brace end so that the corresponding stress concentration factor (SCF)
and the hot spot stresses (HSS) that eventually generated during the
second stage were carefully measured. In the second stage, fatigue
tests were carried out in such a way that cyclic loadings were applied
and the specimens were put under the continuous monitoring of the
Alternating Current Potential Drop (ACPD) crack monitoring system.
In the fatigue tests, three-direction-combined cyclic loadings were
applied at the brace end of the specimen to generate fatigue loadings
until the specimen failed. Finally, the test results were verified against
the S–N curves developed for mild steel hot-rolled rectangular hollow
section (RHS) joints with similar geometrical parameters [12].