AWS D1.1 vs D1.4 - Effective throat

[bcpotter]

I'm trying to determine the effective throats of some flare-bevel groove welds made between steel plates and steel bar stock.

AWS D1.1 states that the effective throat is 5/16 * (bar radius), or .156 * (bar diameter). However, D1.4 states that the effective throat is .4 * (weld size), which comes to .2 * (bar diameter). So the exact same weld size has two different throats depending of if its rebar or if its bar stock.

I'm relatively sure that AWS D1.1 is the correct method to use, but I'd like some clarification on the reasoning behind the difference between the two. What makes a weld to rebar stronger than a weld to structural steel?

 

[Dinosaur]

What page and what year code versions are you using?

 

[gtaw]

Two different codes, two different requirements.

In the case of D1.1, the bar or the corner of a hollow structural shape is smooth and the size is limited by the ability of the weld to "penetrate" into the corner where the groove angle is rapidly diminishing as you approach the point of tangency.

In the case of D1.4, the situation is similar, but you are welding "rebar" with the little "knobby" (deformed bars) things sticking out to provide a "root opening" that improves or increases the likelihood you will achieve a little more weld size.

At least that's how I would justify the difference between the two codes.

Best regards - Al