Calculation of Capacity against Bending based on CNRT-DT200/NTC-18

The capacity Moment is calculated following the equations of paragraph 4.1.4. The maximum design strain in the FRP is calculated according to the equation below:

Where

• ε_sy is the design yield strain of the steel reinforcement
• ε₀ is the maximum tensile strain before the FRP is applied (see section 4.2.2.2)
• E_f is the elastic modulus of the FRP
• and f_fdd,2 is calculated according to the equation below

Where

• k_g,2 is a corrective factor equal to 0.10mm
• k_q is a coefficient equal to 1.25 for distributed loads and 1.0 for all other configurations
• FC is a confidence factor taken from section 3.3.3(6)
• F_c is the concrete compressive strength and fctm is the concrete tensile strength
• t_f is the thickness of the FRP laminate

Using the maximum design strain calculated above the Moment Capacity (M_u) of the FRP strengthened section is then calculated.