## Ratio of Reinforcement is higher then max Ratio of Reinforcement in concrete beam - ACI code

## Ratio of Reinforcement is higher then max Ratio of Reinforcement in concrete beam - ACI code

(OP)

Dear all,

Maybe this question look a bit silly for some Engineers, but I would like to understand If I got that π > π max in a concrete Beam, do I have to switch to double reinforcement?

Regards

Maybe this question look a bit silly for some Engineers, but I would like to understand If I got that π > π max in a concrete Beam, do I have to switch to double reinforcement?

Regards

## RE: Ratio of Reinforcement is higher then max Ratio of Reinforcement in concrete beam - ACI code

Unless you're tightly constrained on space, it's usually more economical to use a larger beam than meeting all the requirements to consider compression steel. It takes alot of steel to reach an overreinforced condition; you'll have to watch the minimum bar spacing requirements fairly closely.

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

## RE: Ratio of Reinforcement is higher then max Ratio of Reinforcement in concrete beam - ACI code

## RE: Ratio of Reinforcement is higher then max Ratio of Reinforcement in concrete beam - ACI code

You can't account for compression steel unless you adequately confine the bars being utilized as compression steel.

## RE: Ratio of Reinforcement is higher then max Ratio of Reinforcement in concrete beam - ACI code

I would like to take example:

if π = 0.02 β As = 0.02 x 40 in x 18 in = 14.4 inΒ²

if π max = 0.015, then π > π max

So, ACI code will not allow to use π = 0.02, right?

So, to solve this issue, I have 2 solutions:

- Increase the Size to Beam

- use π max for Tension reinforcement, and get the required reinforcement for Compression.

Is that right?

But AS I understand, in order to treat a beam as double reinforced concrete beam, I should have the bending moment greater then Balanced Moment, correct?

## RE: Ratio of Reinforcement is higher then max Ratio of Reinforcement in concrete beam - ACI code

In order to treat the beam as a double reinforced concrete beam, you need to ensure that the compression steel is tied as per the column reinforcing requirements.

## RE: Ratio of Reinforcement is higher then max Ratio of Reinforcement in concrete beam - ACI code

Thanks and Regards

## RE: Ratio of Reinforcement is higher then max Ratio of Reinforcement in concrete beam - ACI code

Which one to follow according to ACI code?

## RE: Ratio of Reinforcement is higher then max Ratio of Reinforcement in concrete beam - ACI code

----

just call me Lo.

## RE: Ratio of Reinforcement is higher then max Ratio of Reinforcement in concrete beam - ACI code

## RE: Ratio of Reinforcement is higher then max Ratio of Reinforcement in concrete beam - ACI code

I read this tutorial before, you just hit where I am getting confused:

But As in tension is:

So, for double reinforcement, we should have π > π max cause we have: As = As1 + As2 && As1 = π max x b x d.

## RE: Ratio of Reinforcement is higher then max Ratio of Reinforcement in concrete beam - ACI code

The sole purpose of count on, or add, the compression steel is applicable for a beam with excessive moment demand and with constraints in altering cross sectional dimensions, and material properties, fc' and fy. More often than not, it will result in an over-reinforced condition.

Under the situation that requires a reinforcement ratio in exceeding the maximum allowed by code, the options are,

1. increase cross sectional area,

2. rearrange floor/support layout to reduce the demand,

3. consider axial force in beam-column situation for the load case that causing excessive steel demand,

4. use higher strength reinforcement.

The graph below might help you to get better pictures on the effect of compression steel.

## RE: Ratio of Reinforcement is higher then max Ratio of Reinforcement in concrete beam - ACI code

## RE: Ratio of Reinforcement is higher then max Ratio of Reinforcement in concrete beam - ACI code

Big thanks for you and for the other.

God bless.

## RE: Ratio of Reinforcement is higher then max Ratio of Reinforcement in concrete beam - ACI code

Just remember one thing, if you have slab cast with the beam, you can utilize the slab on each side of the beam, and design the tension steel using the larger effective width (b

_{EFF}) for compression. Thus, you may reduce the tension steel to an extent.