• Tunnel and Underground Space
• /
• v.24 no.5
• /
• pp.354-365
• /
• 2014

The horizontal response spectra using the observed ground motions from 15 Fukuoka earthquake series, including main earthquake (2005/03/20; Mw=6.5), were analysed and then were compared to both the seismic design response spectra (Regulatory Guide 1.60), applied to the domestic nuclear power plants, and the Korean Standard Design Response Spectrum for general structures and buildings (1997). 178 horizontal ground motions, without considering soil types, were used for normalization with respect to the peak acceleration value of each ground motion. The results showed that response spectrum have strong dependency on epicentral distance. The results also showed that the horizontal response spectra revealed higher values for frequency bands at two frequency bands (about 8 - 10 and 16- 20 Hz) than Regulatory Guide 1.60. The results were also compared to the Korean Standard Building Design Spectrum for the 3 different soil types and showed that thehorizontal response spectra revealed higher values for almost all period bands than the Korean Standard Response Spectrum (500 yrs; Return Period; Seismic province 1; SE soil conditions). Through the qualitative improvements and quantitative enhancement of the observed ground motions, the diversity of the observed ground motions should be considered more significantly to improve the certainty of response spectrum.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.4 no.4
• /
• pp.15-26
• /
• 2000

지진파 전파로 인한 매설관에 작용하는 지진하중은 지진특성 및 지반조건에 따른 지반변형률로부터 산정되어야 한다. 그러나. 기존에 사용되고 있는 경험적인 방법에 의해 계산된 지반변형률 모형은 지진 및 지반의 지역적 특수성을 고려할 수 없는 문제점을 내포하고 있다. 따라서, 본 연구에서는 이러한 문제점을 개선하기 위하여 지진특성 및 지반조선을 반영할 수 있는 수정된 지반변형률 모형을 제안하고 개발된 모형을 매설관로의 지진해석에 지진하중으로 적용하였다. 여기서, 지반변형률을 예측하기 위한 지진판 전파속도는 지반조건을 고려할 수 있도록 파 에너지분포에 근거한 분산곡선을 제안하여 산정하였다. 이러한 과정을 통해 얻어진 지반변형률 산정방법에 타당성을 파악하기 위해 예측한 지반변형률과 과거 지진으로 실측된 지반변형률을 비교하였다. 타당성이 입증된 지반변형률 모형을 매설관의 하중으로 적용하여 지진해석을 실시하였으며, 계산결과는 범용 유한요소해석을 통한 동해석 및 응답변위법에 의한 결과와 비교하였다. 이를 통해 지반 변형률 모형을 적용한 매설관 지진해석의 타당성을 검증하였다. 또한, 지진 및 지반환경이 다른 다양한 관의 특성을 반영하기 위해, 지진 지반 및 관의 영향 인자에 대해 매개변수 해석에 실시되었으며, 이로써 본 연구의 활용성을 검토하였다.

• Journal of Korean Association for Spatial Structures
• /
• v.9 no.1
• /
• pp.87-94
• /
• 2009

This paper presents dynamic behavior of double-layer barrelvault systems subjected to earthquake loadings. In order to investigate different seismic behaviors according to Time History Analysis (THA), six open angles were employed and different fundamental frequencies corresponding to each open angle were considered. A total of 24 double-layer structures were developed by using Midas Gen., which is a computer analysis program and then THA with three different earthquakes with 5% damping ratio was performed. This study investigated the characteristics of the dynamic response for X-, Y- and Z- directions, both subjected to the horizontal earthquake (H) and applied to the vertical earthquake (V) with respect to the each variable, which assumed to be important aspects for spatial structure. In order to examine the dynamic characteristics, the ratio of acceleration in specific nodes of barrelvaults was evaluated at the time with maximum response. The main purpose of this study is to obtain equations of the equivalent earthquake loading with respect to the barrelvault systems.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.1
• /
• pp.101-112
• /
• 2002

In this study, a new methodology fur the assessment of liquefaction potential is proposed and characteristics of the proposed methodology are verified. The experimental parameter of this methodology, that is, the plastic shear strain trajectory, is compared with the dissipated energy. It is shown that this parameter can express the liquefaction behavior which is generated by excess pore water pressure. This methodology takes advantage of the shear strain time history determined from the site response analysis based on the real time history of earthquake. In this site response analysis, shock type and vibration type records of similar predominant frequency are inputted. The liquefaction safely factors based on the proposed methodology and Korean detailed assessment related to the classical method are calculated from the results of the site response analysis and laboratory dynamic tests. Through this study, it is found that the proposed methodology can not only simulate the liquefaction behavior of saturated soils hut also express the seismic characteristics reasonably : leading type, predominant frequency, maximum acceleration, duration time.

• Proceedings of the Korean Institute of Industrial Safety Conference
• /
• 2000.06a
• /
• pp.235-240
• /
• 2000

도시가스는 도시생활을 유지하는데 필수 불가결한 라이프라인으로 가스사업자는 평상시 안정공급을 확보하는 것은 물론 지진과 같은 대규모의 자연재해가 발생한 경우에도 대처할 수 있도록 평상시부터 준비를 철저히 하지 않으면 안 된다. 우리나라에서는 1988년 건축물의 내진설계기준이 도입된 이래 일부시설에 대한 내진 설계기준이 설정되어 있다. 가스시설에 대해서도 1997년 한국지진공학회으로부터 우리나라의 지진환경을 고려한 가스시설의 내진성능기준(안) 및 내진설계 표준서(안)이 제시되어 가스시설물의 내진설계를 위한 기본적인 틀을 갖추었다. (중략)

• Journal of the Earthquake Engineering Society of Korea
• /
• v.14 no.3
• /
• pp.59-68
• /
• 2010

Seismic performances of existing structures should be assessed with more accuracy for cost-effective retrofits. Existing bridges are assessed by the current guidelines in which a simple method has been adapted considering the technical level of engineers of the historical time of construction. Recently many probabilistic approaches have been performed to reflect the uncertainties of seismic input motions. Structures are modeled frequently with the neglection of soil foundations or modeled occasionally with elastic soil spring elements to consider the effect of the soil on the structural response. However, soil also shows nonlinearity under seismic events, so this characteristic should be reflected in order to obtain a more accurate assessment. In this study, a 6-span continuous bridge has been analyzed under various seismic events, in which the soil was represented by equivalent linear spring elements having different properties according to the intensities of the input motions experienced. The seismic vulnerabilities with respect to the failure of piers and the dropping of the super-structure were evaluated on the basis of the analysis results.

• Journal of the Korean Geotechnical Society
• /
• v.34 no.8
• /
• pp.51-64
• /
• 2018

Korean peninsula is known to be far from the plate boundary and not to generate large-scale earthquakes. However, earthquakes recently occurred in Gyeongju (2016/09/12, $M_L=5.8$) and Pohang (2017/11/15, $M_L=5.4$). The interest in earthquake engineering has increased, and various studies are actively underway by recently events. However, the seismic station network in Korea is less dense than that of the western U.S., resulting in the lack of data for detailed analyses of earthquakes. Therefore, KMA (Korea Meteorological Administration) set up temporary seismic stations and recorded ground motions from aftershocks. In this study, characteristics of Pohang seismic propagation and generation of bedrock motion are analyzed through the aftershock ground motion records at both permanent and temporary stations, as well as through the collected geological structure and site information. As a result, the response at Mangcheon-Li shows evidences of basin effects from both geology structures and measured aftershock motions.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.13 no.1
• /
• pp.1-8
• /
• 2009

In order to evaluate the effect of shear wave velocity of a seismic control point on site response analysis, one-dimensional equivalent linear site response analysis were performed on the model soil profile based on the results of a detailed site investigation of sedimentary layers at Incheon and Busan. The results of the analysis show that an increase of shear wave velocity on the seismic control point (base rock) results in an increase of acceleration in the soil layers. This was mainly due to an unclear definition of the seismic control point. For this reason, the Korean Seismic Design Standard requires a specific definition of the seismic control point, including spatial conditions and soil properties, similar to the MCE (Maximum Considered Earthquake) in FEMA 369.

• Journal of the Korea Concrete Institute
• /
• v.20 no.1
• /
• pp.51-58
• /
• 2008

Analytical probabilistic vulnerability analysis requires extensive computing effort as a result of the randomness in both input motion and response characteristics. In this study, a new methodology whereby a set of vulnerability curves are derived based on the fundamental response quantities of stiffness, strength and ductility is presented. A response database of coefficients describing lognormal vulnerability relationships is constructed by employing aclosed-form solution for a generalized single-degree-of-freedom system. Once the three fundamental quantities of a wide range of structural systems are defined, the vulnerability curves for various limit states can be derived without recourse to further simulation. Examples of application are given and demonstrate the extreme efficiency of the proposed approach in deriving vulnerability relationships.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.8 no.4
• /
• pp.21-32
• /
• 2004

A Seismic analysis procedure of bi-directional brideg motions is developed by using mechanical bridge model. A three-dimensional mechanical model can consider major phenomena under bi-directional seismic excitations, such as nonlinear pier motion under biaxial bending, pounding and bearing damage due to the rotaion of the superstructure, etc. The analyses utilizing the uni-directional and the bi-directional bridge model for the 3-span simply supported bridge are then performed. The seismic responses in two cases are examined and compared by investigating the relative displacements of each superstructure to both ground and adjacent superstructures and the restoring forces of RC pier. The analysis using either the uni-directional model or bi-directional model is acceptable for estimating the displacement responses of a bridge, but the bi-directional analysis is found to give more conservative results for resisting forces of RC piers. To make general conclusions, therefore, the analysis using the bi-directional bridge model should be performed in evaluating the seismic safety of bridges.