Splice in the mid-span
Splice in the mid-span
(OP)
It is an aluminum beam. The span is 36 feet. The load is 210 plf (dead load + live load). It needs to be spliced at mid-span at the construction site and field welding is impossible. This is requested by the contractor.
I am uncomfortable with this. But the contractor already cut the beam. Can a beam be spliced at mid-span?
Your help is appreciated.
I am uncomfortable with this. But the contractor already cut the beam. Can a beam be spliced at mid-span?
Your help is appreciated.






RE: Splice in the mid-span
Yes, a beam can be spliced at mid-span, but someone has to design and engineer the splice. This would ordinarily be the engineer who originally designed in and ordered the original full-length beam. Said engineer will likely be upset because he probably could have saved some money buying two shorter beams, and now (s)he has to engineer a splice, try to get paid for the extra effort, and answer questions about why there's a splice at mid-span, for the life of the beam.
You probably do not want to be in the same room when that EOR meets that contractor.
Be on the other side of something bullet-resistant.
Mike Halloran
Pembroke Pines, FL, USA
RE: Splice in the mid-span
RE: Splice in the mid-span
RE: Splice in the mid-span
As long as the weld can develop the strength it should be OK; but, it's a bad idea to splice at max moment locations...
You may have him cut the one piece in half and weld the shorter pieces to the ends of the long beam portion, so that the splices are a 1/4 points...
The welds should be tested by NDT...
Dik
RE: Splice in the mid-span
Welding heat leaves aluminum in a near-annealed state, so you can't get back the beam's capacity.
Bolting with lots of bolts and big splice plates is all that remains, other than billing the contractor for a replacement beam.
Mike Halloran
Pembroke Pines, FL, USA
RE: Splice in the mid-span
Simple and win win solution.
Good luck
RE: Splice in the mid-span
I'd certainly not be happy with this situation...
RE: Splice in the mid-span
Dik
RE: Splice in the mid-span
Unalloyed annealed aluminum gets down in the range of Syp <10ksi, so a 36 ft beam wouldn't likely support itself.
Mike Halloran
Pembroke Pines, FL, USA
RE: Splice in the mid-span
The properties of one aluminum alloy discussed:
http://en.wikipedia.org/wiki/6061_aluminium_alloy
RE: Splice in the mid-span
RE: Splice in the mid-span
and charge for the extra design
RE: Splice in the mid-span
RE: Splice in the mid-span
RE: Splice in the mid-span
The contractor proposed end-plated type splice. I mean the beam is welded with end plate and the end plates of the two pieces of beams are bolted together by 8 stainless steel bolts in four rows. Two small aluminum plates are welded to each end plate to increase its out-of-plane stiffness. Is this type of connection good for moment connection?
RE: Splice in the mid-span
RE: Splice in the mid-span
RE: Splice in the mid-span
Could any real contractor be _that_ arrogant AND _that_ ignorant?
Mike Halloran
Pembroke Pines, FL, USA
RE: Splice in the mid-span
RE: Splice in the mid-span
Time to design this from scratch. Put splice(s) in low moment locations (cut beam if needed). Top and bottom splice plates and double shear plates. Use zinc plated bolts instead of stainless steel(closer on galvanic chart). Have any welded sections removed / replaced. OR replace the entire beam (assuming the original design was adequate).
To educate the contractor, show them the strength charts for welded vs non welded aluminum for that beam alloy. It will go a long way to helping future projects. Many only have experience with steel and assume they can use the same methods and connections.
ZCP
www.phoenix-engineer.com
RE: Splice in the mid-span
and your proposing bolting the beams together with the bolts working in tension (for reacting the moment load) if i understand "end plate" correctly.
in this case the welds are doing all the work (they are the connection between the beam 1/2s and the splice) ... bad, very bad
bolt, don't weld !
shear splice, not tension.
where is this building ? (so i know where never to go)
RE: Splice in the mid-span
I am reviewing contractor's engineer's calculation. What is the equation for allowable tension capacity for stainless steel bolt? The bolts are SS316, 3/4 inch diameter. We do not have ASCE 8-02 in office. I can find the allowable shear capacity from book or by google. It is about 3.5 kips to 5 kips.
RE: Splice in the mid-span
RE: Splice in the mid-span
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com