1900 Bridge Design
1900 Bridge Design
(OP)
I'm working on the reconstruction of an historical bridge that was built in the late 1800's (two lane roadway). I'm curious about the live load that might have been used for design at the time it was built?
Thanks.
Thanks.





RE: 1900 Bridge Design
You'll have to go back before 1944, and it may not be found in a national code. I also recommend you research the grade of steel used and the process used to mix and place the concrete. Many pre WWII projects involved a gang of men carrying the river gravel out of the streambed up on the bank where they mixed concrete on site and just poured it into forms, often unreinforced arches. Now, except for self consolidating concrete, everyone emphasizes "Concrete is Placed, no poured."
Good Luck
RE: 1900 Bridge Design
If it is a metal truss and you can identify the manufacturer by a plaque on the bridge or other historical documents then you may be able to determine their standard design loading.
For example, almost all of the lenticluar truss bridges were designed and built by the Berlin Iron Bridge Company in Berlin, CT and there is very good historical info available on their design specifications.
If you can, try to provide more info on the bridge and/or the original designer.
RE: 1900 Bridge Design
Don't know the designer.
RE: 1900 Bridge Design
Is it on the local or national historic register?
If so, the application forms may have information on the designer and possibly the design specification used.
RE: 1900 Bridge Design
What about looking at other, better-documented bridges of the same time period? You may be able to see common live load approaches.
You may want to consider doing a (Working Stress) rating. At least in that way you can model the live loads in accordance to its intended or expect use.
RE: 1900 Bridge Design
Waddell (1925) notes that highway bridge live loads were first assumed to be around 100 pounds per square foot and increased as engineers saw fit. Waddell further explains the nature of such live loads: gathering people, cattle, lorries etc.
Based on my reading of Waddell I believe that live load was treated on a case by case basis and generally measured and then applied without the benefit of statistical increases/decreases.
Regards,

Qshake
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RE: 1900 Bridge Design
(This did happen a few years ago on the Golden Gate Bridge and took the camber out of the road)
The book discusses varies other loads, starting with wagons drawn by horses and provides a interesting chart.
Other parts of the book discuss live load distribution and Chapter VII-B discusses plank flooring, pavement flooring and then stringers and floor beams.
This was not one of my textbooks in college, although I did get bridge design in an architectural-engineering curriculum.
Google the book name and author and a lot of hits come up.
I've worked on some old bridges and they are always a challenge. Good luck.
RE: 1900 Bridge Design
RE: 1900 Bridge Design
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RE: 1900 Bridge Design
Have also posted "bridgebuster's" referenced link to "Design of Steel Bridges" (1915) by F. C. Kunz.
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