Static strength of thick-walled CHS joints and global frame behavior

Abstract

This thesis reports the detail investigations conducted on the static strength of thick-walled Circular Hollow Section (CHS) joints with the objective to develop a nonlinear joint model for the ultimate strength analysis of 3D jacket type structures. Four types of uni-planar CHS joints are studied, with careful calibration of the numerical analyses against published reference tests. An automatic mesh generation program is developed to facilitate the numerical study. A new joint strength definition is proposed for thick-walled joints based on Gerdeena??s plastic limit load approach. The suitability of the Gurson model for the fracture analysis of CHS joints under tensile loading is investigated. The design code formulations are inadequate in consideration of the thick-walled joint strength and the chord stress effect due to the scarce data available. The proposed nonlinear joint model is verified against large-scale experimental results and the applicability of the proposed joint model is ascertained in real jacket and jack-up structures.