Experimental study on seismic performance of an innovative modular steel building connection with cross-shaped plug-in connector

Modular steel buildings represent a significant advancement in industrialized construction, facilitated by the evolution of inter-module connection (IMC) technology, enabling the adaptation of modular building systems for multi-story and high-rise buildings. In this study, an innovative internal IMC comprising a cross-shaped plug-in connector, column end plates, side plates and bolts is proposed. The full-scale cross-shaped IMC specimen underwent quasi-static seismic performance testing with top column-end lateral loading method, examining its failure mode, stiffness, strength, ductility, energy dissipation capacity and strain characteristics. Test results showed that the proposed IMC has moderate ductility and energy dissipation capacity, classifying the IMC as semi-rigid and partial strength connection according to Eurocode 3. In addition, the theoretical mechanical model of the IMC is presented, and the horizontal yield load based on the simplified mechanical model is accurately estimated by the approximate second-order theory specified in Chinese standard for design of steel structures. Furthermore, applying the seismic performance-based design method of high bearing capacity-low ductility stipulated in the Chinese code, a reduction coefficient of the ultimate flexural bearing capacity of module beams is proposed for the IMC's flexural bearing capacity assessment with corresponding design recommendations.