b4. Design method for longitudinal reinforcements of a Tsection in bending at the ULS, A_{sc} and A_{s}
Eurocode 2  Design of concrete sections
Assumptions
1. Plane sections remain plane after straining, so that there is a linear distribution of strains across the section.
2. Reinforcing steels have the same deformation as the nearby concrete.
3. The tensile strength of concrete is ignored.
4. A rectangular distribution of the compressive stress in the concrete is assumed, see 3.1.7 (3).
5. The ultimate limit state occurs when the strain in the reinforcing steel reaches the limit ε_{ud} (Pivot A) and/or the strain in the concrete reaches the limit ε_{cu3} (Pivot B).
Reference moment M_{Tu}
The moment balanced by the compressive flange is given by:
M_{Tu} = b_{eff} h_{f} η f_{cd} (d  h_{f}/2)  (b4.1) 
If M_{Ed} ≤ M_{Tu}, the compressive stress block lies within the compression flange. Because the tensile concrete is ignored, the Tsection can be considered as an equivalent rectangular section of breadth b_{eff}. The method b1 is applied to calculate longitudinal reinforcements A_{s} & A_{sc} of this section.
If M_{Ed} > M_{Tu}, the compressive stress block extends below the flange. the Tsection can be considered as two fictive sections (see Figure b4.2).
Two fictive sections

The first fictive section is a rectangular section b_{w} x d
that balances a fraction M_{Ed1} of the total moment M_{Ed}:
M_{Ed1} = M_{Ed}  M_{Ed2} (b4.2) 
The second fictive section is a Tsection of flange width b_{eff}  b_{w}
and zero web width.
This section balances a moment M_{Ed2}:
M_{Ed2} = (b_{eff}  b_{w}) h_{f} η f_{cd} (d  h_{f}/2) (b4.3)
From the calculation of the first fictive section, we get the stress in the tensile reinforcement σ_{s}. For equilibrium of the second section, the tensile reinforcement A_{s2} is determined as:
A_{s2} = (b_{eff}  b_{w}) h_{f} η f_{cd} / σ_{s}  (b4.5) 
The total tensile reinforcement A_{s} is given by:
A_{s} = A_{s1} + A_{s2}  (b4.6) 
Flowchart
Figure b43 resumes this design method for reinforcements of a Tsection in bending at ULS: