Parametric Study and Full-Stage Moment-Rotation Behavior of Bolt-Spliced Joints in Precast H-shaped Steel Support Structure

Precast H-shaped steel support structures are typically connected by end plate and cover plate connections (E-CPC). This connection method displays semi-rigid behavior. The rational design of these spliced joints lacks clear performance criteria and theoretical guidance. This study investigated the structural behavior of these spliced joints using refined finite element models (FEMs) and developed a predictive model to evaluate the full-stage moment–rotation behavior. These models were developed using ABAQUS and validated against prior experimental results. A parametric analysis was conducted to examine the effects of connection plate thickness, bolt quantity and size, bolt hole size, friction coefficient, and bolt preload on the structural behavior of the spliced joints. Results showed that initial rotational stiffness was significantly influenced by connection plate thickness and end plate bolts, while bolt hole bearing rotational stiffness depended on the strength of bolt holes and cover plate bolts. The influence of various parameters on the bolt slip stage was complex. Specifically, the number of cover plate bolts, friction coefficient, and bolt preload affected the slip moments and slipping end moments, while bolt hole size influenced the length of the slip stage. These parameters also influenced slip rotational stiffness. The ultimate moment was influenced by cover plate thickness, the number of cover plate and end plate bolts, and bolt size. These parameters also affected failure modes (pressure fracture of bolt holes or shear fracture of bolts), except for the number of end plate bolts. Finally, a predictive model incorporating five stages was developed to evaluate the full-stage moment-rotation behavior of the spliced joints. Calculation methods for rotational stiffness, rotation angle, and bending moment at each stage were explicitly defined using the mathematical model. The model was compared with and validated against experimental and finite element results. The results showed good agreement, and potential sources of error and model limitations were analyzed. The proposed model offers a general tool for design applications, enabling the prediction of full-stage moment-rotation behavior for both conventional and novel spliced joints.