Bending load effects on stress concentration factor distribution of multi-planar DTKY tubular joints

Abstract

The stress concentration factor (SCF) in tubular joints is an important parameter in calculating the fatigue life of offshore structures. In design practices, estimating the SCF is usually based on standard empirical formulas, providing the majority for uni-planar tubular joints, and could not be applied directly for multi-planar joint cases. Therefore, accurate SCF estimation became critical for specific multi-planar tubular joints commonly found as members of offshore platforms. More detailed analyses of complex designs are possible with the recent development of finite element analysis and supported by advanced digital computers. Thus, this research is intended to analyze the SCF of multi-planar DTKY tubular joints with finite element analysis. The local model of the tubular joint will be simulated for bending moment load cases. The results show stress distribution characteristic of the joint at both brace and chord sides. The results indicated that the SCF of the joint under the in-plane bending (IPB) loading is higher at the brace than the chord side, with values of 2.83 and 1.47, respectively. Meanwhile, under the out-of-plane bending (OPB) loading, the SCF is 2.43 at the chord saddle location and 3.54 at the brace saddle location.

Meta model-based optimization of jacket offshore platform for resilient marine infrastructures

“…The UC needs to be less than 1.0 for stress and buckling results.Furthermore, the joints between the jacket leg (chord) and the brace must be strong enough to support the loads. As a result, β, τ, and dan γ-the nondimensional parameters-are changed per API recommendations[2], Ahmadi[17], and other studies in tubular joints[18,19]. The chord-brace diameter and wall thickness ratios are denoted by β and τ, respectively.…”