RE: Blacksburg Gym Collapse 1

[DWHA]

After reading through the Blacksbutg Gym Collaspe thread, I have a question regarding who is responsible for welding issues.

If the engineer calls out a weld that is not allowed by AWS, the liability is on the engineer if there is ever a structural issue, correct? Or is it on the fabricator? Or the company producing the shop drawings?

 

[slickdeals]

I would think the ultimate liability would be the structural engineer's. I am not sure if they can implicate the contractor/fabricator or the company producing shop drawings.

We are Virginia Tech
Go HOKIES

 

[Ron]

DWHA...well, first of all that statement in the report about the weld being not allowed by AWS is erroneous.

Generally, the AWS Structural Welding Code doesn't disallow welds (except bad ones), it just has pre-qualified joints that may or may not be used by the structural engineer and the fabricator, as well as a procedure to qualify any non-prequalified joint procedures.

Usually the structural engineer does not call out the welding details...other than to specify complete joint penetration, partial penetration, fillet or other. From there, the fabricator decides on the weld joint to use and submits that through the shop drawing process. The fabricator may use pre-qualified joints or may qualify the joint through a procedure qualification process.

It is easier to use the pre-qualified weld joint procedures and much less expensive. Those will fit most applications. It is rather rare to need to go through a qualification procedure for a new joint and welding procedure specification for general building construction.

So to answer your question, the ultimate responsibility usually lies with the fabricator; although, as we all know, the structural engineer will be brought in and will have to prove his "innocence".

 

[slickdeals]

Ron,
That is interesting to hear. If a structural engineer erroneously specifies something that is barred by the code, then is he not the first one to be brought in?

We are Virginia Tech
Go HOKIES

 

[DWHA]

THANKS RON

 

[Ron]

slickdeals....it's a bit hard to specify something that won't "comply" with AWS. You can essentially specify almost anything, with the result being that the fabricator has to then submit a response in the shop drawings. Most often he will submit an alternate that the structural engineer will likely accept, since if he screwed up in his specification, then he'll certainly accept "the norm" from the fabricator...then it's on the fabricator to meet the code.

Yes, your weld specification might be a bit outlandish; however, when it goes to the fabricator he has two choices...he can prepare a welding procedure specification (WPS) that complies with your specification, test it in accordance with the AWS procedures, and if it passes, move on to fabrication. If it fails, he'll probably submit an alternate prequalified procedure for approval (he can do that before it fails if he wants). In either case, the performance to the code is on the fabricator.

His second choice is just to submit the prequalified procedure at the front end, knowing that the special WPS probably wouldn't work anyway. Keep in mind that the fabricators are probably more savvy about AWS than the structural engineer..sad but true.

 

[dik]

The weld specified or constructed (maybe they were different) may not be barred by code and that opens another bigger can of worms... It may have been a latent defect that, without NDT, may not have appeared to be deficient.

Another interesting thing is the 35 year age and that the recent loading may have been the maximum.

This collapse has a 'whole pile of loose ends' and is not a 'slam dunk' type of failure. It would be a nice one to follow.

Dik

 

[dhengr]

I agree with Ron on most of what he said. But, I would add that I’m pretty nervous about how little structural engineers, in general, seem to know about connection design, and in this case welded joint design. You have to know when you can leave the connection/joint design to a CAD jockey in the fabricators drafting dept.; and you have to know what joints need your design attention or at least a closer look on the shop drawings to be sure the fab’er. did what you wanted and needed, assuming you know. We don’t have the benefit of the structural drawings or the shop drawings so it’s tough to know how this will shake-out.

I don’t think the fabricator is at fault for what really went wrong (was wrong) here, except that an astute checker probably would have raised a question about this bearing detail and kept the structural engineer and himself out of court. That said, that was a pretty crappy weld for that condition, and they may want to talk with their steel suppliers about steel specs. for the material they are getting. The poor weld and the low Fy would never have come to light if the bearing had been properly designed and detailed.

Different fabricators have std. details, both bolted and welded, which they tend to prefer to use, because of their fab’ing. equipment, ways of doing things and their production line, or their pre-qualified welds, etc. If they know the erector, he may have some preferred connections for his methods and equipment of erection.

The attorneys like the fact that there are all the more sub-sub consultants and parties involved in the design, detail, fab., build process, because each level involves a whole new set of attorneys when the whatcha-ma-callit hits the fan. And, of course, they do look to involve the max. number of parties, and particularly those with the deepest pockets.