• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.04a
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• pp.135-142
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• 1996

In this paper, a simple tut accurate method of vibration analysis of structural elements with or without attached mass/masses is presented. The method used has been developed by the senior author since 1974. This method is very effective for the plates with arbitrary boundary conditions and irregular sections. This method is applied to the special orthotropic Plate with two opposite edges simply supported and the other two opposite edges free. Such plate represents the most of the simply supported bridges/decks, including concrete and girders-cross beam systems. Detailed illustration is given for beams and plates for easy understanding. Some laminate orientation for which the special orthotropic equations can be applied are identified.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.723-726
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• 2011

전 세계적으로 사회기반시설 및 신재생 에너지 생산을 위한 공간부족 문제를 해결하기 위하여 초대형 부유구조물에 대한 관심이 증가하고 있다. 다양한 사용분야에 대한 안정성 확보를 위해 파랑하중에 의한 동적 응답과 부유체의 강성 대비 길이 효과로 인해 발생할 수 있는 특이 거동에 대한 분석이 필요하다. 초대형 부유구조물의 경우 중앙부에 비해 양끝 단에서 과도한 응답이 발생하며, 이를 해결하기 위해 입사파가 들어오는 초대형 부유구조물의 단부에 부착되는 다양한 감요장치(anti-motion device)가 제안되어지고 있다. 초대형 부유구조물에 감요장치가 적용될 경우 입사파에 의한 동적 파압을 감소시켜 구조물의 전반적인 응답을 줄여줄 수는 있지만 감요장치의 질량이 클 경우 오히려 끝단의 응답을 증폭시킬 수 있다. 본 논문에서는 양단 자유 경계조건의 탄성지지된 보를 이용하여 초대형 부유구조물의 길이와 끝단에 부착된 감요장치의 질량으로 인한 영향을 분석하였다.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.2
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• pp.87-94
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• 1998

Behavioral characteristics of shallow circular arches with dynamic loading and different end conditions are analysed. Geometric nonlinearity is modelled using Lagrangian description of the motion. The finite element analysis procedure is used to solve the dynamic equation of motion, and the Newmark method is adopted in the approximation of time integration. The behavior of arches is analysed using the buckling criterion and non-dimensional time, load and shape parameters which Humphreys suggested. But a new deflection-ratio formula including the effect of horizontal displacement plus vertical displacement is presented to apply for the non-symmetric buckling problems. Through the model analysis, it's confirmed that fix-ended arches have higher buckling stability than hinge-ended arches, and arches with the same shape parameter have the same deflection ratio at the same time parameter when loaded with the same parametric load.

• Journal of Korean Society of Steel Construction
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• v.18 no.2
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• pp.191-201
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• 2006

New design equations for calculating the lateral-torsional buck ling moment resistances of stepped I-section beams with/without continuous lateral top-flange bracing subjected to a point load, a series of point loads, and a uniformly distributed load, are suggested based on the results of elastic finite-element analyses. The new equations presented in this study are compared with the current moment gradient modifiers presented by other researchers and specifications. Although the study paper presents mainly stepped-beam cases subjected to a point load and a uniformly distributed load. The proposed equations include the length-to-height ratio effects for stepped beams with continuous lateral top-flange bracing. The new moment gradient correction factors could be easily used to calculate the lateral-torsional buckling moment resistance of stepped I-beams.

• Fire Science and Engineering
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• v.24 no.6
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• pp.69-75
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• 2010

A concrete filled square steel tube (CFT) is composed of the external steel material, which its strength is reduced in fire due to sudden temperature increase, and the internal concrete with high thermal capacity that can ensure the fire resistance performance of the structure. Therefore, research about the influence factors of the structural performance of CFT column is required in order to apply CFT column to a fire resisting structure, and additional research about influence for each condition is also necessary. Among the influence factors, the boundary condition between column and beam is important structurally, and it is one of the major factors that determine overall fire resisting performance. This study performed a fire experiment under loading in order to analyse the influences of CFT column to the boundary condition. As the results of the experiment, fire resistance time of 106 minutes was ensured for the clamped-end condition but 89 minutes for the hinge-end condition in case of the 360 cross section. And, fire resistance time of 113 minutes was ensured for the clamped-end condition but 78 minutes for the hinge-end condition in case of the 280 cross section.

• Journal of the Korean Geotechnical Society
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• v.27 no.11
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• pp.17-25
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• 2011

In this study, we considered the bearing capacity of strip footing over clay layers partially replaced by sand. The FEM analysis is performed to calculate the ultimate bearing capacity. Partial replacement is defined by multiples of footing width(B) and inclination of sides. The cases(B'=inf.) of sand layers equal to clay layers are preferentially conducted. The baring capacity of B'=inf. is comparative value for bearing capacity of partial replacement layers. ${\beta}$ is the ratio of ultimate bearing capacity of B'=inf and partial ultimate bearing capacity replacement. ${\beta}$ is used to analyze the characteristic of bearing capacity of clay layers partially replaced by sand. Each of the three undrained shear strengths of clay and friction angles of sand is considered. The result of this analysis shows that ${\beta}$ depends on sand depth.

• Journal of the Korean GEO-environmental Society
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• v.18 no.5
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• pp.55-60
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• 2017

It is critical for Korea to make effective use of limited space as it has dense population and high traffic volume compared to its terrestrial area. To resolve this issue, diverse types of underground structures have increasingly been applied so far, and one of the most representative structures is double-deck tunnel. It has upper and lower roads separated by middle slab that shows dynamic behavior according to the vehicle and earthquake loads. In case of the characteristics of earthquake response, it is necessary to have exploratory study as it has high loads, complex working mechanism, and difficult theoretical approach. In order to understand the characteristics of earthquake response based on the supporting conditions of middle slab in double-deck tunnel, this study conducts indoor shaking table test with 3 test cases: (1) fix both brackets, (2) free and fix at each bracket and (3) free at both brackets for 2 seismic waves of artificial and Gyeongju earthquake. The result shows if the middle slab is free at both brackets, the acceleration response is reduced 41% for artificial earthquake and 60% for Gyeongju earthquake compared to the one with fix at both brackets.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2015.11a
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• pp.152-154
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• 2015

본 논문은 유한요소의 일종인 유한대판법(Finite Strip Method)를 사용하여 양단 단순지지된 3차원 다층 원통쉘의 내측과 외측에 받는 하중이 2층 구조(강재/콘크리트) 및 3층 구조(강재/콘크리트/강재)에 미치는 영향과 이종재료인 다층 원통쉘의 최적 상태에 대해 알아본다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.181-187
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• 2011

This paper deals with free vibrations of the Timoshenko beam supported by two elastomeric bearings at two far ends. The ordinary differential equation governing free vibrations of such beam is derived, in which both effects of rotatory inertia and shear deformation are included as the Timoshenko beam theory. Also, boundary conditions of the free end are derived based on the Timoshenko beam theory. The ordinary differential equation is solved by the numerical methods for calculating natural frequencies and mode shapes. Both effects of the rotatory inertia and shear deformation on natural frequencies are extensively discussed. Also, relationships between natural frequencies and slenderness ratio, foundation modulus and bearing length are presented. Typical mode shapes of bending moment and shear force as well as deflection are given in figures which show the positions of maximum amplitudes and nodal points.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.711-721
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• 2014

PPWS, a large number of which a main cable of a suspension bridge consists of, must be precisely erected at a target location under construction considering the differences among design conditions. The absolute sag is measured for several PPWSs, which are reference strands and the relative sag is surveyed from them to other PPWSs, which are divided into several groups. And the adjustment of PPWS length is performed to erect it at target configuration. When PPWS is being under erection in a real bridge site, the procedures are as follows; evaluate sag sensitivities according to sag variation factors, calculate an adjustment length of PPWS corresponding to them and adjust a sag of PPWS by controlling the calculated amount of PPWS length. In this study, the differential-related equations of sag sensitivity were proposed for support movement of PPWS. Before site demonstration study of a series of them, we established a catenary model system and accomplished verification tests of them. From test results, the validation of them was done.