Torsion And Distortion Effect For Pre-stressed Concrete Skewed Box-section Girder Bridge

At present,in the condition of the continuous developing of the urban bridges and highway bridges,due to the influence of the space or terrain,many bridge types have to choose skewed bridges,which mainly use the type of skewed box-section girder bridges.Especially in the cities,the bridge site should be subordinated to the design of the road network planning.When the bridge site is restricted by the space,it would inevitably to form a certain angle with the planning route.In the background of wide application of skewed box-section girder,because of its structural characteristics different from the right bridge,the forces applied are relatively complicated,coupled with both its theoretical analysis and numerical analysis are currently in the research stage,in particular,compared with the right box girder bridges,the torsion and distortion effects problems of the skewed box-section girder bridges are relatively less research on,this thesis analyzes the influences of the torsion and distortion effects with different parameters.Based on Umansky Second Theory,with the torsion angle ? as the unknown variable the restrained torsion differential equation is derived,from which the normal stress of box girder restrained torsion can be obtained.Secondly,the distortion differential equation of box girder with rectangular section is derived by static equilibrium method.Then the theoretical calculation and modeling analysis of a rectangular single-cell box girder under eccentric load are carried out,and the accuracy of the distortion differential equation and the models is obtained.A series of similar models of simply supported and three-span continuous skewed box girder bridges are established by using finite element software ANSYS.By changing the skewness,the prestress level and the span ratio of skewed box girder bridge and under the action of concentrated load or uniformly distributed load,the distortion angle,the lateral deflection of the distortion and the size of distortional warping of each unfavorable cross section of skewed box girder bridge are studied respectively,and the methods of reducing the torsion and distortion of skewed boxgirder bridge are proposed.