• Journal of Korean Society of Steel Construction
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• v.19 no.2
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• pp.161-170
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• 2007

In this study, to improve on the inaccurate results of the orthotropic plate analysis, we aim to propose a modified coefficient of the orthotropic flexural rigidity for stiffened plates with rectangular ribs considering the dimensions of ribs. The sensitivity of the flexural rigidity and the maximum displacement according to the dimensions of stiffened plates were analyzed and the parametric study on the modified coefficient of the orthotropic flexural rigidity of stiffened plates was performed. The results show that the ratio of modified coefficients can be expressed as a function for each rib height, space and thickness regardless of plate thickness and the modified flexural rigidity can be easily estimated from the ratio functions of modified coefficients. The application of the coefficient function to various types of stiffened plates with different boundary conditions, aspect ratios, rib arrangement and loading size shows that the proposed function improves the accuracy of the orthotropic plate analysis compared with the results of the reference. Therefore, the orthotropic plate analysis of stiffened plates with rectangular ribs can easily achieve more accurate results using the coefficient function proposed in this study.

• Journal of Korean Society of Steel Construction
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• v.17 no.1 s.74
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• pp.23-32
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• 2005

In this paper, the modified coefficient of the orthotropic rigidity for stiffened plates with open ribs is proposed to improve the inaccurate results of the orthotropic plate analysis. For stiffened plates with rectangular and angle ribs having various aspect ratios and boundary conditions, the aspect ratio and the rigidity ratio are selected as parameters and the parametric study on the modified coefficient is performed. Analyzed results of stiffened plates modeling with the isotropic and orthotropic plate element show that the modified coefficient can be expressed as a function of the rigidity ratio for each rib space regardless of the aspect ratio in case of the aspect ratio under 1 and can be represented as a single union function without regard to rib spaces and aspect ratios in the other case. The results also shows that the effects of the boundary condition on the modified coefficient is small and coefficient functions have different values according to rib shapes. The application to examples shows that the modified coefficient of the orthotropic rigidity improves accuracy. Therefore, the orthotropic plate analysis of stiffened plates with open ribs can easily achieve more accurate results using the coefficient function proposed in this study

• Journal of Korean Society of Steel Construction
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• v.10 no.4 s.37
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• pp.731-740
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• 1998

Orthogonally stiffened steel plates are used for orthotropic steel decks of long-span bridges because of high degree of flexural and torsional resistances and good load-distribution behavior. An analytic study is presented for evaluating the buckling strength of orthogonally stiffened plates subjected to uniaxial compression. By using the plate theory, the buckling stress under overall and partial buckling modes, is derived. Parametric studies are performed to show the effects of the stiffness and the number of transverse and longitudinal ribs on the buckling strength. The results show quantitatively strong influence of stiffness and spacing of longitudinal and transverse ribs.

• Journal of Korean Society of Steel Construction
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• v.16 no.2 s.69
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• pp.191-200
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• 2004

In this paper, the modified method of orthotropic rigidities for stiffened plates with open ribs is proposed to solve the problem of the inaccurate results of the orthotropic plate analysis according to the dimensions of stiffened plates. In analyzing various types of stiffened plates with open ribs using the isotropic and orthotropic plate element, orthotropic plates are found to gave smaller maximum displacements compared to isotropic plates in a range that is smaller than the special rigidity ratio and reversely. Therefore, obtaining a more accurate solution of the orthotropic plate analysis requires modifying the orthotropic rigidities of stiffened plates according to the rigidity ratio. This study presents two modified methods using the displacement function and the displacement ratio. The application of the two methods improves the accuracy of the results of the orthotropic plate analysis, although the modified method using the displacement ratio is better than the method using the displacement function in terms of serviceability and safety. The comparison with the experimental example shows that the proposed modified method improves accuracy. Therefore, the orthotropic plate analysis of stiffened plates with open ribs can achieve more accurate results using the proposed method in this study.

• Journal of Korean Society of Steel Construction
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• v.17 no.5 s.78
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• pp.593-604
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• 2005

In this paper, the parametric study on the local displacement and the local moment due to a concentrated load is performed for stiffened plates with open ribs and the orthotropic rigidity ratio of stiffened plates is selected as the parameter. For estimating the local behavior, stiffened plates loaded on the center of plates between the ribs were considered and for the global behavior, stiffened plates loaded on the rib at the center of plates were analyzed. The Analyzed results for the local behavior of stiffened plates show that the increasing ratio of the local moment according to rib sizes is constant regardless of rib spaces and the ratio of the local displacement to the global displacement can be expressed as a function of the rib space and the rigidity ratio. The application of functions to examples shows good accuracy in comparison with the local behavior of stiffened plates loaded on the center of plates and the application to the orthotropic analysis of stiffened plates improves accuracy. Therefore, using functions proposed in this study, the local behavior can easily be estimated from the global behavior of stiffened plates with open ribs.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.983-988
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• 2004

In the present study, the effects of orthogonal ribs on structural warpage during injection molding process were investigated. Basic ribbed models for the evaluation of degree of warpage were introduced and designed. Injection molds for these models are manufactured based on the full 3D CAD/CAM technology and specimens are prepared for experiment. Numerical analysis using commercial plastic injection molding analysis software was also performed to compare the results with experimental ones. The variations of materials and parameters such as injection time, mold temperature, melt temperature, holding time were considered in the present work. It was shown that orthogonal ribs have significant effect on the reduction of warpage during the injection molding process.

• Journal of Korean Society of Steel Construction
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• v.19 no.6
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• pp.621-632
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• 2007

The purpose of this study was the estimation and formulation of orthotropic flexural rigidities considering the deformed shape for a plate stiffened with rectangular ribs. Analytical results of methods modifying the flexural rigidity of the x-direction, the y-direction or both directions were compared at the center, the x-directional quarter point and the y-directional quarter point of stiffened plates loaded at the center. The composite method modifying the flexural rigidity of both directions improves the accuracy compared with the other methods. Moreover, the ratio of modified coefficients for each directional rigidity can be expressed as a function corresponding to each dimension of stiffened plates. The application of modified coefficient functions to various types of stiffened plates with different boundary conditions, aspect ratios and rib arrangement shows that the increment of the error ratio is small compared with examples of this study and the application of proposed functions shows more accurate results than previous methods modifying the flexural rigidity. Therefore, by using the modified coefficient functions proposed in this study, the orthotropic plate analysis of plates stiffened with rectangular ribs can easily achieve more accurate displacement results.

• Journal of Korean Society of Steel Construction
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• v.14 no.6
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• pp.701-710
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• 2002

An analysis program using orthotropic plate elements was developed to simplify the analysis of plates stiffened with open ribs and the orthotropic behavior of stiffened plates and the application of this program were evaluated using the sensitivity analysis and the parametric study. The inertial moment ratio, i.e., the ratio of the inertial moment of the rib to that of the plate was defined and the orthotropic behavior of stiffened plates corresponding to the inertial moment ratio was proved by the sensitivity analysis. To evaluate the application of this program, the parametric study for various types of stiffened plates was performed and then the maximum displacement of this study was compared to that of ABAQUS using isoparametric plate elements. The Results of this study agreed well with that of ABAQUS at the particular inertial moment ratio, that is proposed to the limit ratio of the orthotropic plate analysis and the correlative function between the error ratio and the inertial moment ratio was obtained. Therefore, the orthotropic plate analysis of stiffened plates with open ribs could have safe results over the limit ratio and also have good results simply by using the correlative function of this study.

• Proceedings of the KAIS Fall Conference
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• 2012.05b
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• pp.600-602
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• 2012

폐단면리브 적용 판의 면내 압축좌굴 거동 특성 중에서 보강재 강성이 작고 비교적 낮은 임계하중을 받는 경우 전체기둥좌굴 거동이 예상된다. 본 논문은 폐단면리브 단면 강성의 고려 방안에 따라 단순 보 유사모형을 정립하고 전체좌굴에 대해 에너지 근사해법을 적용하여 전체좌굴강도 근사해를 유도하기 위한 기초적인 연구방안으로써 검토한 내용을 소개하고자 한다. 유사모형의 폐단면리브 중심에서 휨강성이 발휘되는 것으로 가정하여 모형화 하였다. 폐단면리브 보강판의 프로토타입 모델에 대해 직교이방성 $[(0^{\circ})_4]_s$와 Cross-ply $[(0^{\circ}/90^{\circ})_2]_s$ 적층단면을 각각 고려한 유한요소 해석을 실시하였다. U리브 단면강성에 따른 복합적층 보강판의 탄성좌굴강도 해석결과를 근사해 공식과 비교하고 U리브로 보강된 복합적층판의 좌굴모드 변화양상을 수치해석적으로 검토하였다.

• Journal of Korean Society of Steel Construction
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• v.18 no.5
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• pp.563-574
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• 2006

The objective of this study is to determine the effect of the loading size on displacements of stiffened plates with open ribs using the orthotropic rigidity ratio as the parameter. To analyze the displacement behavior of stiffened plates according to the loading size, a concentrated load and three types of uniform distributed loads were applied on the rib at the center of some plates. The results of the analysis of various stiffened plates show that the central displacement ratio of the distributed load to the concentrated load increased according to the decrease in the loading size, and that the ratio can be expressed as a function of the rigidity ratio for each rib space. The maximum displacement of the stiffened plate subjected to the distributed load did not appear at the center of the plate due to the local behavior, and the increasing ratio of the maximum displacement to the central displacement can be expressed as a function of the rigidity ratio for each rib space. Orthotropic plate analysis can achieve more accurate results using the proposed functions, and the application of the functions to examples of a different aspect ratio and support condition shows good accuracy. Therefore, using the functions proposed in this study, the central and maximum displacements can easily be achieved in the orthotropic plate analysis of stiffened plates subjected to the distributed load.