Finite Element Analysis On Mechanical Behavior Of The External PSC Composite Box-Girders With Corrugated Steel Webs

The external PSC composite box-girders with corrugated steel webs is a new type of composite steel-concrete structure. The respective characteristics of the top-and-bottom concrete board, the corrugated steel webs and the external tendons are fully exerted. So the mechanical behavior is different from the general pre-stressed concrete girders. Compared with simple structure, the flexural performance and shear performance, for the complex external PSC composite box-girders with corrugated steel webs, whether with other rules, consistent still needs further research. Through the nonlinear finite element, this article analysed the special mechanical behavior of this structure.(1)The stem department finite element model and the entity finite element model were established respectively by "MIDAS/Civil" and "MIDAS/FEA" relying on the specific bridge.The two calculation results of self-respect and the prestressing effect are accurate within 5% error. So,the model in this paper is reliable. The stem department finite element model is exact,but just only for the overall effect analysis of linear elastic. The entity finite element model can solve the problems of nonlinear analysis and detail analysis.(2)In this paper, basic mechanical behavior was verified of this structure.The distribution of the bending strain in height direction obeys the imitating plane assumption of deformation, and while the stress in the transverse distribution follows shear-lag phenomenon. The shear stress basically beared by the steel webs, and which is constant in height direction.(3)By summarizing the existing stress inerement mrulas of the external tendons,we can see the difference between this mrulas is more than three times. Considering the numerical analysis method is complex, the finite element model was established to analyz the flexural performance. Through this method, the stress inerement of the external tendons in the limit state was calculated clearly.(4)Using the calculation formula of the highway bridge design guidelines for externally prestressed concrete provisions, the flexural strength was calculated. And through the nonlinear finite element analysis, the flexural strength calculation was 5% bigger than the provisions.So we can consider it safety to use this provisions to calculate the flexural strength for this structure.(5) By changing the thickness and the hight and consider initial defects of the corrugated steel webs, the shear buckling performance of the corrugated steel webs was studied at last. The research shows that the thickness of the webs seriously influenced the local shear buckling performance, while the height of the webs seriously influenced the global shear buckling performance.Changing the thickness of the webs seriously influenced the buckling strength. Each of the 2mm thickness changes the influence of the bearing force more than 20%.The larger size initial defects can influence the shear buckling strength. Initial defects of 20mm which is admissible in the standard can influence 20% of the bearing force.