Research on Skew Coefficient for Stresses of Skewly Supported Three-Span Continuous Box Girders

2014 ◽  
Vol 587-589 ◽  
pp. 1483-1487
Author(s):  
Liang Liu
Keyword(s):  
Cross Section ◽  
Shell Element ◽  
Skew Angle ◽  
Box Girders ◽  
Concentrated Load ◽  
Box Girder ◽  
Lag Effect ◽  
The Cross ◽  
Skew Angles ◽  
Bottom Slab

Skewly supported continuous box girders have special mechanical properties compared with common continuous box girders. Skew coefficient for stress of skewly supported three-span continuous box girder is introduced to reflect the decrease degree of the normal stresses at the cross section of the middle span of the box girder. The finite element models of the skewly supported three-span continuous box girders with different skew angles are established by applying the SHELL63 shell element in software ANSYS. The variation of the skew coefficient for stress at different calculation points of middle span cross section under concentrated load is analyzed and the corresponding influence law is revealed. Research results show that the skew coefficient for stress of top slab is different from that of bottom slab at the cross section of the skewly supported three-span continuous box girder. The skew coefficient for stress of top slab is smaller than that of bottom slab. Skew coefficient for stress decreases with the increasing of the skew angle. Because of the shear lag effect, the minimal skew coefficient for stress of flanges occurs at the free tip of cantilever slab while the maximal skew coefficient occurs at the intersection of web and flange slabs.

Effect of diaphragms on stress reduction in box girder bridge sections

1988 ◽  
Vol 15 (1) ◽  
pp. 127-135 ◽  
Author(s):  
A. H. Siddiqui ◽  
S. F. Ng
Keyword(s):  
Cross Section ◽  
Stress Reduction ◽  
Box Girders ◽  
Box Girder Bridges ◽  
Box Girder ◽  
Girder Bridges ◽  
Loading Tests ◽  
The Cross ◽  
Girder Bridge ◽  
Determine Effect

The purpose of this study is to examine the effect of rigid diaphragms in reducing warping and distortion stresses developed in box girders due to deformation of the cross section. Tests were conducted for two Plexiglas box girder models to determine effect of diaphragms on the behaviour of box girder sections. The results of the tests were compared with values obtained from the so-called “beam on elastic foundation (BEF) analogy,” an analytical procedure that permits the calculation of warping and distortion stresses in box sections due to deformation of the cross section.Each box girder model was tested as a simply supported beam with a 1168.4 mm (46 in.) span. Six separate loading positions were used for each of the three predesigned diaphragm spacings. Thus, 18 separate loading tests were conducted for each model in order to obtain sufficient data to determine the amount of reduction in both warping and distortion stresses. Test measurements included the applied load, deflections, and strains at various locations on the webs and bottom flanges.The results indicate that deformation of a box girder cross section due to eccentric loading may cause substantial warping and distortion stresses, and that these stresses can be effectively controlled by judicious installation of rigid diaphragms along the span of the girder. Also, experimental warping and distortion stresses obtained from both tests compare reasonably well with those predicted by the BEF analogy. Key words: warping, torsional, stresses, deformations, box girder bridges, diaphragms.

scholarly journals Influence of Skew Angles on Box Type Bridge

2020 ◽  
Vol 9 (7) ◽  
pp. 64-69
Keyword(s):  
Finite Element ◽  
Earth Pressure ◽  
Live Load ◽  
Skew Angle ◽  
Dead Load ◽  
Shear Forces ◽  
Modeling And Analysis ◽  
Finite Element Software ◽  
Skew Angles ◽  
Bottom Slab

In the present study, modeling and analysis of a three-lane three-span box bridge has been carried out by using finite element software STAAD pro.v8i. The study has been execute to find the effect of skew angle on all bride slabs (top slab, bottom slab, outer walls, inner walls) under various loads (dead load, live load, surfacing load, earth pressure, temperature and live load surcharge) and their combinations using IRC 6:2016. Skew angles taken for study ranges from 00 to 700 with an interval of 100 . Parameters that are mainly examined are longitudinal moments, transverse moments, torsional moments, shear forces and displacements. It has been observed that with the increase of skew angle all the parameters increases with the increase of skew angles in all slabs.

Estimation of Ultimate Longitudinal Bending Moment of Ships and Box Girders

1996 ◽  
Vol 40 (03) ◽  
pp. 244-257 ◽  
Author(s):  
M. K. Rahman ◽  
M. Chowdhury
Keyword(s):  
Cross Section ◽  
Bending Moment ◽  
Fortran Program ◽  
Box Girders ◽  
Limit States ◽  
Box Girder ◽  
Stiffened Panels ◽  
Complete Procedure ◽  
Longitudinal Bending ◽  
Collapse Behavior

The paper describes a methodology of computing the ultimate value of the longitudinal bending moment at any cross section of a ship or box girder. The cross section has been discretized into stiffened panels (one stiffener with its associated effective plating). The limit states for these panels, both tensile and compressive, are modeled in an appropriate manner. Since the ultimate strength of the girder section is largely governed by the behavior of the panels under compression, the authors have paid special attention in modeling the collapse as well as post-collapse behavior of these panels. A new stress-strain relationship is also introduced. The complete procedure has been coded into a FORTRAN program and tested against a number of box girder models and an actual ship for which the true behavior was known. The results obtained from the proposed program appear to be quite satisfactory. Good correlation was also found when compared with the results obtained by more complex and rigorous analytical methods.

Fatigue Evaluation of Flat Steel Box Girders with Closed Stiffeners of Large-Span Suspension Bridges under Different Heavy Trucks

2011 ◽  
Vol 147 ◽  
pp. 157-160 ◽  
Author(s):  
Yong Zeng ◽  
Hong Mei Tan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cross Section ◽  
Suspension Bridges ◽  
Box Girders ◽  
Element Analysis ◽  
Box Girder ◽  
Fatigue Assessment ◽  
Steel Box Girder ◽  
Flat Steel

Due to its outstanding aerodynamic shape and light weight, the trapezoidal cross-section flat steel box girder with orthotropic decks and thin-walled longitudinal stiffeners of trapezoidal cross section are widely used in long-span suspension bridges in the world. However, because of the geometrical characteristics and the relative flexibility of their components, these structures may be quite susceptible to traffic loadings that fatigue cracks tend to appear in these structures. In this paper, Jiangyin Bridge is used as a case study to investigate the fatigue performance of the steel girders of suspension bridge Jiangyin Bridge is the second longest bridge in China, which has the main span of 1385m. The stress analysis of steel box girders is firstly carried out based on the analysis of fatigue life. Fatigue assessment method is proposed on the basis of in-situ measurement data combined with finite element analysis. A complete fatigue assessment is made in this paper. Key words: flat steel box girder; orthotropic decks; finite element analysis; fatigue assessment

scholarly journals Deformation of the cross-section in box girder

1956 ◽  
Vol 1956 (38) ◽  
pp. 55-57
Author(s):  
Sumio Nomachi ◽  
Sadao Komatsu
Keyword(s):  
Cross Section ◽  
Box Girder ◽  
The Cross

Numerical Solution of Section Stress about Steel-Concrete Composite Beams

2010 ◽  
Vol 163-167 ◽  
pp. 1614-1619
Author(s):  
Hai Gen Cheng ◽  
Yan Lou Yu ◽  
Yong Zhang
Keyword(s):  
Differential Equation ◽  
Cross Section ◽  
Beam Theory ◽  
Composite Beams ◽  
Nonuniform Distribution ◽  
Concrete Slabs ◽  
Shear Lag ◽  
Box Girder ◽  
Simply Supported ◽  
Lag Effect

Steel-concrete composite beams are composed of concrete slabs and steel girders by shear connectos. Due to the shear lag effect, the longitudinal normal stress of cross section is nonuniform distribution,and it is difficult to analyse the effect of that by ordinary beam theory. A differential equation of equilibrium is constituted corresponding to the compatibility of deformation and the equilibrium of forces about steel-concrete composite beams under particular assumed condition. The method of variable-separating is applied to solve the differential equation with the simply supported boundary condition. An example of steel-concrete composite box girder is given to analyse the effect of shear lag on its stress and approve its applicability.

The Changes of Internal Forces and the Reliability of Curved Bridge Taking the Cross-Sectional Design of Axial Symmetrical

2014 ◽  
Vol 587-589 ◽  
pp. 1631-1636
Author(s):  
Zheng Jiu Zhao ◽  
Jing Hong Gao
Keyword(s):  
Cross Section ◽  
Variable Cross Section ◽  
Radius Of Curvature ◽  
Variable Cross ◽  
Cross Sectional ◽  
Box Girder ◽  
Curved Bridge ◽  
The Cross ◽  
Cross Sectional Design ◽  
Bridge Models

Taking a bridge of 160m long variable cross-section prestressed continuous curved box-girder as the research object and analyzing the cross-sectional design of axis with axial symmetrical or axial non-symmetrical to research the structure forces change of the upper part of bridge in different curvature. In order to test and verify the variable cross-section of prestressed continuous curved box-girder bridge is safe and reliable via cross-sectional design with axial symmetrical instead of axial non-symtrical within a radius of curvature of the interval. Creating the straight bridge and curved bridge models with different radius of curvature in same span by Midas/Civil to compare their structure forces.

Theoretical Analysis of Temperature and Shrinkage Stresses of Box-Girder Section

2011 ◽  
Vol 243-249 ◽  
pp. 1885-1892
Author(s):  
Wei Zhao Li ◽  
Zong Lin Wang ◽  
Fadhil Naser Ali
Keyword(s):  
Tensile Stress ◽  
Cross Section ◽  
Temperature Difference ◽  
Negative Temperature ◽  
Shrinkage Stress ◽  
Box Girder ◽  
Stress Changes ◽  
Longitudinal Cracks ◽  
Bottom Slab ◽  
The Web

The objective of this study is to analyze the temperature and shrinkage stresses of the mid-span cross-section of a 20 meters box girder to find the reasons which cause the longitudinal cracks in the web and bottom of box girder. According to the results of damage inspeation, there are many longitudinal cracks in the web and bottom slab of box girders, especially the web of the edger beam, the crack is very clear. Ansys ver.10 software is used to analyze two dimensional finite element model of a typical cross section of a real bridge to calculate the temperature stresses caused by temperature difference between inside and out side of the box and the shrinkage stresses based on moisture diffusion. The results of analysis show that the outer surface of the web and bottom slab of the fabricated box girder will produce tensile stress at the effect of negative temperature difference. If the concrete reaches a certain age, the tensile stress does not cause creaks in the cross-section. The shrinkage stress changes with the moisture gradient in the box section. It will reach the maximum in 15 days and then decreases with the growth of the age. Shrinkage stress may cause cracking of the concrete surface because of the tensile strength is low in the early age.

Influence of Main Structural Dimension on the Shear Lag Effect of Box Girder Used in Cable-Stayed Bridge

2013 ◽  
Vol 405-408 ◽  
pp. 1483-1488 ◽  
Author(s):  
Yu Ping Zhang ◽  
Chuan Xi Li
Keyword(s):  
Shell Element ◽  
Parameter Analysis ◽  
Bottom Flange ◽  
Shear Lag ◽  
Shear Lag Effect ◽  
Box Girder ◽  
Thickness Change ◽  
Cable Stayed Bridge ◽  
Flange Thickness ◽  
Lag Effect

Through simulating box girder with shell element, the influence of the top flangebottom flange and web thickness on the shear lag effect of box girder used in cable-stayed bridge was discussed on the background of Jianning bridge in Zhuzhou. Parameter analysis of the thickness change of the top flange, bottom flange and web on shear lag effect of box girder was based on analyzing and comparing the calculated results. The results show that the thickness change of the top flange, bottom flange and web have more influence on the shear lag effect of top flange than that of bottom flange; thickness increase of bottom flange and web can make the shear lag effect intensified obviously; and thickness change of web has the most significant influence on the shear lag effect among them for box girder with single box and three rooms used in cable-stayed bridges.

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