Seismic performance of a square HSS column to H-section beam bolted connection with double cover plate

Abstract

This study presents six pseudostatic tests on square hollow section steel (HSS) column to H-section beam bolted connections with double cover plates. The failure modes, load–displacement hysteresis curves, and backbone curves of the joints were obtained, as were the energy-dissipating capacity, stiffness, and strength. The seismic energy of the connections is dissipated by slip between the contact surfaces and plastic deformation of the beam, clamp plates and bolt holes. The joints have good rotation capacity, energy-dissipation capacity, and reasonable strength and stiffness. The connections are rigid used in bracing frame and unbracing frame before slip and semirigid for both after slip. They are full-strength in terms of strength classification. Before the interstory drift reaches 0.05, no obvious inelastic deformation occurs, indicating that the connections can be easily repaired by repositioning the connection and retightening the bolts after a severe earthquake because the interstory drift will be much less than 0.05 during a severe earthquake. A finite-element model (FEM) was established and validated through a comparison of the finite element analysis (FEA) and test results, and the bolt tension, stress distribution of the beam, and rotation of the column flange splicing connection were obtained from the FEA results. The tension of the bolt in the beam web decreased slightly, while the tension of the bolt in the beam flange decreased to 60–70% of the original pre-tension when the interstory drift reached 0.06. The column flange splice connection is rigid. Simplified formulas for joint strength were deduced and validated by testing and FEA.