Welding steel columns to steel base plates embedded in concrete

[PostFrameSE]

What issues do I need to consider when doing this? Obviously there is going to be heat generated by the welding process. Is that detrimental to concrete? Does how cured the concrete is make a difference? Is base plate thickness an issue?

I'd appreciate any insight or thoughts on this topic.

Thanks.

 

[Bagman2524]

Concrete can take a lot of heat, but I would think you should wait until it has cured sufficiently - i.e. 28 days

Faith is taking the first step even when you can't see the whole staircase. -MLK

 

[TehMightyEngineer]

With careful control of heat I've seen it done successfully. See these though:

http://www.eng-tips.com/viewthread.cfm?qid=290241

and

http://www.millerwelds.com/resource...showthread.php?26706-Welding-an-embedded-pipe

The concrete has moisture trapped in it and aggregate. Heating these causes extreme localized pressure on the concrete. Thus, too much heat and small areas of the concrete can "explode". This can damage the concrete appearance, pop the embedded plate out, or spray molten weld metal around. Caution and short welded passes to limit the HAZ are definitely a good idea.

Maine EIT, Civil/Structural.

 

[jayrod12]

Bagman, you should know for a fact that the contractor would never wait 28 days from time of pouring before erecting columns. You might stand a chance talking him into waiting the 7 days for reasonable working strength but on most of the jobs I've worked on the first floor (or two sometimes) of framing are up by a month after the pour.

Concrete provides a large thermal mass (depending on dimensions obviously) and can as Bagman noted, take a lot of heat. I'd be worried if it was thin topping but if it's a reasonable amount of concrete then I wouldn't even think about it.

 

[Bagman2524]

7 days curing time is probably good enough, but the longer they can wait the better

Faith is taking the first step even when you can't see the whole staircase. -MLK

 

[PostFrameSE]

Excellent! Thanks for your input and reference to previous threads. I failed to search before sending this top. I appreciate your help.