FATIGUE TESTS OF TUBULAR T-JOINTS

Test results of tubular T-joints subjected to repetitive loading are discussed in this report. The T-joint consisted of a larger tube, the chord, and a smaller tube, the brace, welded at right angles to the chord wall. The chord walls of T-joints must sustain severe stress concentration which is typical in tubular joints. The fatigue behavior of about 100,000 cycles is studies for six types of specimens. Fatigue cracks in most specimens initiated at the points of stress concentration near the toe of the welds at the center section of the chord and propagated along the toe of the welds. The number of cycles to detectable crack initiation was about half of that to complete failure. It is concluded that the tests should be extended to a more comprehensive investigation using large-size specimens. (Author)