Equation Pad

Equation Pad › Library › IS 456 › Beams

T-beam moment capacity with the neutral axis in the flange

Moment of resistance of a flanged beam when the neutral axis lies within the flange. Reference: IS 456:2000 Cl. 23.1, Annex G (G-2.2).

Open this sheet in Equation Pad Browse the Library

T-beam moment capacity with the neutral axis in the flange: worked example sheet in Equation Pad with typeset equations and results.

Example only. This sheet shows one way to set out the check. It is not endorsed by the bodies that publish the design codes and does not reproduce them. Check every clause, value and assumption against your own copy of the current edition of IS 456 before you use it, and have the result checked by a competent person. See the disclaimer.

The calculation, line by line

Every line below is typed into Equation Pad exactly as shown; the app typesets it, works out the value with its units and shows checks as TRUE or FALSE. Change any input and everything below it updates.

# Section
b_f := 1200 mm
b_w := 300 mm
D_f := 120 mm
d := 550 mm
f_ck := 25 MPa
f_y := 500 MPa
A_st := 1885 mm^2

# Neutral axis
x_u := 0.87*f_y*A_st/(0.36*f_ck*b_f) =
x_u <= D_f =
x_u.max := 0.46*d =
x_u <= x_u.max =

# Moment of resistance
M_u := 0.87*f_y*A_st*(d - 0.42*x_u) = kN*m

How to use this example

  1. Click Open this sheet in Equation Pad. It opens as a new worksheet in your browser; nothing is installed.
  2. Change the inputs at the top to those of your project.
  3. Check the clauses and coefficients against the code, add your own checks, and save the sheet or export a PDF with your title block.

More IS 456 sheets on beams

The same topic in Eurocode 2