Modeling of post-fire stiffness of E-glass fiber-reinforced polyester composites

A new model is proposed to estimate the post-fire stiffness of FRP composites after different fire-exposure times. The model considers the E-modulus recovery of the material if cooled down from temperatures between glass transition and decomposition during the fire. Furthermore, based on this model, the through-thickness temperature gradients and remaining resin contents (RRC) can be calculated. Post-fire stiffness estimated by the new model and refined two- and three-layer post-fire models based on temperature or RRC criteria was compared with experimental results. A good agreement of calculated and measured post-fire stiffness of two full-scale cellular GFRP panels subjected to mechanical and thermal loading was found for fire-exposure times up to 2 h.