• Journal of Ship and Ocean Technology
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• 제8권4호
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• pp.17-25
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• 2004

Hull girder stress monitoring system for container ship uses four long-base-strain-gages at mid-ship to monitor the resultant stresses and the applied moment components of horizontal, vertical and torsional moments. The bending moments are estimated by using the conventional strain-moment relations, however, the torsional moment related to the warping strain requires the assumption of the shape of torsional moments over the hull girder. Though this shape could be a sine function with an adequate period, it largely depends upon certain empirical formulas. This paper introduces additional four long-base-strain-gages at mid-ship to derive the longitudinal slope of the warping strain because this slope is directly related to the torsional moment by Bi-moment concept. An open-channel-type cantilever beam has been selected as a simplified model for container ship and the result has proved that the suggested concepts can estimate the torsional component accurately. Finally this method can become reliable technique to derive all external moments in hull girder stress monitoring system for container ships.

• 한국농공학회지
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• 제44권3호
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• pp.73-84
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• 2002

Nominal shear strength of concrete beam is the combined strength of concrete shear strength and steel shear strength in current design code. But Torsional moment strength of concrete is neglected in calculation of the nominal torsional moment strength of reinforced concrete beam in current revised code. Tensile stress of concrete strut between cracks is still in effect due to tension stiffening effect. But the tensile stresses of concrete after cracking are neglected in bending and torsion in design. The torsional behavior is similar to the shear behavior in mechanics. Therefore the torsional moment strength of concrete should be concluded to the nominal torsional moment strength of reinforced concrete beam. To verify the validity of the proposed model, the nominal torsional moment strengths according to CEB, two ACI codes(89, 99) and proposed model are compared to experimental torsional strengths of 55 test specimens found in literature. The nominal torsional moment strengths by the proposed model show the best results.

• 콘크리트학회논문집
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• 제14권1호
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• pp.24-32
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• 2002

전단문제에서는 일부 설계기준(AASHTO 1994)에 이미 수정압축장이론이 도입되었다. 그리고 현행 콘크리트 설계기준에는 콘크리트의 전단강도가 철근의 전단강도와 합하여 공칭전단강도를 계산하고 있다. 그러나 최근에 개정된 콘크리트설계기준에는 콘크리트의 비틀림강도가 공칭비틀림강도 계산에서 누락되었다. 콘크리트의 인장응력은 비록 크기가 작으나 균열후에 균열사이의 콘크리트에 존재한다. 그러나 휨과 비틀림문제에서는 균열 후 콘크리트의 인장강성은 생략되고 있다. 역학적으로 콘크리트보의 비틀림거동은 전단거동과 매우 유사하다. 그러므로 균열 후 콘크리트의 비틀림강도를 철근콘크리트 보의 공칭비틀림강도의 계산에 포함시켜야 한다. 본 논문에서는 콘크리트의 평균주인장응력이 이루는 콘크리트의 비틀림강도를 횡방향 비틀림철근의 비틀림강도와 함께 공칭비틀림강도를 구성함을 밝혔으며, 이의 타당성을 검증하기 위해 개정 전후의 ACI 의 설계기준에 의한 공칭비틀림강도와 함께 실험값과 비교하였다. 그 결과 본 논문이 제안한 모델에 의한 공칭비틀림강도가 가장 좋은 결과를 보였다.

• 대한기계학회논문집
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• 제15권2호
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• pp.424-435
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• 1991

To develop the photoelastic experiment method for the orthotropic material under pure torsional moment is the main objective of this research. In the development of photoelastic experiment for orthotropic material under pure torsional moment, the important problems and their solutions are the same as following. In the model material for photoelastic experiment, it was found that C.F.E.C.(Copper Fiber Epoxy Composite) can be used as the model material of photoelastic experiment for orthotropic material. In the stress freezing cycle, it was assured that stress freezing cycle for epoxy can be used as the stress freezing cycle of the photoelastic experiment for orthotropic material. In the slicing method, it was found that the negative oblique slicing method can be effectively used as slicing method in 3-dimensional photoelastic experiment. In the measuring method of stress fringe values and physical properties in the high temperature, it was found that stress fringe values can be directly measured by experiment and physical properties can be directly or indirectly by equation between stress fringe values and physical properties developed by author. In the stress analysis method of orthotropic material under pure torsional moment by photoelastic experiment, it will be studied in the second paper.

• 콘크리트학회논문집
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• 제23권1호
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• pp.57-65
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• 2011

전단과 비틀림모멘트가 동시에 작용하는 경우에 단면에는 각각의 영향으로 인하여 전단응력이 발생하므로 이 두 응력을 더하여 설계할 수 있다. 그러나 현행 콘크리트구조설계기준에서는 전단과 비틀림모멘트 설계식을 단위가 서로 틀린 단면력으로 표현하여 분포도를 그리기 위해서는 각각의 좌표에 분리해서 그려야만 한다. 만약에 이 두 하중으로 인한 단면력을 응력으로 표현하게 되면 두 전단응력을 더하여 하나의 좌표에 표현할 수 있고, 설계 결과도 동시에 그려 넣을 수 있으므로 쉽게 설계과정을 인식하여 실수를 최소화 할 수 있을 것이다. 게다가 현행 기준에서는 전단과 비틀림모멘트에 대한 설계식을 단위 길이 당 스터럽의 단면적으로 표현되는 $A_{\upsilon}/s$나 $2A_{\upsilon}/s$로 제시하여, 설계과정에서 이 값들의 크기나 상황을 정확하게 인식하기 거의 불가능하게 된다. 설계에서 먼저 스터럽의 종류를 결정하여 단면적 $A_{\upsilon}$나 $A_t$가 결정되므로 설계식들을 스터럽의 간격에 대한 식으로 정리하면 설계과정을 명확하게 인식할 수 있고 또한 여러 설계과정도 간단하게 정리되어 이해하기 쉽도록 할 것이다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.167-172
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• 2002

Nonlinear analysis of the reinforced concrete beam subjected to torsion is presented. Seventeen equations involving seventeen variables are derived from the equilibrium equation, compatibility equation, and the material constitutive laws to solve the torsion problem. Newton method was used to solve the nonlinear simultaneous equations and efficient algorithms are proposed. Present model covers the behavior of reinforced concrete beam under pure torsion from service load range to ultimate stage. Tensile resistance of concrete after cracking is appropriately considered. The softened concrete truss model and the average stress-strain relations of concrete and steel are used. To verify the validity of Present model, the nominal torsional moment strengths according to ACI-99 code and the ultimate torsional moment by present model are compared to experimental torsional strengths of 55 test specimens found in literature. The ultimate torsional moment strengths by the present model show good results.

• 한국강구조학회 논문집
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• 제13권2호
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• pp.163-176
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• 2001

본 논문에서는 뒴비틀림 효과를 고려한 휨비틀림 이론을 기초로 연속곡선보를 해석한다. 먼저 단순곡선보에 대해 미분방정식으로 단면력과 변위를 구한다. 다음 에너지법을 이용하여 n경간 연속곡선보에 대한 탄성방정식으로 연속곡선보의 임의점에서 단면력과 변위의 해를 구한다. 작용하중으로 수직집중하중과 수직등분포하중을 고려하여 해석하였으므로 실제 하중이 작용하는 연속곡선박스거더의 단면력과 변위를 쉽게 구할 수 있다.

• 한국구조물진단유지관리공학회 논문집
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• 제6권2호
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• pp.157-165
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• 2002

Nonlinear analysis of the reinforced concrete beam subjected to torsion is presented. Seventeen equations involving seventeen variables are derived from the equilibrium equation, compatibility equation, and the material constitutive laws to solve the torsion problem. Newton method was used to solve the nonlinear simultaneous equations and efficient algorithms are proposed. Present model covers the behavior of reinforced concrete beam under pure torsion from service load range to ultimate stage. Tensile resistance of concrete after cracking is appropriately considered. The softened concrete truss model and the average stress-strain relations of concrete and steel are used. To verify the validity of present model, the nominal torsional moment strengths according to ACI-99 code and the ultimate torsional moment by present model are compared to experimental torsional strengths of 55 test specimens found in literature. The ultimate torsional moment strengths by the present model show good results.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.897-902
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• 2002

The failure of flat plate connection is successive failure process accompanying with stress redistribution, hence it is necessary to compute the contributions of each resistance components at ultimate state. In the present study, the interactions of resultant forces at each faces of connection, i.e. shear, bending moment and torsional moment are considered in the assessment of strength of slab. As a result the strength prediction model for connection is made up as combination of bending resistance, shear resistance and torsional resistance. The proposed method is verified by the experimental data and numerical data of continuous slabs.

• Steel and Composite Structures
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• 제20권1호
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• pp.57-70
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• 2016

The predominant type of buckling that I-steel concrete composite beams experience in the negative moment area is distortional buckling. The key factors that affect distortional buckling are the torsional and lateral restraints by the bottom flange. This study thoroughly investigates the equivalent lateral and torsional restraint stiffnesses of the bottom flange of an I-steel concrete composite beam under negative moments. The results show a coupling effect between the applied forces and the lateral and torsional restraint stiffnesses of the bottom flange. A formula is proposed to calculate the critical buckling stress of the I-steel concrete composite beams under negative moments by considering the lateral and torsional restraint stiffnesses of the bottom flange. The proposed method is shown to better predict the critical bending moment of the I-steel composite beams. This article introduces an improved method to calculate the elastic foundation beams, which takes into account the lateral and torsional restraint stiffnesses of the bottom flange and considers the coupling effect between them. The results show a close match in results from the calculation method proposed in this paper and the ANSYS finite element method, which validates the proposed calculation method. The proposed calculation method provides a theoretical basis for further research on distortional buckling and the ultimate resistance of I-steel concrete composite beams under a variable axial force.