Ultimate strength of specially reinforced tubular joint with brackets

Abstract

The importance of the design of tubular joints in offshore structures, in connection with stress concentration, fatigue strength and ultimate strength capacity, has long been recognized. In this paper the stress concentration factors and ultimate strength capacity of specially reinforced tubular joint with brackets are investigated in order to produce a design basis and manufacture guide for offshore structures. For the simulation of the real deformation pattern in tubular joints. Finite Element Analysis is performed in which material as well as geometrical nonlinearities are incorporated. Also, a series of tests on tubular T-joints is performed for the cases of axial compression, axial tension, and in-plane bending to evaluate the effect of the reinforcement. The structural evaluations on the subject structures are performed by comparing the test results with the results of the Finite Element Analysis and current design codes of nonreinforced tubular joints. Empirical formulae are proposed for predicting ultimate strength of the joints based on the evaluation. The study concludes that, from the view point of the ultimate strength capacity of the joint, the reinforced tubular joint with brackets is very capable of absorbing ultimate loads.