Fatigue of Joints in Aluminum Alloy 6061-T6

Formulas for allowable stresses in aluminum alloy 6061-T6 members under repeated loading are evaluated by comparing them with fatigue strengths obtained in tests of riveted, bolted, and welded joints. The formulas were included in specifications suggested by the ASCE Task Committee on Lightweight Alloys. The experimental investigation included axial-stress tests of double strap riveted and bolted joints and flexural tests of beams connected by riveting. The test results presented for welded joints include flexural fatigue tests of beams connected by welding as well as axial-stress fatigue tests of transverse and longitudinal butt welded joints, and symmetrical transverse and longitudinal fillet welded joints. In most cases, the data show that the formulas provide the desired factors of safety against failure under repeated loading, i.e., 1.35 for bridges and 1.2 for buildings.