Experimental research on seismic performance of column-to-column grouted connection with casted SHS sleeves for high-rise modular integrated construction

Modular integrated construction (MiC) is an innovative construction method. By adopting the concept of factory assembly followed by on-site installation through connection joints, construction efficiency is greatly improved. The transfer of loads between modules totally depends on the inter-module connection, including vertical connections and horizontal connections. In high-rise modular structures, the vertical connections between modules may be subject to large moments due to earthquake effects. Therefore, the bending performance of vertical connections becomes a key factor affecting the seismic performance and robustness of high-rise modular structures. To improve the stiffness and bearing capacity of vertical connection between modules, thereby improving the wind resistance and seismic performance of the structures. Casted inner and outer sleeves with short studs as shear connectors are proposed for connecting square hollow section (SHS) columns in high-rise modular structures through grout. To study its seismic performance, full-scale cyclic loading tests of three grouted connection columns and one through steel column were designed and carried out. The failure mode, bearing capacity, hysteretic energy dissipation, and deformation performance of three grouted connection columns were analyzed and compared with the through steel column. The results show: (1) The specimens without grouting defects all showed yielding of the inner and outer sleeves, and the grouting material was not damaged, so the failure mode was reasonable, and the ductility coefficient was greater than 3, achieving satisfactory ductility; (2) The specimen with grouting defects, the grouting material cracked and fell off, and the stiffness and bearing capacity of the specimen decreased by 43 % and 53 %, respectively; (3) When the axial compression ratio increases to 0.4, grouted connection columns show equivalent bearing capacity and stiffness compared with through columns of the same material strength. Compared with the previous connections, the proposed novel grouted connection can improve the seismic performance of MiC.