• Computational Structural Engineering
• /
• v.5 no.4
• /
• pp.24-28
• /
• 1992

구조물의 지진응답해석에 사용하는 입력지진동 특성을 구성하는 요소로서, (a) 지진동의 최대 지반가속도치 (b) 지진동의 위상특성 (c) 지진동의 계속시간 (d) 지진동의 스펙트럼 특성 등을 들 수 있다. 그러나 이들 지진동을 구성하는 각 요소들이 구조물의 응답 및 손상에 직접 관련되어 지진동의 강도를 나타내는 척도로써 나타나는 것은 아니다. 그리고 이들 지진동 특성을 규정하는 각 인자와 구조물의 응답특성 및 구조물의 손상도와의 관계를 규명하는 것이 입력지진동의 설정에 있어서 매우 중요하다고 생각된다. 또한 탄성 응답특성과 탄소성 응답특성과의 관계를 규명하여, 탄성 응답스펙트럼이 구조물의 손상에 미치는 효과를 정량적으로 파악할 수 있다면 강지진에 대한 구조물의 내진설계는 보다 간편하게 할 수 있을 것으로 생각된다.

• Journal of Korean Society of Steel Construction
• /
• v.22 no.1
• /
• pp.13-20
• /
• 2010

Seismic risk assessment of railway bridges is an important issue for a transportation network, because loss of functionality of railway bridges could result in severe disruption of the railway line, as no redundant routing systems generally exist. Although many studies have been conducted by numerous researchers regarding fragility analyses of bridge structure, little or no studies have been done for fragility analyses of a class of bridge structures considering their geometric variability. This study performs a fragility analysis for Track-on Steel-Plate-Girder (TOSPG) railway bridges in Korea considering their span variability. Seismic fragility curves are developed for a series of bridges with different spans varying from 2 to 15. At last, the fragility curves for the whole TOSPG bridges in Korea are also developed using the total probability theorem. This study is expected to effectively contribute to the seismic risk assessment of railway lines, where a number of bridges are present.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.1
• /
• pp.127-135
• /
• 2018

With the nation showing increasing concern for earthquakes, there have been several methods for the analysis of earthquakes and evaluation of damage. Nevertheless, there is no clear standard to assess the seismic damage to structures quantitatively. Accordingly, this study conducted seismic analysis of several forms of seismic waves and actual seismic load, targeting the cable stayed bridge, which is supported by a cable and proposes a method for evaluating the damage based on the results. The damage index was calculated based on the tilting of the pylon of the cable-stayed bridge and the characteristics of physical seismic damage was suggested with 4 levels, such as A, B, C, and D. In addition, it is not proper to simply judge that the seismic damage index is obtained as large or small at all times depending on the seismic analysis method. Although this study focused on the proposal seismic damage index and an evaluation of the damage targeting the cable stayed bridge, the result was applied to a structure with a similar maximum displacement response.

• Journal of Korean Society of Steel Construction
• /
• v.21 no.1
• /
• pp.45-53
• /
• 2009

More than 40% of railway bridges on the conventional lines in Korea consist of track-on-steel plate girder (TOSPG) bridges. This type of bridge is typically designed without considering seismic loadings, as most of them were built before 1970. The seismic performance of this particular type of bridge could be upgraded through various seismic retrofit schemes, and seismic risk assessment could play a key role in decision-making on the level of the seismic retrofit. This study performed a seismic risk assessment of TOSPG bridges in Korea. The seismic damage of several crucial components of TOSPG bridges--fixed bearings, free bearings, and piers--were probabilistically estimated, and their seismic fragility curves were developed. The probability that the components would exceed their predefined limit states was also calculated by combining the fragility curves and the seismic hazard function. The analysis showed that the piers of TOSPG bridges, which are made of plain concrete without rebars, have relatively low risk against seismic loadings in Korea. This is because the mass of the superstructures of TOSPG bridges is relatively small, and hence, the seismic loading being transferred to the piers is minimal. The line-type bearings typically used for TOSPG bridges, however, are exposed to a degree of seismic risk. Among the bearings, the probability of the free-end bearings and the fixed-end bearings exceeding the slight damage state in 50 years was found to be 12.78% and 4.23%, respectively. The gap between these probability values lessened towards more serious damage states. This study could effectively provide an engineering background for decision-making activities on the seismic retrofit of railway bridges.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.38 no.5
• /
• pp.635-643
• /
• 2018

In the present study, influence of earthquake intensity range on seismic fragility analysis of a RC bridge has been evaluated. For this purpose, a RC bridge damaged by a past earthquake has been selected, and analytical model of the bridge has been developed for nonlinear dynamic time-history analysis. A total of 25 recorded earthquake motions have been employed for the nonlinear analysis from which maximum lateral drift ratio of piers are obtained. Then, seismic fragility analysis has been conducted for the bridge using the nonlinear analysis results. Probability of exceeding damage has been computed in terms of using the maximum likelihood estimation, and effect of earthquake intensity range of the motions on seismic fragility curves has been assessed analytically. Analytical predictions indicate that the earthquake intensity range is of utmost significance for rationale seismic fragility analysis reflecting a physical damage state of a bridge and seismic performance evaluation of such bridge.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.6 no.5
• /
• pp.19-27
• /
• 2002

Dynamic responses of a multi-span simply supported bridge are investigated to examine the effect of bearing damage under seismic excitations. The damaged bearings are modeled as sliding elements with friction between the superstructure and the top of the pier. Various values of the friction coefficients are examined to figure out the effect of damaged bearings with various levels of peak ground accelerations. It is found that the global seismic behaviors are significantly influenced by the occurrence of bearing damage. It should be noticed that the most possible location of unseating failure of superstructures differs from that in the bridge model without considering the bearing damage. It can be concluded that the bearing damage may play the major role in the unseating failure of a bridge system, so that the damage of bearings should be included to achieve more rational seismic safety evaluation.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.12 no.1
• /
• pp.175-182
• /
• 2008

In performing a risk analysis of structure for earthquake, it is imperative to identify the vulnerability of structures associated with various stages of damage. And the earthquake resisting capability is needed for structures like bridge. So the damage analysis of bridges with or without isolator for earthquake effects is necessary. In this paper, the risk analysis of seismic isolated LRB bridges considering earthquake effects such as PGA, PGV, SA, SV, and SI is performed using fragility curves to assure the earthquake resisting capability of the structures. And, the stability of fragility curve is investigated with respect to elastic modulus.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 1998.04a
• /
• pp.220-225
• /
• 1998

레이다를 이용한 콘크리트 구조믈의 지진으로 인한 손상도를 파악하기 위해, 콘크리트의 전자기적 특성(dielectric properties)을 레이다 작용 주파수 대역인 200MHz에서 6GHz 영역까지 측정하였다. 이의 측정을 위해 실험실에서 콘크리트의 전자기적 특성 계측을 가능하게 하는 회로망분석기(network analyser)를 사용하였다. 콘크리트의 전자기적 특성은 open-ended coaxial probe를 회로망 분석기에 연결하여 측정하였고, 실험전 측정값을 보정(calibration)하는 기법을 찾아내었다. 주파수의 변화와 함께 콘크리트 시편안에 포함된 수분의 양을 조절함으로써, 실제 콘크리트 구조물이 가질 수 있는 상태를 시편을 통해 측정하였다. 측정결과는 콘크리트의 전자기적 특성이 주파수와 수분함량에 따라 변하는 것을 보여주었으며, 이는 레이다를 이용한 콘크리트 구조물의 지진 손상도 파악 방법 개발에 필요한 자료를 제공하였다.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.7
• /
• pp.15-24
• /
• 2004

This paper describes a GIS-based assessment of residential building damage caused by the 1994 Northridge earthquake in which the fractions of existing buildings damaged at various percentages of replacement cost are related to a range of seismic parameters. The assessment uses data from safety inspection reports and tax assessor records, both of which were geocoded and linked to seismic parameters derived from strong motion records at 164 different sites. The paper also describes a GIS-based pattern recognition algorithm for identifying locations of most intense building damage. The algorithm provides a framework for rapidly screening remote sensing data and dispatching emerging services.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.14 no.3
• /
• pp.49-57
• /
• 2010

Most previous research on the seismic response of structures with plan irregularities have focused on the relationship between the eccentricity and the amount of torsion. This approach cannot provide the direct relationship between the irregularity and the damage. Therefore, an investigation on the relationship between the eccentricities of buildings with plan irregularities and the damage index was performed. Inelastic dynamic time-history analyses were performed on one-story buildings with various eccentricities. For the damage assessment, a 3D damage index was adopted to reflect the effect of the bi-directional response and torsion. Based on the analysis results, buildings with eccentricities of 10%, 20% and 30% will suffer 3~5%, 13~18%, and 33~47% more damage than their regular counterparts, respectively.