Distortion Effect Analysis Of Thin-walled Box Girder

As an important research subject, distortion effect in thin-walled box girder is not allowed of neglecting during design and analysis of bridge construction. Based on thin-walled bar theory and finite element method, differential equations for the distortion of thin-walled box girder are established using by the principle of minimum potential energy variational method. There are two methods for obtaining element stiffness matrix and equivalent nodal loads. The first method is that stiffness matrix of beam element distortion are derived by the definition of the stiffness coefficient and distortion differential equation. The second method is that stiffness matrix of beam element distortion are obtained via elastic foundation beam analogy method.As a recipient method in engineering design, one-dimensional member structure supplements distortion deformation and definitely defines the generalized force (distortion moment My) correspondingly. In this manner, mechanics concept becomes briefly and distinctly. The contrast between numerical solution and result of model test indicates that the semi-analysis manner can achieve higher calculation accuracy with extremely few discretization freedoms.This paper compares the experimental data and calculation of one-dimensional beam element and found that they are consistent.Compared with the general finite element software, one-dimensional finite element results can better reflect the changes of distortion moment.So one-dimensional finite element method are more easily grasped because its preprocessor and postprocessor is simpler than other finite element softwares.In this paper,taking a 40m span simply supported thin-walled steel box girder as an engineering example,distortion effect of hin-walled steel box girder was deeply researched and founded several conclusions.Firstly, diaphragm play a decisive role on the distortion effects of hin-walled steel box girder. Secondly,the distortion effect of box girder was not considered when the distance of diaphragm is less than the height of box.Finally, the box girder section shape plays a very important influence of distortion effect in many factors.In addition,taking a concrete continuous beam bridge as an engineering example in this paper, distortion effect of concrete continuous beam bridge was deeply researched and founded that distortion warping stress of live loads on continuous beam bridge accounted for 17.7 percents of the total normal stress of the live and dead loads.