Seismic behavior of thread-fixed one-side bolted endplate connection of steel beam to hollow square column

Experimental studies were conducted to investigate the seismic behavior of the Thread-fixed One-side Bolts bolted Endplate Connection (TOBEC) of a steel beam to a Hollow Square Column (HSC). Three forms of strengthening methods were applied to the TOBECs, including the infilled concrete of HSC, the small facing plates, and the big facing plate outside of HSC. In addition, one TOBEC with no strengthening structures and one traditional Standard Nut-fixed Bolted Endplate Connection (SNBEC) were tested for comparative analysis. Presented test results included failure modes, bending moment strength, rotation ability, ductility, strength and stiffness degradation, and energy dissipation capability of connection. Test results indicated that these strengthening methods could effectively improve the mechanical performance of TOBECs. The initial stiffness and ultimate bending moment of the strengthened TOBECs could reach or even exceed those of SNBECs. The strengthened TOBECs could satisfy the rotation limitation requirements specified in both GB50011-2010 and FEMA-350, which proved the applicability of TOBECs in moment-resisting framed structures.