They are welded joints with complete penetration welding. The design is not needed, meaning that the complete penetration welding restores the original cross-section capacity. To these joints the mark KW1 is assigned.
The two cross-sections must be identical.
The welds are however checked, using safe-side criteria, both by EC3 and by AISC-LRFD.
In the following pictures, the available knees.
