Which AISC fatigue weld stress category would this be?

[jgrady]

Hi,

I am trying to determine what fatigue weld stress category would be used for the picture. I was thinking perhaps C'' from description 5.6? but that wouldn't be quite right since it is not a plate and the fillets are not parallel. Category C from description 8.1 would be my other thought. But I am not sure, since the weld would primarily be in bending rather than shear and that category states that the crack starts in the base metal...so not sure.

Thanks in advance.

 

[UcfSE]

AISC does not have a clear fatigue category for Pipe to Plate welds. You have to use judgment. I would turn to Eurocode 3 in this case, part 9, and use Table 8.6 Constructional Detail 8. If you're not used to Eurocode, read it before proceeding. The detail category number in the table is not the CAFL (similar to threshold in AISC).

 

[SAIL3]

this is a one-sided fillet weld where a portion will be in tension.....I would personally use a full penetration weld....

 

[Agent666]

I'd agree with SAIL3, especially if fatigue is a concern, a butt weld to an intermediate plate/CHS generally has a better (higher) detailing category than a similar detail with a fillet weld to a CHS (at least based on the codes I use, not AISC sorry so cannot say for sure in your case).