Calculation of Capacity against Bending based on Fib90/EC8

The bending moment capacity of the FRP strengthened columns and beams is computed according to the 6.2.1.3.1 paragraph of Fib 90. In particular, the stress in the FRP at the ultimate limit state (effective stress) is calculated as:

Where

(a) f_fbd,IC is the design value of the FRP bond strength corresponding to the intermediate crack debonding calculated from the equation below

The parameters k_cr,k, k_k, and k_b in the above equation are taken according to sections 5.3.2.3 and 5.3.3.1 of fib90 while E_f is the Elastic Modulus of the FRP in MPa, f_cm is the concrete strength in MPa and t_f is the FRP thickness in mm.

(b) f_fd is the design tensile strength of the FRP.

Using the effective stress calculated above the Moment Capacity (M_u) of the FRP.