Rivet repacement with bolts - rivet camming

[justhumm]

I am looking at a project involving a lot of rivet replacements (with HS bolts) on an old steel bridge (1930's). And I was talking to someone about a similar project / structure. They were finding that a lot of the existing rivet heads were off-center to the rivet shaft and the contractor ended up doing a lot more field drilling of the steel than was originally anticipated.

I'm assuming that the rivet condition that they found was due to the "camming effect" of the rivet holes.

Has anyone encountered this situation when replacing rivets? And does anyone have a "good" way of planning for & dealing with it?...aside from drills and brute force...

 

[SwinnyGG]

Unless you can use replacement fasteners which are significantly smaller OD than the holes you're expecting for the rivets, you have no choice but to match drill.

 

[BridgeSmith]

If the rivets are being replaced one at a time with bolts, I don't see any way to correct misalignment of the plates; they must be drilled. The drill would be aligned with the hole in the first ply and then the second ply would have an oversized hole, which is allowed. The good news is that if the HS bolts are fully tensioned as they are installed, there should not be any further movement (slippage) of the plates.

If the issue is damage to the hole in the first ply by not knowing where it is, then I would suggest cutting the head off the rivet first and then drilling the shaft out.

 

[BridgeSmith]

jgKRI's suggestion could definitely work also. HS bolts are significantly higher strength than the rivets (by a factor of 3, if I'm remembering correctly). You may be able to provide adequate capacity and slip resistance using bolts that are smaller than the rivets.

 

[dik]

I'd pop off a few rivets at a connection and check alignment. Drill as required and insert some high strength bolts. Then pop off a bunch more rivets. They have devices you can rent that do a great job of removing rivet heads and are fast.

Dik

 

[dhengr]

Justhumm:
I would wonder that you might not want to go to the next size bigger bolt to assure that you could match drill or ream the old holes and still get a proper fit of the new bolts. You may want to use a mag. drill and an end mill in some instances. As HotRod10 suggests, the new HS bolts should probably be tensioned as if in a slip critical connection, otherwise they will not act in unison with the rivets. The rivets are generally tight fitting in the hole, filling it completely, even with some misalignment in the mating holes, so you do not want the new bolts acting as if tightened for a normal bolt bearing fit in a loose hole. The remaining rivets would have to move and start to shear off before the new bolts would come into play. Not a good solution to the problem.

 

[bridgebuster]

If I had a nickel for every rivet I saw removed...anyway, avoid drilling them out because it's slow and you'll go through a lot of bits, unless you own stock in Hougen. Typically, you bust the head off with a helldog then punch the shank through. It usually works well but when you're going through maybe 4+ plies it can get difficult and at times impossible. However, if you have an ironwork who is good with a torch (assuming you trust ironworkers with torches)then burn the problem ones out.

One other thing - safety - make sure someone is catching the heads as they break off.

 

[dhengr]

BB:
'If you had a nickel for every rivet you saw removed...' My goodness, out in your neck of the woods, you wouldn’t have 50% of your iron and steel structures if they didn’t have rivets. Right?

 

[dik]

See evelrod's post in threat: thread725-26778


Catch the clip:

https://www.youtube.com/watch?v=N24MZ6c75GE

Dik

 

[BridgeSmith]

Cool video, Dik. Looks like the helldog works pretty slick. When I mentioned cutting the heads off, I was thinking of an abrasive cutting disc, but that's much better.

 

[dik]

I've seen both torch and hammer used... a torch, in the right hands, is superb... and the rivets do chisel off as shown.

Dik

 

[SAIL3]

are the min/max spacing for rivits the same as for HS bolts.....

 

[hokie66]

You want somebody around to tell the workers how many rivets they can remove at once. The guy in the youtube clip looks like he is just going hell for leather.

 

[Ingenuity]

The guy in the youtube clip looks like he is just going hell for leather.

The "guy" in the YouTube clip is actually a girl.

But, I agree, the max number of rivets to be removed before replacement would be good.

 

[hokie66]

Didn't notice that, was focused on the tool and the rivets. But I am not PC anyway, call everybody "guys".

 

[dik]

Sail3:

Catch the link:

http://www.roymech.co.uk/Useful_Tables/Rivets.html

Dik

 

[bridgebuster]

@dhengr - you're right and pretty soon we won't have many. In my area there's been a lot of bridge replacements but all prestressed concrete. My first boss hated prestressed. He said it's putting painters out of work; funny how that rubbed off on me.

 

[justhumm]

Thanks, all, for the responses!

@hokie66, the contractor's being limited to replacing one rivet at a time, in this case.

@bridgebuster, I was working on a the preliminary design of a partial replacement / widening of an old plate girder bridge, a few years ago. The local historic district was requiring that button head bolts be installed along the proposed rolled sections, but they didn't want to manufacture a new, matching built-up section.