Composite Girders Parallel to Deck Span 2

[chrisrosebud2001]

I am designing a composite floor system with metal decking and concrete and I typically consider only the beams perpendicular to the deck span to act as composite. It has been suggested for this project to also consider the girders running parallel with the deck span as composite. The suggested detail to accomplish is to terminate the metal decking at both sides of the girder flange so that you will have full depth concrete over the entire width of the flange. I don't see a reason right off hand why this wouldn't be sufficient, so I am simply asking is this ok and if not, why?

Thanks in advance for any insight.

 

[JAE]

As long as you require it the deck supplier can provide a layout of the deck segments to work like that. Keep in mind it does add a bit to the costs as the more irregular are the deck segment layouts the more material cost there might be.

But overall this isn't usually a problem.

 

[wiktor]

You have to install shear studs, or some other devices to transfer shear stresses in between the steel beam and composite deck.

 

[jike]

I have always prefered this detail for all composite beams/girders parallel to the deck ribs. Break the deck at both sides of the beam/girder and provide Z-shaped bent metal pieces to close off deck to the top of the beam/girder. This allows the erector to see the top flange so that he can position the studs correctly, otherwise a rib may interfere with stud placement.

Another option is to raise the beam/girder above the other steel by the deck thickness. This will reduce the cost of coping the beams that frame into it.

 

[Calif]

This question has bugged me this week and I have asked my structural manager and a engineer but both seem to design composite beam and girder as if they have a single compression action in the concrete slab although they both run perpendicular to each other and as such, you would think that this causes bi-axial action in the concrete slab. Your reasoning makes much more sense to break up the slab on both sides of the composite girder to frame out the top flange. May I ask, do you provide some sort of metal deck layout sheet for this or do you simple provide a sketch for section.

Thanks

Calif

The resisant virtues of the structure that we seek depend on their form; it is through their form that they are stable, not because of an awkward accumulation of material. There is nothing more noble and elegant from an intellectual viewpoint than this: to resist through form. Eladio Dieste

 

[jike]

Provide a typical section for all beams parallel to the ribs. Require deck shop drawings and they will do the layout and provide deck closures.

 

[Calif]

I'll do that thanks Jike. My building is a irregular in that the floor structure is not consistent from the first to the second so, I will need to provide a section details for each floor for each girder. I appreciate this really.

calif

The resisant virtues of the structure that we seek depend on their form; it is through their form that they are stable, not because of an awkward accumulation of material. There is nothing more noble and elegant from an intellectual viewpoint than this: to resist through form. Eladio Dieste