• Structural Engineering and Mechanics
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• 제82권6호
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• pp.801-812
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• 2022

To better promote the development of fabricated buildings, this paper studies the seismic behavior of precast concrete beam-column bolted joint under vertical low cyclic loading. The experimental results show that cracks appear in the beam-column joint core area. Meanwhile, the concrete and the grade 5.6 bolts are damaged and deformed, respectively. Specifically, the overall structure of the beam-column joint remains intact, and the bolts have good energy dissipation capacity. Based on the experimental study, a new method of beam-column bolted connection is proposed in simulation analysis. The simulation results show that the bolts deform in the core area of the new beam-column joint, which enhances the concrete shear capacity legitimately and protects the T-end of the beam against shear failure. To summarize, both the experimental joint and the simulated joint prolong the service life by replacing the bolts under the seismic loading. The research results provide a reference for applications of the fabricated beam-column joint.

• Nuclear Engineering and Technology
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• 제56권2호
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• pp.644-654
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• 2024

After the Tohoku earthquake and tsunami (Japan, 2011), regulatory efforts to mitigate external hazards have increased both the safety requirements and the total capital cost of nuclear power plants (NPPs). In these circumstances, identifying not only disaster robustness but also cost-effective capacity setting of NPPs has become one of the most important tasks for the nuclear power industry. A few studies have been performed to relocate the seismic capacity of NPPs, yet the effects of multiple hazards have not been accounted for in NPP capacity optimization. The major challenges in extending this problem to the multihazard dimension are (1) the high computational costs for both multihazard risk quantification and system-level optimization and (2) the lack of capital cost databases of NPPs. To resolve these issues, this paper proposes an effective method that identifies the optimal multihazard capacity of NPPs using a multi-objective genetic algorithm and the two-stage direct quantification of fault trees using Monte Carlo simulation method, called the two-stage DQFM. Also, a capacity-based indirect capital cost measure is proposed. Such a proposed method enables NPP to achieve safety and cost-effectiveness against multi-hazard simultaneously within the computationally efficient platform. The proposed multihazard capacity optimization framework is demonstrated and tested with an earthquake-tsunami example.

• 한국지진공학회논문집
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• 제10권1호
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• pp.63-74
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• 2006

원전 구조물 및 주요기기의 지진 안전성 평가에서는 내진성능을 정량화하는 방법으로 취약도 분석이 사용되고 있다. 지진취약도 분석은 격납건물의 설계 시 반영된 보수성을 배제한 실질적인 내진성능을 평가하는 것으로 이러한 보수성을 성능 및 응답에 관련된 확률론적 변수로 고려하여 평가하게 된다. 본 연구에서는 비선형 지진 해석으로부터 얻은 구조물의 변위응답을 기초로 한 지진취약도 분석 방법을 제시하였다. 또한 원전부지에서 선정된 발생가능한 근거리지진, 원거리지진, 설계지진 및 확률론적 시나리오지진을 시나리오지진으로 선정하고 이들 지진동에 대한 비선형 지진해석을 통하여 한국 표준형 원전 격납건물의 지진취약도를 평가하였다.

• 한국전산구조공학회논문집
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• 제27권4호
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• pp.255-263
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• 2014

본 연구에서 피뢰기의 지진취약도 해석은 역량스펙트럼 방법을 이용하여 수행하였다. 많은 구조부재를 가진 구조물의 지진취약도 해석은 수십 혹은 수백 개의 지진하중에 대한 비탄성 지진응답을 계산하는 것이 요구되기 때문에 역량스펙트럼 방법과 같은 간단한 방법이 응답이력해석 보다 적합하다. 일반적으로 역량스펙트럼 방법에 의해 평가된 지진응답의 정확성은 응답이력해석에 의한 결과의 정확성 보다 떨어진다. 역량스펙트럼 방법의 정확성을 향상시키기 위하여 등가단자유도 방법과 성능점 계산기법이 적용되었다. 지진취약도에 대한 지진에 대한 지반효과를 평가하기 위하여 60개의 다른 지반종류의 지반운동을 입력지진으로 선정하여 사용하였다. 역량스펙트럼 방법과 응답이력해석에 의한 지진취약도 곡선의 비교로부터 역량스펙트럼 방법에 의한 지진취약도 곡선이 응답이력해석에 의한 지진취약도 곡선과 상당히 유사함을 알 수 있었다. 또한, 피뢰기의 주된 지진에 의한 파괴모드는 부싱의 파손임을 알 수 있었다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.322-329
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• 2000

Current seismic design codes for building structures are based on the methods which can provide enough capacity to satisfy objected performance level and exactly evaluate the seismic performance of buildings. Pushover analysis of fast becoming an accepted method for the seismic evaluation of building structures. The popularity of this approximate, nonlinear static analysis method is due to its conceptual simplicity and ability to graphically describe a capacity and demand of structure. However, some of the shortcomings of the pushover analysis, especially for longer period and irregular buildings, is the inability of method to identify failure mechanisms due to effects of higher modes. In this paper proposed lateral load pattern which includes the contribution of higher modes of vibration for irregular building structure and compared to seismic response obtained by time history.

• Structural Engineering and Mechanics
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• 제58권2호
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• pp.379-395
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• 2016

A seismic strengthening method using Velcro is proposed to improve the seismic performance of columns in RC frame structures. The proposed method was evaluated experimentally using three fabricated RC specimens. Velcro was wrapped around the columns of the RC-frame specimen to prevent concrete spall falling. The reinforcing performance of the Velcro was determined from comparison of results on seismic performance (i.e., strength, displacement, failure mode, displacement ductility capacity and amount of dissipated energy). As the displacement of the reinforced specimens was increased, the amount of dissipated energy increased drastically, and the displacement-ductility-capacity of the reinforced specimens also increased. The final failure mode of RC frame structure was changed. As a result, it was concluded that the proposed seismic strengthening method using Velcro could be used to increase the displacement ductility of RC columns, and could be used to change the final failure mode of RC-frame structures.

• Structural Engineering and Mechanics
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• 제3권6호
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• pp.569-581
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• 1995

In this paper, the seismic behavior of a 10-story building equipped with viscoelastic dampers is analyzed. The effects of ambient temperature, the thickness, the total area, and the position of the viscoelastic dampers are studied. Results indicate that the energy-absorbing capacity of viscoelastic damper decreases with increasing the ambient temperature. The thickness and the total area of viscoelastic dampers also affect the seismic mitigation capacity. The thickness cannot be too small, which is not effective in vibration reduction, nor can it be too large, which not only increases the cost but also reduces the seismic resistance. The total area of viscoelastic dampers should be determined properly for optimum damper performance at the most economical design. The mounting position of viscoelastic dampers also influences the structure's seismic performance. Numerical results show that, if properly equipped, the VE dampers can reduce the structural response both floor displacement and story shear force and increase the overall level of damping in structures during earthquakes.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1999년도 추계학술발표회요약집
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• pp.370.2-370
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• 1999

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.174-177
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• 2006

To restore an earthquake damaged community as quickly as possible, well-prepared reconstruction strategy is most essential. This paper reports experimental data on the seismic capacity of diagonal reinforced HPFRCC coupling beams with the Japanese Standard for Seismic Evaluation of Existing RC Buildings. Precast Based on the experimental results, HPFRCC specimen have more residual seismic capacity than RC specimen, but much study is necessary to improve the accuracy of the damage evaluation.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 춘계 학술발표회논문집
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• pp.259-266
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• 2003

This paper begins with the seismic performance evaluation of an existing building, which exhibits the need of additional damping to reduce its response. Required damping ratio is found by capacity spectrum method to satisfy a target response. It is expressed with the design parameter of active mass damper by adopting Linear Quadratic Regulator, Optimal gains are obtained and then weighting matrices are found. Finally the seismic performance by added active mass damper is demonstrated, which satisfies the target response.