Calculator for Strength of Reinforced Concrete Beam

This section provides a calculator to estimate the strength of rectangular section of a reinforced concrete beam (singly or doubly reinforced). It also checks for minimum steel for crack control as well as steel for balanced section.

You can use this calculator for either FPS/US Customary units or SI/Metric units.

The following assumptions as per ACI (American Concrete Institute) are adopted in developing the Calculator for the strength of RC beam:

Ultimate compressive strain in concrete is equal to 0.003.

Tensile strength of concrete is ignored.

Strain varies linearly over the depth of the cross section.

Steel stress varies linearly until yielding and remains constant beyond yielding.

Compressive force in the concrete is determined from Whitney's equivalent stress block.



The above figure explains how different values have to be selected for the calculator. The effective depth d is determined from the centroid of tension reinforcement upto the top-edge of beam. If there are two layers of tension rebar, separate them with a clear distance and other criteria as per ACI 318. The user of this calculator is advised to comply with ACI guidelines for beam thickness, rebar spacing and cover etc.

This calculator will be very helpful in determining the nominal moment strength and other parameters of rectangular Reinforced Concrete beam. It will also calculate the strain in the layers of rebar which helps to know whether steel has yielded or not to check if the section is tenion-controlled or not. You can copy and paste the results from these calculators in the document file.

To start calculation please select from the following sections of reinforced concrete beam as per your preferred system of units.