• Water for future
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• v.29 no.1
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• pp.249-263
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• 1996

Presented herein are the results of a laboratory study on structural loads (icing weight and wind loads) associated with icing formation on rigidly fixed, circular power-transmission cables and cylinders. The experiments were carried out using movable wind tunnel under two different conditions: refrigerated and non-refrigerated conditions. Temporal evolution of icing loads were determined in the refrigerated laboratory and wind loads for icings at several stages of icing formation were measured in the non-refrigerated laboratory.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.4
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• pp.77-86
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• 1993

Recently it is reported in many countries that highway bridges are seriously damaged due to increasing volume of overloaded heavy vehicles. The safety of bridges are highly related to the design load level and the characteristics of extreme load effect induced by traffic loads during its lifetime. The maximum structural load effect during lifetime may be produced by simultaneous loading of trucks with moderate weights on a bridge rather than by single loading of extremely heavy trucks. In this study, a simulation technique to estimate extreme load effect due to traffic loadings has been developed, in which important characteristics of traffic loadings, such as heavy vehicle proportion, traffic mode, vehicle weights, headway distribution. daily traffic volume, etc., should be properly considered. In addition. sensitivity analysis on those factors have been performed.

• Journal of the Korean Geotechnical Society
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• v.17 no.3
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• pp.41-50
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• 2001

본 연구는 모래사면의 언덕근처에 설치된 짧은 말뚝의 수평하중의 영향에 관한 것이다. 3차원 탄소성 유한요소법해석과 실내 모형실험의 결과를 비교하였다. 경사 30$^{\circ}$의 사면에 시공된 짧은 말뚝의 특성을 파악하기 위해, 사면언덕에서 모형말뚝까지의 거리를 3종류로 상이하게 하여, 모형실험을 실시하였다. 사용된 모래의 지반특성은 배수조건하의 삼축압축실험으로 결정하였다. 동시에 3차원 탄소성 유한요소법에 의한 수치해석결과와 모형실험결과를 비교하였다. 본 유한요소법의 해석에 있어서 모래지반을 탄성완전소성모델(Elastic-perfectly plastic model)로 가정하여, 파괴기준으로 Mohr-Coulomb 식과 소성 포텐셜에 대해서는 Drucker-Prager 식을 적용한 MC-DP 모델로 하였다. 이러한 MC-DP 모델의 구성식은 유한요소법에서 있어 계산치의 수렴에 유익하다. 3차원 탄소성 유한요소법에 의한 수치해석이 사질토 사면의 언덕 부근에 설치된 단하의 수평거동에 대한 파악에 유효하다는 것을 확인하였다.

• Journal of the Korean GEO-environmental Society
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• v.13 no.11
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• pp.19-26
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• 2012

In the present study, anchor type nail with PC-strand which can add up the pre-stress at the nailing to increase the resistance and shear stress in the whole ground has been investigated. Load-displacement and wall displacement have been analyzed by experimental model and numerical analysis of anchor type nail, nailing, and non-nailing to examine the behavior of anchor type nail. From the experimental results, it was found that horizontal displacement is considerably decreased according to increasing the load in case of anchor type nail added pre-tension. Especially, it was observed that resistance of displacement at the upper wall is increased. The results of numerical analysis show the same results of experimental results.

• The Journal of Engineering Geology
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• v.12 no.1
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• pp.75-88
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• 2002

When unsymmetrical surcharge is worked on polluted soft soils, large plastic shearing deformation such as settlements, lateral displacement, upheavals and shearing failure occured in the soils and they have often done considerable damages to the soils and structures. Accordingly, this study conducts laboratory pilots test to investigate the determination method of lateral flow pressure of polluted soft soils by comparing it to existing equations. The model test is performed that a model stock device is made and polluted soils are filled in a container which fires the soils. Then the displacement is observed as surcharge load is increased by regular intervals at untrained condition. The result shows that test the lateral flow pressure is adequately calculated by the equation (P=K$_{0}$YH) and the maximum value of lateral flow pressure Is found near 0.3H of layer thickness(H) and is higher to ground surface than synthesis pattern, Poulos distribution pattern and soft clay soils(CL, CH) which is not polluted.

• Journal of Korean Society of Steel Construction
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• v.11 no.4 s.41
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• pp.397-407
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• 1999

In this paper, the fatigue safety in the suspension bridge is investigated by using nominal and variable stress, respectively. The technique on structural modeling and the fatigue evaluation using nominal stress are mainly dealt with in this paper. To make the finite element analysis model reflecting the actual structural behavior of the suspension bridge with cross frame, the parametric study is carried out. In this study, the influence of supporting condition. the difference of the results of 2- and 3-D analysis and the number of cross frames modelled in are considered. The nominal stress under the real traffic flow of the bridge is calculated by the combination of the stresses due to the unit DB-24 loading. The nominal stresses for details under consideration are compared with allowable stress ranges specified in the codes and the results are discussed.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.71-71
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• 2011

캣워크는 현수교의 주케이블을 가설을 위해 일시적으로 설치하는 공중작업발판으로 주케이블 가설장비와 작업원 등의 하중을 지지한다. 캣워크는 유연한 구조물로서 풍하중에 상당한 변형이 발생한다. 하지만, 국내외를 막론하고 캣워크의 내풍안정성에 대한 연구는 별로 이루어지지 않았다. 거기에 더하여 캣워크에 작용하는 정적 공기력에 대한 정보도 부족하며, 현재 캣워크 단면에 대한 적절한 풍하중을 산정하지 못하고 경험적인 설계가 이루어지고 있다. 따라서 캣워크의 효율적인 내풍설계를 위하여 풍동실험을 통한 충실률과 공기력계수와의 관계를 알아보는 것이 필요하다. 이를 위하여 축척 1/4인 모형을 사용한 풍동실험을 통하여 메쉬망의 크기를 변화시키면서 충실률에 따른 공기력계수를 측정하고 설계식을 제안하고자 한다. 캣워크는 로프와 아울러 가는 철망으로 아래와 양 옆이 막혀 있다. 즉 바람을 직접 받는 부분인 철망은 가는 원형단면으로 구성되어 있다. 원형 단면의 경우에 레이놀즈 수에 따라 항력계수가 크게 변하는 것으로 알려져 있다. 그러나 가는 원형 단면으로 둘러싸인 캣워크의 항력계수에 레이놀즈 수가 미치는 영향에 대해서는 연구된 바가 없다. 본 연구에서는 캣워크의 공기력계수에 미치는 레이놀즈 수에 대한 영향을 파악하고자 1/4모형과 1/14모형을 제작하여 최대풍속 30m/s까지 변화시켜가면서 공기력계수를 측정하였다. 이때 레이놀즈 수는 최대 20배까지 차이가 나므로 만약 공기력계수가 레이놀즈 수의 영향을 받는다면 확실히 그 영향을 파악할 수 있다. 본 연구에서는 풍동실험을 통해 충실률과 공기력계수와의 관계과 레이놀즈 수의 영향을 살펴보았으며, 정적공기력 계수의 설계식을 제안하였다. 본 연구를 통하여 얻은 결과를 정리하면 다음과 같다. 1. 축척 1/14 및 1/4 모형을 사용하여 다양한 풍속에서 공기력계수를 측정한 결과, 캣워크에 작용하는 정적 공기력계수는 레이놀즈 수의 영향을 받지 않는 것으로 나타났다. 따라서 향후 새로운 형식의 캣워크에 대한 풍동실험을 수행할 경우에 축척에 상관없이 풍동실험 결과를 사용할 수 있을 것으로 판단된다. 2. 풍동실험 결과, 캣워크에 작용하는 정적 공기력계수 중 항력계수와 피칭모멘트계수는 측면 충실률에 따라 달라지고, 영각에 대한 양력계수의 기울기는 하부 충실률의 영향을 받는 것으로 나타났다. 그리고 주케이블이 캣워크 내부에 위치하고 있어도 캣워크의 정적 공기력계수에는 큰 영향을 미치지 않은 것으로 측정되었다. 이를 정리하여 캣워크 충실률에 따른 정적 공기력계수의 추정식을 제안하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1889-1894
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• 2012

A small-scale chamber test laboratory for controlled low strength materials with bottom ash and recycled in-situ soil have been carried out. Laboratory test which was simulated during construction stage was conducted. The vertical deflection of 4.43mm to 6.6mm, and the horizontal deflection of 5.49mm to 15.9 mm were measured during backfilling. In case of loading, the vertical deflection of 2.41mm to 8.69mm, and the horizontal deflection of 1.66mm to 2.53mm were measured. Its residual deflections were 1.40mm to 5.93mm for vertical and 1.66mm to 2.53mm for lateral. The vertical and horizontal deflecto of controlled low strength materials were smaller than that of sand backfill. Also, it was same trend for the measured surface settlement.

• Journal of the Korean Geotechnical Society
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• v.21 no.2
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• pp.105-111
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• 2005

Shaking table tests are performed to investigate the seismic behavior of the batter pile and to bring up the countermeasures to improve the seismic performance of the batter pile. First of all, this study demonstrates how batter piles and vertical piles behave under static lateral loadings. Secondly, the vulnerability of batter plies under dynamic lateral loadings is demonstrated showing the axial forces and bending moments mobilized at the pile heads during shaking table tests. Thirdly, countermeasures to overcome the vulnerability of behavior piles during earthquakes are pursued. The countermeasures investigated in this study include introduction of a rubber element at the pile head and the deck plate connection, and introduction of hinge connection. Finally, the slope of batter piles which induces the minimum pile forces during the dynamic loadings are investigated and found to be 8:3 (Vertical to Horizontal).

• Geotechnical Engineering
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• v.13 no.4
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• pp.55-66
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• 1997

In order to investigate the influence of installation angle of reticulated root piles(RRP) on their lateral load capacities, model tests of lateral loads on RRP with various installation angles $0^{\circ}\;, 5^{\circ}\;, 10^{\circ}\;, 15^{\circ}\;, 20^{\circ}\;,and 25^{\circ}$ are carried out. One set of RRP consists of 12 piles which are installed in circular patterns forming two concentric circles, each of which has 6 piles. Each pile made of a steel bar of 5mm in diameter and 350mm in length, is coated with sand until the bar has the diameter of 6.5mm. According to the test results, RRP's response is travily influenced by the displacement level. At low displacement level(1m), lateral load capacity increases as the installation angle is increased. However, the value of the optimum installation angle decreases as the displacement level is increased. In fact, it is found to be $17.5^{\circ}$ at 6mm lateral displacement. The ratios of the lateral resistances for the optimum installation angles to those for the vertical RRP decrease as the lateral displacements are increased. Thus the effect of slant ins angle of RRP is expected to be reduced at higher level of lateral displacement.