Moment connection with bolts in circulat pattern... 3

[ImagineerGr]

Hello everybody...

some help please...

I want to calculate a moment beam to beam connection (tubes actually) with bolts in a circular pattern...

Is there any software to do this?
Or is there any methodology for calculating this...?

Any help would be really really appreciated...!!

THANK YOU ALL...!

 

[Stillerz]

Genuinely looking forward to an answer to this.
I have designed some connections in the past like this through rigorous FEM and checking every thing i could think of.
For round baseplates i used an approach i founf in ASCE 48-05 for steel transmission structures....steel poles.

 

[ishvaaag]

I quite agree with Stillerz. Do not remember to have seen in print that thing; so for specific details, in beams, FEM.

 

[ImagineerGr]

Is there any other solution except FEM? Like a program that calculates this kind of connection or any hand calculation procedures? An excel maybe...

 

[cntw1953]

There is no straightforward method by handcal. You can work by utilizing linear elastic stress & strain relationship, however, quite messy though. The best & easiest is to use a FEM program with "tension only" type of support to simulate the anchors as linear springs.

 

[racookpe1978]

Why not tackle it like a simple 4 bolt baseplate with shear and moment loads?

You have a series of bolts - some in tension, some in comression, each at a different moment arm from the nuetral axis intersection of the baseplate and support body.

 

[desertfox]

hi ImagineerGr

I have uploaded a method that I would use to calculate my bolt loads in your situation.
Just to clarify "M" in my uploaded file would be the moment your beam is subjected to at the joint.
Hopefully I have interpreted your question correctly.

Regards

desertfox

 

[desertfox]

Hi ImagineerGr

I forgot to mention you will need to account for the direct shear on the bolts as the file I have uploaded only caters for the tensile load due to the moment.

desertfox

 

[GalileoG]

Why wouldn't linear elastic strain compatibility not work? I would think that would give a conservative solution, would it not?

Clansman

If a builder has built a house for a man and has not made his work sound, and the house which he has built has fallen down and so caused the death of the householder, that builder shall be put to death." Code of Hammurabi, c.2040 B.C.

 

[cntw1953]

Yes. It would work, but quite difficult to find compression area and the N.A. (thinking the bolts won't be stressed in compression, and the compression flange is in semi circular shape). May need several iterations, even with a FEM program.

 

[Lion06]

I would use an elastic analysis of the bolt pattern. Assume the plate is rigid and do a simple elastic bolt pattern analysis - you can find this in any steel textbook.

 

[Lion06]

The elastic analysis would obviously be conservative, since it doesn't account for the ductility of the connection, but it's valid.

 

[dvd]

If you care to extrapolate between baseplates and beam connections there is design methodology in "Tubular Steel Structures":

https://ssl.lincolnelectric.com/foundation/item.asp?prodnum=TS&PID=16

The paper below may also be of interest:

http://www.risatech.com/downloads/risatower/Technical_Manual_1.pdf

 

[desertfox]

Hi StructuralEIT

The method I posted does exactly what you suggest, it assumes that the joint is rigid and the bolts take the tensile load its very similar to a splice joint.

desertfox

 

[cntw1953]

Great reference. Thanks.

 

[Stillerz]

There is a lot of talk about the bolt design here, but I dont think this is the difficult part. You still have to size the plates in the flange-type connection and that can get hairy.
I have found myself, in designing this type of connection, assuming many different "bend lines" in order to size the plate thickness.

As far as determining bolt axial loads due to moment I always used a bending stress analogy in the form of F=Mc/I with "c" being the distance from the neutral axis of bending and I = 1.0 assuming the bolt area equal to unity.
I hope i am making sense here... it is new years day...at 12:38 am...catch my drift...i am a geek

 

[Stillerz]

in other words, the bolts will take a load proportional to their distance from the n.a. of bending.
That however stills leaves you designing welds and plates.

 

[ImagineerGr]

Thank you for your pdf desertfox!

Interesting approach cntw1953 with the tension only concept and the linear springs in FEM modeling!

Thank you dvd for the references, the paper is very extensive and I think it covers many cases!

Stillerz ishvaaag racookpe1978 Clansman StructuralEIT, thank you for your remarks...!

Great reference everyone...!!

Thank you ALL...! I'm working it out...

 

[desertfox]

Hi imagineerGr

Your welcome and happy new year.

You can see the method used at this site for bolts under bending loads:-

http://www.roymech.co.uk/Useful_Tables/Screws/Bolted_Joint.html

Its a relatively simple hand calculation but takes no account of plate stiffness.

desertfox

 

[IFRs]

You may find some help in pipeline design handbooks...they have flanges, etc...