Calculation of Capacity against Bending based on ACI 440/ACI 318

The flexural strength φΜ_nof the FRP strengthened reinforced concrete members should satisfy the following requirement:

where M_u is the ultimate moment demand resulting from combined gravity and seismic demands.

The nominal flexural strength of the section with FRP external reinforcement is calculated through the following relationship

Where:

• β₁ is calculated through table 16.3c of ACI 440
• f_fe is the effective stress in the FRP calculated according to equation (10.2.6)
• φ is the strength reduction factor calculated using the equation (10.2.7) of paragraph 10.2.7 of the ACI 440.
• ψ_f is a reduction factor for the FRP with a recommended value equal to 0.85