Girder Bridge Types

BlackDiamond1964 · Apr 10, 2019

I'm working on a project where the railroad used deck girder bridges and through girder bridges. Does anybody know the reason why a particular type of girder bridge would be used?

kgp · Apr 10, 2019

Im sure it depends on the types of locomotives and cargo which will be passing over the bridge... a deck girder has more mass below the track whereas a through girder has the structural support above, so as to allow cars and trucks to pass under? Im just spit-balling here. The same concept could also apply to rivers and wetlands, a through girder is less likely to washout or be destroyed by a flood or other natural disaster

BlackDiamond1964 · Apr 10, 2019

kgp said:
Im sure it depends on the types of locomotives and cargo which will be passing over the bridge... a deck girder has more mass below the track whereas a through girder has the structural support above, so as to allow cars and trucks to pass under? Im just spit-balling here. The same concept could also apply to rivers and wetlands, a through girder is less likely to washout or be destroyed by a flood or other natural disaster

In this case, it's an electric 3rd rail powered railroad. The bridges in question are all going over roads. For some reason some are deck girders but most are through girder type bridges. I'm confused on why the two types of bridge were used. The only real difference that I can see so far is that the through girders were built over bigger or busy roads, where the deck girders where used more on residential type streets.

kgp · Apr 11, 2019

and its exactly that. Eighteen wheel trailers and other tall vehicles wont use a residential street.

teddytoot · Apr 11, 2019

One thing occurs to me. In through girder bridges the girders will be under compression loads whereas in a bridge deck they will be under tension. I am not an engineer so do not know what makes the designer choose.

JCitron · Apr 12, 2019

This website has some great information on various bridge types.

[FONT=Verdana,Arial,Tahoma,Calibri,Geneva,sans-serif]https://theconstructor.org/

[/FONT]Where it says questions in the search category, change that to posts. The reason for the difference is due to loading capabilities according to the article I read.

Girder Bridge Types

BlackDiamond1964

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kgp

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BlackDiamond1964

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kgp

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teddytoot

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JCitron

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