Numerical Analysis On Torsion And Distortion Effect Of Concrete Thin-walled Box Girder

The concrete thin-walled box girder has been widely applied to engineering due toit’s good whole space performance, on the the concrete thin-walled box girder there isnot only longitudinal bending deformation caused by eccentric static loadings,but aslotwisted, transverse bending distortioncaused by torsion and distortion effect.Accordingto the influence of the thickness and spacing of diaphragm on torsion anddistortion,numerical analysis were analysised of concrete component thin-walled boxgirder subjected to torsion,the results list as follows:1、Through choosing proper element type and material modle,the whole proces ofsteel fibre reinforced concrete thin-walled box girder pure twisting test was simulated.The results show that the analysis ANSYS fixes with the experiment results very well,Cracked torque error is2.1%，Extreme torque error is less than5%.which confirmedthat ANSYS could be used to simulate the load and deformation of thin-walledconcrete box section well.2、The layout of diaphragms can improve the whole torsion stiffness of the concretethin-wall box girder wrest resistant stiffness of the concrete thin-walled box girder,Reducing torsion and distortion effects which are negative effects on concretethin-walled box girder.Thickness of diaphragm is not directly proportional to theoverall torsional stiffness increase value, With increased thickness of diaphragm，Overall improvement of torsional stiffness value and the ratio of thickness isincreasing。When the diaphragm has a certain stiffness，Across the thickness ofdiaphragm make a small impact on distortion of thin-walled box girder concrete.3、If concentrated load on the girder is permanent load,when there is a diaphragmset at the point of the laod,the influence of torsion and distortion effect areminimum;when the concentrated load is live load,the diaphragm spacing has greatinfluence for for torsion and distortion capacity of the girder,for the model in thispaper,when the diaphragm spacing is L/7along the span of the girder, the,the value ofmaximum normal stress is basically reach its minimum.For the cantilever torsionalcomponent under uniformly distributed loads, the diaphragm at the end of the girderare needed,which can reduce the adverse effect caused by torsion and distortion, as thequantities of diaphragms increased, the decreased value of the maximum normal stress are limited.4、The flange Plates have little influence on the torsion and distortion effect, theweb plates have great influence on the torsion and distortion effect,so setting stiffenerat the web lacation can improve the anti-twisting property of the box girder.