Shear performance of steel plug-in joints for the precast concrete sidewalls of subway entrance/exit structures

Steel plug-in joints are proposed in this study to connect the precast concrete (PC) sidewalls of subway entrance/exit structures. I-section steels cross the joint and transmit internal force with one end embedded in the upper wall panel and the other end grouted into the steel box embedded in the lower wall panel. To describe the shear bearing capacity of steel plug-in joints, shear performance experiments were performed on three specimens. Different grouted lengths (L) of steel were set as 2 times, 2.5 times and 3 times the section height of steel (h). Test results showed that different L produced no marked effect on the shear bearing capacities of the specimens, and the collected shear strengths were larger than the calculated sectional shear bearing capacities according to the concrete-steel composite design. L affected the initial shear stiffness of the specimen to a certain extent. The stiffness increased moderately as L changed from 2 h to 2.5 h. When comprehensively considering mechanical performance and material savings, the grouted length of I-section steel is recommended to be 2.5 times the section height of the steel.