Behavior of novel steel-encased beam-end (SEBE) joints for precast concrete (PC) link walls in latticed CFST pier systems under cyclic shear

This study proposes a novel steel-encased beam-end (SEBE) joint for connecting precast concrete (PC) link walls to concrete-filled steel tubular (CFST) columns, aiming to meet the demands of efficient assembly and reliable seismic performance in precast CFST pier systems. Quasi-static tests were conducted on seven CFST double column–PC link wall specimens, considering key parameters such as loading protocol, steel encasement length and wall-thickness, number of PBL shear connectors, PC link wall height, and joint configuration. Test results demonstrate that a properly designed SEBE joint can effectively integrate the PC link wall with the CFST columns, ensuring composite action and excellent structural performance. Two representative failure modes were identified: shear failure of the PC link wall and pull-out failure of the SEBE joint. Parametric analysis reveals that variations in encasement length, side plate thickness, number of PBL connectors, and wall height significantly influence the failure mode and overall behavior, with underlying mechanisms related to bond-slip behavior, stress redistribution, and deformation capacity. A modified shear capacity formula for PC link walls is proposed, incorporating shear-span ratio effects and contributions from dowel action of horizontal reinforcement, which exhibits high predictive accuracy compared to existing codes.