Because a smart isolation system cannot be used as a base isolation system for tall buildings, top-story or mid-story isolation systems are required. In this study, adaptability of a smart top-story isolation system for reduction of seismic responses of tall buildings in regions of low-to-moderate seismicity has been investigated. To this end, 20-story example building structure was selected and an MR damper and low damping elastomeric bearings were used to compose a smart base isolation system. Artificial earthquakes generated based on design spectrum of low-to-moderate seismicity regions are used for structural analyses. Based on numerical simulation results, it has been shown that a smart top-story isolation system can effectively reduce both structural responses and isolation story drifts of the building structure in low-to-moderate seismicity regions in comparison with a passive top-story isolation system.

현재까지 스마트 면진시스템은 일본이냐 미국 같은 강진지역에서 개발되고 적용되어 왔다. 이렇게 강진지역에 있는 건축물을 지진하중으로부터 보호하기 위하여 개발된 스마트 면진시스템은 우리니라와 같은 중약진 지역에 있는 건축물에 그대로 적용되기에는 많은 한계점이 있다. 따라서 본 연구에서는 강진지역에 건설되는 건축물을 위한 스마트 면진시스템을 중약진 지역에 건설되는 건축물에 작용하였을 때 발생하는 문제점음 검토해보았다. 이를 위하여 예제구조물로 대공간 아치구조물을 선택하였고 스마트 면전시스템은 MR 감쇠기와 저감쇠 탄성베어링을 사용하여 구성하였다. 강진지역과 중약진 지역에서 발생하는 지진하중으로는 기존에 발생한 역사지진을 바탕으로 인공지진을 생성하였다. 수치해석결과 강진지역에 건설되는 대공간구조물을 위하여 개발된 스마트 면진시스템을 그대로 중약진 지역에 적용하면 면진효과가 상당히 줄어들므로 스마트 제어장지의 용량이 중약진 지역에 맞추어 주의 깊게 설계되어야 함을 알 수 있었다.

최근의 근단층지반운동인 Northridge 지진(1994, 미국), Kobe 지진(1995, 일본), Izmit 지진(1990, 터키)은 큰 수직성분의 영향으로 건축물 및 교량에 심각한 손상을 주었다. 일반적인 건축구조물의 내진설계에서 지진하중의 수직성분을 고려하여 설계하는 경우는 드물다. 본 연구에서는 지진하중의 수직성분 영향의 고려 유무에 따른 예제구조물의 기둥부재의 축력의 변화와 부재 단부의 소성힌지회전각을 산정하여 시스템의 손상상태를 평가하여 보았다. 해석결과 축력의 증가는 기둥부재의 손상에 의한 전체 구조시스템의 story collapse mechanism의 가능성을 주게 되므로 근단층지반운동이 예상되는 부분에서는 지진하중의 수직성분에 대한 영향을 고려하여야할 것으로 판단된다.

For areas such as the Korean Peninsula, which have moderate seismic activity but no available records of strong ground motion, synthetic seismograms can be used to evaluate ground motion without waiting for a strong earthquake. Such seismograms represent the estimated ground motions expected from a set of possible earthquake scenarios. Local site effects are especially important in assessing the seismic hazard and possible ground motion scenarios for a specific fault. The earthquake source and rupture dynamics can be described as a two-step process of rupture initiation and front propagation controlled by a frictional sliding mechanism. The seismic wavefield propagates through heterogeneous geological media and finally undergoes near-surface modulations such as amplification or deamplification. This is a complex system in which various scales of physical phenomena are integrated. A unified approach incorporates multi-scale problems of dynamic rupture, radiated wave propagation, and site effects into an all-in-one model using a three-dimensional, fourth-order, staggered-grid, finite-difference method. The method explains strong ground motions as products of complex systems that can be modified according to a variety of fine-scale rupture scenarios and friction models. A series of such deterministic earthquake scenarios can shed light on the kind of damage that would result and where it would be located.

국내와 같이 풍하중이 지배 횡하중으로 작용하는 중/약진대라 할지라도 초고층건물의 설계를 담당하고 있는 구조기술자는 특정세기의 잠재지진(가령 재래기 500년 정도의 설계용지진동 또는 재래기 2400년 정도의 최대한도지진)이 구조시스템에 미칠 수 있는 구조적 영향을 합리적으로 평가할 수 있어야 한다. 본 연구에서는 중/약진대로 분류되는 국내의 지진환경하에서, 국내 구조사무소의 평균적 실무관행에 따라 내풍설계된 초고층 철골중심가새골조를 가정하여 지진해석을 수행하고 내진성능을 평가하였다. 내풍설계에서 요구되는 사용성 요건 및 횡력저항 철골부재에 부과돠는 폭-두께비 제한 등으로 인해 상당한 크기의 시스템 초과강도(system overstrength)가 유입됨을 확인할 수 있었다. 내풍설계과정에서 부차적으로 기인하는 이 시스템 초과강도로 인하여, 본 연구의 세장비 6 이상의 철골조 초고층 중심가새골조는 2400년 재래기의 최대한도지진에 대해서도 즉시입주 가능한 거동수준에서 탄성적으로 저항할 수 있음을 확인하였다.

This paper reports a part of research work on earthquake resistance consideration in regions of moderate seismicity, which is being carried out in the Department of Civil Engineering, Hong Kong University of Science & Technology. The possible seismic hazard in Hong Kong, which is located in a region of moderate seismicity, is described. A case study is presented to compare the wind and earthquake effects on Hong Kong buildings and to assess whether seismic analysis and desing is necessary for building structure. Potential problems of reinforced concrete buildings under earthquake effects in regions of moderate seismicity are discussed.

Korea is located in either low of moderate seismicity continental region. It is realized that the design codes and underlying design concept of high seismicity region may not be a, pp.opriate to low and moderate seismicity regions. The aim of this paper is to search seismic design concept that is deemed to be a, pp.opriate to low and moderate seismicity regions. To this end, the seismicity of Korea will be introduce first and important aspects of seismic design in moderate seismicity region will be discussed. The two-level code system that is going to be adopted in the future seismic regulations of Korea will be introduced.

In order to reduce seismic responses of a structure, additional dampers and vibration control devices are generally considered. Usually, control performance of additional devices are investigated for optimal design without variation of characteristics of a structure. In this study, multi-objective integrated optimization of structure-smart control device is conducted and possibility of reduction of structural resources of a building structure with smart top-story isolation system has been investigated. To this end, 20-story example building structure was selected and an MR damper and low damping elastomeric bearings were used to compose a smart base isolation system. Artificial earthquakes generated based on design spectrum of low-to-moderate seismicity regions are used for structural analyses. Based on numerical simulation results, it has been shown that a smart top-story isolation system can effectively reduce both structural responses and isolation story drifts of the building structure in low-to-moderate seismicity regions. The integrated optimal design method proposed in this study can provide various optimal designs that presents good control performance by appropriately reducing the amount of structural material and damping device.

Adaptability of a smart top-story isolation system for reduction of seismic responses of tall buildings in regions of low-to-moderate seismicity has been investigated in this study. To this end, 20-story example building structure was selected and an MR damper and low damping elastomeric bearings were used to compose a smart base isolation system. Artificial earthquakes generated based on design spectrum of low-to-moderate seismicity regions are used for structural analyses.