flare grove weld

huangyhg

flare grove weld
we are showiing a 3/16" plate stringer being welded to a 1 1/2"x1 1/2"x11 ga steel tube.  historically we use a 3/16" fillet weld due to the radius of the tube.  we are being challenged for using a 3/16" weld on a 11 ga. tube.  we may use a flare grove weld.  how do you determine the design value of these weld?
9th edition aisc says that the effective throat of the weld is 5/8*t1.  t1 in your case would be the thickness of the 11 gauge tube steel.  i believe this is a btc-p10 partial pen weld.  
is this just a plate being welded to a small piece of tube steel with overhang of the plate on both sides?
the effective throat for flare bevel groove welds is 5/8(t) where t is the thickness of the tube.  this is illustrated in the steel manual (p.4-173).  this number is dependent on the radius of the curve, so if your tube is something other than the r=2t of the steel manual you have to adjust accordingly.
the stringer depth is 12" and will extend past the tube.  therefore, weld will be on both sides of the tube.
the tube is 11 gauge. if this is smaller that the t1 dimension (3/16 in) in btc-p10 or btc-p10-gf, then imo, the prequalified joint will not work.
prequalified joints in the aisc manual are based on d1.1 prequalified joints. d1.1 is not intended for steel less than 1/8 in thick.
henri2 is correct as usual!  these are not prequalified joints and must be qualified to comply with aws and aisc, both of which must be complied with for code compliance.
11 gage is slightly less than 1/8" thickness.
as for weld thickness, the design value cannot be thicker than the thinner part welded and sometimes even less.
you should check the aisi code as as well, especially if the tube is cold-formed or classifies as cold-formed or light-gauge.