• Earthquakes and Structures
• /
• 제15권1호
• /
• pp.1-8
• /
• 2018

A new site classification system and site coefficients based on local site conditions in Korea were developed and implemented as a part of minimum design load requirements for general seismic design. The new site classification system adopted bedrock depth and average shear wave velocity of soil above the bedrock as parameters for site classification. These code provisions were passed through a public hearing process before it was enacted. The public hearing process recommended to modify the naming of site classes and adjust the amplification factors so that the level of short-period amplification is suitable for economical seismic design. In this paper, the new code provisions were assessed using dynamic centrifuge tests and by comparing the design response spectra (DRS) with records from 2016 Gyeongju earthquake, the largest earthquake in history of instrumental seismic observation in Korea. The dynamic centrifuge tests were performed to simulate the representative Korean site conditions, such as shallow depth to bedrock and short-period amplification characteristics, and the results corroborated with the new DRS. The Gyeongju earthquake records also showed good agreement with the DRS. In summary, the new code provisions are reliable for representing the site amplification characteristic of shallow bedrock condition in Korea.

• Earthquakes and Structures
• /
• 제10권5호
• /
• pp.1233-1251
• /
• 2016

In this paper, it is aimed to determine the stochastic response of a suspension bridge subjected to spatially varying ground motions considering the geometric nonlinearity. Bosphorus Suspension Bridge built in Turkey and connects Europe to Asia in Istanbul is selected as a numerical example. The spatial variability of the ground motion is considered with the incoherence, wave-passage and site-response effects. The importance of site-response effect which arises from the difference in the local soil conditions at different support points of the structure is also investigated. At the end of the study, mean of the maximum and variance response values obtained from the spatially varying ground motions are compared with those of the specialised cases of the ground motion model. It is seen that each component of the spatially varying ground motion model has important effects on the dynamic behaviour of the bridge. The response values obtained from the general excitation case, which also includes the site-response effect causes larger response values than those of the homogeneous soil condition cases. The variance values calculated for the general excitation case are dominated by dynamic component at the deck and Asian side tower. The response values obtained for the site-response effect alone are larger than the response values obtained for the incoherence and wave-passage effects, separately. It can be concluded that suspension bridges are sensitive to the spatial variability of ground motion. Therefore, the incoherence, the wave-passage and especially the site-response effects should be considered in the stochastic analysis of this type of engineering structures.

• 한국지진공학회논문집
• /
• 제8권3호
• /
• pp.23-32
• /
• 2004

본 논문에서는 국내 148개 지반에 대한 전단파속도 주상도, 기반암 깊이 및 지반의 동적변형특성을 획득하여 미국 서부해안지역의 지반특성과 비교하였고, 등가선형해석을 수행하였다. 해석은 1등급 붕괴방지수준인 0.154g를 암반노두에 적용하여 수행하였다. 해석결과 국내 지반특성에 적합한 증폭계수 $F_a$와 $F_v$는 UBC 기준의 증폭계수와 매우 다른 경향을 보였다. 단주기 증폭계수 $F_a$의 경우 UBC 기준보다는 큰 값이 얻어졌고, 장주기 증폭계수 $F_v$는 UBC 기준보다 작은 값으로 나타났다. 따라서, 국내 지반특성을 적절히 반영할 수 있는 설계지반운동 결정방법을 개선해야할 필요를 확인하였다.

• 한국지진공학회논문집
• /
• 제8권4호
• /
• pp.11-20
• /
• 2004

반응수정계수의 핵심구성요소인 연성계수를 토질조건에 따라 제시하였다. 47개의 지진에서 얻어진 총 1,860개의 지진기록이 사용되었으며, 지반 전단파의 평균속도에 따라 4가지의 토질조건을 고려하였다. 이러한 분류는 현재 사용되고 있는 UBC(1997), NEHRP(1997) 및 IBC 200(1997)의 토질조건과 일치한다. 통계적 회귀분석으로부터, 토질조건에 따른 연성계수를 평가하기 위한 단순화된 식이 제안되었다. 제안된 식은 상대적으로 간단하면서도 평균연성계수와 잘 일치하는 결과를 보였다. 제안된 식에 근거하여, 현재의 기준과 일치하는 토질조건에 따른 연성계수를 평가할 수 있을 것으로 기대한다

• 한국측량학회지
• /
• 제34권2호
• /
• pp.161-169
• /
• 2016

This paper is intended to propose a novel approach to select an optimal site for a small-scaled artificial recharge system installation using TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) with geospatial data. TOPSIS is a MCDM (Multi-Criteria Decision Making) method to choose the preferred one of derived alternatives by calculating the relative closeness to an ideal solution. For applying TOPSIS, in the first, the topographic shape representing optimal recovery efficiency is defined based on a hydraulic model experiment, and then an appropriate surface slope is determined for the security of a self-purification capability with DEM (Digital Elevation Model). In the second phase, the candidate areas are extracted from an alluvial map through a morphology operation, because local alluvium with a lengthy and narrow shape could be satisfied with a primary condition for the optimal site. Thirdly, a shape file over all candidate areas was generated and criteria and their values were assigned according to hydrogeologic attributes. Finally, TOPSIS algorithm was applied to a shape file to place the order preference of candidate sites.

• 한국지진공학회논문집
• /
• 제7권2호
• /
• pp.39-48
• /
• 2003

반응수정계수의 핵심구성요소인 연성계수에 대하여 통계적 분석을 수행하였다. 연성계수의 체계적인 산정을 위하여 총 1,860개의 지진기록을 수집하였다. 수집된 지진기록을 지반 전단파의 평균속도에 따라 4가지로 분류하고, 탄소성 이력거동을 가지는 단자유도 구조물에 대하여 비탄성 스펙트럼을 작성하였다. 작성된 비탄성 스펙트럼으로부터 연성계수를 구하고, 변위연성비, 토질조건, 규모 및 진앙거리가 연성계수에 미지는 영향을 분석하였다. 토질 조건별로 평균연성계수를 구하고, 산정된 연성계수의 산포도를 검토하기 위하여 변동계수를 산정하였다.

• 한국농촌건축학회논문집
• /
• 제14권4호
• /
• pp.1-9
• /
• 2012

Recently, the central and local government support various improvement projects on existing public buildings and areas. Improving public use and environment of these areas is adequate because financial condition of local city is not enough to build new infrastructures. As one of the projects, Geochang-Eup(Geochang-Gun, Gyeongnam Province) is selected as the project site since most of the public buildings and areas of the city are located close each other in downtown but not streamlined in function and use nor easily accessible. The purpose of this study is to analyze the causes of decline in local city and to present strategies to vitalize the city through improving environment of public areas. And we analyzed the problems by discussion with local officer, field investigation on the site and paper survey. The analysis shows that public infrastructures are grouped by function: administration, education, life support, culture, health, etc, but not well-connected, easily accessible, adequately located, various in use nor enough in quantity. This study summarized the problems into five categories: Access&Linkage, Safe&Comfort, Identity&Image, Usage&Activity and Ownership&Management and proposes strategy in three phases. The first phase is to improve functions and design of public places per each area: more consistent design on public buildings, better civil facilities and better accessibility to public areas. The second is to vitalize of the areas and to improve efficiency in use through linking each other physically and sharing uses. The third is to encourage citizen's participation and by developing civil programs to streamline public areas each other.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2001년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2001
• /
• pp.83-90
• /
• 2001

The site effects of local geological conditions on seismic ground motion are performed using 2D numerical method. For the analysis, a numerical method far ground response analysis using FE-BE coupling method is developed. The total system is divided into two parts so called far field and near field. The far field is modeled by boundary element formulation using the multi-layered dynamic fundamental solution that satisfied radiational condition of wave. And this is coupled with near field modeled by finite elements. In order to verify the seismic response analysis, the results are compared with those of commercial code. As a result, it is shown that the developed method can be an efficient numerical method to solve the seismic response analysis of the site effect in 2D problem.

• Ocean Systems Engineering
• /
• 제9권1호
• /
• pp.43-77
• /
• 2019

A local-analytic-based Navier-Stokes solver has been employed in conjunction with a compound ocean structure motion analysis program for time-domain simulation of passing ship effects induced by multiple post-Panamax class ships in the exact condition of a real waterway. The exact seabed bathymetry was reproduced to the utmost precision attainable using the NOAA geophysical database for Virginia Beach, NOAA nautical charts for Hampton Roads and Norfolk harbor, and echo sounding data for the navigation channel and waterfront facilities. A parametric study consists of 112 simulation cases with various combinations of ship lanes, ship speeds, ship heading (inbound or outbound), channel depths, drift angles, and passing ship coupling (in head-on or overtaking encounters) were carried out for two waterfront facilities at NAVSTA Norfolk and Craney Island Fuel Terminal. The present paper provides detailed parametric study results at both locations to investigate the site-specific passing ship effects on the motion responses of ships moored at nearby piers.

• 환경영향평가
• /
• 제7권1호
• /
• pp.71-80
• /
• 1998

The purpose of this study is to investigate and analyze a conservation state and a sustainable use of coastal wetland in Sindu-ri Tae-an, using the plant community structure analysis and the awareness result of local residents by published paper. To investigate a forest structure in Sindu-ri area, twenty plots were set up and surveyed. The community, is divided by three groups. The divided groups are Robinia pseudoacacia(I), Pinus thunbergii-Robinia pseudoacacia(II), Robinia pseudoacacia(III). Survey site I is simple canopy layer and deteriorative forest. Survey site II is grassland and swamp, where Pinus thunbergii-Robinia pseudoacacia is dominant trees of vegetation. Robinia pseudoacacia is competition species with Pinus thunbergii in survey site II. Survey site III is barren land(sand-hill) where main species is Robinia pseudoacacia. As a result, survey II district is considered as the most suitable for the conservation of species diversity. It is proposed in this paper that the ecological nature trail would be connected in survey site I and II for environmental education. The local residents of Tae-an, where natural environment is well-conserved, prefer conservation to development of the region. In case of Tae-an, where the condition of the natural environment is well conserved and the development potential exists, the development is in harmony with the environmental education program.