Structural analysis of assembly steel frames considering rotational deformation of external extended end-plate connection components

The end-plate bolted connection represents a critical technology in prefabricated steel structures, presenting challenges in accurately capturing force transmission and joint deformation within engineering design and structural analysis. This study performed loading tests on end-plate bolted connections, examining the shear deformation in the end-plate region, the relative deformation between the end-plate and column flange, and the yield deformation of the end-plate stiffeners and their collective impact on rotational behavior. Based on these findings, an equivalent rotational spring model was developed to integrate these three deformation components. The model’s moment-rotation relationship was then employed to establish equivalent rotational springs within rigid, semi-rigid, and hinged prefabricated steel frame models, followed by static pushover and dynamic time-history analyses of the overall structural system. Results demonstrate that the equivalent rotational spring model effectively simulates a range of connection behaviors from hinged to rigid. By adjusting the rotational characteristics of the equivalent spring model and the floor locations, the sequence of plastic hinge formation can be modified, enhancing structural deformation and energy dissipation capacity, thus enabling efficient overall structural analysis. These findings offer significant insights for designing prefabricated steel frame structures based on joint performance.