Seismic performance and inter-module load transfer mechanism of bolted-connector connections in modular steel structures

A novel bolted-connector connection is proposed for modular steel structures, enabling horizontal and vertical inter-module connections through the integration of L -shaped connectors, bolts, and vertical connectors. Two full-scale joint specimens were subjected to low-cycle reversed loading tests to evaluate the hysteretic behavior, energy dissipation capacity, and residual deformation characteristics of the proposed connection. The experimental results demonstrate that the proposed connection exhibits satisfactory ductility and energy dissipation capacity, thereby meeting the requirements of the seismic design principles of "strong-column–weak-beam" and "strong-joint–weak-member". Furthermore, twelve finite element models were developed to conduct a parametric analysis of the failure modes, load-carrying capacity, and ductility coefficient of the connection. The results indicate that the extension length of the L -shaped connector significantly influences both the load-carrying capacity and ductility of the connection. Through theoretical analysis, the inter-module load transfer mechanism was clarified. Based on this mechanism, a rotation prediction model was established, and analytical expressions for the rotation angle of the L -shaped connector and the internal forces of inter-module components were derived. The proposed model and analytical formulations were validated against numerical simulations, demonstrating satisfactory accuracy.