• Earthquakes and Structures
• /
• v.22 no.1
• /
• pp.95-107
• /
• 2022

This paper introduces a novel, rigorous, and efficient probabilistic methodology for the performance-based optimal design (PBOD) of semi-active tuned mass damper (SATMD) for seismically excited nonlinear structures. The proposed methodology is consistent with the modern performance-based earthquake engineering framework and aims to design reliable control systems. To this end, an optimization problem has been defined which considers the parameters of control systems as design variables and minimization of the probability of exceeding a targeted structural performance level during the lifetime as an objective function with a constraint on the failure probability of stroke length damage state associated with mass damper mechanism. The effectiveness of the proposed methodology is illustrated through a numerical example of performance analysis of an eight-story nonlinear shear building frame with hysteretic bilinear behavior. The SATMD with variable stiffness and damping have been designed separately with different mass ratios. Their performance has been compared with that of uncontrolled structure and the structure controlled with passive TMD in terms of probabilistic demand curves, response hazard curves, fragility curves, and exceedance probability of performance levels during the lifetime. Numerical results show the effectiveness, simplicity, and reliability of the proposed PBOD method in designing SATMD with variable stiffness and damping for the nonlinear frames where they have reduced the exceedance probability of the structure up to 49% and 44%, respectively.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.10 no.5 s.51
• /
• pp.107-115
• /
• 2006

The power supply system is one of the most important infrafacilities which should maintain their inherent function during and after earthquakes. This study was performed to analyze dynamic characteristics and seismic performance of Korean typical 154kV transformer porcelain bushing. For the purpose of this study, actual 154kV porcelain bushings were selected and tested on the shaking table. The vibration tests consist of modal identification tests, seismic performance tests, and fragility tests. The sine sweep waves, artificial earthquake waves, and continuous resonant sine waves were used as shaking table motions. This paper describes the test specimens, shaking facilities, and test methods. Natural frequencies and damping ratios of the bushing have been evaluated from the experimental data. The failure mode and the performance level of the Korean transformer bushing have been first identified in this study.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2009.04a
• /
• pp.383-386
• /
• 2009

본 연구는 HAZUS에서 제시하고 있는 비보강 조적조 건축물의 구조적 손상상태에 대한 지진취약도함수와 관련하여 층간변위율 및 스펙트럼 변위 등의 매개변수를 평가하고 또한 국내 상황에 적합한 기존 비보강 조적조 건축물의 지진취약도곡선의 도출을 목적으로 하였다. 국내 상황을 고려한 지진피해를 추정하기 위하여 먼저 기존 비보강 조적조 건축물의 현황파악 및 지진취약도함수 산출방법을 분석하였다. 일반적으로 HAZUS에서 제시하고 있는 지진취약도함수는 역량스펙트럼을 변환시킨 가속도-변위응답 스펙트럼법을 기본적으로 사용하는 상황으로 국내 기존 비보강 조적조 건축물에 대한 지진취약도함수 개발을 위하여 Midas GEN Ver.741 구조해석프로그램을 사용하여 실제 23개동의 비보강 조적조 건축물을 대상으로 역량스펙트럼 해석을 수행하였다. 연구결과를 통하여 지진취약도함수의 주요 매개변수인 손상상태별 층간변위율 및 스펙트럼 변위를 제시하였다.

• Structural Engineering and Mechanics
• /
• v.82 no.3
• /
• pp.385-400
• /
• 2022

Sky-bridges between adjacent buildings can enhance lateral stiffness and limit the impact of lateral forces. This study analysed the structural capabilities and dynamic performances of sky-bridge-coupled buildings under various sets of ground motions. Finite Element (FE) analyses were carried out with the link being iteratively repositioned along the full height of the structures. Incremental dynamic analysis (IDA) and probabilistic damage distribution were also applied. The results indicated that the establishment of sky-bridges caused a slight change in the natural frequency and mode shapes. The sky-bridge system was shown to be efficient in controlling displacement and Inter-Storey Drift Ratio (%ISDR) and reducing the probability of damage in the higher floors. The most efficient location of the sky-bridge, for improving its rigidity, was found to be at 88% of the building height. Finally, the effects of two types of materials (steel and concrete) and end conditions (hinged and fixed) were studied. The outcomes showed that coupled buildings with a sky-bridge made of steel with hinged connection could withstand ground motions longer than those made of concrete with fixed connection.