For the design of the longitudinal tension reinforcement, the effective depth of a section, d is defined as the distance from the extreme concrete fiber in compression to the center of gravity of the longitudinal tension reinforcement.

For the design of the longitudinal compression reinforcement, the effective depth in compression, d2 is defined as the distance from the extreme fiber in compression to the center of gravity of the longitudinal compression reinforcement.

The effective depth of section in a concrete beam is defined as the distance from the extreme compression fiber to the centroid of the tensile reinforcement. It is used in the design of the beam to determine the amount of flexural reinforcement required.

## The effective depth of section is calculated using the following equation:

`d = d' - kd`

**where:**

- d is the effective depth of section
- dâ€™ is the overall depth of the beam
- k is a coefficient that depends on the type of loading and the reinforcement ratio
- d is the depth of the neutral axis

The value of k can be found in the ACI 318-19 code. For a beam with a uniformly distributed load and a reinforcement ratio of 0.01, the value of k is 0.9.

For example, consider a beam with an overall depth of 600 mm (24 in.), a reinforcement ratio of 0.01, and a uniformly distributed load. The effective depth of section would be calculated as follows:

`d = 600 mm - 0.9 * 600 mm = 480 mm`

This means that the tensile reinforcement in the beam must be able to resist the bending moment over a depth of 480 mm.

The effective depth of section is an important factor in the design of concrete beams. It is used to determine the amount of flexural reinforcement required and to ensure the safety of the beam.

## Here are some factors that can affect the effective depth of section:

- The type of loading on the beam
- The reinforcement ratio
- The concrete strength
- The size and shape of the beam
- The presence of any other structural elements in the beam

If you are unsure about the effective depth of section for a particular beam, it is always best to consult with a structural engineer.