Rebar butt welded to end plate - full strength?

[bugbus]

Is this following butt weld detail able to develop the full strength of the rebar? (Assuming that the weld is not reinforced with a fillet weld).

I am assuming the bar material is roughly 2x the strength of the plate, and the weld tensile strength is enough to develop the full strength of the bar (e.g. Grade 500 MPa bar, Grade 250 MPa plate, 620 MPa weld strength).

Is the weakest plane not along the red line I've shown? I realise that the welding process causes the welded zone being locally stronger than the plate itself, but not sure if this is enough to prevent the plate breaking along the red line.

 

[jaskamakkara]

The strength of a full penetration butt weld is that of the weaker connected member, provided the properties of the consumable are better than those of the parent material. Refer to §4.7.1 of EN 1993-1-8 if you have access to Eurocodes.

 

[kingnero]

True, but gusmurr brings up an excellent remark with respect to lamellar tearing. That's why Z-quality steel (EC 3-1-10) is invented.
For thinner plates and smaller welds, don't worry about it. EN 1993-1-10 Table 3.2 might be of help.
I'd select steels with a low S % for the plate, and a bit of preheat regardless of the steel quality.

 

[bugbus]

Thanks for the replies so far. My question wasn’t really about lamellar tearing although it hadn’t crossed my mind at first. Would be good to get some more insights on that.

I had two points to elaborate on:

1. Yes, since the plate is Grade 250, we would expect some localised yielding at the face of the plate when the stress in the bar reaches 250 MPa. Would this not then redistribute some of the force to a wider area beyond the immediate area under the bar?

2. My understanding (and I could be wrong) was that as the weld material melts into the parent metal, there is a mixing/alloying effect that causes a gradual transition in material strength from the weld strength to the plate strength. Therefore maybe the point at which the strength of the interface is actually 250 MPa might be a few millimetres under the face of the plate and therefore associated with a larger area (hence more strength).

 

[Tomfh]

I wouldn’t expect it to develop the bar if the plate is 250.

 

[kingnero]

I believe jaskamakkara has very clearly responded to those particular questions.

What other insights do you want regarding lamellar tearing?