Section properties are calculated separately for the concrete, reinforcing and steel and then combined using the modular ratio to calculate the transformed section properties. The steps involved in this calculation are outlined below.
1. Calculate limits of concrete and steel sections (extreme tension fiber)
2. Calculate concrete section properties
3. Calculate reinforcing section properties, including distance to extreme tension rebar (ym).
4. Calculate steel section properties. Note that these properties should correctly account for the thickness of the shapes.
5. Calculate transformed section properties using a modular ratio of Es/Ec (not rounded).
6. Calculate balanced steel distance Xbal for reinforcing and steel shape and use the smaller value.
(For variables, see Design Criteria section)