Fatigue Strength of Rolled and Welded Steel Beams

Fatigue tests were conducted on rolled and welded steel beams to provide information that can be used as a basis for the development of design specifications. The principal variables were grade of steel, type of beam and detail, and stress variables. Three grades of steel were included in the study: ASTM A36, A441 and A514. Two of the four basic beam types investigated are examined hereiin, namely plain-rolled and plain-welded beams. It was found that: (1) Stress range was the dominant stress variable for all rolled and welded beams; (2) fatigue life was not significantly influenced by grade of steel; (3) rolled beams provided the longest life and the most scatter of the data; and (4) plain-welded beams without attachments constitute an upper bound for welded beams. The treatment of plain-welded beams the same as base metal or rolled beams grossly overestimates their fatigue life.