Seismic behavior of a novel steel-encased beam-end connection (SEBC) between precast RC beam-CFST column for simple on-site assembly

A novel steel-encased beam-end connection (SEBC) between concrete-filled steel tubular (CFST) column and precast reinforced concrete (PRC) beam is proposed, to achieve the simple on-site assembly of prefabricated CFST bridge piers. Quasi-static tests were carried out to evaluate the seismic behavior of nine SEBC specimens and the key parameters are the encasement length of U-shaped steel jacket and the shear connectors at the jacket's bottom flange. The test results indicate that the proposed beam-end connection with rational encasement length and sufficient shear connectors can effectively transfer the bending moment from the beam to the column. In this case, specimens occurred ideal flexural failure at the beam-end, and the plastic hinge was concentrated at the transition zone between the steel jacket and RC beam, exhibiting excellent energy dissipation capacity and good ductility, which is close to that of a fixed-end RC beam. Besides, the force transfer mechanism of this joint was explained through preliminary theoretical analysis, and the test results were compared with the theoretical results obtained from the classical RC beam bending capacity formula, verifying the reliability of this connection.