A project was undertaken to develop mathematical design relationships that would define in general terms the fatigue strength of rolled and welded beams, rolled and welded beams with cover plates, and welded beams with flange splices under cyclic loading. In all, 374 steel beams were made and tested, of which 204 had cover plates with two weld details. The design variables were grouped in three major categories: type of detail, stress condition, and type of steel. Particular emphasis was laid on detail type. minimum, maximum, and range were the stress conditions. Steels A36, A441, and A514 were used.

The weld toe is a primary source of fatigue cracking because of the severity of the stress concentration it produces. Weld toe improvement can increase the fatigue strength of new structures significantly. It can also be used to repair or upgrade existing structures. However, in practice there have been wide variations in the actual improvements in fatigue strength achieved. Based on an extensive testing programme organised by the IIW, this report reviews the main methods for weld toe improvement to increase fatigue strength: burr grinding, TIG dressing and hammer and needle peening. The report provides specifications for the practical use of each method, including equipment, weld preparation and operation. It also offers guidance on inspection, quality control and training as well as assessments of fatigue strength and thickness effects possible with each technique. IIW recommendations on methods for improving the fatigue strength of welded joints will allow a more consistent use of these methods and more predictable increases in fatigue strength. Provides specifications for the practical use of each weld toe method, including equipment, weld preparation and operation Offers guidance on inspection, quality control and training, as well as assessments of fatigue strength and thickness effects possible with each technique This report will allow a more consistent use of these methods and more predictable increases in fatigue strength

Fatigue is a mechanism of failure which involves the formation and growth of cracks under the action of repeated stresses. Ultimately, a crack may propagate to such an extent that total fracture of the member may occur. To avoid fatigue it is essential to design the structure with inherent fatigue strength. However, fatigue strength for variable amplitude loading is not a constant material property and any calculations are necessarily built on a number of assumptions. Cumulative damage of welded joints explores the wealth of research in this important field and its implications for the design and manufacture of welded components.After an Introduction, chapter two introduces the constant amplitude database, which contains results obtained in test conditions and which forms the basis of the basic S-N curves for various types of joint. Chapter three discusses the influence of residual stresses which can have a marked effect on fatigue behaviour. Chapter four explores variable amplitude loading and the problem of how information from laboratory tests, obtained under constant amplitude conditions, can be applied to the design of structures for service conditions. This problem is further investigated in the next chapter which is devoted to two and three level load testing. Chapters six, seven and eight look at the influence that the variety of variable loading spectra can have on fatigue strength, whether narrow or wide band loading or cycles of small stress range. Taking all of this knowledge, chapter nine discusses structure designs.Cumulative damage of welded joints is a comprehensive source of invaluable information for welding engineers, supervisors, inspection personnel and designers. It will also be of great interest for academics working in the fields of structural and mechanical engineering. - Covers the wealth of research in the field of fatigue strength and its role in the design and manufacture of welded components - Invaluable reference source for welding engineers, supervisors, inspection personnel and designers