design of fin plate connection as per Eurocodes 6

[GD_P]

Hello,
Hope I will have good interaction with the experts here.
Please do share your opinion about the following query;

I am designing the fin plate connection manually,

1) How do you calculate the eccentricity "z" of connection, when the fin plate is welded to web as well as to flanges of the supporting beam.

SCI P358 dont have guidance for this case.

As per the AISC design manual, this welds dont provide enough torsional restraint so it is better to consider z as dist from web of supporting beam to 1st bolt line (for single bolt line).

Does anyone know the rigorous method which gives exact z for this case.

2) For connection using short fin with one bolt line and notched beam, if the bolt line coincides with the notch of flange

is it necessary to check the overall stability of beam for lateral torsional buckling assuming the beam is unrestrained.

3)If the supported beam is channel section, does any one know the guidance in such cases.

Since the channel is unsymmetrical, on which side do you recommend to place the fin plate

a) At the back of channel

b)from inside the channel (within the flanges)

I think, it should be near to the shear center of channel i.e., at the back of channel.

4) In SCI P358, the bearing resistance of fin plate is the resultant of vertical & horizontal bearing resistance.

Why is it so?

Does it mean the shear force can be in any direction (i.e., need not to be in vertical direction only)?

5) For an application, we want to mount one equipment on the beams using bolts.

so for this bolting is it necessary to follow the end & edge distance criterias given in the table 3.3 of EN 1993-1-8.

Regards,
GD_P

 

[ukbridge]

1) You need to be more specific to what z is, in relating to which design check etc, what worked example youre referring to.

2) It depends on the connection, do you mean a beam with these connections at given intervals?

3) Sketches would help otherwise its hard to answer without guessing what you mean

4) Not sure of the specific equation, presumably allows for shears in both the x and y direction.

5) Yes you will need to follow these end and edge distances - the design resistances of the connections depend on the amount of "plate" around the bolts, if theres not enough you could get localised failure of the edge bolts.

In general Id recommend using the edge and end spacings given in the TATA steel blue book which are a bit bigger than the minimum allowed by the Eurocodes to make it easier on the people actually installing the bolts.

 

[GD_P]

Hello ukbridge,
Thanks for your prompt reply and sorry for being late to respond.
Please find attached pdf which will clarify my doubt in the 1st post.
See you soon.



Regards,
GD_P

 

[GD_P]

Hello forum,

Awaiting your response.


Regards,
GD_P

 

[Istructeuk]

1/ Yes, it does.

2/ Yes, it is.

3/ Concept is similar, designers need to justify.

4/ See below:

5/ Yes, it is.

Regards,

 

[GD_P]

Hello istructeuk,
Thanks for your reply.
I really appreciate your explanation for point no. 4, which has cleared my doubt.

Now for point no 1:
SCI P358 has the guideline to calculate the eccentricity z, for fin welded only to web of supporting beam,
But in case fin plate is welded to web as well as both the flanges of the supporting beam (please refer attachment posted on 6th july), can i take the advantage of the stiffening provided by the weld connecting the fin to flange, and reduce the eccentricity z?

Now for point no 2:
Actually beam is laterally unrestrained.
Also in this case beam is notched till bolt line only (please refer attachment posted on 6th july).
So it will be unnotched beam from support(bolt line) onward, Hence i personally think it should not be checked for notch stability.

Awaiting your response.

Thanks & regards,



GD_P

 

[dik]

Istructeuk: What is the source of your publication for Check 2 and Check 6?

Dik

 

[Istructeuk]

@GD_P:
Point 1 extent: In this case, it depends on (i) the thickness of the fin-plate to beam web, (ii) thickness of welding to supporting beam => so you may assume it is a rigid support and bolts are to be checked for shear only.
Point 2 extent: It should be because beam length is to be considered normally from centre line to centre line.

@dik:
SCI P358

 

[Agent666]

Istructeuk, regarding the response to Point 1, not sure I would agree with the fact that you can design it as rigid and only design the bolts for shear. The load is still ultimately being carried through to the supporting beam web so there is a bending moment on the bolts/welds. With welding to the flanges there is no argument that the connection is more rigid, however you cannot avoid the eccentricity in applying the shear.

 

[dik]

Istructeuk:

Thanks... good publication.

Dik

 

[BridgeSmith]

Unless the supporting beam is braced against torsional rotation, the bolted connection has to carry the moment due to the eccentricity (centerline of the supporting beam to the bolt line) as well as the shear. Since the fin plate is welded to the flanges, the fin plate to web weld carries only shear. If the supporting beam is braced against rotation, the bolted connection carries only shear and the moment is resisted by the fin plate to flange welds, so the fin plate to web weld still carries only shear (and only a portion of the shear, since some is carried as tension and compression loading to the flanges).

 

[dik]

HR10... that's the way I'd have designed it... taking the eccentricity to the shear centre of the channel.

Dik

 

[BridgeSmith]

Yes, to shear center of the channel. I forget the supporting beam was a channel, and was thinking of a WF beam.

 

[GD_P]

Thank you all for your valuable suggestions.

I am designing the joint (weld design and bolt design) as if there is no flange to fin plate weld.

But only for fin plate classification i.e., long fin or short fin, i am considering the effect of the weld, and using the eccentricity from outer edge of the beam flange (weld) to bolt line rather than beam web to bolt line.
Is my consideration right?
If this is acceptable, i need not to use the stiffener or use higher thickness fin plate (this option not possible bec of max thk limitation in order to allow for rotation capacity).



GD_P

 

[GD_P]

Hello forum,

Awaiting your comments.

GD_P