Seismic experiment on blind-bolted joint in concrete-filled double steel tubular structure

Abstract

In this study, blind-bolted joints were designed for use between steel beams and concrete-filled double steel tubular (CFDST) columns to utilize the structural advantages offered by double steel tubes. Six joint specimens were tested under a constant axial load and lateral cyclic load for a CFDST column. The seismic behaviors of these blind-bolted joints were estimated in terms of the hysteretic curves, ductility, and energy dissipation. The effects of a T-plate section type and steel beam-type on the semi-rigid joints were studied. The test results showed that the failure of the joints began with the yielding of the T-plates, and that the final failure mode was plastic deformation at the steel beam ends. The obtained hysteretic curves were complete, and the energy dissipation ability of the bolted joint was strong. The bearing capacity and energy dissipation of ribbed joints were higher than those of unribbed joints. Based on a steel volume comparison, the installation of stiffening ribs proved to be considerably more effective than the thickening of the T-plate flanges. The strain response of the inner tube in each CFDST column was also estimated. It was concluded that the blind-bolted joints exhibit excellent deformation capacities and structural internal force redistributions. The results of this experimental research could be helpful for the application of blind-bolted joints in fabricated CFDST structures.