Equation Pad

Equation Pad › Library › IS 800 › Members

Section strength under axial force and bending

Simplified interaction check of a plastic section under axial compression and bending about one axis. Reference: IS 800:2007 Cl. 9.3.1.1.

Open this sheet in Equation Pad Browse the Library

Section strength under axial force and bending: 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 800 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.

# Inputs
f_y := 250 MPa
gamma_m0 := 1.10
A_g := 5000 mm^2
Z_p := 651e3 mm^3
N_u := 300 kN
M_u := 60 kN*m

# Strengths
N_d := A_g*f_y/gamma_m0 = kN
M_d := Z_p*f_y/gamma_m0 = kN*m

# Interaction
U := N_u/N_d + M_u/M_d =
U <= 1 =

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 800 sheets on members

The same topic in Eurocode 3