지진은 예상하지 못한 위치와 규모로 지반을 흔들어서 막대한 물적 및 인적 피해를 발생시킨다. 따라서 지진으로 인 한 진동을 최소화하고 피해를 방지하기 위하여 다양한 내진 기술 개발 연구가 수행되고 있다. 최근에는 우수한 성능을 나타내 는 다양한 신소재가 개발되고 있으며 이를 접목된 내진 기술 개발 연구가 하나의 트렌드가 되고 있다. 본 연구에서는 반영구적 이고 자동복원이 가능한 신소재를 적용한 새로운 개념의 영구마찰 자동복원 댐퍼를 제안하고 핵심 부재에 대한 물리적 특성 검 증 연구를 수행한다. 영구마찰 자동복원 댐퍼의 핵심은 복원 특성을 나타내는 초탄성 형상기억합금과 폴리우레탄을 부재로 장 착시키고 추가적인 마찰 특성을 나타내는 네오디뮴 영구자석을 사용하였다. 이러한 핵심 부재는 재료실험을 통해 특성을 검증 하였고 도출된 거동 응답 결과를 통해 영구마찰 자동복원 댐퍼의 구조실험 예측 거동을 도출하였다. 우수한 복원 성능을 나타 내는 영구마찰 자동복원 댐퍼는 최대 하중 성능과 에너지 소산 능력이 우수하여 구조물에 적용 시 강한 지진에도 버티면서 발 생된 손상도 회복 시킬 수 있을 것으로 기대된다.

This paper presents a systematic numerical analysis to obtain the re-centering and energy dissipation capacities of Chevron braced steel frames subjected to seismic loadings. In order to develop a recentering seismic resistance system excluding a residual deformation, the chevron braced steel frames are assembled using super-elastic SMA (Shape Memory Alloy) braces. The three-dimensional nonlinear finite element models are constructed to investigate the horizontal stiffness, hysteretic behaviors, and failure modes of the re-centering Chevron bracing system.

In this paper a systematic numerical analysis is performed to obtain the energy dissipation and re-centering capacities of diagonal steel braced frames subjected to cyclic loading. This diagonal steel bracing systems are fabricated with super-elastic SMA (Shape Memory Alloy) braces in order to develop a recentering seismic resistance system without residual deformation. The three-dimensional nonlinear finite element models are constructed to investigate the horizontal stiffness, drifts and failure modes of the re-centering bracing systems.

This study investigates a new type of recentering damper system combining a shape memory alloy bar with initial tension force is proposed to improve the recentering of frictional damper dissipating energy. The recentering damper is a damper device with improved energy dissipation capability as well as a reduction in maintenance and reinforcement cost, and can be said to be a low-cost, high-efficiency damper device conforming to domestic reality. For the implementation of the theoretical mechanism for the recentering damper device, various parameters were selected and the theoretical and detailed design were carried out. In order to verify the design validity of the recentering damper, a high dimensional finite element analysis model was fabricated and analyzed using cyclic load. As a result of comparing and analyzing the behavior response of the recentering damper, it proved its superiority in terms of energy dissipation ability and stability. Based on these results, we propose an optimized system design method of recentering damper.

This study is on the seismic response of new buckling-restrained braced frames(BRBFs) with superelastic SMA bracing system. The superelastic SMA materials can return to undeformed shape without additional heat treatments only after removal of applied loads. 6-story braced frame buildings were designed in accordance with the current design specifications in order to verify the performance of such bracing systems. Based on the anlysis results, Superelastic SMA bracing systems were also compared to those with conventional steel bracing system. And at last, analysis results show that the superelastic SMA bracing systems are very effective to reduce the residual inter-story drifts.

The researches related to active control systems utilizing superelastic shape memory alloys (SMA) have been recently conducted to reduce critical damage due to lateral deformation after severe earthquakes. Although Superelastic SMAs undergo considerable inelastic deformation, they can return to original conditions without heat treatment only after stress removal. We can expect the mitigation of residual deformation owing to inherent recentering characteristics when these smart materials are installed at the part where large deformation is likely to occur. Therefore, the primary purpose of this research is to develop concentrically braced frames (CBFs) with superelastic SMA bracing systems and to evaluate the seismic performance of such frame structures. In order to investigate the inter-story drift response of CBF structures, 3- and 6-story buildings were design according to current design specifications, and then nonlinear time-history analyses were performed on numerical 2D frame models. Based on the numerical analysis results, it can be comparatively verified that the CBFs with superelastic SMA bracing systems have more structural advantages in terms of energy dissipation and recentering behavior than those with conventional steel bracing systems.