Talk:Girder bridge

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Why is there no category for this kind of bridge? Without such, what should I use for girder-type bridges? - Denimadept 20:25, 7 September 2007 (UTC)

Report text moved here[edit]

The following was added by an anonymous editor. Perhaps we can use it, but we need refs. - Denimadept (talk) 15:04, 19 September 2009 (UTC)

Girder Bridge A girder bridge is perhaps the most common and most basic bridge. A log across a creek is an example of a girder bridge in its simplest form. In modern steel girder bridges, the two most common girders are I-beam girders and box-girders. Typical Span Lengths 10m - 200m World's Longest Ponte Costa e Silva, Brazil Total Length 700m Center Span 300m

If we look at the cross section of an I-beam girder we can immediately understand why it is called an I-beam (illustration #1.) The cross section of the girder takes the shape of the capital letter I. The vertical plate in the middle is known as the web, and the top and bottom plates are referred to as flanges. To explain why the I shape is an efficient shape for a girder is a long and difficult task so we won't attempt that here.

A box girder is much the same as an I-beam girder except that, obviously, it takes the shape of a box. The typical box girder has two webs and two flanges (illustration #2.) However, in some cases there are more than two webs, creating a multiple chamber box girder. Other examples of simple girders include pi girders, named for their likeness to the mathematical symbol for pi, and T shaped girders. Since the majority of girder bridges these days are built with box or I-beam girders we will skip the specifics of these rarer cases. Now that we know the basic physical differences between box girders and I-beam girders, let's look at the advantages and disadvantages of each. An I-beam is very simple to design and build and works very well in most cases. However, if the bridge contains any curves, the beams become subject to twisting forces, also known as torque. The added second web in a box girder adds stability and increases resistance to twisting forces. This makes the box girder the ideal choice for bridges with any significant curve in them. Box girders, being more stable are also able to span greater distances and are often used for longer spans, where I-beams would not be sufficiently strong or stable. However, the design and fabrication of box girders is more difficult than that of I beams. For example, in order to weld the inside seams of a box girder, a human or welding robot must be able to operate inside the box girder.



You can cross both bridges and they are secure


As far as I can tell from reading the two articles, a beam bridge is more or less a synonym for a girder bridge, so I suggest merging the beam bridge article into the girder bridge article. --DavidCary (talk) 10:26, 22 April 2013 (UTC)

  • Oppose "As far as I can tell from reading the two articles," is no reason. FFS! If you don't understand an article, at least do sufficient research from detailed sources, don't just fall back on "Well if I don't understand it, it can't be important". Andy Dingley (talk) 10:36, 22 April 2013 (UTC)
  • From the lead: "A girder bridge is often referred to as a beam bridge.[2][3][4][5] However, some authors define beam bridges slightly differently than girder bridges.[6]". If there is a clear and widely accepted difference between the two concepts, then it should be explained much more clearly in the article. --Superzoulou (talk) 17:19, 20 May 2013 (UTC)
  • Beam bridges are any form of bridge that behaves statically as a simple conceptual beam.
Girder bridges are also beam bridges, however they're a subset of beams that use a girder as their beam. Beam bridges are ancient: wood and stone clapper bridges go back to pre-history. The girder bridge doesn't appear until the 19th century, after the invention of the girder. Girders are a relatively late invention. Girders rely on wrought iron processed by large industrial rolling mills. A handful of cast iron girders were tried in the decades before this (see Bishop's Bridge), but they generally failed (see Dee Bridge disaster). Even the truss bridge, when constructed from timber, is much older. Andy Dingley (talk) 13:18, 18 June 2013 (UTC)
  • Support There doesn't seem to be any difference between the two. These should be merged unless someone can explain (with references) what the difference is. Both articles cover the same thing and neither explains differences between the two. I believe the new merged page should be at Beam Bridge even though the current article is shorter as this seems like a more universal term. ShakyIsles (talk) 23:36, 17 June 2013 (UTC)
  • Support, per ShakyIsles comment above (and mine). Can change my mind, if the content of the article changes, but that does not seem to happen for now.--Superzoulou (talk) 13:01, 18 June 2013 (UTC)
  • Neutral, as a bridge designer myself, "beam bridge" is a more generic term while "girder bridge" is specific to bridges built with steel girders. Beams could be concrete (box, tee, cellular, or channel) or steel (open/closed box, I-beam, plate, or wide flange). Suggestion: change the "beam bridge" article to "bridge beams" specific to the types of beams in bridges, not the bridge style itself, and have links or a subsection about each of the various styles of bridges that utilize beams (girder, concrete beam, over/under/through trusses, suspension, cable-stayed... basically almost everything but an earth filled concrete arch). Note that I have also made additions and corrections to the girder bridge article. My issue with the original article is that it relied heavily on general webpages... the governing sources for bridge design are AASHTO and the FHWA, the primary literature being the LRFD (at least in the US). So hopefully my corrections will help with the "to merge or not to merge" conundrum. (talk) 14:48, 1 December 2014 (UTC)
  • Oppose The engineering concept of a beam bridge, similar to post and lintel construction, is different subject than a girder bridge which is a beam bridge made using girders. Beam bridge could be more clear about it being a generic term and engineering principle and that a beam bridge can be stone, wood or steel. Jim Derby (talk) 02:58, 20 April 2015 (UTC)

Merge Plate girder bridge[edit]

Plate girder bridge seems to describe the same subject, but from the perspective of railroad rather than road bridges. Doodle77 (talk) 17:22, 13 May 2017 (UTC)

  • Oppose Not all girders are plate girders. This distinction has nothing to do with road vs. rail bridges. Andy Dingley (talk) 23:17, 13 May 2017 (UTC)