• 한국지반공학회논문집
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• 제20권2호
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• pp.47-58
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• 2004

강관은 Northridge 지진이 발생했을 당시 산사태가 일어나는 언덕이나 산악지역에 매설되어 있었다. 본 논문은 지리정보체계(GIS) 시스템에서 위치에 따라 강관을 서로 다른 유형별로 분류하고 정의하였다. 이 논문은 지반속도와 강관의 손상관계를 분석하고 Northridge 지진 시 발생한 산사태의 영향을 받았던 지역을 조사하였다. 하나의 주목할 만한 사실은 Northridge 지진 후 강관의 손상률이 다른 종류의 매설관, 특히 캐스트아이런(CI)보다 더 높았다는 것이다. Northridge 지진으로 인한 상대적으로 높은 강관의 손상률은 가장 큰 내부압력을 요하는 곳에서의 설치관례와 부식으로 인한 영향으로 해석될 수 있다.

• 한국지진공학회논문집
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• 제5권3호
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• pp.9-17
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• 2001

본 논문은 지진으로 인한 라이프라인과 공공설비에 대한 위험 지역 묘사 및 물리적 손실추정에 중점을 두었으며, 또한, 지리정보시스템(GIS)과 지진영향의 공간적 특성 평가에 사용된 송수관망을 통한 GIS 적용이 강조되었다. 1994년도의 Northridge 지진에서 얻어진 물 공급 능력이 기록된 GIS 자료를 통하여 매장된 라이프라인 피해와 다양한 지진 매개변수들의 상호 관계가 검증되었으며, 통계학적으로 가장 뚜렷한 상호 관계를 갖는 지진 매개변수들이 발견되었다. Northridge지진으로부터 얻어진 GIS 자료를 이용하여 송수관의 손상률, 종류, 직경, 그리고 다양한 지진 매개변수들이 평가되었다.

• Structural Engineering and Mechanics
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• 제11권6호
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• pp.663-672
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• 2001

Numerous failures in welded connections in steel moment-resisting building frames (SMRF) were observed when buildings were inspected after the 1994 Northridge Earthquake. These observations raised concerns about the effectiveness of such frames for resisting strong earthquake ground motions. The behavior of SMRFs during an earthquake must be assessed using nonlinear dynamic analysis, and such assessments must permit the deterioration in connection strength to capture the behavior of the frame. The uncertainties that underlie both structural and dynamic loading also need to be included in the analysis process. This paper describes the analysis of one of approximately 200 SMRFs that suffered damage to its welded beam-to-column connections from the Northridge Earthquake is evaluated. Nonlinear static and dynamic analysis of this SMRF in the time domain is performed using ground motions representing the Northridge Earthquake. Subsequently, a detailed uncertainty analysis is conducted for the building using an ensemble of earthquake ground motions. Probability distributions for deformation-related limit states, described in terms of maximum roof displacement or interstory drift, are constructed. Building fragilities that are useful for condition assessment of damaged building structures and for performance-based design are developed from these distributions.

• 한국지진공학회논문집
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• 제3권4호
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• pp.33-46
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• 1999

캘리포니아의 강구조 모멘트프레임은 1994년 노스리지 지진시 6.8의 규모와 진앙지에서 근접한 지리적인 악조건에도 불구하고 붕괴나 인명피해 없이 잘 견뎌냈다. 그러나 이후 시행된 조사에서 경제적으로 지진시 안전하다고 믿어져 널리 쓰인 welded flange-bolted web(WFBW) 강접합부(moment connection)의 기둥과 용접의 경계면에서 취성 파괴가 다수 발견되었다. 이논문은 선형파괴역학과 노스리지진이후의 WFBW 강접합부 실험을 이용하여 WFBW 강접합부와 노스리지지진이후 기존 강접합부의 대안으로 추천되고 있는 reduced beam section (RBS) 강접합부의 취성 파괴강도를 결정하는 수치적인 방법을 제안하고 이를 이용하여 이들 강접합부의 취성 파괴모드를 추정하였다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1997년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Fall 1997
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• pp.173-181
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• 1997

To investigate the effects of haunch repair on the system seismic performance of steel moment-resisting frames (steel MRFs), a case study was conducted for a 13-story frame damaged during the 1994 Northridge earthquake. It was assumed that only those locations with reported damage would be repaired with haunches. A new analytical modeling technique for the dual panel zone developed by the author was incorporated in the analysis. Both the inelastic static and dynamic analyses did not indicate detrimental side effects resulting from the repair. As a result of the increased strength in dual panel zones, yielding in these locations were eliminated and larger plastic rotation demand occurred in the beams next to the shallow end of the haunches. Nevertheless, the beam plastic rotation demand produced by the Sylmar record of 1994 Northridge earthquake was still limited to 1.7% radians. The repair resulted in a minor increase in earthquake energy input. In the original structure, the panel zones should dissipate about 80%(for the Oxnard record) and 70%(for the Sylmar record) of the absorbed energy, assuming no brittle failure of moment connections. After repair, the energy dissipated in the panel zones and beams were about equal.

• 한국지반공학회논문집
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• 제20권7호
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• pp.15-24
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• 2004

본 논문은 1994 Northridge 지진에 의해 발생된 주거건물손상에 관하여 건물 교체시의 가격에 대한 상대적 수리비용의 개념으로 GIS기반의 손상평가에 관하여 기술하였다. 빌딩손상은 164개의 서로 다른 지역에서 얻어진 지진기록으로부터 유도된 지진매개변수와 빌딩위치 및 안전조사보고서를 바탕으로 평가하였다. 본 논문은 가장 심한 건물피해를 받은 위치를 규명하는 인식 알고리즘이 GIS를 통하여 개발되었다. 이러한 알고리즘은 지진 후 신속한 응급조치와 위성으로부터 얻어진 데이터를 짧은 시간에 분석할 수 있는 프레임을 제공한다.

• Computational Structural Engineering : An International Journal
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• 제1권1호
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• pp.1-9
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• 2001

Collapse behavior of Mission-Gothic Undercrossing under Northridge earthquake is studied by performing nonlinear time-history analysis and three-dimensional nonlinear finite element method for flared columns. Bridge structural model is characterized as three-dimensional with consideration of columns, superstructures, and abutment conditions. Three components of ground motion, corresponding to bridge's longitudinal, transverse, and vertical direction and their combinations are used to investigate bridge collapse. Studies indicate that bridge collapse is dominantly caused by transverse ground motion and the consideration of three-dimensional ground motion leads to a more accurate assessment. Failure mechanism of flared columns is analyzed applying nonlinear finite element method. Reduction of column capacity is observed due to orientation of flare. Further investigation demonstrates that the effects of flare play an important role in predicting of bridge failure mechanism. Suggestions are offered to improve the performance of bridges during severe earthquake.

• 공학논문집
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• 제8권1호
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• pp.5-11
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• 2006

In order to evaluate the seismic performance of a reinforced concrete building structure, four different analyses are carried out. Firstly, conventional pushover analysis with code-specified inverted triangular load pattern is conducted. Secondly, the pushover analysis with uniform load pattern is performed. Thirdly, adaptive pushover analyses with spectral amplification for both EC 8 artificial and Northridge earthquake are carried out. Lastly, Incremental dynamic analyses under a number of scaled PGA for both EC 8 artificial and Northridge earthquake record are performed. Comparative studies demonstrate that the adaptive pushover analysis may be able to explain the response characteristics that conventional pushover analysis with fixed load distribution fails to capture.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.381-384
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• 2006

In order to evaluate the seismic performance of a reinforced concrete building structure, four different analyses are carried out. Firstly, conventional pushover analysis with code-specified inverted triangular load pattern is conducted. Secondly, the pushover analysis with uniform load pattern is performed. Thirdly, adaptive pushover analyses with spectral amplification for both EC 8 artificial and Northridge earthquake are carried out. Lastly, incremental dynamic analyses under a number of scaled PGA for both EC 8 artificial and Northridge earthquake record are performed. Comparative studies demonstrate that the adaptive pushover analysis may be able to explain the response characteristics that conventional pushover analysis with fixed load distribution fails to capture.

• Steel and Composite Structures
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• 제5권4호
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• pp.271-287
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• 2005

The seismic behavior of two steel moment-resisting frames, which satisfy all the current seismic design requirements, are evaluated and compared in the presence of pre-Northridge connections denoted as BWWF and an improved post-Northridge connections denoted as BWWF-AD. Pre-Northridge connections are modeled first as fully restrained (FR) type. Then they are considered to be partially restrained (PR) to model their behavior more realistically. The improved post-Northridge connections are modeled as PR type, as proposed by the authors. A sophisticated nonlinear time-domain finite element program developed by the authors is used for the response evaluation of the frames in terms of the overall rotation of the connections and the maximum drift. The frames are excited by ten recorded earthquake time histories. These time histories are then scaled up to produce some relevant response characteristics. The behaviors of the frames are studied comprehensively with the help of 120 analyses. Following important observations are made. The frames produced essentially similar rotation and drift for the connections modeled as FR type and PR type represented by BWWF-AD indicating that the presence of slots in the web of beams in BWWF-AD is not detrimental to the overall response behavior. When the lateral displacements of the frames are significantly large, the responses are improved if BWWF-AD type connections are used in the frames. This study analytically confirms many desirable features of BWWF-AD connections. PR frames have longer periods of vibration in comparison to FR frames and may attract lower inertia forces. However, calculated periods of the frames of this study using FEMA 350 empirical equation is longer than those calculated using dynamic characteristics of the frames. This may result in even lower design forces and may adversely influence the design.