scholarly journals A Finite Segment Method for Skewed Box Girder Analysis

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Xingwei Xue ◽  
Jiawei Wu ◽  
Junlong Zhou ◽  
Hongnan Li
Keyword(s):  
Three Dimensional ◽  
Beam Element ◽  
Dimensional Structure ◽  
Elastic Displacement ◽  
Box Girders ◽  
Box Girder ◽  
Significant Saving ◽  
Finite Segment ◽  
Skew Plate ◽  
Finite Segment Method

A finite segment method is presented to analyze the mechanical behavior of skewed box girders. By modeling the top and bottom plates of the segments with skew plate beam element under an inclined coordinate system and the webs with normal plate beam element, a spatial elastic displacement model for skewed box girder is constructed, which can satisfy the compatibility condition at the corners of the cross section for box girders. The formulation of the finite segment is developed based on the variational principle. The major advantage of the proposed approach, in comparison with the finite element method, is that it can simplify a three-dimensional structure into a one-dimensional structure for structural analysis, which results in significant saving in computational times. At last, the accuracy and efficiency of the proposed finite segment method are verified by a model test.

Quasi-Static Modelling and Computer Simulation of Hanging Cables on Robots

1994 ◽  
Author(s):  
Li-Ping Yang ◽  
Shin-Min Song
Keyword(s):  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Finite Segment ◽  
Revolute Joints ◽  
Highly Nonlinear ◽  
Finite Segment Method ◽  
Newton Raphson ◽  
Static Modelling ◽  
Parameter Perturbation Method ◽  
Raphson Method

Abstract This paper presents a computer method to simulate the quasi-static motion of hanging cables on robots. The shape of the flexible cable is changing during motion and the finite segment method is applied to determine its configuration. The cable is modeled as a series of rigid segments segments connected together through revolute joints in 2-D case and spherical joints in 3-D case. The elasticity of cable is represented by torsional springs at the joints. In both cases, a set of highly nonlinear equations are derived based on force equilibrium and the Newton-Raphson method is applied to calculate the solution. In order to assure convergence and improve computational efficiency, the parameter perturbation method is applied together with the Newton-Raphson method. Also, some computational strategies are developed to simplify the three dimensional problem. Finally, the developed methods are demonstrated in displaying the motion of a hanging cable which is attached to a revolute joint, a prismatic joint and a three degrees of freedom robot.

Shear Lag Effect of Continuous Curved Box Girder with Initial Curvature

2012 ◽  
Vol 538-541 ◽  
pp. 1701-1704
Author(s):  
You Ming Wu ◽  
Yong Jun Lu ◽  
Han Shi
Keyword(s):  
Model Tests ◽  
Shear Lag ◽  
Shear Lag Effect ◽  
Box Girder ◽  
Finite Segment ◽  
Homogeneous Solutions ◽  
Initial Curvature ◽  
Lag Effect ◽  
Finite Segment Method ◽  
Displacement Patterns

The homogeneous solutions of the governing differential equations for shear lag are used as the displacement patterns of the finite segment are presented. A finite segment model with consideration of initial curvature, bending, torsion and shear lag is established. In addition, the tests of the two-span continuous curved box girder and numerical calculations of the model tests by finite segment method and finite element method are made. The results of the model tests and numerical calculation are consistent with each other. An actual example was given to investigate the shear lag effect of a continuous curved box girder under load. The research results show that the initial curvature has an obvious influence on the shear lag effect of a continuous curved box girder.

Use of Finite Element and Finite Segment Methods in Modeling Rail Flexibility: A Comparative Study

2012 ◽  
Vol 7 (4) ◽  
Author(s):  
Martin B. Hamper ◽  
Antonio M. Recuero ◽  
José L. Escalona ◽  
Ahmed A. Shabana
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Element Mesh ◽  
Finite Segment ◽  
Safety Requirements ◽  
Contact Points ◽  
Rigid Finite Element Method ◽  
Contact Formulation ◽  
Finite Segment Method ◽  
Railroad Vehicle

Safety requirements and optimal performance of railroad vehicle systems require the use of multibody system (MBS) dynamics formulations that allow for modeling flexible bodies. This investigation will present three methods suited for the study of flexible track models while conclusions about their implementations and features are made. The first method is based on the floating frame of reference (FFR) formulation which allows for the use of a detailed finite element mesh with the component mode synthesis technique in order to obtain a reduced order model. In the second method, the flexible body is modeled as a finite number of rigid elements that are connected by springs and dampers. This method, called finite segment method (FSM) or rigid finite element method, requires the use of rigid MBS formulations only. In the third method, the FFR formulation is used to obtain a model that is equivalent to the FSM model by assuming that the rail segments are very stiff, thereby allowing the exclusion of the high frequency modes associated with the rail deformations. This FFR/FS model demonstrates that some rail movement scenarios such as gauge widening can be captured using the finite element FFR formulation. The three procedures FFR, FSM, and FFR/FS will be compared in order to establish differences among them and analyze the specific application of the FSM to modeling track flexibility. Convergence of the methods is analyzed. The three methods proposed in this investigation for modeling the movement of three-dimensional tracks are used with a three-dimensional elastic wheel/rail contact formulation that predicts contact points online and allows for updating the creepages to account for the rail deformations. Several conclusions will be drawn in view of the results obtained in this investigation.

scholarly journals Investigation of Load Distribution Factors for Two-Span Continuous Composite Multiple Boxgirder Bridges

2021 ◽  
Author(s):  
Manal Ibrahim
Keyword(s):  
Load Distribution ◽  
Three Dimensional ◽  
Bending Moment ◽  
Box Girders ◽  
Box Girder Bridges ◽  
Box Girder ◽  
Girder Bridges ◽  
Truck Loading ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Bridges formed of concrete deck slab over built-up steel-box girders are frequently used in bridge construction for their economic and structural advantages. Box girder bridges impose structural challenges to get the straining actions for the design of girders. The objective of this study is to determine the load distribution characteristics for continuous composite multiple–box girder bridges under CHBDC truck loading. An extensive parametric study was conducted using the three-dimensional finite element to evaluate the moment and shear distribution factors when bridges subjected to CHBDC truck loading. The parameters considered in this study are the span length, number of lanes and number of boxes. Then, simple empirical formula for the bending moment and shear force were developed for the structural design. Correlation of the developed expressions based on FEA results with available CHBDC and AASHTO-LRFD formula showed that the former allow engineers to design such bridges more economically and reliably.

scholarly journals Investigation of Load Distribution Factors for Two-Span Continuous Composite Multiple Boxgirder Bridges

2021 ◽  
Author(s):  
Manal Ibrahim
Keyword(s):  
Load Distribution ◽  
Three Dimensional ◽  
Bending Moment ◽  
Box Girders ◽  
Box Girder Bridges ◽  
Box Girder ◽  
Girder Bridges ◽  
Truck Loading ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Bridges formed of concrete deck slab over built-up steel-box girders are frequently used in bridge construction for their economic and structural advantages. Box girder bridges impose structural challenges to get the straining actions for the design of girders. The objective of this study is to determine the load distribution characteristics for continuous composite multiple–box girder bridges under CHBDC truck loading. An extensive parametric study was conducted using the three-dimensional finite element to evaluate the moment and shear distribution factors when bridges subjected to CHBDC truck loading. The parameters considered in this study are the span length, number of lanes and number of boxes. Then, simple empirical formula for the bending moment and shear force were developed for the structural design. Correlation of the developed expressions based on FEA results with available CHBDC and AASHTO-LRFD formula showed that the former allow engineers to design such bridges more economically and reliably.

scholarly journals Finite segment method for calculating the shear lag in thin-walled curved box girders

2009 ◽  
Vol 58 (6) ◽  
pp. 4002
Author(s):  
Wu You-Ming ◽  
Yue Zhu-Feng ◽  
Lyu Zhen-Zhou
Keyword(s):  
Shear Lag ◽  
Box Girders ◽  
Finite Segment ◽  
Finite Segment Method ◽  
Thin Walled

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

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