매설가스배관의 지진 취약도 해석

이도형,전정문,오장균,이두호 한국지진공학회 2010 한국지진공학회논문집 Vol.14 No.5

본 연구에서는 국내에서 널리 사용되고 있는 매설가스배관인 API X65에 대해 지진 취약도 해석을 수행하였다. 이를 위해, 15가지 경우의 배관 해석모델에 대해 12본 세트의 다양한 지진파를 0.1g 등간격으로 스케일링하여 비선형 시간이력해석을 수행한 후, 비선형 시간이력해석으로 얻어진 매설가스배관의 최대 변형률을 이용하여 지진취약도 해석을 수행하였다. 지진 취약도 해석을 위해 본 연구에서는 또한, 지반조건, 단부지점조건, 매립깊이 및 배관형태 등을 변수로 고려하여 지진 취약도 해석을 수행하였다. 지진 취약도 해석결과, 지반조건, 단부지점조건 및 매립깊이는 매설가스배관의 취약도 곡선에 영향을 끼치는 것으로 판단되었고, 특히 지반조건이 미치는 영향은 다른 두 변수에 비해 다소 큰 것을 확인할 수 있었다. 반면에, 배관형태가 취약도 곡선에 미치는 영향은 미미한 것을 알 수 있었다. 종합적으로, 매설가스배관의 지진 취약도 해석과 관련된 연구가 많지 않은 현실을 감안할 때, 본 연구결과는 매설가스배관의 지진 취약성 평가해석에 초석으로 고려되어질 수 있고, 추후 관련분야 연구에 좋은 참고자료가 될 것으로 사료된다. In this paper, earthquake fragility analysis has been comparatively performed with regard to a buried gas pipeline of API X65 which has been widely used in Korea. For this purpose, a nonlinear time-history analyses has been carried out for 15 different analytical models of a buried gas pipeline in terms of the selected 12 sets of earthquake ground motions with 0.1g of scaling interval. Following that, earthquake fragility analyses have been conducted using the maximum axial strain of the pipeline obtained from the nonlinear time-history analyses. Parameters under consideration for subsequent earthquake fragility analyses are soil conditions, end-restraint conditions, burial depth and the type of pipeline. Comparative analyses reveal that whereas the first three parameters influence the fragility curves, particularly soil conditions amongst the three parameters, the last parameter has a little effect on the curves. In all, the present study can be considered as a benchmark fragility analysis of a buried gas pipeline in the absence of an earthquake fragility analysis of the pipeline and thus is expected to be a useful source regarding earthquake fragility analyses of a buried gas pipelines.

다양한 비선형지진해석방법에 따른 철근콘크리트 전단벽 구조물의 취약도곡선 평가

장동휘,송종걸,강성립,박창호 한국지진공학회 2011 한국지진공학회논문집 Vol.15 No.4

지진취약도 분석은 원자력 발전소의 내진성능평가를 위하여 발전되어져 왔지만, 현재는 적용성이 건물과 교량 등에도 확대되어지고 있다. 일반적으로 지진취약도 곡선은 수많은 지진가속도 기록을 이용하여 비선형 시간이력해석으로 구한다. 비선형 시간이력해석에 의한 지진취약도 분석은 구조물의 모델링과 해석에 많은 시간이 소요되는 과정을 요구한다. 비선형 시간이력해석의 이와 같은 약점을 보완하기 위해서 변위계수법과 역량스펙트럼 방법과 같은 간단한 해석방법을 지진취약도 분석에 적용하였다. 변위계수법과 역량 스펙트럼 방법을 적용한 지진취약도 곡선의 정확성을 평가하기 위하여, 철근콘크리트 전단벽 구조물에 대한 변위계수법과 역량스펙트럼 방법을 적용한 지진취약도 곡선을 비선형 시간이력해석에 의해 구해진 지진취약도 곡선과 비교하였다. 지진취약도 곡선의 작성을 위해서는 설계스펙트럼에 대응되는 190개의 인공지진과 Shinozuka 등이 제안한 방법이 적용되었다. Seismic fragility analysis has been developed to evaluate the seismic performance of existing nuclear power plants, but now its applicability has been extended to buildings and bridges. In general, the seismic fragility curves are evaluated from the nonlinear time-history analysis (THA) using many earthquake ground motions. Seismic fragility analysis using the nonlinear THA requires a time consuming process of structural modeling and analysis. To overcome this shortcoming of the nonlinear THA, simplified methods such as the displacement coefficient method (DCM) and the capacity spectrum method (CSM) are used for the seismic fragility analysis. In order to evaluate the accuracy of the seismic fragility curve calculated by the DCM and the CSM, the seismic fragility curves of a reinforced concrete shear wall structure calculated by the DCM and CSM are compared with those calculated by the nonlinear THA. In order to construct a numerical fragility curve, 190 artificially generated ground motions corresponding to the design spectrum and the methodology proposed by Shinozuka et al. are used.

Robustness of meta-analysis results in Cochrane systematic reviews: A case for acupuncture trials

Jiyoon Won 한국한의학연구원 2022 Integrative Medicine Research Vol.11 No.4

Introduction Fragility index (FI) refers to the smallest value that change statistical significance of study results. Meta-analyses of Cochrane systematic reviews are considered as the best evidence for stake holders because they enable effect size estimation that cannot be derived by individual studies, particularly in the field of complementary and integrative medicine (CIM). Thus, this study aimed to evaluate robustness of meta-analysis in Cochrane systematic reviews of acupuncture, one of the most used CIM treatment, using FI of meta-analysis. Methods Meta-analyses of acupuncture Cochrane systematic reviews with binary benefit outcome measures were searched in PubMed, Embase, and CENTRAL and subject to analysis. Randomized clinical trials (RCTs) or quasi RCTs adopted penetrating needles as treatment and compared with controls such as sham acupuncture, usual care, and active control were included. FI of meta-analyses was calculated in web (https://clinicalepidemio.fr/fragility_ma/); and fragility quotient (FQ) was calculated by dividing FI by total sample size of meta-analysis. Results Of 248 retrieved studies, 12 Cochrane systematic reviews with 48 meta-analyses were analyzed. The median FI for statistically significant and non-significant meta-analyses was 7 [interquartile range: 3 - 12] and 6 [interquartile range: 3 - 10]. FQ was similar irrespective of statistical significance. Among controls, meta-analyses adopting sham acupuncture displayed the widest range of FI and FQ. Conclusion Robustness of meta-analyses in Cochrane systematic reviews for acupuncture was similar irrespective of statistical significance. Impact of control intervention cannot be determined in this study. As FI enables intuitive interpretation, applications for CIM field can be useful.

Seismic Fragility Analysis of a Buried Gas Pipeline Based on Nonlinear Time-History Analysis

이도형,김병화,정성훈,전종수,이태형 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.1

Seismic fragility analysis was performed for API X65, a type of buried gas pipeline that is widely used in Korea. For this purpose, nonlinear time-history analyses were carried out using 15 different analytical models of the pipeline, which represent variations of modeling parameters. The nonlinear Winkler approach was adopted to simulate the soil-pipeline interaction during an earthquake loading. A set of 12 recorded ground motions were selected for the time-history analyses and scaled to represent a range of earthquake intensity levels. Then, fragility functions were developed with respect to the damage states, which are defined in terms of the maximum axial strain of the pipeline. The parameters under consideration for subsequent seismic fragility analyses are the soil conditions, boundary conditions, burial depth, and type of pipeline. Comparative analyses revealed that the first three parameters, most notably the soil conditions, influence the fragility curves, but the last parameter negligibly affects the fragility curves. It is concluded in short that this study is promising to give a useful insight for a rapid seismic performance evaluation of a buried gas pipeline based on nonlinear and fragility analyses.

A New Method for Developing Seismic Collapse Fragility Curves Grounded on State-Based Philosophy

Aref Baharvand,Abdolrasoul Ranjbaran 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.2

Since the current process to achieve the collapse fragility curve in practical applications seems too complicated, also time-consuming to dominant by structure designers, the focus of this study is on introducing of a new approach for establishing collapse fragility curves which requires less analytical effort. To achieve this goal, state-based philosophy (SBP) has been taken into consideration. This theory benefits from some similarities in the nature of every failure process in solid mechanics regardless of its source. In this study these similarities are used intelligently in procedure of formulating new fragility function which has couple of unknown parameters. Next, it will be shown that these parameters can be attained from two different sources: the pushover curves of the structure, some selective damage data from incremental dynamic analysis analyses. Finally a complete form of new collapse fragility function which is called "SBP fragility function" proposed as a substitute for conventional collapse fragility function. The most important advantage of this new fragility function is its non-probabilistic structure that will make a huge difference in the amount of effort required to achieve the fragility curves. In this research, in order to ensure the efficiency, accuracy of this fragility function all steps of SBP fragility analyses are done on some special moment frames models, their results are presented.

지진격리된 원전배관의 지진취약도 분석

전법규,최형석,함대기,김남식 한국지진공학회 2015 한국지진공학회논문집 Vol.19 No.1

Base isolation is considered as a seismic protective system in the design of next generation Nuclear Power Plants (NPPs). If seismic isolation devices are installed in nuclear power plants then the safety under a seismic load of the power plant may be improved. However, with respect to some equipment, seismic risk may increase because displacement may become greater than before the installation of a seismic isolation device. Therefore, it is estimated to be necessary to select equipment in which the seismic risk increases due to an increase in the displacement by the installation of a seismic isolation device, and to perform research on the seismic performance of each piece of equipment. In this study, modified NRC-BNL benchmark models were used for seismic analysis. The numerical models include representations of isolation devices. In order to validate the numerical piping system model and to define the failure mode, a quasi-static loading test was conducted on the piping components before the analysis procedures. The fragility analysis was performed by using the results of the inelastic seismic response analysis. Inelastic seismic response analysis was carried out by using the shell finite element model of a piping system considering internal pressure. The implicit method was used for the direct integration time history analysis. In addition, the collapse load point was used for the failure mode for the fragility analysis.

한국인 정신지체 환자에 있어서 취약 X증후군의 빈도 : 세포유전학적 및 분자유전학적 분석

최영민(Young Min Choi),황도영(Do Yeong Hwang),전종관(Jong Kwan Jun),최진(Jin Choe),박성효(Sung Hyo Park),노미경(Mee Kyung Noh),오선경(Sun Kyung Oh),구승엽(Seung Yup Ku),서창석(Chang Suk Suh),김석현(Seok Hyun Kim),양세원(Se Won Yang) 대한산부인과학회 1999 Obstetrics & Gynecology Science Vol.42 No.11

취약 X증후군은 정신지체를 일으키는 가장 흔한 유전성 질환으로서 외국의 경우 정신지체 환자의 0.2-2.7%를 차지하는 것으로 알려져 있으며 이는 분자유전학적 방법에 의한 정확한 진단에 근거하고 있다. 그러나 국내 정신지체 환자들에서 취약 X증후군의 정확한 유병율이 밝혀져 있지 못하다. 이에 본 연구에서는 분자유전학적 검사 방법을 이용하여 한국인 정신지체 환자에 있어서 취약 X증후군의 빈도를 파악하고자 하였다. 한국인 정신지체 환자 212명 및 가계 구성원들을 대상으로 취약 X증후군 진단을 위한 세포유전학적 검사와 분자유전학적 검사를 시행하였다. 분자유전학적 검사로서는 남자 환자들의 경우 일차적으로 중합효소연쇄반응을 시행하였으며, 결과가 불분명한 경우 Southern blot 분석을 수행하였다. 여자 환자들의 경우 Southern blot 분석을 수행하였다. 세포유전학 검사상 정신지체환자 212명중 6명(2.8%)에서 취약 X염색체가 관찰되었다. 분자유적학적 검사에서도 정신지체환자 212명중 6명(2.8%)이 취약 X 증후군으로 판명되었으며, 이들은 모두 세포유전학 검사에서 취약 X염색체가 보인 환자였으며 모두 남성들이었다. 취약 X증후군으로 판명된 6명의 환자들의 모친 6명, 즉 보인자들에서 분자유전학적 검사를 시행한 결과 보인자 양상을 나타내었다. 그러나 이들에서 세포유전학적 검사를 시행하였으며 이들중 1명(16/7%)에서만이 취약 X염색체가 관찰되었다. 그리고 취약 X증후군으로 판정된 환자의 부친 2명과 남동생 1명에서 분자유전학적 검사를 시행한 결과 정상으로 판정되었다. 112명의 정신지체 환자들을 대상으로 Klentaq1과 Pfu polymerase를 사용하는 새로운 PCR 방법과 기존의 Exo(-) Pfu polymerase를 이용한 방법을 비교한 결과 동일한 결과를 얻었으며, Klentaq1과 Pfu polymerase를 사용하는 실험 기법상 편리하다는 점에서 추천된다고 하겠다. 이상의 결과 한국인 정신지체 환자에 있어서 취약 X증후군의 유병율은 2.8%였으며, Caucasian에서의 유병율과 유의한 차이가 없었다. 그리고 진단 결과에 있어서 세포유전학적 방법과 분자유전학적 방법은 일치하였다. Fragile X syndrome is the most common cause of inherited mental retardation. It accounts for 0.2% - 2.7% of patients with mental retardation, based upon the molecular genetic diagnosis. However, the exact prevalence of fragile X syndrome in Korean patients with mental retardation is unknown. We have performed cytogenetic and molecular analysis for fragile X syndrome in 212 Korean patients with mental retardation. Among them, six patients (2.8%) was identified as carrying fragile X syndrome by both cytogenetic and molecular analysis. The results by cytogenetic analysis was identical to those by molecular analysis. Cytogenetic analysis of 6 carriers (mothers of patients with proven fragile X syndrome) showed a fragile X chromosome in one patients (16.7%) while molecular analysis revealed premutation in all patients. PCR method using Klentaq1과 Pfu polymerase showed the same results as those by PCR method using Exo(-) Pfu polymerase, but the former method is recommended because of its simplicity in technical aspect. These data suggest that the prevalence of fragile X syndrome in Korean patients with mental retardation is 2.8%, not significantly different from those in Caucasians.

2주탑 콘크리트 사장교의 주요 부재 지진 취약도 분석

신연우,홍기남,권용민,연영모 한국구조물진단유지관리공학회 2020 한국구조물진단유지관리공학회 논문집 Vol.24 No.4

This study intends to present a fragility analysis method suitable for concrete cable-stayed bridges by performing an analysis reflectingdesign criteria and material characteristics from the results of inelastic time-history analysis. In order to obtain the fragility curve of the cable-stayedbridge, the limit state of the main component of the cable-stayed bridge is determined, and the damage state is classified by comparing it with theresponse value based on inelastic time history analysis. The seismic fragility curve of the cable-stayed bridge was made by obtaining the probabilityof damage to PGA that the dynamic response of the vulnerable parts to input ground motion would exceed the limit state of each structural member. According to the pylon's fragility curve, the probability of moderate damage at 0.5g is 32% for the longitudinal direction, while 7% for the transversaldirection, indicating that the probability of damage in the longitudinal direction is higher in the same PGA than in the transversal direction. The seismicfragility curve of the connections showed a very high probability of damage, meaning that damage to the connections caused by earthquakes is verysensitive compared to damage to the pylon and cables. The cable's seismic fragility curve also showed that the probability of complete damage stateafter moderate damage state gradually decreased, resulting in less than 30% probability of complete damage at 2.0g. 본 연구에서는 2주탑 콘크리트 사장교를 모델링하고 취약부재에 대한 비탄성 시간이력해석 결과들로부터 설계기준과 재료특성을반영한 취약도 분석을 수행하여 콘크리트 사장교에 적합한 취약도 분석을 제시하고자 한다. 사장교의 지진 취약도 곡선을 작성하기 위해 사장교의 주요 취약부재에 대한 한계상태를 결정하고 비탄성 시간이력해석에 의한 응답값과 비교하여 손상상태를 구분한다. 입력지반운동에 대한취약부위들의 동적응답이 각 구조부재의 한계상태를 초과할 손상확률을 최대지반가속도(PGA)에 대해 구함으로써 사장교의 지진 취약도 곡선을 작성하였다. 주탑의 취약도 곡선에 의하면 0.5g에서 보통손상상태의 확률이 교축방향의 경우 32%인데 반해 교축직각방향의 경우 7%로나타나 동일 PGA에서 교축직각방향에 비해 교축방향의 손상확률이 더 높은 것으로 나타났다. 연결부의 지진 취약도 곡선을 보면 심한 손상상태의 손상확률이 다른 부재에 비해 매우 높은 수준을 보였는데 이는 지진에 의한 연결부의 손상이 주탑과 케이블의 손상에 비해 매우 민감하다는 것을 의미한다. 케이블의 지진 취약도 곡선에서는 보통손상상태 등급 이후의 손상확률이 점차 낮아져 완전손상상태에 이를 확률은 2.0g의큰 지진에서도 30%미만의 확률을 가지는 것으로 나타났다.

Fragility curves for the typical multi-span simply supported bridges in northern Pakistan

Muhammad Waseem,Enrico Spacone 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.64 No.2

Bridges are lifeline and integral components of transportation system that are susceptible to seismic actions, their vulnerability assessment is essential for seismic risk assessment and mitigation. The vulnerability assessment of bridges common in Pakistan is very important as it is seismically very active region and the available code for the seismic design of bridges is obsolete. This research presents seismic vulnerability assessment of three real case simply supported multi-span reinforced concrete bridges commonly found in northern Pakistan, having one, two and three bents with circular piers. The vulnerability assessment is carried through the non-linear dynamic time history analyses for the derivation of fragility curves. Finite element based numerical models of the bridges were developed in MIDAS CIVIL (2015) and analyzed through with nonlinear dynamic and incremental dynamic analyses, using a suite of bridge-specific natural spectrum compatible ground motion records. Seismic responses of shear key, bearing pad, expansion joint and pier components of each bridges were recorded during analysis and retrieved for performance based analysis. Fragility curves were developed for the bearing pads, shear key, expansion joint and pier of the bridges that first reach ultimate limit state. Dynamic analysis and the derived fragility curves show that ultimate limit state of bearing pads, shear keys and expansion joints of the bridges exceed first, followed by the piers ultimate limit state for all the three bridges. Mean collapse capacities computed for all the components indicated that bearing pads, expansion joints, and shear keys exceed the ultimate limit state at lowest seismic intensities.

면진장치를 설치한 회전기기의 지진취약도 개선효과 분석

김민규,대조정수,전영선,최인길 한국지진공학회 2007 한국지진공학회논문집 Vol.11 No.6

본 연구에서는 원자력발전소 비상디젤발전기의 내진안전성을 정량적으로 평가하기 위하여 지진취약도 분석방법을 제안하고 제안한 방법을 이용하여 비상디젤발전기의 지진취약도를 평가하여 정량적인 지진위험도를 제시하였다. 기존의 비상디젤발전기뿐만 아니라 면진장치를 설치하여 지진력 저감효과를 증대시킨 비상디젤발전기에 대한 지진취약도 분석을 함께 수행하여 비상디젤발전기와 같은 대형 회전기기의 경우 면진장치를 통한 지진취약도의 변화를 살펴보았다. 최종적으로 지진취약도 결과를 이용하여 HCLPF값의 변화를 비교하여 면진에 의하여 비상디젤발전기의 취약도를 크게 개선 할 수 있는 것을 알 수 있었으며, 면진된 경우 면진장치의 파괴가 전체 거동을 지배하므로 면진장치의 성능개선이 필요한 것을 알 수 있었다. In this study, for the evaluation of seismic safety of the isolated Emergency Diesel Generator (EDG) System more quantitatively, the seismic fragility analysis method were proposed. Using the proposed method, seismic fragility analysis performed and a seismic risk of EDG system was present. The fragility analysis performed not for an existing EDG system but also for an isolated EDG system which increases the seismic capacity. At first, numerical models for existing and isolated EDG system were constructed and seismic response analysis performed according to input seismic waves and peak ground accelerations. An uncertainty factors and failure modes of both fixed and isolated EDG system were assumed for fragility analysis. The HCLPF values were evaluated for the compare the improvement effect using the isolation system. As a result, the isolation system can make better the seismic fragility of EDG system, but the failure of isolation system was govern the behavior of whole system.