• 한국전산구조공학회논문집
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• 제15권1호
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• pp.189-195
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• 2002

이 논문은 크로소이드 완화곡선을 갖는 수평 곡선보의 자유진동에 관한 연구이다. 곡선보가 진동할 때 부재의 미소요소에 발생하는 합응력과 관성력에 대한 동적 평형방정식을 이용하여 변화곡률을 갖는 수평 곡선보의 자유진동을 지배하는 무차원 상미분방정식과 단부조건에 대한 무차원 경계조건을 유도하였다. 유도된 미분방정식을 크로소이드 완화 곡선을 갖는 수평 곡선보에 적용하여 회전-회전 및 고정-고정 보의 고유진동수 및 변위와 합응력의 진동형을 산출하였다. 구조해석용 범용프로그램인 ADINA와 본 연구의 결과를 비교하여 본 연구의 타당성을 검증하였으며, 수치해석의 결과로 무차원 고유진동수와 곡선보의 변수들 사이의 관계를 표 및 그림에 나타내었다.

• 한국전산구조공학회논문집
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• 제14권3호
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• pp.371-379
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• 2001

이 논문은 연속성을 갖는 탄성지반 위에 놓인 곡선부재의 자유진동에 관한 연구이다. 연속성을 갖는 탄성지반을 Pasternak 지반으로 모형화하여 곡선부재의 자유진동을 지배하는 무차원 상미분방정식을 유도하였다. 상미분방정식에는 회전관성과 전단변형효과를 고려하였다. 곡선부재의 선형은 원호형, 포물선형, 정현형, 타원형의 4가지를 채택하였고, 단부조건으로는 회전-회전, 회전-고정, 고정-고정의 3가지를 채택하였다. 실험실 규모의 실험을 실시하고 본 연구의 결과와 비교하여 연구의 타당성을 검증하였다. 수치해석의 결과로 무차원 고유진동수와 곡선부재의 변수들 사이의 관계를 표 및 그림에 나타내었으며 진동형의 예를 그림에 나타내었다.

• 전산구조공학
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• 제9권1호
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• pp.133-139
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• 1996

이 논문은 원호형 곡선보의 면외 자유진동에 관한 연구이다. 곡선보 요소의 동적 평형방정식에 Timoshenko 이론을 적용하여 원호형 곡선보의 자유진동을 지배하는 상미분방정식을 유도하고 이를 수치해석하여 고유진동수를 산출할 수 있는 개략해법 중 하나인 수치해석기법을 개발하였다. 수치해석기법에서 미분방정식의 수치적분은 Runge-Kutta method를 이용하였고, 고유진동수의 결정은 Regular-Falsi method를 이용하였다. 실제 수치해석예에서는 회전-회전보, 고정-고정보에 대하여 시행하고 고유진동수에 미치는 무차원 변수들의 영향을 고찰하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1996년도 봄 학술발표회 논문집
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• pp.151-156
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• 1996

The differential equations governing free, out of plane vibrations of horizontally curved beams are derived and solved numerically to obtain the natural frequencies and the mode shapes. The Runge-Kutta method and Regula-Falsi method are used to integrate the differential equations and to determine the natural frequencies, respectively. In nu- merical examples, the hinged-clamped end constraint is considered and four lowest frequency parameters are reported as functions of four non-dimensional system parameters: (1) opening angle, (2) slenderness ratio, (3) shear parameter and (4) stiffness parameter. Also, typical mode shapes of displacements and stress resultants are shown.

• Structural Engineering and Mechanics
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• 제8권3호
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• pp.257-272
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• 1999

In this paper a simple finite element is proposed for analyzing out of plane vibration of thin walled curved beams, with both open and closed sections, considering shear flexibility. The present element is obtained from a variational formulation governing the dynamics of a three-dimensional elastic body in which the stress tensor as well as the displacements are variationally independent. The element has two nodes with four degrees of freedom in each. Numerical examples for the first six frequencies are performed in order to assess the accuracy of the finite element formulation and to show the influence of the shear flexibility on the dynamics of the member.

• Structural Engineering and Mechanics
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• 제76권3호
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• pp.395-412
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• 2020

In this article, the values of internal force and deformation of a curved beam under any action with the firm or elastic supports are determined by using structural matrices. The article presents the general differential formulation of a curved beam in global coordinates, which is solved in an orderly manner using simple integrals, thus obtaining the transfer matrix expression. The matrix expression of rigidity is obtained through reordering operations on the transfer notation. The support conditions, firm or elastic, provide twelve equations. The objective of this article is the construction of the algebraic system of order twenty-four, twelve transfer equations and twelve support equations, which relates the values of internal force and deformation associated with the two ends of the directrix of the curved beam. This final algebraic system, expressed in matrix form, is divided into two subsystems: twelve algebraic equations of internal force and twelve algebraic equations of deformation. The internal force and deformation values for any point in the curved beam directrix are determined from these values in the initial position. The five examples presented show how to apply the matrix procedures developed in this article, whether they are curved beams with the firm or elastic support.

• Structural Engineering and Mechanics
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• 제5권3호
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• pp.257-268
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• 1997

The elastic deflections and Euler buckling loads are investigated for a class of tapered and initially curved cantilevered beams subjected to loading at the tip. The beam's width increases linearly and its depth decreases linearly with the distance from the fixed end to the tip. Unloaded, the beam forms a circular are perpendicular to the axis of bending. The beam's deflection responses, obtained by solving the differential equations in closed form, are presented in terms of four nondimensional system parameters: taper ratio ${\kappa}$, initial shape ratio ${\Delta}_0$, end load ratio f, and load angle ${\theta}$. Laboratory measurements of the Euler buckling loads for scale models of tapered initially straight, corrugated beams compared favorably with those computed from the present analysis. The results are applicable to future designs of the end structures of highway guardrails, which can be designed to give the appropriate balance between the capacity to deflect a nearly head-on vehicle back to its right-of-way and the capacity to buckle sufficiently that penetration of the vehicle may be averted.

• 콘크리트학회지
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• 제24권5호
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• pp.46-48
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• 2012

• International Journal of Concrete Structures and Materials
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• 제10권sup3호
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• pp.1-17
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• 2016

Recently, advanced transit systems are being constructed to reduce traffic congestions in metropolitan areas. For these projects, curved bridges with various curvatures are required. Many curved bridges in the past were constructed using aesthetically unpleasant straight beams with curved slabs or expensive curved steel box girders with curved slabs. Therefore, many recent studies have been performed to develop less expensive and very safe precast prestressed concrete (PSC) curved girder. One method of reducing the construction cost of a PSC curved girder is to use a reusable formwork that can easily be adjusted to change the curvature and length of a girder. A reusable and curvature/dimension adjustable formwork called Multi-tasking formwork is developed for constructing efficient precast PSC curved girders. With the Multi-tasking formwork, two 40 m precast PSC box girders with different curvatures were constructed to build a two-girder curved bridge for a static flexural test to evaluate its safety and serviceability performance. The static flexural test results showed that the initial cracking load was 1400 kN, exceeding the design cracking load of 450 kN. Also, the code allowed deflection of 50 mm occurred at a load of 1800 kN, verifying the safety and serviceability of the precast PSC curved bridge constructed using the multi-tasking formwork.

• 대한기계학회논문집A
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• 제23권11호
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• pp.2067-2077
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• 1999

Recently, turbomachine blades are becoming larger and more flexible, it is necessary to calculate natural frequencies of a rotating blades for avoiding resonance. This problem is complicated by the fact that blades are tapered, twisted and curved. To keep with this demands, the designer must rely on more exact methods of calculation. In this paper, natural frequencies of a single straight or curved blade with variable R.P.M. are calculated by a stiffness matrix method. Results of investigation on the correspondence between the calculated and other values of the literature are described. The calculated values are agree with the other values but with a small error. Furthermore, the influence of Coriolis force on the natural frequency for rotating, curved turbo blades is described.