How to Calculate Beam Strength

Updated July 20, 2017

When calculating the strength of a beam, structural engineers may need to consider certain variables. According to Structural Software Inc in their Description of the Reinforced Concrete Beam Analysis Program, "In practice most beams are designed with only tensile reinforcement (singly reinforced). However, in certain situations it might be necessary to design beams with both tensile and compression reinforcement (doubly reinforced)." Structural and civil engineers need to consider these factors because of certain codes required by the American Concrete Institute, or ACI.

Open your browser.

Visit the website There you will find a Java applet program that will allow you to input the information required to calculate the strength of the beam you are investigating.

Input the required variables to calculate your beam's strength. Enter a number in the rectangle labelled "b," "d," "d'," "As," "As'," "fc'," and "f7," which stand for width of section, distance from top of section to centroid of tensile steel, distance from top of section to centroid of compression steel, area of tensile steel, area of compression steel, cylinder strength of concrete and yield stress of steel, respectively.

Choose a category for your beam. You can either choose Rectangular Beam, T Beam, L Beam or U Beam.

Select either U.S. or SI (metric) system as your units of measurement.

Click the "Calculate" button, and you should be able to see a list of different values for your beam. The list will contain the following outputs: nominal capacity at failure, design moment at failure, depth of neutral axis at failure, depth of rectangular stress block at failure, tensile stress in steel at failure, compression stress in steel at failure, total compressive force in concrete at failure, total tensile force of steel at failure, value of beta one, tensile reinforcement ratio, compressive reinforcement ratio, balanced reinforcement ratio for tensile steel, maximum allowable tensile steel ratio according to ACI and minimum allowable tensile steel ratio according to ACI.

Things You'll Need

  • Computer with Internet capabilities
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About the Author

Paul Mesler began writing professionally in 2006. His work has appeared in the "The Scroll" newspaper, as well as in numerous online publications. He holds a Bachelor of Science in English education from Brigham Young University in Idaho.