소성변형을 고려한 압연형교의 평가

鄭庚熙 철도전문대학교 2002 論文集 Vol.17 No.-

The maximum moment occured at inter support of continuous bridges. Due to maximum moment occured local yield at inter support, plastic behavered and occured moment redistribute. The Strength design L.F.D method redistributed 10% of negative moment at elastic analysis. this method accounted moment because at local yield of inter support about the contimun. This moment is called auto-moment. The Moment-Rotation curve needed fined auto-moment. The thesis Moment-Rotation curve suggested at AASHTO Guid Speciffication at compact section finded auto-moment and limit states specification method is rating of the 3 span contimun composition bridge

I-Beam연속교 내측지점의 소성변형에 관한 연구

정경희,김진성,양승이 한국산업안전학회 2002 한국안전학회지 Vol.17 No.4

The steel shows plastic deformation after the yield point exceeds. Because of overloads, the plastic deformation occurs at the interior support of a continuous bridge. The plastic deformation is concentrated at the interior support, and the permanence deformation at the interior support remains after loads pass. Because local yielding causes the positive moment at the interior support, it is called "auto moment". Auto moment redistributes the elastic moment. Because of redistribution, auto moment decreases the negative moment at the interior support of a continuous bridge. In this paper, the moment-rotation curve from Schalling is used. The plastic rotation is computed by using Beam-line method, and auto moment is calculated based on the experiment curve. The design example is presented using limit state criterion.

압연형교의 ALFD설계에 관한연구

정경희 ( Chung Kyung-hee ),김진성 ( Kim Jin-sung ),양승이 ( Yang Seung-ie ) 한국구조물진단유지관리공학회 2003 한국구조물진단유지관리공학회 논문집 Vol.7 No.4

연속교의 내측지점에는 최대모멘트가 발생한다. 보다큰 모멘트가 작용하면 내측지점에 국부적 항복이 발생할 수 있고 소성거동을 하면서 모멘트를 재분배 시킨다. 강도설계법인 LFD방법은 탄성해석으로부터 구한 부모멘트의 10%를 막연히 재분배 시켜주고 있다. 그러나 ALFD방법은 내측지점에서 국부항복에 의하여 발생되는 모멘트를 계산하여 설계에 반영하도록 하고있다. 이러한 국부항복에 의하여 발생되는 모멘트를 자생모멘트라 한다. 자생모멘트를 구하기 위해서는 모멘트-비탄성회전각곡선이 필요하다. 본 논문에서는 조밀단면에서 AASHTO 지침시방서에서 제시한 모멘트-비탄성회전곡선을 이용하여 자생모멘트를 구하였다. 또한 ALFD 한계상태 규준을 적용하여 3경간 연속합성교를 설계하였다. The maximum moment may occur at interior supports of continuous bridges. If the bigger moment is applied on them, a local yielding at interior supports may occur. They may show plastic behaviors, and the moment will be redistributed. The strength design, L.RD., redistributes 10% of the negative moment which is obtained from the elastic analysis. However, A.L.F.D method computes the moment which is redistributed. This moment is called automoment. The moment-rotation curve is needed to find automoment. In this paper moment-rotation curve for compact sections suggested from AASHTO Guide Specifications is used to find automoment. Based on A.L.F.D. limit states specification method, a three-span continuous bridge is designed.

Moment of Inertia of Gas as a Source of Added Gravitational Field in Galaxies

Portnov, Yuriy A. The Korean Space Science Society 2022 Journal of astronomy and space sciences Vol.39 No.2

In this paper we propose a new perspective for explaining galaxy rotation curves. We conjecture that there is a gravitational moment of inertia which, together with gravitational mass, contributes to the gravitational potential. We substantiate a formula for the potential created by the moment of inertia. We validate our model by computing orbital rotation velocities for several galaxies and showing that computed rotation velocities correspond to the observed ones. Our proposed approach is capable of accounting for constant gas velocities outside of a galactic disc without relying on the dark matter hypothesis. Furthermore, it addresses several problems faced by the application of the dark matter hypothesis, e.g., the absence of inward collapse of dark matter into a galaxy, the spherical distribution of dark matter around galaxies, and absence of traces of the effect of dark matter in two ultra-diffuse galaxies, NGC 1052-DF2, and NGC 1052-DF4.

Moment of Inertia of Gas as a Source of Added Gravitational Field in Galaxies

Yuriy A. Portnov 한국우주과학회 2022 Journal of Astronomy and Space Sciences Vol.39 No.2

In this paper we propose a new perspective for explaining galaxy rotation curves. We conjecture that there is a gravitational moment of inertia which, together with gravitational mass, contributes to the gravitational potential. We substantiate a formula for the potential created by the moment of inertia. We validate our model by computing orbital rotation velocities for several galaxies and showing that computed rotation velocities correspond to the observed ones. Our proposed approach is capable of accounting for constant gas velocities outside of a galactic disc without relying on the dark matter hypothesis. Furthermore, it addresses several problems faced by the application of the dark matter hypothesis, e.g., the absence of inward collapse of dark matter into a galaxy, the spherical distribution of dark matter around galaxies, and absence of traces of the effect of dark matter in two ultra-diffuse galaxies, NGC 1052-DF2, and NGC 1052-DF4.

On the Influence of the Moment of Inertia of Gas on the Galactic Rotation Curves

Portnov, Yuriy A. The Korean Space Science Society 2022 Journal of astronomy and space sciences Vol.39 No.3

There are two models that explain the rotation curves of galaxies: dark matter, which gives the missing contribution to the gravitational potential of the standard theory of gravity, and modified theories of gravity, according to which the gravitational potential is created by ordinary visible mass. Both models have some disadvantages. The article offers a new look at the problem of galactic rotation curves. The author suggests that the moment of inertia creates an additional gravitational potential along with the mass. The numerical simulation carried out on the example of fourteen galaxies confirms the validity of such an assumption. This approach makes it possible to explain the constancy of gas velocities outside the galactic disk without involving the hypothesis of the existence of dark matter. At the same time, the proposed approach lacks the disadvantages of modified theories of gravity, where the gravitational potential is created only by the mass of visible matter.

On the Influence of the Moment of Inertia of Gas on the Galactic Rotation Curves

Portnov, Yuriy A. The Korean Space Science Society 2022 Journal of Astronomy and Space Sciences Vol.39 No.3

There are two models that explain the rotation curves of galaxies: dark matter, which gives the missing contribution to the gravitational potential of the standard theory of gravity, and modified theories of gravity, according to which the gravitational potential is created by ordinary visible mass. Both models have some disadvantages. The article offers a new look at the problem of galactic rotation curves. The author suggests that the moment of inertia creates an additional gravitational potential along with the mass. The numerical simulation carried out on the example of fourteen galaxies confirms the validity of such an assumption. This approach makes it possible to explain the constancy of gas velocities outside the galactic disk without involving the hypothesis of the existence of dark matter. At the same time, the proposed approach lacks the disadvantages of modified theories of gravity, where the gravitational potential is created only by the mass of visible matter.

FE Model of Three-Dimensional Steel Beam-to-Column Bolted Extended End-Plate Joint

Concepción Díaz,Mariano Victoria,Osvaldo M. Querin,Pascual Martí 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.3

The rotational behaviour of three-dimensional steel end-plate connections can be studied using the fi nite element method for the following four reasons: (1) such models are inexpensive and robust; (2) they allow the understanding of local eff ects; (3) they can be used to generate extensive parametric studies; (4) current version of the component method lacks the appropriate components to predict the behaviour of minor-axis and three-dimensional joints. This work presents a full ANSYS fi nite element parametric model of a three-dimensional steel beam-to-column bolted extended end-plate joint in both axes for use to obtain their behaviour. The model allows to study four joint confi gurations (internal, external, corner, and plane) and includes: contact and sliding between diff erent elements; bolt-pretension, and geometric and material non-linearity. This model was calibrated and validated with experimental results found in the literature. The results from the fi nite element analysis were verifi ed by comparing the obtained moment–rotation curve of the joint. Three parametric studies are presented to show the versatility of the FE model. The results were compared with those obtained with the model proposed by Eurocode 3. The developed ANSYS FE model can be downloaded for free as a single ZIP compressed fi le from the Technical University of Cartagena (UPCT): http://www.upct.es/goe/publi cacio nes/FEM_3D_EEP.zip .

Evaluation of the Moment-Rotation Curve of I Beam-to-CFT Column Connection with Endplate, Using Mechanical Modeling

Gholamreza Abdollahzadeh,Sakhi Yapang Gharavi,Morteza Hoseinali Beigy 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.4

Through this study, a method is presented to estimate moment-rotation (M-) curve of I beam-to-the concrete filled tube (CFT) connections. This method is based on the components method in which components are analyzed and modeled as different mechanical models. These components are considered as springs with specific mechanical properties of stiffness, strength, and rigid bars. Their force-displacement relationship is assumed bi-linear and 3-linear. The connection behavior is assumed through assembling the stiffness of different components. In this study, connection of I beam-to-CFT column with bolted endplate connection under monotonic loading, which has been tested in the laboratory, is evaluated. It must be mentioned that those bolts which penetrated into the column depth have been used in order to create continuity between flanges of the column. The suggested method has been compared with the experimental test and the advanced finite element model in terms of stiffness, strength, and rotational capacity; moreover, its operation was satisfactory.

A Generalized Analytical Method to Evaluate the Post-limit Properties of Joints in Bending Moment According to Eurocode3

Marzieh Obeydi,Maryam Daei,Mehran Zeynalian 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.5

On the structural analysis, connection eff ects should be evaluated in terms of rotational stiff ness and ultimate strength; this makes it possible to obtain realistic behavior of the structure. In this research, a simple analytical evaluation is carried out to predict the behaviors of the connections as a bi-linear curve. Mechanical properties of the initial and the second parts of this curve are obtained by component-based method and a suggested classifi cation method, respectively. The component-based method represents a joint by using a combination of rigid and fl exible components. Each of the components is modeled by means of specifi c stiff ness and strength values and they are assembled together to obtain the initial mechanical properties of the joint. The suggested classifi cation method classifi es all the components in a connection into three groups based on comparing the ultimate and the design moment strength of each component with those of the connection. By considering this procedure, a new equation is proposed to determine joint post-limit rotational stiff ness. This simple and fast method is applicable to any type of joints regardless of profi le type and applied loading. The proposed method is applied to a bolted angle, an end-plate to rectangular hollow section column and two bolted end-plate beam-to-column connections. The results are compared with those obtained from some other analytical, numerical and experimental methods. The outputs confi rm that the proposed method is simpler, more accurate and less time consume than the other methods.