Composite Steel Beam with Concrete Slab

[Arun4567777]

Hi!

I am designing a composite section with concrete slab having depth 250 mm and a WB Steel Section. I came to know that they will cast 150 mm concrete first and then the 100mm. So for conposite action I should consider full 250 mm or only 150 mm. Any help is appreciated.

 

[JAE]

Without spending time researching the possible composite benefit of the topping slab (based on bond to the lower, first slab, I'd just rely structurally on the lower slab.

 

[bridgebuster]

Use 150. To make 250 work, the beams will have to be fully shored during the second placement and you would need to make it a bonded overlay.

 

[BridgeSmith]

I agree with using the 150mm only...unless there is more than a cold joint between the 100mm portion and the 150mm portion - reinforcing crossing the joint, shear connectors extending 50mm into the 100mm topping, transverse shear keys at <4' spacing, etc.