The Analysis On Torsion And Distortion Effect Of Single Box Triple-cells Girder With Corrugated Steel Webs And The Optimization Study Of Concrete Encasement

Since the arrival of the box girder bridge with corrugated steel web,it quickly becomes the most popular bridge type when people decide to design a bridg because of its great advantages on structural performance,reducing quantity,shortening the construction period and reducing the cost..However,compared with normal concrete web box girder the section flexural and torsional rigidity of the box girder with corrugated steel web are much smaller because of the corrugated steel.The box girder with corrugated steel web produces larger buckling stress under the eccentric load,especially for the single box multiple-cells box girder bridge and its torsion and distortion effect is obvious under the eccentric load.So we systematically research the torsion and distortion effect of the single box multiple-cells box girder with corrugated steel web based on the of Nanfeihei river bridge as the background in this paper,.(1)This paper concluded the theoretical calculation method for torsion effect of the single box multiple-cells girder with corrugated steel web on the basis of the Second Theory of A.A.Umanskii and applied the method to practical engineering example.So this paper geted the constrained torsion normal stress values and the torsion shear stress values and provided theoretical analysis method of torsion effect for the similar bridge type.(2)This paper adopted the finite element method to analyze the distortion effect after considered the diseconomy when applied the B.E.F analogy calculation method for the distortion effect of the single box single-cell box girder to single box multiple-cells variable cross-section box girder.and built the whole bridge finite element model by finite element software ANSYS.The bending load was equaled to the torsion load and the distortion load and respectively applied the two loads on the finite element model.Then obtained the torsion effect and distortion effect results of the single box triple-cells box girder with corrugated steel web under eccentric load.And verified the accuracy of the method by comparing the torsion effect results by finite element method with the results by theoretical formula method.Finally compared the steel web girder distortion effect with concrete web distortion effect under eccentric load,and obtained a whole of torsion and distortion effect results under the eccentric load.(3)Analyzed the main factors of affecting torsion and distortion effect by theoretically analyze,and obtained the laws which the partial load coefficient how to change withparameters by changing the model parameters and gived design suggestions about improving torsion and distortion effect on engineering examples.(4)Researched the impact of concrete encasement where at the root of box girder with corrugated steel web for the mechanical property of the corrugated steel webs and gived optimized suggestions about the concrete-encased structural sizes including the length of concrete encasement,the maximum thickness at the root part and the the minimum thickness at the end of steel and concrete segment.