ScholarWorks@성균관대학교

초록

In this study, an innovative U-bar connection was developed to assemble precast sidewall components and bottom slabs for a prefabricated subway station structure. Overlapping U-shaped bent bars were used to realize the stress transfer of the discontinuous longitudinal reinforcement between the precast sidewall and bottom slab. The primary goal was to achieve an effective on-site connection between the dense steel bars in the core region of the sidewall bottom joint. The tensile anchorage performances of the developed U-bar connections were thoroughly assessed using direct pullout tests. The test results demonstrated that the tensile performances of the U-shaped bar and the 90-degree hooked bar connection were essentially similar. Cyclic loading tests were subsequently conducted on a full-scale precast sidewall specimen with the proposed connection and a monolithic cast-in-place specimen without a connection for comparison. The test results showed that the proposed connection could experience anchorage failure characterized by the fracture of the bend region under cyclic loading, resulting in a lower bearing capacity and ductility of the precast sidewall than those of the cast-in-place sidewall. The failure mode can be attributed to the excessive end-compressive force acting on the bend region of the U-shaped bar during compression. Eventually, an approximate method based on the plane section assumption and tensile anchorage strength of U-shaped bars was proposed to evaluate the resisting moment of the connection section. A comparison between the evaluation and measurement results verified the applicability of the developed formula to the design of precast sidewalls. © 2025 Elsevier Ltd

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