Seismic performance of a full-scale modular steel structure with high-performance grouted joints: Experimental study on global response

To evaluate the seismic performance of high-rise modular structures incorporating innovative grouted joints, seismic tests were carried out in this study on a substructure taken from an actual 20-story modular structure. Cyclic loading tests were performed on a full-scale, two-story, two-span substructure under realistic axial compression ratios to systematically evaluate the seismic performance of the structural system. The test specimen consisted of box-shaped welded steel columns, box-shaped cold-formed steel beams, and innovatively designed grouted joints. A novel grouting process enabled rapid assembly of the modules. Detailed descriptions of the specimen design, test apparatus, loading scheme, construction process, and measurement schedule were provided. The experimental behavior of the beams, columns, and joints were presented in detail. The hysteretic performance of the specimen, including hysteretic curves, skeleton curves, global deformation, and energy dissipation behavior, was thoroughly discussed. The results demonstrated that the structure exhibited excellent cyclic performance, lateral bearing capacity, and ductility, with an ultimate loading drift ratio up to 5% rad. The primary failure mode was characterized by local buckling and tearing at the ends of the module beams, with plastic hinges primarily forming at the beams of each story and the bases of the columns at the bottom story. This study provides important experimental evidence for the seismic design of modular steel structures and validates the engineering applicability of the novel grouted joint.