Table 1 gathers the dimensions of the circumferential sections
(S1, S2 and S3) of the 80 m high towers analysed, placed
(respectively) on the first, second and third stretch, as shown in
Fig. 4. These sections were judged by the owner as the critical ones
in terms of the structural integrity of the towers. Section S1 is made
of S355J2 steel [15], S2 is made of S235J0 steel [15] and, finally, S3
is made of S235JR steel [15], all of them being non-alloy structural
steels. Table 2 shows the corresponding mechanical properties
(C and m are the material constants in the Paris law), that can
be considered applicable for both the base material and the weld
(no mismatch analysis is required). The Paris law provided is a
lower bound value of the actual ones, including the effect of the
R ratio. Therefore, the integration of this law is made by using the
stress variations without any consideration of the mean stress.
Before the welding process, the edges of the rings being joined
were machined and prepared as shown in Fig. 5, in order to perform
double V butt welds (Fig. 1). The welds were developed from both
the inner and the outer surface of the final tower.