Rivetted half thorugh bridge deck plate girders 2

[shaurya241100]

HI All,
Could anyone drop some pointers/literature on how to work out spacing of rivets while designing half through rivetted plate girders supporting bridge decks?
Any quick response would be much appreciated.
Regards.

 

[SlideRuleEra]

In all seriousness, since design of rivetted girders is old technology, old reference material may be best.
Go to Google Books and search there - you will get many complete pre-1923 books on the subject. Here is an example:

http://books.google.com/books?as_brr=1&q=riveted+girder+bridge+design&btnG=Search+Books

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[youngstructural]

Mostly for my own curiosity:

You need to be certain that you really WANT rivets. I've seen an engineer struggle to do a design with rivets in a desire to be "sympathetic" to the existing structure, only to find that no contractor would (or I've sometimes thought even could!) undertake the work.

Oh, and at least in Ottawa when working on the Laurier street expansion project, the historic structures consultants involved demanded that the new structure be similar, but readily distinguishable so that the original bridge components could always be picked out. Essentially the design (not mine) was in the same shape and form as the original, only using modern materials and methods. Thus continuously welded arches with crossed rolled member bracing in the same shape and next to the original rivetted plate arches with latticed cross bracing members.

Can you tell us what you're needing to design rivets for? Perhaps a review of existing capacity? In that case you actually want a modern reference to the design of an older style component for your design review. These are available in some codes, particularly the New Zealand NZS 3404 code for steel is an excellent source... Infrastructure seems to last forever when you don't throw salt on it, nor overtax the capacity, and as a result New Zealand has numerous beautiful old bridges. The code committee there seems to have had the foresight to maintain all sorts of good stuff in their code (latticed compression members, rivets, etc, etc).

Cheers,

YS

B.Eng (Carleton), P.Eng (Ontario), MIPENZ (Structural-New Zealand)
Working in Canada, and missing my adoptive New Zealand family... at least I brought the little Kiwi with me!

 

[jike]

Years ago, we designed a shopping mall with the "old look" of latticed columns and batten plates. We use "interference body bolts" with rounded heads for the rivet look. Since that time, TC bolts now have rounded heads, which have the look of rivets.

 

[shaurya241100]

Thanks guys.
It is worth to explain why I need this ionformation. I am providing a solution to our client to strengthen an exisitng half through wrought iron rivetted plate girders which carries a timber deck to support railway tracks and loading. I will be strengthening the top flange of theese wi girders by adding new steel plates and therefore will need to replave exisitng rivets with hsfg or tcb's. I am trying to udnerstand why the rivets are at roughly 100mm c/c spacing as if I know why they were needed at close spacing, I can check if we can reduce the nukmbers of bolts in the girder while adding new flange plates.

Regards

 

[youngstructural]

In many cases rivets were placed at close spacing for the following reasons (not always obvious to the uninitiated):

1. It was shown in the 1890s that spacing of rivets less than 6" would reduce (and at 4" - Your spacing - nearly always prevent) rust jacking.

2. The designers typically considered one in four rivets to be "dead"; Basically this is because a rivet only serves the proper purpose if it is fully jacked into filling the hole; This is difficult to achieve, can be hard to inspect (unless you're checking every bolt), and over-jacking can cause fatigue if the rivet cools too greatly.

3. While throwing rivets around is very dangerous, it was fairly common practice. As was insulated (asbestos) buckets to hold waiting rivets... But, in either case, bridge connections often had a fair distance from the oven, increasing the likelihood of installation problems.

4. Alignment of connections was no easier sixty years ago and prior... Engineers knew that if two bolt holes did not fully line up, the construction crew would still likely install the rivet, and simply end up with less rivet. Remember, hot rivets fill the available space; They don't make space and pull holes into alignment very well.

5. Rivets were not normally available in a tremendous number of sizes. Typically there were much fewer choices than our modern bolts (and thus more discrete jumps in number of bolts). Engineers typically favoured more rivets over fewer rivets.

In short I am not at all surprised to hear that the bolt spacing is ~100mm (4"), even if the loads say the spacing could have been 180 or 250mm.

Cheers,

YS

B.Eng (Carleton), P.Eng (Ontario), MIPENZ (Structural-New Zealand)
Working in Canada, and missing my adoptive New Zealand family... at least I brought the little Kiwi with me!

 

[SlideRuleEra]

YS - Many thanks for that insight!

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[paddingtongreen]

This question brings back memories of updating one of the Philadelphia Elevated Railways. As with other A/E joint ventures, we expected to just replace the lead painted, riveted trusses with the deep wide flanges, but the Architect decided he wanted them to stay. This gave us some interesting questions to answer.

Were the trusses adequate as they were? No, we were increasing the load.

Could the truss handle the existing dead load and our new cover plates just share in carrying the additional loads? Yes if we replaced or reinforced some of the web members at the ends.

Could we shore up the truss, even jack it up to it's pre-deflected position, while the work was going on? No, the stations were carefully placed over the top of crossroads. Pity because we could have used a smaller cover plate and and had it share in carrying all of the load.

Not being able to shore it up meant that we couldn't pop all of the rivets to the existing plates. We had to punch holes in some of new the cover plates where the rivets were so we could drop the new plates down onto the existing plates.



Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[youngstructural]

I thought I might chime in with one more point:

Much like our modern steel member tables, you'll find that old rivet tables list a very great number of sizes (something like everything between 1/4 and 1-1/16" in 1/16" increment, however these were not commonly available. The most popular sizes were readily available and everything else had lead time. Thus you'll find that nearly all of the rivets you'll encounter in the real world are 1/2, 5/8, 3/4 or 1".

I've also heard of rivets with child's fist-sized heads; That doesn't make it normal! lol...

Oh, and as for assessing the capacity of the rivets, you're going to have to use some gross assumptions unless you know more about rivets than engineers normally do... The permissible stress on a rivet depends on the installation methods.

Glad at have helped a little,
Cheers,

YS

B.Eng (Carleton), P.Eng (Ontario), MIPENZ (Structural-New Zealand)
Working in Canada, and missing my adoptive New Zealand family... at least I brought the little Kiwi with me!

 

[youngstructural]

I've had a middle of the night, wake up in a cold sweat moment... And it's not even one of my projects! I just need to point out that my list of common rivet sizes has omitted THE most common bridge rivet size; 7/8", AND I've also incorrectly listed 1" as a common size! The 1" diameter rivet was common only to shop rivets in some locations. 7/8" diameter was the common "top of the range" rivet for field work, and often for shop work as well.

Please forgive my oversight.

Cheers,

YS

P.S. I normally only get those sit-up-in-bed thoughts from my own designs and go straight to a desk to furiously re-check some assumption or size a la Hoover...

B.Eng (Carleton), P.Eng (Ontario), MIPENZ (Structural-New Zealand)
Working in Canada, and missing my adoptive New Zealand family... at least I brought the little Kiwi with me!