max Ratio Reinforcement to Concrete area ?

[BauTomTom]

I was studying different codes and realized that the ration of Reinforcement area to concrete area varies very much from code to code.

What is actually the reason for? Why is it critical when you have to much steel in a column? What if you could still provide enough clearance between the bars, so that the concrete aggregates could still pass?
What if you would even use a concrete with smaller aggregate size?

How critical is it actually if you exceed the ration for example of 10% in the splicing areas?

Bau Tom Tom

 

[rscassar]

I don't go past 4% (8%) at the column splice. I have seen details of composite sections which have over 10% of the gross sectiom consisting of steel.

 

[BauTomTom]

-- to hoki66 --

but how can this be that the compressive strenght will be negative influenced if you still specifie for example 35 Mpa concrete and the test cubes will also give you this strenght so it seams that if the concrete design is properly done it can't have a negavite impact


BauTomTom

 

[Lion06]

bautomtom-
I think hokie means assuming everything else remains the same and all you do is reduce the size of the coarse aggregate that it will have a negative impact on the compressive strength. Of course you can juice up the amount of cement, but maybe you have the amount of cement for a 8 ksi mix in a 6 ksi mix with smaller aggregate.

 

[slickdeals]

To elaborate a little more on what Lion06 said regarding 8 ksi cement in a 6 ksi mix with smaller aggregage, the smaller aggregate have a larger surface area and will need more cement to cover the surface area.