Multi-scale-space Grillage Mixed Method of Mechanical Behavior of Composite Box Beams with Finite Element Method (FEM)

Due to different composition materials, steel–concrete composite box beams have interface slip, shear deformation, and other characteristics. Composite box beams have significant spatial effects and complex mechanical behavior under external loads. To simultaneously realize the simulation of macro mechanical properties and refined analysis of local mechanical behavior of composite box beam structure, this paper proposes a method to connect multi-scale models to space grillage models. In the macro model part, the space grillage method is used to consider the overall spatial mechanical characteristics; the multi-scale method is adopted to establish the refined model for the fine analysis of local primary stress parts. The contact element based on the constraint equation connects the multi-scale and the space grillage models to ensure the coordinated deformation of the two at the interface. This paper establishes a multi-scale-space grillage model of box section steel–concrete composite beams based on the Finite Element Method (FEM) and ANSYS program. Based on the model, experimental comparison verification and numerical example verification were carried out. The accuracy of the multi-scale-space grillage model for simulating the static and dynamic behavior of composite box beams is investigated. The research results show that the multi-scale-space grillage mixed simulation method has the advantages of high accuracy, low cost, and high efficiency. It provides a new idea and strategy for the mechanical behavior simulation analysis of complex composite box beam bridges.