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Seismic Behavior and Estimation for Base Isolator Bearings with Self-centering and Reinforcing Systems

자동복원 및 보강 시스템과 결합된 면진받침의 지진거동과 평가

  • 허종완 (국립인천대학교 도시환경공학부, 국립인천대학교 방재연구센터)
  • Received : 2015.04.28
  • Accepted : 2015.07.02
  • Published : 2015.10.01

Abstract

Flexible base isolation bearings that separate superstructure from ground have been widely used in the construction field because they make a significant contribution to increasing the fundamental period of the structure, thereby decreasing response acceleration transmitted into the superstructure. However, the established bearing devices installed to uphold the whole building give rise to some problems involved with failure and collapse due to lack of the capacity as modern structures are getting more massive and higher. Therefore, this study suggests new isolation bearings assembled with additional restrainers enabled to reinforcing and recentering, and then evaluates their performance to withstand the seismic load. The superelastic shape memory alloy (SMA) bars are installed into the conventional lead-rubber bearing (LRB) devices in order to provide recentering forces. These new systems are modeled as component spring models for the purpose of conducting nonlinear dynamic analyses with near fault ground motion data. The LRB devices with steel bars are also designed and analyzed to compare their responses with those of new systems. After numerical analyses, ultimate strength, maximum displacement, permanent deformation, and recentering ratio are compared to each model with an aim to investigate which base isolation models are superior. It can be shown that LRB models with superelastic SMA bars are superior to other models compared to each other in terms of seismic resistance and recentering effect.

지반과 상부 구조물 사이의 경계에서 유연성이 확보된 지진동 격리 받침 시스템을 설치한 후에 전체 구조물의 고유 주기를 연장하고 구조물에 전달되는 지진 가속도를 저감하여 구조물을 보호하는 면진 설계 방식이 최근 건설 현장에서 널리 활용되고 있다. 하지만 도심지의 현대 구조물이 점차 대형화 및 고층화 되면서 기존의 면진 받침을 그대로 사용하기에는 지진 발생시 저항 능력의 부족으로 인한 전단파괴 혹은 잔류변형이 발생하여 구조물의 사용성 향상을 위한 보수 및 붕괴 위험에 따른 철거의 문제점을 발생시킨다. 따라서 본 연구에서는 기존에 주로 사용되는 면진 받침의 저항 강도와 복원성을 향상시키기 위하여 부가적인 개장 시스템을 설치하고 지진 하중에 대한 성능을 평가하고자 한다. 초탄성 형상기억합금 소재의 보강 봉을 납 적층 고무 받침에 설치한 면진 시스템을 설계하고 단자유도 스프링 모델로 모형화하여 지진 데이터를 활용하고 비선형 동적 해석을 실시하였다. 본 연구에서 제안된 면진 시스템이 성능적인 우수성을 입증하기 위하여 기존에 사용된 면진 받침과 여기에 추가로 강재 봉으로 보강된 면진 시스템과의 극한 전단 저항력, 복원성 및 잔류변형 발생 등을 해석을 통하여 비교 평가하였다. 그 결과 초탄성 형상기억합금 소재의 제어 봉으로 보강된 면진 받침이 다른 면진 받침과 비교하여 지진저항 성능에 있어서 우수함을 확인하였다.

Keywords

References

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