Parametric Investigation on the Axial Compressive Performance of Grouted Connection Segments in Deep-Water Offshore Wind Jacket Structures

Grouted connection segments are key load-transfer components in offshore wind jacket structures, and their axial compressive performance is essential for the safety and reliability of the foundation system. This paper develops a finite element model of a grouted connection segment incorporating steel-fiber-reinforced high-strength grout to investigate its mechanical behavior and parametric effects under axial compression. A 1:7-scale model test is conducted to verify the numerical model through comparisons of the load–displacement response and strain responses at key locations. The steel tubes are simulated using a trilinear hardening elastoplastic model, while the steel-fiber-reinforced high-strength grout is represented using the concrete damaged plasticity model with corresponding tensile and compressive constitutive relationships and damage parameters to characterize its nonlinear response. Based on the validated model, a full-scale numerical model is established to analyze the effects of steel tube thickness, shear key spacing, shear key height, and shear key width using the control variable method. The results indicate that steel tube thickness has the most significant influence on the ultimate bearing capacity and can improve the load-bearing capacity and ductility of the structure. Shear key spacing mainly affects axial stiffness and deformation compatibility, while shear key height and width have limited effects on the ultimate bearing capacity but contribute to local deformation control and stiffness enhancement. The findings provide a validated numerical basis for evaluating the axial compressive behavior of steel-fiber-reinforced grouted connections and offer a useful reference for the design and parameter optimization of grouted connection segments in deep-water offshore wind jacket structures.