Study On Torsional Behavior Of Composite Box Girder With Corrugated Steel Webs

Based on Umansky's second theory and finite element method,this paper establishes the analysis model of the polygonal composite box girder with corrugated steel webs.The torsional characteristics of composite box girder with corrugated steel webs and the influence of structural parameters of corrugated steel webs on torsional performance of the polygonal composite box girder with corrugated steel webs were studied.The results show that under eccentric loading,the effect of wave height and plate thickness on torsional performance of composite box girder is greater than that of horizontal section length.Polygonal composite box girder with corrugated steel webs tends to have large torsional normal stress in the position of fold angle.Adding a diaphragm at the location of the fold angle can effectively reduce the maximum value of the torsional normal stress of the box girder.The paper establishes a finite element model of a large-span composite box girder bridge with variable cross-section and corrugated steel webs.Then the effect of bridge structure type and variable thickness arrangement of corrugated steel webs on the torsional performance of box girder bridges were studied.Compared with composite box girders with corrugated steel web with minimum thickness and equal-thickness,the use of variable thickness arrangement of corrugated steel webs can reduce the torsional normal stress in most areas of the main pier and control the torsional normal stress near the main pier.Compared with composite box girders with corrugated steel webs with maximum thickness and equal-thickness,the use of variable thickness arrangement of corrugated steel webs can reduce the structural deflection while torsional performance of most parts of the box girder is not change.The paper analyzes the influences of the structural parameters and arrangement of stiffeners and the quantity of corrugated steel webs on torsion resistance.In addition,the setting method and related suggestions of variable wave height of corrugated steel webs is proposed.The study shows that increasing the number of corrugated steel webs and the thickness,width,and number of stiffeners can improve the torsion resistance of box girders with corrugated steel webs.When the width,height and thickness of stiffeners are not changed,using double-sided arrangements will reduce the torsional behavior of composite box girders with corrugated steel webs.Under the condition of constant dead load,appropriately reducing the thickness of corrugated steel webs to increase the wave height of corrugated steel webs can further improve the torsional performance of box girders.Based on this analysis result,the method of changing the wave height of the corrugated steel web is proposed,that is,the wave height of the corrugated steel web is increased in the area where the structural torsion resistance is weak.Through the verification of the effect of the anti-torsion performance on the arrangement of the variable wave height of corrugated steel webs on real bridges,it is further illustrated that the arrangement of variable wave height of corrugated steel webs can be applied to engineering practice.