Non-composite I beam section

[dada23]

Hey guys,

i currently design a bridge deck with a non-composite I beam section (reinforced concrete slab rested on two steel beams with no fixed attachment)for simplcity using FEM. What will be the restraint of the connection between concrete and the top flange of steel if the deck is a non-composite system? is it a pinned connection?

 

[MikeHalloran]

There's no connection, except a little friction from the weight of the slab, which in turn depends on how much dirt/rust/paint/grease/dust is in the interface.


Mike Halloran
Pembroke Pines, FL, USA

 

[IDS]

There's no connection

Well there is a vertical connection.

As for how the connection should be modelled, that depends on how the beams are modelled. If it is a 3D model, with the steel and concrete members at a different elevation, then you would have to insert rigid links to the elevation of the interface, and a friction connection at the interface to allow slip at that surface. If it is a 2D grillage model the centroid of all the members will be at the same elevation, so the effect of the offset won't be included in the model anyway.

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[dada23]

Thank you for the information. Actually i use shell elements to represent the members, including the I section beam and i offset the I beam, according to the geometry of the deck. So, i just need to make the mutual nodes of the concrete and steel vertically restained.

 

[IDS]

dada23 - You could do that, as long as you make sure that there is no horizontal linkage between the two element types, and that the concrete elements are restrained against horizontal deflection, in a way that won't over-restrain them. But it would seem much easier to do a 2D analysis, which will give the same answer.

Also why use shell elements for the steel beams, rather than beam elements?

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/