Numerical Validation on Post-Fire Performance of GFRP SIP Formwork for Concrete Bridge Decks at High Temperature

This study focuses on the validation of a finite element (FE) model developed in ABAQUS/Standard to simulate the post-fire behavior of concrete bridge decks incorporating glass fiber-reinforced polymer (GFRP) stay-in-place (SIP) formwork. The model integrates thermal and structural analyses to simulate the coupled behavior of the hybrid system under fire exposure. Validation against experimental data demonstrated strong correlation in thermal distribution, load-deflection response, failure mechanisms, and crack propagation patterns. The FE model accurately predicted internal temperature evolution with less than 4% deviation from experimental peak values. Structural response predictions under both ambient and post-fire conditions showed less than 10% error in ultimate load and within 15% for displacement. Although the simulation was constrained by the inability to implement GFRP failure criteria for solid elements, the model effectively captured overall mechanical behavior. Interestingly, fire-damaged specimens exhibited a slight increase in ultimate load, suggesting a beneficial restressing effect from thermal expansion and contraction of GFRP. The developed FE framework offers a reliable tool for performance assessment and design optimization of GFRP-concrete composite bridge decks subjected to fire.