• 한국지반환경공학회 논문집
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• 제18권10호
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• pp.5-14
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• 2017

In recent years, world has witnessed many man-made activities related to both above and underground blasts. Details on behaviour of shallow foundations subjected to blast loads and induced liquefaction is scarce in literature. In this paper, typical shallow strip foundation in saturated cohesionless soils subjected to both above and underground blasting have been simulated by using finite difference based numerical model FLAC3D. Peak particle velocity (PPV) has been obtained to propose critical values for which bearing capacity failure for shallow foundations with soil liquefaction can occur. Typical results for pore pressure ratio (PPR) for various scaled distances are compared to PPR values obtained by using empirical equation available in literature which shows good agreement. Critical design values obtained in the present study for PPV and PPR to estimate the scaled distance, bearing capacity failure and liquefaction susceptibility can be used effectively for design of shallow strip foundation in cohesionless soil subjected to both above and under ground blast loads.

• Wind and Structures
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• 제11권6호
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• pp.441-453
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• 2008

In this study, a partially earth-anchored cable system is studied in order to reduce the dynamic wind response of cable-stayed bridges. The employment of earth-anchored cables changes the dynamic characteristics of cable-stayed bridges under wind loads. In order to estimate the changes in the member forces, the spectral analysis for wind buffeting loads are performed and the peak responses are evaluated using 3-D finite element models of the three-span cable-stayed bridges with the partially earth-anchored cable system and with the self-anchored cable system, respectively. Comparing the results for the two different models, it is found that the earth-anchored cables affect longitudinal and vertical modes of the bridge. The changes of the natural frequencies for the longitudinal modes remarkably decrease the peak bending moment in the pylon and the movements at the expansion joints. The small changes of the natural frequencies for the vertical modes slightly increase bending moments and deflections in the girder. The original effects of the partially earth-anchored cable system are also shown under wind loads; the decrement of girder axial forces and bearing uplifting forces, and the increment of cable forces in the earth-anchored cables.

• 한국해양공학회지
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• 제15권1호
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• pp.36-44
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• 2001

To predict the influence on fish stocks which were caused by environmental change in the fishing ground of shallow sea areas, we have developed the Shallow-Sea Ecological Model(SSEM) which that focuses on living organisms, especially fish and benthos. By applying the SSEM in the Seto-Inland Sea of Japan, we have simulated another aspect of influence on fish stocks that was caused by oxygen deficient water mass and nutrient loads. From the simulated result of the fish stocks, it was indicated that the stock of fish and benthos has shown a relative difference between the western sea and the eastern sea in the Seto-Inland Sea. According the to prediction, results of fish stocks that were caused by oxygen deficient water mass, it was estimated that the pelagicfish stock increases about 6 %, whereas the stocks of demersalfish and benthos decreases about 30% and 70%, respectively. On the other hand, it seemed that there was an increased in the fish stocks of demersalfish and benthos in the eastern sea of Seto-Inland Sea by nutrient loads reduction.

• Wind and Structures
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• 제31권6호
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• pp.523-532
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• 2020

As the height and flexibility of high-rise buildings increase, the wind loads become more dominant and the combination coefficient of Equivalent Static Wind Loads (ESWLs) should be considered when they are used in the structural design. In the first phase of the study, a brief introduction to the theory on the combination coefficient for high-rise buildings was given and then the time history of wind-induced responses of a 208-meter high-rise building with an elliptical cross-section was presented based on the wind tunnel test results for pressure measurement. The correlation between wind-induced responses was analyzed and the combination coefficients of ESWLs of the high-rise buildings using Turkstra's rule, and Asami's method, were calculated and compared with related design codes, e.g., AIJ-RLB, ASCE 7-10, and China Load Code for structural design. The results of the study showed that the combination coefficients from Asami's method are conservative compared with the other three methods. The results of this paper would be helpful to the wind-resistant design of high-rise buildings with elliptical cross-section.

• 한국습지학회지
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• 제16권3호
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• pp.403-409
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• 2014

수질오염총량관리 대상물질로 총 유기탄소(Total Organic Carbon, TOC)항목의 적용을 검토 하고 있는 가운데 이 항목에 대한 가축분뇨의 발생 및 배출 원단위 확보가 시급한 실정이다. 따라서 본 연구에서는 가축 분뇨 중 수질오염 기여도가 가장 높은 것으로 알려진 양돈 분뇨에 대해 TOC를 포함한 원단위를 산정하였다. 4대강 수계의 56개 농장을 대상으로 수계별, 사육방식별, 축사의 형태 및 규모별 양돈 분뇨의 농도, 분뇨 발생량(세척수 포함) 및 부하를 산정하였다. 분뇨 발생량은 한강수계와 낙동강수계에서 모돈 사육이 밀집된 소규모 농장 내 스크래퍼 형태의 축사에서 많은 것으로 나타났고, 양돈분뇨 발생량은 전체 수계 평균 7.4 L/두/d로 나타났다. 평균 발생 농도는 TOC가 16,037 mg/L, BOD가 10,559 mg/L, TN이 4,145 mg/L, TP가 503 mg/L로 조사되었으며, 이때 발생 부하는 TOC가 117.1 g/두/일, BOD가 77.1 g/두/일, TN이 34.7 g/두/일 그리고 TP가 3.67 g/두/일로 도출되었다.

• 한국습지학회지
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• 제24권4호
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• pp.367-376
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• 2022

LID 기술은 다양한 토지이용에서 발생되는 비점오염원(NPS)을 저감하는 기술이다. 점오염과 비점오염원의 증가와는 별도로 불투수지역 내 도심지는 일반적으로 도시기후에 영향을 준다. 본 연구에서는 LID 기술이 도시열섬현상(UHI)을 저감에 대한 영향분석을 공주대학교를 대상으로 수행하였다. 공공부지인 학교는 보행자의 통향량, 차량운행이 특정시기에 증가되기에 일반적인 원단위 부하량보다 낮은것으로 나타났다. LID 시설은 강우유출수 내 오염물질을 여재부 내 흡착, 여과 등을 통해 오염물질이 저감되는 것으로 분석되었다. 또한 LID 시설 내 강우유출수 저감 및 저류를 통해 유역 내 불투수면적보다 최대 7.2 ℃ 낮은것으로 나타났다. 따라서 LID 시설은 비점오염물질 저감 및 도시열섬 현상을 완화시키는 것으로 분석되었다.

• 대한조선학회논문집
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• 제43권5호
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• pp.560-567
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• 2006

FPSO and shuttle tanker are connected to each other by a mooring hawser and a loading hose through which cargo oil is off-loaded. Even in mild sea-state. environmental loads can cause unstable large drift motions between two vessels in tandem off-loading operations, which may result in collision incidents. Accordingly. the analysis on the relative motion between two vessels due to the environmental loads should be investigated in initial design stage. In this study, the low speed maneuvering equation is employed to simulate nonlinear motions of FPSO and shuttle tanker. Low frequency wave drift forces including hydrodynamic interactions between two vessels are evaluated by near field approaches. Current loads are determined by mathematical model of MMG and wind loads are calculated by employing the wind spectrum according to the guidelines of API-RP2A. Mooring forces produced by turret mooring lines and a flexible hawser are modeled quasi-statically by catenary equations. The effect of environmental loads that affect nonlinear motion is investigated through variation in their magnitudes and the nonlinear motions between FPSO and shuttle tanker are simulated under wave, current and wind in time domain.

• 콘크리트학회논문집
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• 제19권2호
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• pp.209-216
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• 2007

본 연구는 강섬유 보강 초고강도 콘크리트가 적용된 슬래브-기둥 접합부의 구조적 특성을 파악하였다. 2개의 슬래브-기둥 시험체와 4개의 독립 기둥 시험체의 기둥 하중 전달 실험이 수행되었다. 기둥 하중 실험 수행시, 슬래브-기둥 접합부의 실제 구속 상태를 고려하기 위해 슬래브 하중을 적용하였다. 주 변수로는 강섬유 보강 초고강도 콘크리트의 확대 타설이며, 이에 더하여 슬래브의 접합부 구속 효과, 강섬유 보강, 그리고 접합부의 콘크리트 강도 등이 실험을 통해 파악되었다. 또한, ACI Code(2005)와 CSA Standard(2004)의 예측식과 실험 결과를 비교하였다. 슬래브-기둥 접합부를 통한 기둥 하중 전달에 대한 강섬유 보강 초고강도 콘크리트의 효과를 실험을 통해 확인하였다.

• Ocean Systems Engineering
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• 제10권3호
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• pp.243-266
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• 2020

In-place analysis for offshore platforms is required to make proper design for new structures and true assessment for existing structures. In addition, ensure the structural integrity of platforms components under the maximum and minimum operating loads and environmental conditions. In-place analysis was carried out to verify the robustness and capability of structural members with all appurtenances to support the applied loads in either operating condition or storm conditions. A nonlinear finite element analysis is adopted for the platform structure above the seabed and the pile-soil interaction to estimate the in-place behavior of a typical fixed offshore platform. The SACS software is utilized to calculate the natural frequencies of the model and to obtain the response of platform joints according to in-place analysis then the stresses at selected members, as well as their nodal displacements. The directions of environmental loads and water depth variations have an important effect on the results of the in-place analysis behavior. The influence of the soil-structure interaction on the response of the jacket foundation predicts is necessary to estimate the loads of the offshore platform well and real simulation of offshore foundation for the in-place analysis. The result of the study shows that the in-place response investigation is quite crucial for safe design and operation of offshore platform against the variation of environmental loads.

• Earthquakes and Structures
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• 제8권5호
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• pp.977-994
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• 2015

In this study, earthquake loads are investigated statistically and compared with the nominal earthquake loads calculated according to the Turkish Earthquake Code, namely: "Specifications for Structures to be Built in Earthquake Areas". For this purpose, the "actual" mean load values estimated from statistical methods and the nominal load values computed according the Seismic Code are compared, with respect to some variations in the basic parameters, such as the importance factor, building height, site coefficient, seismic zone and seismic load reduction factor. In addition to the data compiled from different regions of Turkey, the published data and information in the foreign literature are also used in the determination of the earthquake load statistics. Although the dead and live loads acting on a structure are independent of the geographical location of the structure, environmental loads, such as earthquake loads are highly dependent on the location of the structure. Accordingly, for the assessment of statistical parameters associated with earthquake loads, twelve different locations which can represent the different seismic zones of Turkey as accurately as possible are chosen. As a result of the code calibration procedure considered in this study, it is observed that the load values obtained from the Turkish Seismic Code may overestimate or underestimate the actual seismic loads in some of the seismic zones.