Fatigue Behaviour of Welded Composite Tubular T-Joints under in-Plane Bending
Hollow section T-joints made up of square hollow section chords and braces, SHS-SHS T-joints, had their chords concrete-filled to form welded composite tubular T-joints. The welded composite tubular T-joints were tested under static loading to determine stress concentration factors at hot spot locations and were also tested under cyclic loading to obtain fatigue design data. The maximum stress concentration factor (SCF) at hot spot locations in a welded composite tubular T-joint was found to be generally lower than the maximum SCF in an empty hollow section SHS-SHS T-joint. Fatigue failure in welded composite tubular T-joints occurred through the initiation and propagation of cracks at weld toes in either the chord or brace member, with the majority of tests exhibiting the first visual crack at weld toes in the chord. The welded composite tubular T-joints were found to have better fatigue strength compared to the empty hollow section SHS-SHS T-joints.