The Fatigue Behavior of Large-Scale As-Welded and Stress-Relieved Tubular T Joints

The changing strain distribution within large-scale tubular T joints, subjected to fully reversed axial brace fatigue loading, were measured in as-welded and stress-relieved conditions. Initial static loading enabled estimation of stress concentration factors and comparisons with the predictions of available published formulas. Dynamic load amplitudes were selected to give approximately equal hot-spot strains in all joints, thus facilitating direct comparison between specimens with different dimensions. Post-weld heat treatment increased the cycles needed for crack initiation and also reduced the crack propagation rates.