Mechanical Behavior of Concrete-filled Steel Tubular Space Intersecting Nodes in High-rise Oblique Diagrid Tube Structures

What is it about?

In recent years, the researches on concrete-filled steel tubular (CFST) intersecting nodes mainly focused on the plane intersecting nodes, while that on space intersecting nodes with off-plane angles was relatively less. In this study, the nonlinear analyses of CFST space intersecting node models established in ABAQUS were performed under the monotonic axial compression and reciprocal axial tension-compression loads, respectively. The stress distributions of steel tubes and core concrete were analyzed, and the hysteresis characteristics and stiffness degradation of the node were studied. The in-plane angle, off-plane angle, out-of-plane constraint effect, steel tube diameter-to-thickness ratio, and core concrete strength were used as control parameters to analyze their effects on the mechanical behavior of the nodes. The results show that the bearing capacity of the nodes meets the design requirements, the hysteresis loop is full, the initial stiffness is large and the stiffness degrades slowly. The off-plane angle, out-of-plane constraint effect, steel tube diameter-thickness ratio and core concrete strength have significant effects on the bearing capacity and lateral stiffness of the nodes. In order to reduce the adverse effect of out-of-plane displacement, the space intersecting nodes in practical engineering can use reinforced floor beams or prestressd cables to impose out-of-plane constraint, and the recommended value of out-of-plane constraint effect is 10–30 kN/mm.

Featured Image