Stress Concentration Factors in FRP Strengthened Tubular T-joints Under Brace In-Plane Bending and Out-of-Plane Bending Moments

This research is dedicated to study the relative stress concentration factors (SCF) at FRP strengthened tubular T-joint subjected to brace in-plane and out-of-plane bending moments using Finite Element Analyses performed by ABAQUS software package. Validation analysis for the finite element model of the unstiffened joint is performed against the experimental results together with the Lloyd’s Register and API equations. The effectiveness of using three different types of FRP materials such as Glass/Vinyl ester, Glass/Epoxy (Scotch ply 1002) and Carbon/Epoxy (T300-5208) on enhancing the fatigue life of tubular T-joints through computing the SCFs was investigated in three schemes. At first the chord alone was strengthened in order to investigate the effects of strengthening the chord member on SCFs. In the second phase, FRP was applied only on the brace member to study the brace strengthening effects, and in the third phase, both of the chord and brace members were strengthened. Promising results derived from analysis which show that FRP strengthening method can effectively decrease the SCF values at T-joints.