Blodgett's vs. AISC Steel Manual 10

[JD P.E.]

I was wondering if someone could take a look at these simple calcs and offer advice regarding my approach on weld sizing. I use Blodgett's handbook and use the weld line method and then I use AISC fillet weld capacity and get different answers. I suppose that's due to the way I couple the moment and only count on top weld for the tension.

Thoughts?

 

[CANPRO]

bhiggins - your comment about welders is way off the mark. Whoever "welded" that joint in your picture was not a welder, that was someone with a welding machine claiming to be a welder. The solution here isn't to increase your weld size until you get enough shit weld to be acceptable, the solution here is to reject that horrible work and not allow it to continue until a qualified welder is available to do the work. I've seen plenty of bad welds, similar to the picture you posted, but I've also worked with lots of welders that produce world class products. Drug use is not limited to any particular job-type or class of people - your comment says more about you than any welder.

 

[kingnero]

Star for CANPRO, from someone who works on a daily base with welders.
I agree, the problem with the picture above is the supervision, not the so-called welder. Whoever let that guy perform structural welds without assessing his capabilities upfront, should be fired. The "welder" simply shouldn't have been hired for this job.

 

[bhiggins]

I never said ALL welders are meth addicts, only a certain percentage which is a 100% true statement. Ya'll need to hang out more with the people who build the structures, I was one of them. They are great people with their own share of problems like everyone in this world. Drug use and alcoholism is pretty rampant in the construction industry, moreso than the general population. It's a real problem which must be accounted for with realistic expectations. I have nothing against welders, however you must be prepared for when the bad ones show up, which happens to everyone at some point. On this particular project all of the welds were rejected and the entire structure had to be re-welded. I would never advocate for more shitty weld, just don't design the bare minimum because you never know what defects are lurking and are invisible. Don't blindly trust your calcs.

When you load fillet welds transversely like the OP's sketch you lose ductility, which makes the connection even more critical. I would personally modify the detail to have some more redundancy or ductility.

 

[MacGruber22]

As much as I want this site to be mostly about engineering, these claims need to be addressed and not permitted to stand on their own.

"...a certain percentage which is 100% true".

Boy howdy, that is some serious obfuscation/double speak. This is what happens when hasty generalizations are called out and someone isn't willing to own up to it.

"Ya'll need to hang out more with the people who build the structures, I was one of them."

Translation: his anecdotes are bigger than everyone else's combined, so here is an ad hominem to get everyone to go away.

"It's a real problem which must be accounted for with realistic expectations."

"Of course drug and alcohol addiction are high amongst construction workers (there is mental health data that supports it), and it would be nice to reduce it. However, you were making a weird claim about the likeness of a welder to be a meth addict. Oddly specific that encourages people to think "likely a meth addict" when they come across a welder rather than just assess the situation at hand and give people you don't know a charitable starting point. Back in the office... when designing a welded joint, there are reasonable ways to evaluate the risk of the joint that can certainly include the difficulty of field conditions, redundancy/plastic redistribution, % sustained loading, ductility, etc. Oversizing a joint to some degree from theoretical vectors/magnitudes is a normal practice when determined with care. Randomly increasing weld sizes and lengths while dreaming the imagery of a stereotypical movie/tv show meth addict is not one of them.

"I have nothing against welders, however you must be prepared for when the bad ones show up, which happens to everyone at some point."

First, if you have nothing against welders, you would own up to the generalization and implication of your words. Second, when I am called out to the field to address poor welding, there is literally ZERO value in maintaining the presumption of the welder, who I don't know, quite possibly being a meth addict. And, "must be prepared", is an absurd retort to no one in this thread downplaying the need to be prepared to fix improper weld joints.





-Mac