Fire performance simulation of insulated FRP-strengthened RC members

Externally bonded (EB) fiber-reinforced polymer (FRP) systems have become a widely used technology for strengthening of reinforced concrete (RC) structures. However, in case of indoor applications such as building structures, a signficant concern with the polymer matrix's poor fire performance (flammability, smoke generation, and rapid degradation in mechanical properties). To achieve structural fire-resistance ratings as specified in building design codes, an insulatin layer ofer needs to be provided. This presentation reports a three-dimensional finite element (FE) approach for the fire performance simulation of insulated FRP-strengthened RC beams. The proposed approach gives careful considerations to the constitutive modeling of concrete, steel, and FRP as well as the bond-slip behavior of FRP-to-concrete and steel-to-concrete interfaces. Comparisons between FE predictions and existing test data are prepsented to demonstrate the accuracy of the proposed FE approach. Numerical results obtained with the present FE approach show that the assumption of perfect bonding between FRP and cocnrete as adopted in previous numerical appraoches leads to underestimations of deflections and thus unsafe predictions of fire resistance. The validated FE approach was also used to examine how the degradation of the FRP-to-concrete interface affects the fire performance of the beam. The FE approach presented in the paepr can be directly applied in performance-based fire safety design, or in parametric studies aimed at developing simplified design rules.