| The composite box girder with corrugated steel web,steel bottom plate and concrete roof(this paper refers to the new composite box girder with corrugated steel web)is a new type of box girder structure composed of corrugated steel web,steel bottom plate and concrete roof.Although there are many researches on the torsional properties of this new structure,However,there are few studies on the torsional characteristics of the nonlinear pure torsion of the new corrugated steel web composite box girder,so this paper combines the formula derivation,the finite element material nonlinear analysis and the comparative analysis with the test data in the references.The specific research contents are as follows:(1)According to the closed thin-wall bar theory,the section of the composite box girder is equivalent to the all-steel section.Combined with the theory of free torsion of the section of the closed thin-wall bar,the theoretical formula of the torsional stiffness of the new-type composite box girder with corrugated steel webs at the elastic stage is derived.(2)In this paper,the method of superposition principle is used to divide the new-type corrugated steel web composite box girder into the box section formed by concrete wing plate and the steel box after the whole component is equivalent.The cracking torque and ultimate torque of the structure are jointly borne by the two parts after equivalent.Then,according to the theory of thin-wall box girder and the existing variable Angle space truss model theory,The formulas for calculating the cracking torque and ultimate torque of a new type composite box girder with corrugated steel webs are deduced.(3)Considering the influence of material nonlinearity in ANSYS modeling,the influence of the range of parameters set by relevant elements in ANSYS on the results of pure torsional finite element numerical simulation of a new type of composite box girder with corrugated steel webs was studied.In particular,the effect of open crack shear transfer coefficient and closed crack shear transfer coefficient on the numerical simulation results of pure torsional failure of new corrugated steel web composite box girder in literature is considered.(4)Considering the influence of diaphragm and longitudinal stiffeners on the pure torsional finite element numerical simulation results of a new type composite box girder with corrugated steel webs,the torque-torsion curve of concrete roof and the torque-strain curve of web and reinforcement were compared by changing the number and thickness of diaphragm and stiffener.(5)Parameters such as the thickness of the bottom plate,the height and thickness of the web,the reinforcement ratio and the strength of concrete were changed,and the torque-torsion curve of the concrete roof and the torque-strain curve of the web and the steel bar were compared by the finite element simulation results.The influence of these parameter changes on the pure torsion finite element numerical simulation results of the composite box girder with new corrugated steel web was compared and analyzed. |
