Experimental investigation on the seismic performance of concrete-filled steel tubular joints in diagrid structures

Abstract

Concrete-filled steel tubular (CFST) joints are widely used as a common joint form in diagrid structure systems. However, previous studies on CFST diagrid joints have mainly focused on the compressive bearing capacity, and they lack relevant experimental studies on the seismic performance of diagrid structure joints. In this paper, five CFST diagrid joints are tested under cycle loading to study the failure mode and hysteretic characteristics. In addition, the influence of the intersection angle, structural forms and the wall thickness of the steel tube on the seismic performance of the joints, such as the bearing capacity, ductility, and energy dissipation, are analysed. Three CFST joints are mainly damaged by shear cracking in the centre of the joints, and the other two specimens are damaged by buckling of the inclined column. Test results showed that the increase in the intersection angle reduces the bearing capacity of the specimen and changes the distribution of the main energy dissipation; the increase in the wall thickness of the steel tube can effectively improve the bearing capacity and energy dissipation capacity of the specimen. The joint reinforcing ring can effectively improve the ductility, energy consumption and other seismic performance of the joint. In the CFST diagrid joints, the weak parts along the horizontal intersecting line of the joint and the intersection between the joint and inclined column need to be strengthened in the actual structure.