What design criteria regarding fatigue does AWS D1.1 address?

The correct focus of AWS D1.1 in relation to fatigue is centered on the design of welds in fatigue-sensitive applications to mitigate crack propagation. The code provides guidelines that help engineers and designers understand the behavior of welded connections when subjected to cyclic loading. This is critical because repeated stresses can lead to fatigue failure, which is characterized by the initiation and growth of cracks over time, ultimately compromising the integrity of structures.

The AWS D1.1 code addresses various aspects of weld design, including geometrical considerations, the choice of materials, and the importance of stress concentrations. It offers formulas and design recommendations that support enhancing the fatigue resilience of welded joints, thereby ensuring safety and longevity in structural applications.

In contrast, the other options focus on unrelated areas, such as aesthetic considerations or quality of materials, which do not directly contribute to the fatigue performance of welds. Therefore, the emphasis of AWS D1.1 on fatigue-sensitive applications is essential for maintaining structural integrity where repeated load conditions exist.