Torsion Mechanical Performance Analysis Of Single Cell Box Uniform Cross Section Composite Box Girder With Corrugated Stell Webs-steel Bottom-concrete Roof

Domestic and foreign scholars have conducted a lot of research on the torsional mechanical properties of the traditional composite box girders with corrugated steel webs and obtained relatively mature theoretical results,but it is rare to study the torsion performance of the composite box girder with corrugated stell webs-steel bottom-concrete roof,in this paper,the torsion performance of this composite box girder is studied,and the main research contents and results are as follows:(1)The torsion stress solution formula of the composite box girder with corrugated stell webs-steel bottom-concrete roof was derived based on the theory of Umanski torsion theory,and used finite element method to verify the torsion stress solution formula.(2)This paper not only calculated but also comparative studied the angle of torsion,constraint torsional moment,warping deformation coefficient and restraint torsional stress of the composite box girder with corrugated stell webs-steel bottom-concrete roof and the traditional composite box girders with corrugated steel webs,which the section size of the box girder is equivalent to the former box girder,the results show that the steel completely replace the concrete floor of the traditional composite box girders with corrugated steel webs,from the perspective of torsion analysis had the feasibility.(3)Using ANSYS analysed the torsion and distortion stress of the composite box girder with corrugated stell webs-steel bottom-concrete roof and the traditional composite box girders with corrugated steel webs,it is found that the torsion and distortion of roof are approximately equal,also the former box girder generated more torsion and distortion normal stress,but the torsion and distortion shear stress of the former box girder is less than the box girder,this reflected that the composite box girder with corrugated stell webs-steel bottom-concrete roof can absorb the torsion and distortion deformation energy,this type of bridge can be considered from the perspective of torsion stress.(4)Using the Hamilton principle deduced the torsional vibration frequency formula of the composite box girder with corrugated stell webs-steel bottom-concrete roof which considered the free torsional torque and restrained torsional torque,also its correctness is validated by finite element.(5)It is studying that the geometrical parameters and diaphragm to the torsional vibration of the composite box girder with corrugated stell webs-steel bottom-concrete roof,which elicited that high-to-span ratio is too large or too small all can reduce the torsional rigidity of the box girder,when the thickness of the webs is larger than the thickness of the steel plate,the effect of the antagonism is not obvious,at the same time,the thickness and height change of stiffening rib in the orthotropic plate are not obvious to the first-order frequency of torsional vibration,in the actual design,the influence of economy and stiffening rib on other mechanical properties of the box girder should be considered.The diaphragm can improve the torsional vibration frequency of the composite box girder with corrugated stell webs-steel bottom-concrete roof.However,the number of diaphragm increases gradually,the effect of torsional vibration frequency is no longer obvious.