This standard provides guidelines for strengthening existing reinforced concrete structures using externally bonded Fibre Reinforced Polymer (FRP) composite systems. It covers material properties, design principles for flexural, shear, and axial strengthening, as well as crucial aspects of workmanship, quality control, and testing.
Provides guidelines for the use of FRP composites in strengthening existing concrete structures.
Quick Reference Values
Minimum substrate pull-off tensile strength1.5 MPa
Minimum corner radius for FRP wraps13 mm
Minimum concrete surface profile (CSP)CSP 3
Glass Transition Temp (Tg) requirementAt least 20°C higher than max design temperature
Environmental reduction factor C E for Carbon FRP (Interior)0.95
Key Formulas
f_fd = C_E * f_fu — Design tensile strength of FRP
V_f = (A_fv * f_fe * (sin(α) + cos(α)) * d_fv) / s_f — Shear contribution of FRP
ε_fe = E_c * ε_cu * ((f'_c)^0.5 / (n * E_f * t_f))^0.5 ≤ 0.9 * ε_fu — Effective strain in FRP for shear
Mn = Mn_o + ψ_f * M_frp — Nominal flexural strength of strengthened member
Practical Notes
Surface preparation is the single most critical factor for a successful FRP strengthening project. A clean, dry, and adequately roughened concrete surface (min. CSP 3) is essential to achieve the required bond strength.
The performance of FRP systems is sensitive to temperature. Ensure the glass transition temperature (Tg) of the epoxy resin is well above the maximum service temperature the structure will experience.
These guidelines are for strengthening structurally sound concrete. They are not a substitute for repairing heavily deteriorated, spalled, or crumbling concrete, which must be addressed prior to FRP application.