Cracking at welded connections 1

[mscud]

This is my first post so I apologize if something is incorrectly set up.

I am a young engineer at a precast concrete company just finishing up my first project. Through out the job we had a number of locations where cracking occurred in the concrete around welded connections. This cracking was determined by the head engineer to be created by the heat caused during welding. On Thursday I have to go sit in on a close out meeting with the GC at which they are going to accuse us (the manufacture/designer) of causing these cracks.

I am looking for an unbiased opinion on who is typically at fault when it comes to these issues, the producer, the engineer, or the welder.

Some details:

- All of the connections are 100% stainless steel (304)
- Cracks have been observed on wall-to-wall, DT-to-DT (JVI vectors), and even anti-roll connections under beams.

From what I’ve read, it sounds like this is an issue with both welding and production. No clear space was provided between the plates and the concrete. So the plates did not have any room to expand. Also, the welders never allowed the plate to cool during welding on any connections.

Any information or links to publications on this topic would be greatly appreciated.

Thank you

 

[MintJulep]

Did the designer not understand that metal gets hot when welded?

Did the designer not understand the hot metal expands?

Is there any possible welding procedure that could make the specified welds without causing cracks?

Did the designer provide a welding procedure?

Did the designer just assume that the welder would "do the right thing" when making the welds?

 

[jwhit]

If the welders didn't control interpass temperature, there is a possibility of having formed some sigma phase in the joint, both weld metal and heat affected zone. Sigma phase tends to be brittle compared to the austenite matrix. A true welding expert will probably have a better idea about this, but, I think it is worth considering. Also, what filler metal did they use? 308 would be the recommended filler metal.

 

[stanweld]

Why did the Designer specify so much welding after concrete setting? Was it because SS is highly weldable? Expansion of austenitic SS is nearly twice the rate for carbon steel. Did the designer understand that fact and compensate?

 

[metengr]

I am looking for an unbiased opinion on who is typically at fault when it comes to these issues, the producer, the engineer, or the welder.

Not enough information to provide an opinion. You better get all of the facts and work with an experienced engineer or hire one to carefully sort them out. I see a lot of finger-pointing so be prepared.

 

[mfgenggear]

A welding & a senior structural engineer should have been consulted with the parameters of the design.
and should have been involved with the preliminary & during construction.
this will be one of those failure to communicate with senior members.

now what should be looked at is how this will be repaired.

HTH
Mfgenggear