The fracture analyses were made using the Failure Assessment
Diagram (FAD) methodology proposed in [1] and maximum
allowable crack sizes (2aall , see Fig. 7) were obtained for the
different hypotheses of crack geometry. Every cracked component
subjected to a certain load can fail due to a fracture mechanism, due
to a plastic collapse mechanism or, finally, due to a combination
of both mechanisms (fracture and plastic collapse). The FAD
methodology [1,8,24–26] allows all these three possible situations
to be assessed with a single comprehensive tool.
Once the tensile properties of the material are known, the
Failure Assessment Line (FAL) can be defined, which determines
the region corresponding to safe conditions in the component
(area within the FAL and the coordinate axes defined below). Here,
FAD Option 1 in FITNET FFS Procedure (Eq. (1)) for discontinuous
yielding material has been used (given that the materials used in
the towers usually show the Lüders strain during yielding), which