Are you talking of the fillet weld connecting a web to the flanges of an I beam? In this case stiffeners have angles removed (not reaching the corners) in order to avoid meeting welds at 90 degrees, that could introduce triaxial stresses.
For typical applications, the corner of the stiffener will be snipped (or clipped depending on where you're from) to allow the stiffener to fit at the W-shape fillets. The size of the snip will be controlled by the size of the k1 and k distances given in the AISC Manual. The weld usually goes pretty well to the ends of the stiffeners near the snips and I do not know of a standard detailing practice for this and have never heard of this distance causing a problem. You could consult the AISC detailing manual to see if they show anything. You could also send a technical question to AISC. The AISC Solutions Center gets back to me pretty quickly when I send a question.
If you have special seismic requirements, you'll have to look in the governing document, FEMA 350 for example.
thank you all. excuse me because I couldn't explain my question well. I ment the minimum distance between the groove weld of web plate and fillet weld of stiffner to web.
For the case of built-up members with transverse stiffeners, the AISC Spec gives a dimension from the end of the stiffener to the flange. This is primarily meant for shear stiffeners, but it gives an indication how close that weld can come to the flange without causing problems with triaxial stress states. It's the closest guidance I can think of for your problem.
It depends of the current and voltage you will use to weld. The aim is that the Heat Altered Zones of the welds not to be in touch with each other. When you homologate the welds, the HAZ must be under 350HV, anyway, it is always higher than what you can measure inside the weld. If the second HAZ from the second weld touches the first one, it will heat-treat again the first HAZ, and you might have higher hardness than 350HV, and it will lose the mechanical properties of the base metal. If you have fatigue type stresses, it will result in cracs. But I also don't know clear specs for minimum distances. It is about your good sense, where would you place the welds, and also if the welder has the necessary space to get there to make those welds.
