Concrete On Metal Deck - Concrete Strength + Min Composite Action

[sgs114]

Hello,

I have a project where we have a concrete on metal deck floor with composite steel beam framing. We had specified f'c = 4000 psi on our drawings, and the mix design we received in the submittal had a listed min f'c = 6000 psi with pretty much all of the test data coming back in excess of 6500 psi. This increase in concrete strength will reduce the composite percentage of some of my beams to <25% based on the number of studs we have shown.

How big of a concern is this? Should I request they submit a different mix with lower f'c?

 

[BridgeSmith]

So it takes less concrete to provide the composite capacity required by the design, which means the composite section has greater capacity than what it was designed for. I'm not sure I understand the concern.

Rod Smith, P.E., The artist formerly known as HotRod10