• Title/Summary/Keyword: Seismic fragility curve

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Stability of Analytical Fragility Curve of Bridge on Elastic Modulus (탄성계수의 변화에 따른 교량의 해석적 손상도 곡선의 안정성)

  • Lee, Jong-Heon;Kang, Shin-Yeol;Kim, Tae-Hyeong;Lee, Soo-Choul
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.1
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    • pp.175-182
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    • 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.

Stability of Analytical Fragility Curve of Bridge on Earthquake (지진의 변화에 따른 교량의 해석적 손상도 곡선의 안정성)

  • Lee, Jong-Heon;Lee, Soo-Choul
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.13 no.2 s.54
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    • pp.145-152
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    • 2009
  • In performing a risk analysis on 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 input earthquake.

Development of Fragility Curves of Concrete Bridges (콘크리트 교량의 손상도 곡선 개발)

  • 김상훈;김두희;서형렬;김종인
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2003.09a
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    • pp.319-325
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    • 2003
  • The fragility curves of seismic retrofitted bridges by steel jacketing of bridge columns and restrainers at expansion joints after the 1994 Northridge earthquake are developed. Fragility curves are represented by lognormal distribution functions with two parameters(fragility parameters consisting of median and log-standard deviation) and developed as a function of peak ground acceleration (PGA). Two parameters in the lognormal distribution are estimated by the maximum likelihood method. The sixty ground acceleration time histories for Los Angeles area developed for FEMA SAC project are used for the dynamic analysis of the bridges and a computer code is developed to calculate hysterestic parameters of bridge columns before and after steel jacketing. The effect of retrofit is expressed in terms of the increase of the median value of the fragility curve for the retrofitted bridge from that of the bridge before retrofit. The comparison of fragility curves of the bridges before and after column retrofit demonstrates that the improvement of the bridges with steel jacketing on the seismic performance is excellent for the damage states defined in this study. The comparison of fragility curves of the bridges before and after restrainers at expansion joints also shows the improvement in the seismic performance of restrained bridges for the severe damage states.

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Seismic Fragility Analysis of Ground Supported Horizontal Cylindrical Tank (수평원통형 저장탱크의 지진취약도 해석)

  • Chaulagain, Nabin Raj;Sun, Chang-Ho;Kim, Ick-Hyun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.7
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    • pp.145-151
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    • 2019
  • The fragility analyses for the partially filled horizontal cylindrical tank having a flexible wall were conducted to evaluate seismic performance. An equivalent simplified model with two lumped masses representing to impulsive and convective masses was used to represent the liquid storage system. This simplified model was validated by comparing its time history analysis results with the 3D FSI model results. The horizontal tank was analyzed under bi-directional excitations. Seismic fragility curves for the stability were developed in transverse and longitudinal directions. Fragility curves show that seismic damage for the horizontal storage system is more susceptible in the transverse direction.

Influence of time-varying attenuation effect of damage index on seismic fragility of bridge

  • Yan, Jialei;Liang, Yan;Zhao, Boyang;Qian, Weixin;Chen, Huai
    • Earthquakes and Structures
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    • v.19 no.4
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    • pp.287-301
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    • 2020
  • Fragility as one of the most effective methods to evaluate seismic performance, which is greatly affected by damage index. Taking a multi span continuous rigid frame offshore bridge as an example. Based on fragility and reliability theory, considering coupling effect of time-varying durability damage of materials and time-varying attenuation effect of damage index to analyze seismic performance of offshore bridges. Results show that IDA curve considering time-varying damage index is obviously below that without considering; area enclosed by IDA of 1# pier and X-axis under No.1 earthquake considering this effect is 96% of that without considering. Area enclosed by damage index of 1# pier and X-axis under serious damage with considering time-varying damage index is 90% of that without considering in service period. Time-varying damage index has a greater impact on short pier when ground motion intensity is small, while it has a great impact on high pier when the intensity is large. The area enclosed by fragility of bridge system and X-axis under complete destruction considering time-varying damage index is 165% of that without considering when reach designed service life. Therefore, time-varying attenuation effect of damage index has a great impact on seismic performance of bridge in service period.

Limit States and Corresponding Seismic Fragility of a Pipe Rack for Maintaining Operation (운전성 유지를 위한 파이프랙의 한계상태와 지진취약도)

  • Kim, Juram; Hong, Kee-Jeung;Hwang, Jin-Ha
    • Journal of the Earthquake Engineering Society of Korea
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    • v.27 no.6
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    • pp.283-291
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    • 2023
  • Unlike other facilities, maintaining processes is essential in industrial facilities. Pipe racks, which support pipes of various diameters, are important structures used in industrial facilities. Since the transport process of pipes directly affects the operation of industrial facilities, a fragility curve should be derived based on considering not only the pipe racks' structural safety but also the pipes' transport process. There are several studies where the fragility curves have been determined based on the structural behavior of pipe racks. However, few studies consider the damage criteria of pipes to ensure the transportation process, such as local buckling and tensile failure with surface defects. In this study, an analysis model of a typical straight pipe rack used in domestic industrial facilities is constructed, and incremental dynamic analysis using nonlinear response history analysis is performed to estimate the parameters of the fragility curve by the maximum likelihood estimation. In addition, the pipe rack's structural behavior and the pipe's damage criteria are considered the limit state for the fragility curve. The limit states considered in this paper to evaluate fragility curves are more reasonable to ensure the transportation process of the pipe systems.

Seismic Fragility Analysis of Container Crane Considering Far-Fault and Near-Fault Ground Motion Characteristics (원거리와 근거리 지진파의 특성을 고려한 항만 컨테이너 크레인의 지진취약도 분석)

  • Park, Ju-Hyun;Min, Jiyoung;Lee, Jong-Han
    • Journal of the Earthquake Engineering Society of Korea
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    • v.27 no.2
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    • pp.83-90
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    • 2023
  • The recent increase in earthquake activities has highlighted the importance of seismic performance evaluation for civil infrastructures. In particular, the container crane essential to maintaining the national logistics system with port operation requires an exact evaluation of its seismic response. Thus, this study aims to assess the seismic vulnerability of container cranes considering their seismic characteristics. The seismic response of the container crane should account for the structural members' yielding and buckling, as well as the crane wheel's uplifting derailment in operation. The crane's yielding and buckling limit states were defined using the stress of crane members based on the load and displacement curve obtained from nonlinear static analysis. The derailment limit state was based on the height of the rail, and nonlinear dynamic analysis was performed to obtain the seismic fragility curves considering defined limit states and seismic characteristics. The yield and derailment probabilities of the crane in the near-fault ground motion were approximately 1.5 to 4.7 and 2.8 to 6.8 times higher, respectively, than those in the far-fault ground motion.

Seismic Fragilities of Bridges and Transmission Towers Considering Recorded Ground Motions in South Korea (한국의 지반거동을 고려한 교량과 송전철탑의 지진취약도 분석)

  • Park, Hyo Sang;Nguyen, Duy-Duan;Lee, Tae-Hyung
    • Journal of the Earthquake Engineering Society of Korea
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    • v.20 no.7_spc
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    • pp.435-441
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    • 2016
  • The Korean peninsula has known as a minor-to-moderate seismic region. However, some recent studies had shown that the maximum possible earthquake magnitude in the region is approximately 6.3-6.5. Therefore, a seismic vulnerability assessment of the existing infrastructures considering ground motions in Korea is necessary. In this study, we developed seismic fragility curves for a continuous steel box girder bridge and two typical transmission towers, in which a set of seven artificial and natural ground motions recorded in South Korea is used. A finite element simulation framework, OpenSees, is utilized to perform nonlinear time history analyses of the bridge and a commercial software, SAP2000, is used to perform time history analyses of the transmission towers. The fragility curves based on Korean ground motions were then compared with the fragility curves generated using worldwide ground motions to evaluate the effect of the two ground motion groups on the seismic fragility curves of the structures. The results show that both non-isolated and base-isolated bridges are less vulnerable to the Korean ground motions than to worldwide earthquakes. Similarly to the bridge case, the transmission towers are safer during Korean motions than that under worldwide earthquakes in terms of fragility functions.

Seismic Fragility Functions for Steel Moment Resisting Frames using Incremental Dynamic Analyses (증분동적해석을 이용한 철골모멘트골조의 지진취약도 함수)

  • Lee, Seung-Won;Yi, Waon-Ho;Kim, Hyung-Joon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.27 no.6
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    • pp.509-516
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    • 2014
  • Accuracy of seismic response evaluated by a capacity spectrum method (CSM) is generally known to be less than that by Incremental dynamic analysis (IDA). In this paper, a procedure for IDA based seismic fragility curves for steel moment resisting frames was suggested. This study compares seismic fragility curves using the suggested method (IDA method) with those using a CSM and intends to verify the validity of the IDA method. The shapes of both seismic fragility curves are similar in slight and moderate damage states. However, in the case of extensive and complete damage states, the fragility curves obtained from the IDA method presents a more steep slope due to less variation (or uncertainties). This is due to the fact that the IDA method can properly capture the structural response beyond yielding rather than the CSM.

Reliability-based fragility analysis of nonlinear structures under the actions of random earthquake loads

  • Salimi, Mohammad-Rashid;Yazdani, Azad
    • Structural Engineering and Mechanics
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    • v.66 no.1
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    • pp.75-84
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    • 2018
  • This study presents the reliability-based analysis of nonlinear structures using the analytical fragility curves excited by random earthquake loads. The stochastic method of ground motion simulation is combined with the random vibration theory to compute structural failure probability. The formulation of structural failure probability using random vibration theory, based on only the frequency information of the excitation, provides an important basis for structural analysis in places where there is a lack of sufficient recorded ground motions. The importance of frequency content of ground motions on probability of structural failure is studied for different levels of the nonlinear behavior of structures. The set of simulated ground motion for this study is based on the results of probabilistic seismic hazard analysis. It is demonstrated that the scenario events identified by the seismic risk differ from those obtained by the disaggregation of seismic hazard. The validity of the presented procedure is evaluated by Monte-Carlo simulation.