Gaps in slip-resistant connections

[Bubik]

Hi everyone!!!


I would be thankful if anybody answered my question regarding gaps in slip-resistant connections.

I am on a cement plant project and such connections are literally in all structures. The problem is that fabrication of steel elements is of very poor quality. The gaps are massive regardless of if it is beam to beam or column to beam elements. In case of beam to beam the connections can't fulfil their design purpose as gaps are so big that they became load bearing connections, so contractor's workers just stack bolt washers in the gaps....
Does anybody know a good method to solve the problem with the gaps?? Also, the structures are already erected so preferably it needs to be worked around it.

Thank you.

 

[BAretired]

Maybe it is time for a meeting to discuss the acceptability of the steel fabricator's work.

BA

 

[Bubik]

Too late for that..It comes from China. Everything erected. Anybody any suggestions?

 

[12345abc6ttyui67]

Do you have any pictures of some of the issues? Much easier to comment on potential solutions.

 

[klaus.]

Hi
yes a pic would be helpful to understand the problem
There are some liquid shims...like this

 

[Bubik]

Just to say , there are cases more sever that the one on the picture.

Guys, Thanks so much for your help.

 

[12345abc6ttyui67]

And just to ask the obvious question, do they need to be slip resistant connections, or are they designed as bearing connections?

 

[Bubik]

They are designed as slip resistant connections.

 

[Bubik]

A lot of vibration going on there from machinery

 

[klaus.]

Does not look like a slip critical connection to me
Does not look like high strength slip critical bolts

 

[Bubik]

hmmm..what makes you think that (would be good if it wasn't thou). They all inspected as pre-tensioned bolts thou. M22 bolts 650 Nm torque force.

 

[12345abc6ttyui67]

Just because the bolts are torqued does not mean the connection is slip critical. They may be pretensioned to avoid loosening of the nuts (which would make sense if there is vibrating machinery nearby).

I suggest you need to speak to the engineer / designer of the connections and determine whether they are slip critical (e.g. need a faying surface between end plates) or are bearing only.

 

[Bubik]

I will do so. Thank you very much for your help.

 

[BAretired]

If the supported beams in the photos above have a similar connection at the opposite end, the beam length would need to be very precise in order to avoid gaps between end plates. This seems to be a questionable design idea, particularly if significant temperature change can be expected during the life of the structure which causes beams to expand and contract.

As shown, the connections cannot work properly as slip-resistant or bearing connections. Filling gaps with tightly fitted shims might appear to be a solution, but would make no allowance for change in length due to temperature change, so member buckling could be an issue.

BA

 

[SAIL3]

I agree with BA...poor design in not accounting for possible length variations...