• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2010.04a
• /
• pp.187-190
• /
• 2010

기초세굴에 따른 교각에서의 1차 모드 고유진동수 변화를 이용하여 교량 세굴 건전성을 정량적으로 평가하기 위하여 공용중인 광탄1교의 T형 교각 1기에 대하여 충격진동실험을 수행하였으며, 교축직각방향의 1차 모드 고유진동수를 수치해석결과와 비교하였다. 교량 상부구조물의 모델링 방법에 따라 상부구조물을 전체 모델링한 방법과 교각만을 모델링하고 상부구조물의 영향범위를 가정하여 교량받침 위치에 질점질량으로 변환하여 적용한 방법으로 구분하여 수치해석을 수행하였다. 상부구조물을 전체 모델링한 경우와 집중하중 형태로 상부구조물을 모델링한 경우 모두 고유진동수는 충격진동실험결과와 큰 차이를 보였다. 충격진동실험을 통해 얻은 고유진동수는 교각의 국부적인 진동수로 사료되는 반면, 수치해석을 통해 구한 결과는 교량 상부와 하부의 Coupling 효과가 반영된 시스템 전체의 고유진동수이기 때문에 결과의 큰 편차가 생기는 것으로 판단된다. 따라서 충격진동실험에서 구한 고유치 양상을 올바로 구현하기 위한 모델링을 찾기 위해서는 새로운 접근 방법이 필요할 것으로 사료된다.

• Journal of the Korea Concrete Institute
• /
• v.25 no.4
• /
• pp.429-438
• /
• 2013

An object oriented numerical analysis program of axial-flexural elements and the step-by-step method (SSM) has been developed to analyze concrete long-term behaviors of structures constrained internally and externally. The results of the numerical analysis for simple and continuous prestressed (PS) concrete box and composite girders, pre-cast slab of continuous steel composite girder, and simple preflex composite girder show that the adjusting coefficient decreases by increasing constraint. The loss rates of pre-tension force were not sensitive but those of pre-compression force were increased rapidly by decreasing adjusting coefficient. This indicates that the design based on the loss rate of pre-tension can over-estimate the pre-compression force in a concrete section constrained internally and externally. The adjusting coefficients which satisfy results of the numerical analysis are 0.35~0.95, and it can be used as an index of constraint of concrete long-term deformation. The adjusting coefficient 0.5 of Bridge Design Specifications can under-estimate residual stress of PS concrete slab, and the coefficient 0.7 or 0.8 of LRFD Bridge Designing Specifications can under-estimate the loss rates of continuous PS concrete girders. The adjusting coefficient of hybrid structures should be less then 0.4.

• 전기의세계
• /
• v.28 no.3
• /
• pp.27-34
• /
• 1979

회로망을 해석하는데는 i) 지로해석법, ii) 루우프해석법, iii) 메슈해석법, iv) 마디해석법, v) 컷세트해석법및 vi) 상태공간해석법 등이 사용됨은 이미 알고 있다. 다루는 회로가 비교적 간단한 구성의 선형, 시불변 회로망이고 또한 종이와 연필로 회로망해석을 수행하여야 될때에는 익혀온 이들 해석법을 관례대로 따르면 될 것이나, 다룰려는 회로망이 대형인 복잡한 구조의 것이든지 혹은 비선형소자, 시변소자 등을 포함하는 경우에는 독립회로방정식들을 체계있게 세워 나가는데에도 어려움이 있거니와, 설혹 회로방정식군을 세웠다 하드라도 이들을 풀어 나가는데에도 이젠 우리가 할 수 있는 능력한계를 느끼게 된다. 전자계산기가 스스로 독립성을 지닌 필요한 개수의 회로망방정식들을 작성하고, 또한 풀이도 요구되는 특성을 갖는 회로망을 설계하여주면, 많은 수고와 번거로움이 덜어진다. 이러한 뜻에서 전산기의 활용에 의한 회로망의 해석, 설계 (computer oriented network analysis and synthesis)이론이 바람직하다. 여기서는 이러한 전산기의 사용에 의한 회로망의 해석, 설계이론의 기초가 되는 부분을 가려서 위상 그래프이론에 따른 회로망 해석방법을 해설한다.

• 한국전산유체공학회:학술대회논문집
• /
• 2010.05a
• /
• pp.86-92
• /
• 2010

A metal diaphragm compressor has been widely used for supplying a high pressures gas. This compressor mainly consists of gas oil space and metal diaphragm. Gas sucked in the gas space is compressed by an oscillating metal diaphragm existed between the gas and oil space. A non-return discharge and suction check-valve are components of the compressor that draw off the compressed oil and gas. Those components are self-actuated by differential pressures. Therefore, the rapid response and stable operating conditions are required. In the present study, to find out the dynamic behavior of the suction, discharge valve and diaphragm compressor, the unsteady flow field has been investigated numerically by using the unsteady two-way FSI (Fluid Structure Interaction) simulation method, $k-{\omega}$ turbulent model and mesh deformation.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1995.04a
• /
• pp.130-135
• /
• 1995

Wind-induced vibration of buildings with viscoelastic dampers are studied analytically. The added viscoelastic dampers change the damping distribution and reduce the response of buildings. The distribution of damping resistance that results from these viscoelastic dampers is known as non-classical or non-proportional. Non-classically damped structures are analyzed by state-space approach. However, this approach is complex and time-consumming compared to classical approach. This paper is aimed at the analysis of wind-induced Vibration Of buildings With Viscoelastic dampers. The Process Of State-Space approach is studied and the approximate analysis is suggested to overcome the complex and time-consuming access. For numerical certification, PSDF(Power Spectral Density Function) is obtained. Autocorrelation function is obtained in time domain and PSDF is obtained by fourier transformation of this function in frequency domain. It is found that Approximate method can give close approximation to exact solution.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2000.04b
• /
• pp.35-42
• /
• 2000

Among the various models proposed for the description of semi-rigid connection behavior, Kinney's fixity facto. (=f) definition is adopted. If one follows this definition, f=1.0 signifies a completely fixed connection and f=0.0, the frictionless hinge. Kim's new slope-deflection equations based on the Kinney's fixity factors are the principal idea of this paper. Proposed finite element program also includes the effect of axial shortening of column, which is neglected in the stress analysis of frame leg conventional slope-deflection method. For the economic design, especially for the saving of beam weight in the high-rise office buildings or apartment houses, the proposed method can be applied.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2000.04b
• /
• pp.263-270
• /
• 2000

It is generally known that the stress and displacement of a member or a system under dynamic load with frequency ω are magnified by the factor 1/[1-(ω/ω/sub 0/)sup/ 2/]. When the member assumes non-prismatic shape, the natural frequency, ω/sub 0/ is hard or impossible to determine if the conventional method are adopted. In these cases, the numerical methods are provide powerful tools for the solution of frequency problems. In this paper, finite element method is applied to determine the natural frequencies of the non-symmetrically tapered members. The shape of the member is assumed to change sinusoidally along its axis. The results obtained by finite element method are expressed by some simple algebraic equations. The estimated frequencies calculated by the proposed equations coincide well with those by the finite element method.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2004.04a
• /
• pp.333-340
• /
• 2004

This paper deals with geometric nonlinear analyses using a new meshfree technique which improves the numerical integration accuracy. The new method called the Petrov-Galerkin natural element method (PGNEM) is based on the Voronoi diagram and the Delaunay triangulation which is based on the same concept used for conventional natural element method called the Bubnov-Galerkin natural element method (BGNEM). But, unlike BGNEM, the test shape function is differently chosen from the trial shape function. In the linear static analysis, it is ensured that the numerical integration error of the PGNEM is remarkably reduced. In this paper, the PGNEM is applied to large deformation problems, and the accuracy of the proposed numerical technique is verified through the several examples.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2004.04a
• /
• pp.251-258
• /
• 2004

This paper presents the parameter study of multiple tuned liquid damper (MTLCD) applied to the 76-story benchmark building. A parameter study involves the effects of number of TLCD, frequency range, and central tuning frequency ratio, which are important parameters of MTLCD. The performance of MTLCD is carried out numerical analysis which reflects the nonlinear property of liquid motion. The parameters of TLCD exist different each optimal values according to mass ratio. The performance of single-TLCD (STLCD) is sensitive for tuning frequency ratio. Therefore, MTLCD is proposed to protect such the shortcoming of STLCD. The result of numerical analysis presents improved performance for robustness of MTLCD

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2005.04a
• /
• pp.712-718
• /
• 2005

In this study, a translator for transferring structural analysis data among commercial structural analysis programs was developed. The translator adopted the neutral format type based on ISO standard STEP AP 209 not only for the international standardization and robustness but also for the efficient management of structural analysis data Additional load entity is developed and added to AP 209 for the prevention of loss of information in retrieving exact loading condition. A modulization which is needed for efficient management and extension of the translator was made for the encapsulation of file format of each commercial code. Pilot tests peformed with 3-D frame analysis data of Sung-su bridge show that the developed translator guarantees the integrated management of analysis information as well as the exact transferring and retrieving of analysis data and related information.