Pull-out performance and damage monitoring of cast SHS grouting sleeve connection for modular steel building

In this paper, a novel cast grouted sleeve connection with short stud shear keys is proposed for high-rise modular steel buildings. The tensile properties and the damage process monitoring of this connection are investigated through push-out tests. The experimental results reveal that the axial bearing capacity of the specimen is between 4508.9 kN and 5649.5 kN, and the anchorage strength is between 19.15 MPa and 24.0 MPa. The overall bearing capacity of the connection is found to consist of three parts, including the shear capacity of the studs, the friction and adhesion force of the interface. The connections demonstrate ductile behavior, with ultimate slips ranging from 6.56 mm to 13.6 mm and ductility coefficients between 2.6 and 6.2. Based on these results, design recommendations and a bearing capacity calculation method are provided. Finally, a refined load-slip relationship is established, and a novel quantitative damage index-slip correlation is developed for effective connection damage assessment, providing a robust foundation for the application of cast grouted joints in modular steel structures.