Web panel zone shear - shear force diagram

[RattlinBog]

Assuming a typical flange plate moment connection of one beam connecting to a column flange:

When you draw your shear force diagram for web panel zone shear (AISC 360-16 J10.6), do you ever include the vertical shear demand from the beam into the web panel zone shear demand? Or can we safely assume the vertical beam shear simply becomes axial force in the column and does not affect panel zone shear?

See attached 2 pg pdf for an example. This is not an actual design--just going through a made up connection problem to practice.

 

[RattlinBog]

Does anyone have some insight on this?

I see a couple viable options, but I'm not confident about which is correct:

1) Vertical beam shear / beam reaction simply adds to the column axial force and does not add to or interact with column web panel zone shear.

2) Vertical beam shear / beam reaction acts as a longitudinal shear in the column and gets added to the transverse shear for web panel zone shear.

I'm specifically talking about web panel zone shear in beam-to-column moment connections. However, the same scenario would occur at a chevron brace connection to a beam. You would have web panel zone shear in the beam due to vertical components from the brace forces. You would also have a horizontal shear at the gusset-to-beam connection with tension/compression braces. I'm just not sure if that horizontal shear (longitudinal to beam) would add to the panel zone shear demand. Obviously, you design the gusset weld for the horizontal shear, but I'm not sure if the horizontal shear can just be taken as the beam axial force from that point or not.

 

[Eng16080]

I'm not an expert with this, but I'll just write something dumb and perhaps somebody more knowledgeable will respond:
[ol 1]
[li]Not sure it's relevant, but I don't understand how you arrived at a moment of "Mu=330 ft-k" in your FBD.[/li]
[li]In this particular example, doesn't the web shear induced be the vertical beam shear counteract that in the column?[/li]
[li]If the web of the column were removed at the location of the beam but the column flange was still braced (to prevent buckling), I think the shear connection would still work, meaning that the column web isn't necessary in that capacity.[/li]
[/ol]

 

[KootK]

Or can we safely assume the vertical beam shear simply becomes axial force in the column and does not affect panel zone shear?

That one. The beam shear surely does impact the state of stress within the panel zone in some, small way. That said, given that the axial force can utilize a long stretch of the column web outside of the panel zone to move the axial load into the body of the column, we assume that the impact within the panel zone is small.

You're not wrong about this. You're just thinking about it more deeply than most folks do and to a degree that surpasses the conventional design procedure.

 

[RattlinBog]

Eng16080 - you're right, my bad. I made the problem in a hurry and had some funny math. See new attachment for what's hopefully a better example that doesn't break statics. I could see how the column flange would take the bulk of the beam shear.

KootK - thank you, that makes sense. I'm still relatively fresh to concentrated force checks and web panel zone shear. All the examples I looked through ignored any effect from the beam shear/reaction, but I wasn't convinced. I figured there was some local effect as the shear became axial force (is that even accurate to say?), but I wasn't sure how large or small.

My new attachment has 4 pages for a moment connection, and then 2 pages for a chevron brace gusset connection. Similar web panel zone shear checks for both. The shear longitudinal with the column (moment connection) and beam (chevron brace) can be significant, so I didn't want to ignore it if it mattered for the web panel zone when designing a doubler or checking the web.

 

[human909]

You're not wrong about this. You're just thinking about it more deeply than most folks do and to a degree that surpasses the conventional design procedure.

Agreed. And far better to start thinking too deeply than to think too shallowly. So kudos RattlinBog.

My new attachment has 4 pages for a moment connection, and then 2 pages for a chevron brace gusset connection. Similar web panel zone shear checks for both. The shear longitudinal with the column (moment connection) and beam (chevron brace) can be significant, so I didn't want to ignore it if it mattered for the web panel zone when designing a doubler or checking the web.

I like those nicely laid out calculations, even if the non metric world hurts my head somewhat.

I'm curious, and this is a bit of a tangent;

Do you normally hand calculate this sort of thing? Are you an oldskool engineer, a fresh engineer who is practicing for exams?

I ask because, probably to my loss, I avoid extensive hand calculations like the plague and lean heavily on computational packages whenever I can. Maybe I'm the odd one out and I'm just a mediocre mathematical engineer?

FYI. I actually have a full undergrad in some pretty deep mathematics if that means anything. So presumably I have some mostly forgotten capability. But like I said, I try to let the computer do lots of the heavy lifting. *Quick mathematic scratchings for sanity checks I do all the time. Deep crunching I do occasionally when I encounter a really complex problem, where I want to double check the black box computer output.

I'm asking just to get a gauge of the approaches people are using out there... I'm mostly a lone structural engineer who isn't surrounded by structural peers. So such questions on this forums help inform me.

 

[RattlinBog]

human909 - I'm pretty young, just 6 years out of undergrad. A bit of backstory--I worked in consulting for 4 years then moved over to the owner side in heavy industry a couple years ago. I do less design now, at least on big projects. I do my own design on small to medium sized projects and contract the rest. Most of my work is infrastructure rehabilitation--dealing with the effects of 50+ years of corrosion and wear. Lots of inspection, analysis of corroded member properties and strength, design of reinforcement or shoring for replacement, and lots of planning and budgeting. Some days I feel like I left consulting (and daily mentorship) too soon, but I do really enjoy what I'm doing now. I'm a lone structural engineer, too. I still reach out to some peers or old coworkers (or eng-tips) for occasional guidance.

Having said all that, I don't have the stress of being "billable" right now. I can afford to do more detailed hand calculations as I see fit, which is maybe a little selfish of me. Also, I've been working on a CE graduate degree part time the last few years and will be done this fall. I've been able to do a deep dive in topics I'm interested in, especially steel design and steel connections. I learned some approximate analysis methods and try to use them occasionally to keep muscle memory.

I'd say the main reasons I sometimes do detailed hand calculations (not always) are because I enjoy them, I like to get practice to stay sharp, and I also don't fully trust software output (mostly because I don't trust myself on inputs) until I've run the calc or an approximate method by hand a couple times. Plus, software can't do everything. For example, Risa-3D isn't going to check concentrated forces for me; and RisaConnection isn't going to tell me what loads to use from analysis.

I still do plenty of modeling in Risa-3D and whip out RisaConnection occasionally. I've been building a nice homemade spreadsheet catalog as I've been going through grad school. Once I go through something by hand a few times and have a spreadsheet built or software available, I'll usually skip the hand calcs unless it's been a long time and I'm feeling rusty.

What do you do--do you have your own consulting firm?

 

[human909]

Hey RattlingBog...

Thanks for the comprehensive reply. I too am not yet a true veteran of the industry. 'Young' might be generous for me as I went back to study Engineering as mature age student, after a complex backstory.

Having said all that, I don't have the stress of being "billable" right now. I can afford to do more detailed hand calculations as I see fit, which is maybe a little selfish of me.

That is a fantastic opportunity IMO. The stress of billiable hours IMO hampers proper development of young engineers as they simply don't have the time to dig deeper into problems or optimise their designs.

What do you do--do you have your own consulting firm?

Sort of... I'm mostly salaried but have a growing side hustle. I've been lucky enough to never have been "billable" in my salaried positions. That is still the case though I now have a side hustle where I'm my own boss and thus "billable" to myself.

I've been able to do a deep dive in topics I'm interested in, especially steel design and steel connections.

Structural steel has been my specialty along with bulk material storage. I'm having to catch up on concrete/timber.

Some days I feel like I left consulting (and daily mentorship) too soon, but I do really enjoy what I'm doing now. I'm a lone structural engineer, too. I still reach out to some peers or old coworkers (or eng-tips) for occasional guidance.

Not having a great group of peers can slow some aspects of learning. But it also forces you to do the deep dives yourself. So you don't get the quick answers to a novel question but once you manage to get to your answer you probably have a better grasp of things than if you had a peer in the next cubicle.

That said, a few trusted mentors are essential. It took me a bit of time to find those myself.