Welding Rebar To Plates

[Pina2424]

When welding A706 rebar parallel to a steel plate via flare bevel groove welds, we typically reference the Design Aid 6.15.3 to establish a length of weld. This design aid shows the effective throat of the weld as 0.2db. AWS D1.4 (Welding of Rebar) also shows the weld effective throat to be 0.2db in Figure 4.1.

My question: Is the 0.2db effective throat a standard no matter what the plate thickness and not a variable? Is there a reason why we wouldn't start increasing the weld throat when the plates get thick as shown in AISC Table J2.3? Attached is a pic of the references.

Thanks in advance!

 

[dauwerda]

The effective throat of the flare bevel weld is based on the geometry of the joint (and is also impacted by welding process and position). Changing the thickness of the plate does nothing to change the geometry of the joint, changing the diameter of the bar does change the geometry of the joint and is therefore what impacts the effective throat. This is pretty obvious in the below image (from your attachment):

Now, you could specify a fillet overlay over the top of your flare bevel weld to increase the overall weld throat (which is the shortest distance from the root of the weld to the face of the weld), but technically this would not be increasing the effective throat of the flare bevel weld, it is now a combination weld with it's own effective throat.