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Beams and girders

Beams and girders

Beams and girders

Is there any difference between the words "beam" and "girder" ?

Alessio Spigarelli
Structural Engineer

RE: Beams and girders

Typically a girder is larger than a beam, or may support several beams.

RE: Beams and girders

I use the term "girder" to describe a member that has other members framing into it, and the term "beam" to describe a member that supports only decking or sheathing, with no other members framing into it.


RE: Beams and girders

The way that I was taught in school and now in professional practice is that:

A girder is a memeber that is in the floor system and has other members tying into the side of it.

A beam is a member that is dropped or below the floor system and has members bearing on top of it.

RE: Beams and girders

In the steel bridge world, they often use "girder" to mean "built-up plate girder" and "beam" to mean "rolled section".


Eng-Tips policies:  FAQ731-376

RE: Beams and girders

In structural mechanics, a beam is a virtual device which can only resist bending. A girder also resists bending but also has some torsional resistance. I vote for Keysol's definition.

RE: Beams and girders

But a beam element in FEA has torsional rigidity, so I think your definition is rather restricted. I can't remember  Shigley, Timoshenko or Roark making that distinction.

To me a girder has an implication of being fabricated from sub-components, as HgTX suggests.


Greg Locock

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