Shear Storage Capacity of Vertical Stiffener Joints between Concrete-Filled Double Steel Tubular Columns and Steel Beams

摘要

Based on the low cyclic loading test results of vertical stiffener joints between concrete-filled double steel tubular (CFDST) columns and steel beams, the shear transfer mechanism and shear resistance were analyzed in this paper. A conceptual model formulated was presented in terms of equilibrium and stress-strain relationships. The results calculated by the theoretical model and the available experimental data were compared, and then one new concept of shear storage coefficient was proposed for the determination of the shear storage capacity of the joint, which quantitatively explained the ductility failure progression of the joint specimens in the seismic performance test. It was concluded that the vertical stiffener joint had sufficient shear resistance, which met the seismic design principle of strong shear and weak bending. Results show that the ribbed joints have greater shear resistance than unribbed ones; lengthening the overhang of the vertical stiffener can both increase shear resistance and shear storage capacity of the joint; axial compression ratio can reduce the shear storage capacity. The paper also suggests that the joint design should ensure enough safety storage of shear resistance to improve the seismic performance.