I don't think D1.1 addresses a specific radius. It does address slope in many incidences. As a general rule for D1.1 it should be a 1:2.5 ratio. Starting from zero at the weld toe, and moving into the center of the weld. If this particular requirement is in contracts, then for every 1 mm you go up in reinforcement of a groove weld, the lateral distance should be 2.5 mm.
Look to table 2.4 and figure 2.2 for examples of this.
If your looking for beam copes and acceptable profiles then look to figure C 5.2 and paragraph 5.17 beam copes and weld access holes, and the same in C5.17