Numerical Calculate And Experimental Research About Shear Lag Effect Of Curved Thin Wall Box Girders

Analysis of shear lag effect is an important issue of thin-walled box girder. Domestic and foreign experts make a lot scientific researches on shear lag effect of linear box girder, and put forward many mature theories. These methods have certain assumptions and cumbersome analysis process, can not adapt to the complex structure analysis.Curved girder bridge is different from the straight bridge, one of its features is that even if only in the vertical loads, due to the presence of curvature, will also torsion, the effects of the so-called coupling effect of bending and torsion, which makes their structural analysis complicated than the straight one. As the enhancement of computer's capability, numerical analysis method to fully consider the various factors affecting the mechanical problem, and has good precision, to become an important method of shear lag analysis.In this paper, a shell finite element model of single-box and single-cell box-girder based on the shell finite element method is proposed and a model test is carried out to verify the shear lag as well as the nonlinear bearing behavior of curtred box- girder further.The main content is as following:1. The box girder mechanical characters and the concept of shear lag are introduced in this dissertation, the theories and methods for solution to shear lag effect are expatiated; their suitability and constraint of use are discussed too.2. Summarize the methods that a variety of specifications in many countries how to deal with shear lag effect, and comparative study was carried out.3. Based on finite element theory, Use Large general-purpose software ANSYS modeled curved box girder in different factors, analyzed the various factors on the shear lag effect. The affecting factors include: radius of curvature, the ratio of height to width, the ratio of thickness of boards, and the ratio of width to span. The rules of shear lag coefficients changing with affecting factors are summarized. From this, the ratio of width to span is the most importantfactors, and the suggestions in design process on diminishing the shear lag effect are made.4. Used a dual-beam stick finite element model to analyze the response of curved box girder.Contrast and analysis the result respectively based on the shell element model and the solid element model, evaluate the reliability of the dual-beam stick model. In addition, analyzed the factors that the distance between two sticks and the distance between two diaphragms.5. A model test of curved thin-walled box girder on the static loads has been performed. The experiment and analysis values exposed that: the shear lag phenomenon has been showed.The results agree well with the ANSYS simulation results.6. For the first time to consider the shear lag effect of curved box girder structure under seismic loads, and by comparing the result to obtain the different rule of shear lag in the static and seismic loads, educe some new conclusion of shear lag effect research with curved box girder. These results have great value for perfect the theory and Specific Application of shear lag effect in curved box girder.