고층건물의 자연 진동실험 및 시스템판별

국문 초록 (Abstract)

구조물의 특성치를 결정하기 위하여 18층 규모의 사무용 건물 3동에 대하여 자연진동 조건하에서 동적계측실험을 수행하였다. 대상건물은 기본적으로 보-기둥 골조시스템에 횡하중을 보다 효율적으로 지지하기 위하여 추가적으로 코아가 배치된 혼합 구조형식을 나타낸다. 매층 마다 측정한 일련의 진동기록으로부터 고유진동수, 모드형태 및 감쇠율 등과 같은 모달계수를 추출하기 위하여 최신주파수- 및 시간영역-기반 응답의존 시스템판별법인 FDD, pLSCF 및 SSI를 적용하였다. 3방법에 의하여 추출한 결과는 대체로 일치하였으나, 초기 FE 해석결과와 비교하여 저차 3개 고유진동수는 대략 1.2~1.7배나 되는 단단한 거동을 나타냈다. 진동응답으로부터 추출된값, 기준에서 제시하는 약산식 및 FE해석에 의하여 산정된 고유주기를 비교하여 보면, FE결과가 가장 유연한 거동을 예측하였으며, 높이를 변수로 하는 약산식이 추출된 값에 가장 근접한 결과를 나타냈다. 이러한 차이는 현재의 실험 추출치에는 콘크리트 균열 등과 같은강성저감 요인을 포함하고 있지 않으며, 또한 FE 해석치는 비구조체 및 사용된 재료의 실제성능 등과 관련된 강성증가 요소를 포함하고있지 않기 때문이다.

다국어 초록 (Multilingual Abstract)

Dynamic response measurements from natural excitation were carried out for three 18-story office buildings to determine their inherent properties. The beam-column frame system was adopted as a typical structural form, but a core wall was added to resist the lateral force more effectively, resulting in a mixed configuration. To extract modal parameters such as natural frequencies, mode shapes and damping ratios from a series of vibration records at each floor, the most advanced operational system identification methods based on frequency- and time-domain like FDD, pLSCF and SSI were applied. Extracted frequencies and mode shapes from the different identification methods showed a greater consistency for three buildings, however the three lower frequencies extracted were 1.2 to 1.7 times as stiff as those obtained using the initial FE models. Comparing the extracted fundamental periods with those estimated from the code equations and FE analysis, the FE analysis results showed the most flexible behavior, and the most simple equation that considers the building height as the only parameter correlated fairly well with test results. It is recognized that such a discrepancy arises from the fact that the present tests exclude the stiffness decreasing factors like concrete cracking, while the FE models ignore the stiffness increasing factors, such as the contribution of non-structural elements and the actual material properties used.

참고문헌 (Reference)

1 조순호, "초고층건물의 성능평가를 위한 응답의존 시스템판별 및 모델향상" 한국지진공학회 12 (12): 19-33, 2008

2 대한건축학회, "건설교통부 제정 건축물 하중기준 및 해설"

3 Reynders, E., "What’s New in System Identification for Experimental and Operational Modal Analysis" 2007

4 Peeters, B., "The PolyMAX frequency-domain method: a new standard for modal parameter estimation" 11 : 395-409, 2004

5 Applied Technology Council, "Tentative provisions for the development of seismic regulations for buildings ATC 3-06" ATC 1978

6 Peeters, B., "System identification and damage detection in civil engineering" Katholieke Univ. 2000

7 Van Overschee, P., "Subspace identification for linear systems: Theory—Implementation—Applications" Kluwer Academic Publishers 1996

8 Peeters, B., "Stochastic system identification for operational modal analysis: a review" 123 (123): 659-667, 2001

9 Peeters, B., "Reference-based stochastic subspace identification for output-only modal analysis" 13 (13): 855-878, 1999

10 Reynders, E., "Reference-based combined deterministic-stochastic subspace identification for experimental and operational modal analysis" 22 (22): 617-637, 2008

11 Brinker, R., "Modal identification from ambient responses using frequency domain decomposition" 2000

12 Standard Association of Australia, "Minimum design loads on structures, Part 4: Earthquake loads AS1170.4"

13 Midas IT, "Midas/Gen: General Structural Design System for Windows, Online Manual, V.7.1.1 (R2)"

14 Ho, B. L., "Effective construction of linear state variable models from input/output data" 14 : 545-548, 1966

15 Brincker R., "Automated Frequency Domain Decomposition for Operational Modal Analysis" 2007

16 Juang, J. -N., "Applied system identification" Prentice-Hall 1994

17 Cauberghe, B., "Applied frequency-domain system identification in the field of experimental and operational modal analysis" Vrije Universiteit Brussel 2004

18 Structural Vibration Solutions, "ARTeMIS Extractor: Ambient Response Testing and Modal Identification Software, User’s Manual"

19 Brinker, R., "A way of getting scaled mode shapes in output only modal testing" 2003