Numerical investigation of FRP-strengthened tubular T-joints under axial compressive loads

This paper presents the failure pattern, ultimate static strength and detailed behavior of steel tubular T-joints strengthened by fiber reinforced polymer (FRP) obtained from numerical investigations under an axial brace compressive loading. The joints were analyzed in two cases in which FRP was included and excluded considering typical glass/epoxy composite. The results obtained from the numerical modeling revealed the influence of the FRP wrap in joint ultimate capacity enhancement. In addition, the state of stresses and deflections of the steel substrate were all improved as a result of FRP application which clearly showed an upgrade in overall joint behavior. The orientation and extent of FRP reinforcement has been proposed based on practical applications. The modes of failure observed throughout the numerical analysis were local bending of the chord member, punching shear due to ovalization and plastic failure of the chord. The FRP-Strengthened joint hindered the occurrence of these failure modes. The FRP plies were capable to withstand a minimum of 50% of the joint ultimate load with no sign of failure. The critical regions of the plies were around the saddle point and the adjacent ovalized area of the chord shell.

► FRP application on steel tubular T-joints was proposed as a reinforcing technique.
► FRP-strengthened tubular T-joints experienced ultimate capacity enhancement.
► Improvement of T-joint behavior was observed due to FRP reinforcement.
► The FRP was capable to sustain a minimum of 50% of the ultimate load without failure.
► The critical plies were located in the saddle point region and the ovalized area.