Analysis On Restrained Torsion And Distortion Effect Of Composited Box Girder With Corrugated Steel Webs

The composited box girders with corrugated steel webs is a relatively novel form of composite section.Compared with the traditional concrete box girder,it has many advantages.Thus,it has been increasingly used in actual bridge projects in recent years.However,due to the difference in the mechanical properties of the plates element materials of composited box girders with corrugated steel webs,its torsion resistance is greatly reduced,so the torsion and distortion problems are particularly prominent.In this dissertation,a single cell composited box girders with corrugated steel webs is taken as the research object.On the basis of fully considering its mechanical properties,the torsion effect and distortion effect are studied and analyzed.In order to analyze the restrained torsion effect of composited box girder with corrugated steel webs more reasonably,the restraining effect of top and bottom plates on corrugated steel webs is considered.The concept of the common bending section of corrugated steel webs is introduced.Considering the accordion effect,an analytical method for analyzing the torsional effect is proposed.A new generalized sector coordinate distribution model is introduced to study the restrained torsion warpage normal stress and secondary shear stress of composited box girders with corrugated steel webs.The governing differential equation of restrained torsion effect and its initial parameter solution are derived.The concept of common bending section is verified through finite element analysis.Through numerical examples,the differences between the results of the proposed method and the traditional method and ANSYS finite element method are analyzed.The reasonable height of the common bending section is determined,and the correctness of the derived formula is verified.The research results show that: compared with the calculation results of the traditional method,the calculation results are more accurate after considering the restraint effect of the top and bottom plates on the corrugated steel webs;there is no shear stress at the end of the cantilever plate of the box girder;there is large secondary shear stress of the restrained torsion on the corrugated steel webs,so it should not be ignored;the normal stress in the common bending section can reach the bending normal stress level,showing that it is necessary to consider the restraint effect of top and bottom plates on corrugated steel webs in the analysis of restrained torsion of box girder with corrugated steel webs.In order to analyze the distortion effect of composited box girder with corrugated steel webs more reasonably,on the basis of the concept of common bending zone,the distortion angle is redefined,and an analytical method of distortion effect is proposed,which is similar to the analysis method of restrained torsion.The calculation formulas of distortion normal stress and shear stress are derived through section equivalence.Using the principle of energy variation,the differential equations for the control of distortion effects are deduced,and the initial parameter solutions are deduced in combination with the boundary conditions.Numerical examples and ANSYS finite element analysis verify the correctness of the deduced formula.The normal stress coefficient is introduced to reflect the relative relationship between the torsion and distortion normal stress and bending normal stress,and the shear stress coefficient is introduced to reflect the influence of the torsion and distortion shear stress on the total shear stress.Combined with a numerical example,a detailed analysis of the related geometric parameter changes on the stress the influence law of the coefficient.The research results show that: compared with the calculation results of the traditional method,the calculation results of this method are more accurate;the distortion effect normal stress is greater than the torsion effect normal stress,and is equivalent to the bending normal stress.The shear stress generated by torsion and distortion accounts for the bending shear stress the ratio is also large,so the torsion and distortion effects of the composited box girders with corrugated steel webs should be paid attention to.