• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.1
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• pp.59-68
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• 2003

An optimization Program is developed to produce new topologies of plane structures under multiload case. A four-node finite element is used in the response analysis to reduce the computation time and to ultimately achieve practical topology optimization. The bilinear finite element is prone to produce chequer-boarding phenomenon and a simple filtering process is therefore adopted. An artificial material model is employed to represent the structural material and the resizing algorithm based on the optimality criteria is adopted to update the material density parameter during optimization process. With newly developed optimization program, the comparison study has been made between single and multiload cases and its results are described in this paper. From numerical results, it appears that multiload case should be considered to achieve the practical topology optimization.

• Journal of the Korean Geotechnical Society
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• v.24 no.8
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• pp.43-52
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• 2008

In this study, the verification test and creep test for both a single-rebar nail and a multi-rebar nail are carried out to investigate a tensile strength for both nails. The adhesion effects between a rebar and a cement grout, a mobilized frictional force induced by pull-out load, and load transfer characteristics are examined. The results obtained from the field pull-out tests and from the numerical analysis using $FLAC^{2D}$ which is one of the programs developed based on the finite difference method are analyzed and compared for a single-rebar nail and a multi-rebar nail. The field pull-out test results for a multi-rebar nail relative to a single-rebar nail show that a tensile failure load is relatively large and the pull-out loads are well transferred to the ground in deep depth.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.1
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• pp.189-197
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• 2011

In the field of structural test, it is a very important factor to apply with an appropriate test jig to enhance test accuracy and efficiency. Especially in the large scale structure test, proper test apparatus scheme will reduce overall cost and time of the test project. Actuators, oil jack and UTM is generally used to evaluate the flexural capacity of the test beam. But in the case of multiple loading point or asymmetric loading of large scale test specimen, existing test method such as UTM have a difficulty in giving an accurate load. In this study new test method which is composed of existing test apparatus will be developed to improve test accuracy and economic efficiency.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.15-20
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• 2005

Most of studies for the ground load and ground behavior of landing gear have been conducted with an assumption that the structure of landing gear was rigid body. The assumption of rigid body during design process results in many errors or discrepancy. High ground load occurs in 3 directions on the shock absorbing strut during landing. This ground load initiated high structural deformation. In this study, the flex-multi-body dynamics is applied to adapt flexible bodies, so the results of analysis can be described close to landing gears real behaviour.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.138-149
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• 2014

This study proposes an estimation method of strain distribution for multi-span steel beam structure under unspecific loading conditions. The estimation method in this paper employs the curve fitting using the least square method from measured strain data, not analytical method. To verify the proposed estimation method, a static loading test for multi-span steel beam on which distributed and concentrated loads act was conducted. The strain data for verification was measured by FBG sensors that have multiplexing technology. The analysis of the accuracy of strain estimation for distributed and concentrated loads and the errors by considering the number of measured points used in the estimation were conducted. In the maximum strain points, the strains could be estimated with the errors of 5.89% (loading step 1) and 6.26% (loading step 2). In case of decreasing the number of sensors, it was also confirmed that the errors increased (0.26~0.37%). Through the curve fitting method, it is possible to estimate the strain distribution (maximum strains and their locations) of multi-span beam for unspecific loads and go over the limit of the analytical estimation method which is suitable for specific distributed loads.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.2
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• pp.13-22
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• 2001

지진하중을 받는 다경간 단순형교의 낙교방지대책으로 적용되는 cable restrainer를 적절하게 설계하기 위해서는 restrainer의 보강효과에 대한 분석이 우선적으로 이루어져야한다. 본 연구에서는 단순지지 다경간 교량시스템을 중심으로 restrainer로 보강된 교량의 보강효과와 다양한 교량의 영향 요소를 고려할 수 있는 단순화된 해석모형을 개발하였으며, 이를 바탕으로 대상교량의 인접 진동계간의 상대거리, 충돌력, 하부교각으로 전달되는 전단역과 휨모멘트의 변화 등의 동적거동특성을 조사하여 restrainer의 보강효과를 분석하였다. 또한, restrainer의 여유길이 변화, 강성변화, 그리고 restrainer 길이변화에 따른 응답특성을 분석하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.3
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• pp.509-518
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• 1999

교량거동의 동적 특성과 인접거덩간의 충돌의 영향을 파악하기 위하여 여러 단순보로 이루어진 교량시스템의 교축방향에 대한 거동을 분석하였다. 충돌은 물론 교각의 비선형, 그리고 기초의 병진 및 회전운동을 고려할 수 있는 단순화된 다자유도시스템을 소개하고 이에 상응하는 운동방정식을 유도하여 교량거동을 예측하는 방법을 개발하였다. 개발된 다자유도시스템은 지진하중을 받는 교량시스템의 거동분석에 대한 적절한 정보를 제공할 수 있는 것을 밝혔다. 충돌의 주 영향은 강진시 인접거더간의 상대변위를 감소시키며, 미진 시에는 상대적으로 증가시킴을 밝혔다. 따라서, 강진이 아닌 지진하중을 받는 교량의 거동분석 시에도 이러한 충돌로 인한 영향에 대하여 각별한 주의가 필요하다는 것을 제안한다.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.1 s.41
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• pp.17-24
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• 2005

Response of reinforced concrete (RC) column-bent piers subjected to bidirectional seismic loadings was experimentally investigated. RC column-bent piers represent one of the most popular shapes of piers used in Korea highway bridges. Four column-bent piers were constructed in 400 mm diameter and 2,000 mm height. Each pier has two circular supporting columns. These piers were tested under bidirectional lateral load reversals with an axial load of $0.1f_{ck}A_g$. The test parameters included : different transverse reinforcement contents and lap-spliced longitudinal reinforcing steels. Test results indicate that the lap splice of longitudinal reinforcing steels have significantly influenced on hysteretic response of column-bent piers similar to previous test results for single columns with corresponding test parameters. Column capacity was changed with the level of transverse confinement. From the comparison of test result for single column under unidirectional loading, the damage of single column was concentrated on lower plastic hinge region but the damage of column-bent piers was scattered to upper and lower plastic hinge region.

• 한국방재학회:학술대회논문집
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• 2009.02b
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• pp.80.1-80.1
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• 2009

• 한국방재학회:학술대회논문집
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• 2009.02b
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• pp.80.2-80.2
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• 2009