Doubler plate with gaps on all edges? 3

[X4vier]

Hello, can a doubler plate with gaps on all edges work in a panel zone?

I've always seen the doubler going to the flange and weld to it. But if the double is separated from the flanges and stiffener, does it still work?
My short answer is not, but someone with an IDEA model including the gaps between double and flanges and web says "See, this works.".

 

[human909]

Most of the time it is buckling web buckling or web crippling (which is still buckling) that what your doubler is trying to prevent. You aren't talking about actual web yielding. So you don't need to bring it all the way to the edges if that is the case.

IMO doublers are an extremely inefficient and uneconomic approach to the problem that can be solved in many better ways. Transvers stiffeners are often useful and more effective but they are annoying regarding bolts.

Personally in most cases I generally go for a heavier column section. Which might not be more efficient use of material, but it is generally more economic given the cost of labour.

 

[X4vier]

Where can I find a calculation for buckling, clipping or yielding on shear at the panel zone?

 

[X4vier]

Transvers stiffeners are often useful and more effective but they are annoying regarding bolts.

Personally in most cases I generally go for a heavier column section. Which might not be more efficient use of material, but it is generally more economic given the cost of labour.

If labour is not a issue, so the transverse stiffener and the better option?
Why a diagonal stiffener seems to resolve the knee but various horizontal stiffeners are needed?

 

[dik]

Can you weld it across the toe of the W shape to increase ry to permit a higher compressive strength in the column... maybe reduce the plates to 1/2" and no prepared weld? Just wondering... I used that approach for an auto plant in Windsor to accommodate new roof loads for 60' unsupported length columns.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[human909]

Where can I find a calculation for buckling, clipping or yielding on shear at the panel zone?

I didn't answer this earlier because the calculations can get quite complex (at least for my small mind). Various codes guideline have checks that check the capacity of the panel zone based on theoretical/experimental calculations. I use ASI checks and they are not freely availabe.

The other challenge is that the solutions from guidelines to avoid buckling, crippling, and yielding are generally overengineered as they are designed to be catch all solutions. So I find that if my web is 0.5mm too think or my flange is 0.5mm too thin then my code guidelines state recommending me to add 12mm plate doubles on my flanges and web!

If I was clever enough or had enough time I'm sure I could be more efficient than that. But honestly I spend enough time optimising my structures I don't want to muck around with complex connection when I can simplify things.

This offers a good explanation of what is going on:

https://www.youtube.com/watch?v=kHrVL75qWK4

More here:

https://www.youtube.com/watch?v=MqowNtEchfE

https://www.youtube.com/watch?v=L6R9bqhxrnM

If labour is not a issue, so the transverse stiffener and the better option?
Why a diagonal stiffener seems to resolve the knee but various horizontal stiffeners are needed?

I'm not sure I understand the question.

When I said transverse stiffener previously I meant diagonal stiffener. Sorry my poor use of terminology there.

EDIT:

Wow this seems comprehensive! I haven't listened to all 90mins, but if you want to know more about doublers and stiffeners then go nuts.

https://www.youtube.com/watch?v=wzVCON-baSw

 

[dik]

Great link...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[X4vier]

I can't find the calculations and/or assumptions for the horizontal stiffeners at the knee as web reinforcement.