LAUSR

Abstract This paper develops a new joint representation to indicate the nonlinear load-deformation behavior and ultimate strength of FG K joints in the global pushover analysis. To simulate the ductile fracture of FG K joints, the study establishes the fracture locus of steel S355 and incorporates the fracture locus into the Johnson-Cook model for fracture simulation. The joint representation is developed through regression analyses of the FE results with/without fracture simulation and validated against the reported test data. The load-deformation formulation and ultimate strength equation are functions dependent on the geometric parameters, covering the brace to chord diameter ratio β from 0.4 to 1.0 and the chord diameter to thickness ratio 2γ from 20 to 50. The study finally implements the local joint behavior into the pushover analysis of a 3D jacket platform to evaluate the overall performance after grouting the critical joints. The proposed load-deformation formulation and ultimate strength equation prove to be effective in representing the local FG K joints in the frame analysis.