factor for finite element analysis: Concept, simulation, and experiment, Advances in Mechanical Engineering, SAGE, 9(9), 1-10.
  9. KDS 54 17 00 (2019), Dam Seismic Design, Ministry of Environment, Korea.
  10. KISTEC (2019), Estimation Method for Seismic Performance of Existing Infra-structure(Dam), Korea Infrastructure Safety Corporation.