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reformulated question - Brackets length

reformulated question - Brackets length

(OP)
Hi,

I've made this question before. But in the lack of answer i'll try to ask in a different manner.

I'm trying to ensure fixed behaviour of steel column base through adding some brackets/stiffeners

After reviewing the design for tubular HSS with annular base plate, found design procedures for the base plate and triangular bracket (thickness & strength) but cannot find the required length of triangular bracket to ensure fixed behaviour of column base.

I wonder if there is a minimum length of brackets to provide almost full rotational restraint. Or i just have to set brackets near the tension bolts to avoid base plate rotation contribution and set the length/heigth ratios restriccion of bracket desing.
If so, does weld deformation need to be included? or is enough to assume that perpendicular loaded weld is stiff enough to ignore it? If I must to consider weld elongation, does 'Butler and Kulak' or 'Lesik and Kennedy' stress-strain curves of welds has some thickness limitations to be applied?

I'm trying to be really sure about rotational restraint because it's fundamental to ensure structure stability and i need to place small brackets.

I'm working with 3mm HSS and they are NOT particularly stresses by large moments.

any guide,
thanks!

RE: reformulated question - Brackets length

Hi

Try posting a sketch of what you are asking, remember you are familiar with the problem you're having but we can only see what you write.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

RE: reformulated question - Brackets length

(OP)


Thanks for reply.
I attached the scheme.

My loads gives me the moment in green. I need to ensure rotational restraint. I work with international units and the inch and kN*ft are approximations.

Loads are applied at free edge and mid span. I'm not particularly worried about shear deformation.

I need to keep free space between support and midspan so must install small brackets/stiffeners.

the 4/5" triangular brackets are drawn as an option.

RE: reformulated question - Brackets length

Hi

If you are attempting to eliminate any rotation of the base plate i.e. Zero rotation I doubt that you will achieve this in pratice, I believe this topic as been discussed before here so maybe if you do a search it might yield something of interest.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

RE: reformulated question - Brackets length

(OP)
Nop, I wasn't looking for a 90% moment. I just have some doubts about the restraint capacity because the stiffeners were smaller than usual documentation and practice.

RE: reformulated question - Brackets length

But what exactly is you question ?
If you want to know the rotation you might need to do simple FEA Model


best regards
Klaus

RE: reformulated question - Brackets length

Do some searches on "gussets". Blodget talks about them qualitatively below:

http://weldingdesign.com/processes/using-gussets-a...

He's the king for this sort of design. I thought his book, "Design of Weldments" might directly address the stiffness calculations but I can't find much in it.

RE: reformulated question - Brackets length

Forget about the stiffeners and go to a thicker base plate. You get nearly the same rigidity, and unless you are constructing a kazillion of them using automated welding, it's likely less costly.

Dik

RE: reformulated question - Brackets length

Thanks Brian, but, unless you're looking at fairly large connection plates, testing shows that there is little difference in rotational resistance. I'll see if I can dig up the citation.

Well aware of Blodgett, and he's a good authority.

Dik

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