Incomplete moment connection

[LUGuy]

I recently documented a beam splice connection at about 1/4-point of a 25 -30 ft simple span beam. The bottom plate has 4 bolts in each flange, the web plate has 4 bolts in each web but there is no top plate. The beam is of course kinked quite a bit at the connection. It was installed as a replacement for a damaged concrete beam in what had been an all-concrete floor system. The beam was packed on top with grout to support the concrete slab. There is no composite action with the concrete.

Effectively, the upper flanges are taking their share of the couple in direct bearing on each other. The lower flange connection plate is transferring all of its forces through bolt shear.

As improper as this installation appears, it is not in imminent jeoardy of failure, and it could be argued that it is effectivly performing.

I am debating the proper response to a prospective buyer of this property and would appreciate some commentary.

Regards,
Miscmetals

 

[RiBeneke]

I think you should check the possibilities of abnormal failures that could occur in the top flange as a result of the unusual splice :
1) Is it possible for the flanges to 'kick' past each other under ultimate loading conditions ?
2) Does the discontinuity in the top flange affect the lateral (compression) stability of the top flange, or is it effectively restrained by the grout ?
3) Is there a chance of local crippling failure in the flange at the butt joint (similar to the failure mode in a web at a concentrated load or support) ?
4) Are the flanges exactly aligned so that there is no eccentric loading (of the flanges as compression members).
If the connection is ok in these respects, and your code does not prohibit something like this, then it is probably acceptable.

 

[AlohaBob]

"The beam is of course kinked quite a bit at the connection."

In my mind this equates to "failed - Overstressed - Overloaded". In such cases, buildings get shut down, condemned or is deemed unsafe.

The picture itself should provide justification to properly analyze and make a repair.

 

[LUGuy]

The "kink" is because the lower splice plate was detailed with a slight gap between the flanges. Once the bolts settled into bearing, and the upper flanges came into contact, the two beams end up with a very slight but noticable angle between them.

The beam certainly fails any detailing standard, but it might technically pass the individual engineering checks in the code.

It's not to the point yet that they are hiring me to bless it. That, I probably wouldn't do in any case.