Torsion Mechanical Behavior Analysis Of The Prestressed Concrete Box Girder With Corrugated Steel Web

The box girder with corrugated steel web is a kind of combination of steel and concrete materials-concrete roof and concrete base slab under bending moment, the box girder with corrugated steel web under shear-which both play mechanical properties by themselves and are made full use of. Considering the torsion factors, the corrugated steel web instead of the traditional concrete web has special folding effect, thin plate and a certain variation degree of stress, compared with the average stress of the traditional box girder. Because the cross section of box girder with corrugated steel web is lesser than the traditional box girder’s torsion moment of inertia and torsion stiffness of box girder with corrugated steel web will be greatly reduced, under the external torsion forces, the buckling coefficient of the cross section, buckling stress, longitudinal displacement and torsion change rate of angle will be bigger than general prestressed concrete box girder. To study mechanical properties the box girder with corrugated steel web under external torsion forces, this paper can mainly finish the following work:1Through consulting relevant literature and the completing production of model test beam in the laboratory, in order to understand construction technology, the internal structure and the processing problems of connection parts, this paper summarizes the structural characteristics of this kind of composite structure, mechanical properties, advantages and research status at home and abroad.2Through the way of the equivalent stiffness and displacement to find out the three dimensional elastic modulus of corrugated steel web and simplifying the three dimensional corrugated steel web problem into a two-dimensional problem, the main purpose draws a conclusion that the longitudinal elastic modulus is far less than the rest of the other two directions and this is why the folding effect of the box girder with corrugated steel web.3Based on the theory of thin-walled box girder and the elastic theory of plate and shell, the torsion moment of inertia of the box girder with corrugated steel web is deduced, through the calculating of the box girder with corrugated steel web, it is concluded that the torsion moment of inertia of cantilever part of concrete roof account for0.5%of the entire section and it is feasible to study the close section of box girder only, furthermore, theoretical formula which is derived from the model test results has certain difference and need to further correct through the theoretical analysis results.4Using the energy variation principle to deduce the torsion differential equation of constraint corrugated steel web, under two kinds of special external force status of the beam-uniform torsion torque and concentrated span, the general solution and analysis of special solution in the governing differential equation are derived from the commonly used parameters,such as section torsion angle, warping factor, double moment and beam section torque which are very sensitive to the cross-section torsion and warping coefficient,and will be more prominent in long span long cantilever state of these parameters compared with the general box girder with corrugated steel webs.5Considering the box girder with corrugated steel webs torsion stiffness lower than the general box girder and under the dynamic load in the torsion vibration,the girder will be in a disadvantageous status, by using the energy principle to solve the torsion free vibration differential equations which the torsion vibration natural frequency and modal parameters can be calculate by separation variable method.6Refer to laboratory scale model test beam sizes, the establishment of ANSYS model, meshing, boundary conditions and external load, it can extracted section map from longitudinal stress and displacement of concrete roof and concrete base slab and shear stress of steel webs, compared with the theoretical calculation results to discuss the feasibility of the research method. Through the extraction of box girder with corrugated steel webs of natural frequency, and remove the first three order torsion frequency, the theoretical results and test results show that:the first torsion frequency is close to the theoretical value, and two order torsion frequencies are a certain difference.