Strength evaluation of inserted bolt-type shear connectors for use in small CFTs

초록

This study investigates the structural performance of inserted bolt-type shear connectors designed for use in small concrete-filled tube (CFT) columns. To evaluate their feasibility, three series of experiments were conducted: (1) a conventional push-out test based on Eurocode provisions, (2) a CFT-based test applying axial load directly to composite members, and (3) a bond strength test. The results show that the CFT-based test method yielded shear capacities approximately 1.94 times higher than the conventional method due to the confinement effect of the steel tube. The proposed bolt-type connectors using high-strength bolts achieved shear strength comparable to or exceeding that of traditional stud-type connectors. In contrast, connectors with mediumstrength bolts exhibited premature yielding and lower capacities. Theoretical predictions based on AISC, Eurocode, and Chinese codes were also compared, revealing that current design equations could be considered overly conservative for high-strength bolts but insufficient for medium-strength bolts. The findings demonstrate that the inserted bolt-type shear connectors are structurally viable and provide a more efficient construction method, particularly for prefabricated CFT components.

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