• Steel and Composite Structures
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• 제44권3호
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• pp.325-337
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• 2022

In this research, an earthquake-resistant structural system consisting of a pin-connected steel frame and a bracing with metallic fuses is proposed. Contrary to the conventional braced frames, the main structural elements are deemed to remain elastic under earthquakes and the seismic energy is efficiently dissipated by the damper-braces with an amplification mechanism. The superiority of the proposed damping system lies in easy manufacture, high yield capacity and energy dissipation, and an effortless replacement of damaged fuses after earthquake events. Furthermore, the stiffness and the yield capacity are almost decoupled in the proposed damper-brace which makes it highly versatile for performance-based seismic design compared to most other dampers. A special attention is paid to derive the theoretical formulation for nonlinear behavior of the proposed damper-brace, which is verified using analytical results. Next, a direct displacement-based design procedure is provided for the proposed system and an example structure is designed and analyzed thoroughly to check its seismic performance. The results show that the proposed system designed with the provided procedure satisfies the given performance objective and can be used for developing highly efficient low-damage structures.

• Steel and Composite Structures
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• 제50권6호
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• pp.721-734
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• 2024

In this research, the efficiency of a metallic energy dissipation device for seismic retrofit of an existing structure is evaluated by cyclic loading test. The proposed device, which is called multi-slit damper, is made of weak and strong slit dampers connected in series. Its energy dissipation mechanism consists of two stages: (i) yielding of the weak-slit damper under minor earthquakes; (ii) restraint of further deformations of the weak slit damper and activation of the strong slit damper under major earthquakes using a gap mechanism. A reinforced concrete (RC) frame with characteristics similar to soft-first-story structures is tested under cyclic loading before and after retrofit using the proposed device. The details of the experimental study are described and the test is simulated in an available commercial software to validate the analytical model of the damper. To further verify the applicability of the damper, it is applied to an analysis model of a 4-story structure with soft first story and its seismic performance is evaluated before and after retrofit. The experimental and analysis results show that the multi-slit damper is effective in controlling seismic response of structures.

• Earthquakes and Structures
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• 제3권1호
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• pp.83-95
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• 2012

Seismic damage and vulnerability of five historical masonry structures surveyed after the 1999 Kocaeli and Duzce, Turkey earthquakes are discussed in this paper. The structures are located in two neighboring cities that have been struck by five very large ($M_s{\geq}7.0$) earthquakes during the $20^{th}$ century alone. Older masonry mosques with arches and domes and their masonry minarets (slender towers) were among the most affected structures in this highly seismic region. While some of the religious and historical structures had virtually no damage, most structures suffered significant damage or collapsed. In the city of Bolu, for example, approximately 600-year-old Imaret, 500-year-old Kadi, 250-year-old Sarachane, and 100-year-old Yildirim Bayezid mosques suffered substantial structural damage after the 1999 earthquakes. Another historical mosque surveyed in Duzce partially collapsed. Most common factors contributing to deterioration of historical structures are also presented. Furthermore, a brief overview of issues associated with analysis and modeling of historical masonry structures is provided.

• Spatial Information Research
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• 제17권1호
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• pp.15-23
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• 2009

u-City의 계획, 건설 및 운영 관리를 지원하기 위한 "유비쿼터스도시의건설등에관한법률(이하 'u-City법'이라고 함)"이 제정 공포되었다(2008.3.28). u-City 통합운영센터(이하 '운영센터'라고 함)는 u-City의 의미와 상징성에 있어서 그 역할이 매우 크며, 그 제도적 정착이 u-City 실현에 가장 중요한 요소라고 하겠다. 운영센터의 설치는 u-City가 일반도시와 구별되는 가장 상징적 의미를 가질 뿐만 아니라, 일반도시가 u-City화 되기 위한 필수 구현요소에 해당한다. 또한 도시내 다양한 시설, 서비스 및 이를 지원하기 위한 관련 정보시스템과 인프라기반 등의 융복합화를 총괄적으로 관할하는 핵심시설로서 그 의미와 중요성이 매우 크다. 이러한 핵심역할과 상징성에도 불구하고 운영센터의 기초 개념정의, 구조 및 운영방안 등 전반적 사항에 대한 재정리와 이를 적극적으로 표준화하여 제도적으로 정착시키는 방안마련이 매우 미진한 것이 현실이다. 본 연구의 목적은 운영센터의 성공적 구현을 위한 법적 기반 조성의 일환으로 이제까지 거론된 운영센터의 제반 현안들을 정의와 위상을 중심으로 정리하고, 성공적 운영센터구현을 향한 제도적 정착방안 마련을 위한 기본방향과 추진전략을 제시하는데 있다.

• 한국구조물진단유지관리공학회 논문집
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• 제11권3호
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• pp.116-122
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• 2007

대도시의 콘크리트 구조물은 주로 탄산화에 노출되고 이에따라 매립된 철근은 시간이 경과함에 따라 부식이 발생한다. 콘크리트 구조물의 조사 및 진단에서, 건전부의 탄산화 깊이가 주로 평가되며, 이를 근거로 내구수명이 평가된다. 그러나 일반적으로 교각과 같은 매스 콘크리트 구조물에서는 적절한 타설을 위하여 조인트를 설치하게 되며, 초기재령에서 균열이 쉽게 발생한다. 본 연구에서는 20년 경과된 국내 대도시의 교각 구조물을 대상으로 탄산화 깊이를 평가하였으며, 건전부, 균열부, 시공이음부와 같은 국부적인 환경을 고려하여 탄산화 거동을 분석하였다. 균열부 및 시공이음부의 탄산화 깊이는 건전부에 비하여 크게 증가하였으며, 피복두께가 작은 구조물에 대해서는 이러한 영향을 고려하는 것이 바람직하게 평가되었다. 또한 균열폭의 함수로 균열부 탄산화 깊이를 예측할 수 있는 기법을 제시하였으며, 기존의 실태조사 결과와 비교하여 그 적용성을 검증하였다.

• 건축사
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• 통권545호
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• pp.96-100
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• 2014

• 건축사
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• 통권547호
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• pp.91-97
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• 2014

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.655-660
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• 2002

Major deterioration in concrete structures are salt attack and carbonation. Especially severe problems due to carbonation occur in tile concrete structures of city, tunnel, underground structures. Cracks in concrete during service life including early age due to hydration heat and/or shrinkage accelerate the diffusion of concrete so that the deterioration is also accelerated. In this study, carbonation depths of both non-cracked concrete and cracked concrete are evaluated and weight change test and TGA are carried out. Through the tests, a relation between water-cement ratio and carbonation depth is derived and also carbonation increase rate is derived in the function of crack width.

• Wind and Structures
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• 제2권2호
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• pp.127-131
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• 1999

This paper describes probabilistic characteristics of damping in a tall building based on the results of full-scale measurement. It is found, through statistical analysis of the damping data, that the probability density function(PDF) of damping at the high amplitude plateau can be well represented by Normal distribution (Gaussian distribution). A stochastic damping model is proposed to estimate amplitude-dependent damping for practical application.

• Steel and Composite Structures
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• 제44권2호
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• pp.283-294
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• 2022

In this study, a new seismic retrofit scheme of building structures is developed by combining a steel moment frame and steel slit plates to be installed inside of an existing reinforced concrete frame. This device has the energy dissipation capability of slit dampers with slight loss of stiffness compared to the conventional steel frame reinforcement method. In order to investigate the seismic performance of the retrofit system, it was installed inside of a reinforced concrete frame and tested under cyclic loading. Finite element analysis was carried out for validation of the test results, and it was observed that the analysis and the test results match well. An analytical model was developed to apply the retrofit system to a commercial software to be used for seismic retrofit design of an example structure. The effectiveness of the retrofit scheme was investigated through nonlinear time-history response analysis (NLTHA). The cyclic loading test showed that the steel frame with slit dampers provides significant increase in strength and ductility to the bare structure. According to the analysis results of a case study building, the proposed system turned out to be effective in decreasing the seismic response of the model structure below the given target limit state.