Talk:Truss bridge
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[edit] Price of steel vs labour
I'm not sure I agree with this recently added comment. In Europe and I understand elsewhere, the cost of steel has increased enormously in recent years, but in most places the cost of labour is considerably larger, which is one reason we weld girders in automated machines rather than employ people to rivet them. Can I suggest that the wording be amended to note that the "relative" price of materials and labour will affect design decisions, and remove the reference to "decreasing"? --Kvetner 11:53, 29 November 2006 (UTC)the truss is so cool.
[edit] History in the US seems missing
Various reversions didn't always get all the way back and it looks like we've lost some content. will investigate shortly if someone doesn't beat me to it. ++Lar: t/c 18:16, 11 January 2007 (UTC)
- Sorted, i think. Normally I'd just revert but it was so bad I figured I better give a heads up in case there was substantive intermediate change lost. ++Lar: t/c 19:31, 11 January 2007 (UTC)
[edit] 2nd paragraph
"In the bridges illustrated above the vertical members are in tension, lower horizontal members in tension, shear, and bending, diagonal and top members are in compression." This sentence doesn't seem to reference any illustrations on the page, I'm assuming it has been copied from elsewhere, or the illustrations subsequently removed. Does anyone have any good diagrams illustrating the forces on truss members? RoscoHead 00:07, 13 January 2007 (UTC)
- Well spotted. That text looks changed by LeonardG and others to now refer to the image in the infobox. Perhaps what happened is that the image previously was at the top of the article, but when the infobox was added, the text wasn't changed to refer to where the image was? I am not sure, you'd have to check the history. I'm not a bridge expert by any means (my Brown truss article had the tension and compression all wrong, sadly) but I agree that force diagrams for various truss types would be nice. The West Point bridge simulation program (which I used to make the Brown truss illustration and which you can get free from the US Army here: [1] ) will show forces but it has the flaw of only allowing pinned connections, you can't have a long member with a connection in the middle, as it doesn't seem to simulate bending moments. I tried drawing something in Inkscape by hand, but it would have been a very long and slow process so I gave up. It would be nice if someone created these for the common truss types (I have been toying with the idea of writing articles for Pratt, Howe, Warren, Bowstring, etc... I think those are the most common truss types but am not sure) which is why the article has redlinks, I put them there I think... Commons does have a category though: Commons:Category:Truss drawings, but they lack force annotation for the most part. ++Lar: t/c 13:57, 13 January 2007 (UTC)
[edit] Pratt? Expansion request.
Regarding this sentence: "The bowstring truss design fell out of favor due to a lack of durability, and gave way to the Pratt truss design, which was stronger." This sentence is the only place in the article that a Pratt design is mentioned. What is it? My reason for asking is that I want to write an article about a specific bridge on the National Register of Historic Places; my documentation describes it as a "Pratt Through Truss bridge," and I'd like to be able to internally link to an article which would explain what that is. Could anybody add a bit about it? (Especially nice would be source citations, which the article currently lacks and is worse for it.) Thanks for any help. --Malepheasant 09:02, 26 January 2007 (UTC)
The main truss article really needs expansion to cover the various truss types properly. In the meantime, the external links and Wikimedia commons links on the truss bridge page will at least show you what a Pratt truss looks like. I'll see if I can get time to do an update on some common truss types but have a lot of other things I need to do at present. -- Kvetner 09:47, 26 January 2007 (UTC)
