• 제목/요약/키워드: seismic engineering

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중약진 지역에서의 지진격리교량의 비용효율성 평가 (Cost Effectiveness Evaluation of Seismic Isolated Bridges in Low and Moderate Seismic Region)

  • 고현무
    • 한국지진공학회:학술대회논문집
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    • 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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    • pp.440-447
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    • 2000
  • In order to evaluate the cost effectiveness of seismic isolation for bridges in low and moderate seismic region, a method of calculation minimum life-cycle cost of seismic-isolated bridges under specific acceleration level and soil condition is developed. Input ground motion is modeled as spectral density function compatible with response spectrum for combination of acceleration coefficient and site coefficient. Failure probability is calculated by spectrum analysis based on random vibration theories to simplify repetitive calculations in the minimization procedure. Ductility of piers and its effects on cost effectiveness are considered by stochastic linearization method. Cost function and cost effectiveness index are defined by taking into consideration the characteristics of seismic isolated bridges. Limit states for calculation of failure probability are defined on superstructure, isolator and pier, respectively. The results of example design and analysis show that seismic isolation is more cost-effective in low and moderate seismic region than in high seismic region.

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확률밀도함수 보간에 의한 교량의 지진취약도 분석 (Seismic Fragility Analysis Utilizing PDF Interpolation Technique)

  • 이진하;김상훈;윤정방
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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    • pp.495-502
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    • 2003
  • This study proposed the Probability Density Function (PDF) interpolation technique to evaluate the seismic fragility curves as a function of the return period. Seismic fragility curves have been developed as a function of seismic intensities such as peak ground acceleration, peak pound velocity, and pseudo-velocity spectrum. The return period of design earthquakes, however, can be more useful among those seismic intensity measurements, because the seismic hazard curves are generally represented with a return period of design earthquakes and the seismic design codes also require to consider the return period of design earthquake spectrum for a specific site. In this respect the PDF interpolation technique is proposed to evaluate the seismic fragility curves as a function of return period. Seismic fragility curves based on the return period are compared with ones based on the peak ground acceleration for the bridge model.

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동일한 지진구역에 위치한 건축 구조물의 내진거동을 기초로한 기존 내진설계 평가 (Evaluation of the Current Seismic Design Procedures Based on the Seismic Performance of the Building Located in the Same Seismic Area)

  • 한상환;이리형
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 1997년도 봄 학술발표회 논문집
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    • pp.160-166
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    • 1997
  • Current Seismic Design Procedure has been developed and improved mostly based on the experiences of the past earthquakes. Many engineers and researchers believe that the seismic codes and provisions are adequate for the basic objective of the code which is "life-safe". However they doubt the performance of the structure during the earthquake. The seismic code seems the black box for the designers which means it is not transparent since the designer can not predict the level of the damage of the structure under future earthquakes. This purpose of this study is to check the validity of the current seismic design procedures. Two structures with different heights are designed and their seismic performances are evaluated for this purpose. Both structures are assumed to be located at the same strong seismic zone.

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시추공 탄성파탐사 및 이의 토목공학적 응용 (Borehole Seismics: Review and Its Application to Civil Engineering)

  • 장현삼;임해룡;홍재호
    • 한국지구물리탐사학회:학술대회논문집
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    • 한국지구물리탐사학회 1999년도 제2회 학술발표회
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    • pp.176-201
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    • 1999
  • 지반조사를 위하여 흔히 시행하는 시추공 탄성파탐사, 즉 하향 탄성파탐사(downhole seismic), 수직 탄성파탐사(vertical seismic profiling; VSP), 시추공간 속도측정(crosshole seismic), 탄성파 토모그래피(seismic tomography)에 대하여 원리, 현장측정, 자료처리 등을 간략히 설명하고, 현장자료의 예를 제시하였으며 토목공학적 응용에 대해 검토하였다.

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단자유도 해석모델을 활용한 응답스펙트럼과 지진취약도 곡선과의 관계에 대한 연구 (A Study on the Relationship between Response Spectrum and Seismic Fragility Using Single Degree of Freedom System)

  • 박상기;조정래;조창백;이진혁;김동찬
    • 한국지진공학회논문집
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    • 제27권6호
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    • pp.245-252
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    • 2023
  • In general, the design response spectrum in seismic design codes is based on the mean-plus-one-standard deviation response spectrum to secure high safety. In this study, response spectrum analysis was performed using seismic wave records adopted in domestic horizontal design spectrum development studies, while three response spectra were calculated by combining the mean and standard deviation of the spectra. Seismic wave spectral matching generated seismic wave sets matching each response spectrum. Then, seismic fragility was performed by setting three damage levels using a single-degree-of-freedom system. A correlation analysis was performed using a comparative analysis of the change in the response spectrum and the seismic fragility concerning the three response spectra. Finally, in the case of the response spectrum considering the mean and standard deviation, like the design response spectrum, the earthquake load was relatively high, indicating that conservative design or high safety can be secured.

GIS를 이용한 항만구조물의 내진성능 평가기법 (Evaluation on the Seismic Performance of Port Structures using GIS)

  • 김나영;강인준;최현;김태효
    • 대한공간정보학회지
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    • 제22권4호
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    • pp.31-38
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    • 2014
  • 한반도의 지진은 1,900여회에 달할 정도로 심각하다. 최근 세계적으로 발생하는 지진으로 인해 지반 및 구조물에 대해 내진설계에 대한 투자가 국민의 소중한 생명과 재산을 지키는 수단으로 대두된다. 본 연구에서는 기존항만시설물 중에서 내진설계가 적용되지 않은 시설물을 대상으로 지진발생시 설계기준이상의 내진성능을 갖추었는지를 평가하였다. 그 결과를 중심으로 액상화 우려 지역을 분류하고, 내진안정검토 평가 및 분석을 지리정보시스템(GIS)을 이용하여 지진에 따른 액상화 재해 위험성과 구조적인 내진성능에 따른 내진성능 평가도를 작성하였다. 액상화 평가와 내진성능검토를 통한 정량적이고 구체적인 입력데이터베이스를 구축하고 분석된 모든 지진관련 자료들은 지진발생 우려지역의 보수 보강에 평가 자료로 직접적으로 사용 될 수 있었다.

Peak seismic response of a symmetric base-isolated steel building: near vs. far fault excitations and varying incident angle

  • Pavlidou, Constantina;Komodromos, Petros
    • Earthquakes and Structures
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    • 제18권3호
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    • pp.349-365
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    • 2020
  • Since the peak seismic response of a base-isolated building strongly depends on the characteristics of the imposed seismic ground motion, the behavior of a base-isolated building under different seismic ground motions is studied, in order to better assess their effects on its peak seismic response. Specifically, the behavior of a typical steel building is examined as base-isolated with elastomeric bearings, while the effect of near-fault ground motions is studied by imposing 7 pairs of near- and 7 pairs of far-fault seismic records, from the same 7 earthquake events, to the building, under 3 different loading combinations, through three-dimensional (3D) nonlinear dynamic analyses, conducted with SAP2000. The results indicate that near-fault seismic components are more likely to increase the building's peak seismic response than the corresponding far-fault components. Furthermore, the direction of the imposed earthquake excitations is also varied by rotating the imposed pairs of seismic records from 0◦ to 360◦, with respect to the major construction axes. It is observed that the peak seismic responses along the critical incident angles, which in general differ from the major horizontal construction axes of the building, are significantly higher. Moreover, the influence of 5% and 10% accidental mass eccentricities is also studied, revealing that when considering accidental mass eccentricities the peak relative displacements of the base isolated building at the isolation level are substantially increased, while the peak floor accelerations and interstory drifts of its superstructure are only slightly affected.

최대-최소 스펙트럼에 대응하는 인공합성지진에 대한 면진된 원전구조물의 지진취약도 곡선 평가 (Evaluation of Seismic Fragility Curve of Seismically Isolated Nuclear Power Plant Structures for Artificial Synthetic Earthquakes Corresponding to Maximum-Minimum Spectrum)

  • 김현정;송종걸
    • 한국지진공학회논문집
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    • 제23권2호
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    • pp.89-99
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    • 2019
  • In order to increase the seismic safety of nuclear power plant (NPP) structures, a technique to reduce the seismic load transmitted to the NPP structure by using a seismic isolation device such as a lead-rubber bearing has recently been actively researched. In seismic design of NPP structures, three directional (two horizontal and one vertical directions) artificial synthetic earthquakes (G0 group) corresponding to the standard design spectrum are generally used. In this study, seismic analysis was performed by using three directional artificial synthetic earthquakes (M0 group) corresponding to the maximum-minimum spectrum reflecting uncertainty of incident direction of earthquake load. The design basis earthquake (DBE) and the beyond design basis earthquakes (BDBEs are equal to 150%, 167%, and 200% DBE) of G0 and M0 earthquake groups were respectively generated for 30 sets and used for the seismic analysis. The purpose of this study is to compare seismic responses and seismic fragility curves of seismically isolated NPP structures subjected to DBE and BDBE. From the seismic fragility curves, the probability of failure of the seismic isolation system when the peak ground acceleration (PGA) is 0.5 g is about 5% for the M0 earthquake group and about 3% for the G0 earthquake group.

Prediction of seismic displacements in gravity retaining walls based on limit analysis approach

  • Mojallal, Mohammad;Ghanbari, Ali
    • Structural Engineering and Mechanics
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    • 제42권2호
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    • pp.247-267
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    • 2012
  • Calculating the displacements of retaining walls under seismic loads is a crucial part in optimum design of these structures and unfortunately the techniques based on active seismic pressure are not sufficient alone for an appropriate design of the wall. Using limit analysis concepts, the seismic displacements of retaining walls are studied in present research. In this regard, applying limit analysis method and upper bound theorem, a new procedure is proposed for calculating the yield acceleration, critical angle of failure wedge, and permanent displacements of retaining walls in seismic conditions for two failure mechanisms, namely sliding and sliding-rotational modes. Also, the effect of internal friction angle of soil, the friction angle between wall and soil, maximum acceleration of the earthquake and height of the wall all in the magnitude of seismic displacements has been investigated by the suggested method. Two sets of ground acceleration records related to near-field and far-field domains are employed in analyses and eventually the results obtained from the suggested method are compared with those from other techniques.

앵커공법을 적용한 기존 콘크리트 중력식 댐의 내진성능 보강방안 (Seismic Performance Improvement of Concrete Gravity Dam by Post-tensioned Anchors)

  • 김용곤;김세일;옥승용
    • 한국안전학회지
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    • 제28권5호
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    • pp.49-53
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    • 2013
  • This paper describes the assessment of seismic performance of the concrete gravity dam seismically reinforced by post-tensioned anchors. In order to evaluate the seismic performance, the response spectrum analyses have been carried out for 7 different configurations of the post-tensioned anchors, and then their performance improvement in the maximum tensile and compressive stresses is compared to each other. The comparative results demonstrate that the layout of the post-tensioned anchors strongly influences the seismic performance of the concrete gravity dam. In this study, the slightly-inclined vertical anchorage system shows the largest improvement on the overall performance of the seismically-excited concrete gravity dam.