Download the Spreadsheet here.

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If any mistakes are found they will be added to the Addendum portion you will find under each spreadsheet. Also, if a new version is uploaded the version will change (all versions will start at v1.0 and update accordingly). It is up to you to do your own research and make certain that you have reviewed the spreadsheet you're using and that you are using the most up-to-date spreadsheet available

What does the Concrete Beam/1-way Slab spreadsheet solve?

Concrete Beam Design
Fig. 1: Concrete Beam/Slab Variables

This spreadsheet will find the flexural capacity of a rectangular concrete beam or 1-way slab. It is solved using LRFD loads.

If the area of steel (As) is known then it can be entered into the Inputs section, otherwise minimum steel (As-min) will be used.

The diagram in Figure 1. shows the compression block and tension steel of a concrete beam in a balanced condition. Certain variables are also shown graphically for clarification.

How to Understand this Spreadsheet
  1. Where to Download
  2. How to use this spreadsheet
  3. Notes
  4. Addendum
  5. Spreadsheet FAQ's

Where to download?

Download the Spreadsheet here.

How to use this Spreadsheet:

This spreadsheet works in Microsoft Excel 2007 and later. A complete walkthrough of how this spreadsheet works can be found here for beams and here for 1-way slabs.

The top portion of the spreadsheet allows you to change your inputs:

Concrete Beam/Slab Variables
Fig. 2: Spreadsheet Inputs


h = height of the beam
bw = width of the beam
cov = rebar cover
d = distance to rebar
var = is it a slab (1), or a beam (0)
var2 = This variable determines whether spiral or other reinforcement is being used
fy = the strength of the rebar (psi)
fc' = the strength of the concrete (psi)
β1 = Strength Reduction Ratio
= Strength Reduction Factor - See Figure 3 below for information on how the Strength Reduction Factor is being calculated
As = Steel area in member (in2)

Concrete Strength Reduction Transition Zones
Fig. 3: Strength Reduction Transition Zones

The bottom portion of the spreadsheet calculates Mn (the factored capacity of the beam using LRFD)

Concrete Beam/Slab Results
Fig. 4: Spreadsheet Results


The following notes must be considered when using this spreadsheet:

  1. v1.0: Created using the ACI 318-05
  2. v1.1: Created using the ACI 318-08


  • V1.0: This is the original version of the concrete slab/beam checker spreadsheet.
  • V1.1: Updated the spreadsheet to automagically calculate the strength reduction factor for compression, tension, and transition zones. Special thanks to J. Brown for finding an original error in v1.0 when calculating rho and then helping to upgrade the spreadsheet to be more complete.



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