Before I get too far, the match marking procedure is one thing and a splice alignment & drilling procedure is another. You could incorporate both into one procedure but it isn't required.
Generally, AISC doesn't get into how to drill your splices; they DO get into the results (maximum gap, erected member position and alignment, hole size & alignment per the RCSC, etc).
AASHTO and various state DOTs do get into acceptable methods (drill from solid, sub-punch then ream, sub-drill then full size drill, a template with hardened drill bushings, etc.)
One method we use is to have all splice plates drilled full-size at a local machine shop, then use the actual plate as the template for a full size Hougan-type drill. The hougan cutter has been proven to not elongate the holes in the splice plate when doing this, but we get approval from the DOT before we do it (and we do mark that plate for that location - just to be safe.)
Heck, you could even drill the beam first, then match drill the plates to it. That will surely raise eyebrows but a drill-line will make holes in thick flanges faster than a Hougan drill can.
In theory, you could use one plate for all the splicing as you described. Today's machinery is certainly capable of the achieving the required accuracy. The specs were written to prevent problems with the "older" methods (rightfully so) which might not be an issue in every situation. For that reason, you will likely have to prove whatever you propose to do, simply because the specs might not directly address it. But most DOT folks are willing to work with you.
Hey Chet,
how about if we cut, burn and punch the holes in the splice plates, then use the slpice plates as the template to drill the holes in the main members. They aren't that thick, only 1" and we have a big portable mag drill with plenty of hougen bits. I will write it so that which ever orientation the plate is in whenwe drill the holes, it will be "stamped" so that the field knows which orientation to re install it.
These are actually columns and beams for a structure, not a building, not a bridge, but it calls for D1.1, and D1.5 and my spec asks for a match mark and match drill procedure, even though its what we do all the time in the building industry and everything always lines up.
I guess we would clamp the pieces together and once a couple of holes are installed, put in a few bolts incase something slipped accidently.
Thanks again, for the input.
Chris
Are punched holes acceptable without reaming in this sort of work? Just asking, as I know what punched holes look like in regards to break & shear of the inner surface.
Dave,
I know what you are referring to. We can program to make them a little smaller, so that either by punching, reaming, or in this case drilling, they will be neat and clean when it's all said and done.
Dave's right in that punched holes in splice plates might not be allowed - unless sub-punched and reamed to size. It is not for bridge work, but I would check the contract specs on the D1.1 work. It might be OK in your situation but your customer is asking for a procedure for a reason.
Pins *and* bolts are a good idea. The pins are most important keep the plates from shifting around, and the bolts keep the plates snug for more accuracy (and can be more secure than clamps).
The "for dummies" match marking includes a drawing of your plate identification scheme, and a match mark on the girder and on the splice plate near each other. You get them more than about six inches apart and the field starts saying they couldn't find any match marks.
Hg
on a side note per Chet's Rule 6, at a recent jobsite the erector explained why they had to remove some splice plates for erectability issues...which will occur from time to time. on this particular bridge job the fabricator had unique match-marking on the steel that made it nearly impossible (i say nearly impossible because of the nature of the beast) to mix up the splice plates. but the point being that sometimes the erector has to remove splice plates due to erectability issues.
and just an observation on HgTX's good suggestion for having typical match-marking details on drawings; at this particular site when i asked to take a look at the erection drawings all i got was a blank stare...the drawings were available. but as far as the bolting crew was concerned they were relying on the match-marks to get the thing built.
ziggy
Yup. Need all of it. Need the paper, but still need idiot-proof match-markings that DON'T rely on the paper.
I have also heard the "helper took all the plates off and threw them in a pile" story.
And the "Nothing fits! ... Match marks? What match marks? ... Oh..." story.
Hg
Great tips from all of you, very much appreciated. I am writing it up this weekend.
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