Concrete beam section calculator

The concrete beam section calculator is a convenient tool for a quick check/design of a reinforced concrete section for flexure. It allows you to instantly see the section capacity based on the following input parameters:

The section geometry in terms of the shape (rectangular, or Tee or L), depth and width (and flange and web thicknesses in case of T and L sections).
The top and bottom cover to the centroid of the reinforcement (Ct and Cb).
The material properties of the concrete (f’c) and steel (fsy).
The design actions for positive and negative bending (M*(+) and M*(-)).

The calculator will display an initial design by providing the necessary top and bottom reinforcement so that the section capacity in bending matches the applied design actions. In addition, the calculator also provides graphs as an overview comparison of the current capacity compared to the optimal capacity of the section. The top graph shows the negative bending capacity versus the top area of steel based on a specified amount of bottom steel. Similarly, the bottom graph shows the positive bending capacity versus the bottom area of steel based on a specified amount of top steel. As you vary any of the input parameters the capacity will be reflected instantly in the graphs.

The following example applies to a rectangular section with D = 520mm, B = 250mm, f’c = 50 MPa, fsy = 500 MPa, cover to centroid of reinforcement = 35mm and M*(+) = 700 kNm. The calculator has arrived at an initial solution of top steel = 1500 mm2 and bottom steel = 4074 mm2 with a capacity of Mu = 700.6 kNm. The bottom graph shows the positive bending capacity of the section based on a top area of steel of 1500 mm2. You can see from the bottom graph that the section has reached close to 100% of its maximum positive bending capacity. Providing more bottom steel without also increasing the top steel wouldn’t significantly increase the positive bending capacity and you can see this by sliding the Bot "Area Steel" slider to the right.