Cracking of concrete cover in FRP reinforced concrete elements under thermal loads

The effects of thermal loads on the structural performance of FRP reinforced concrete elements are analyzed in this paper. The difference in transverse coefficient of thermal expansion (CTE) between FRP and concrete causes the presence of tensile stresses within the concrete and, eventually, the formation of cracks when the temperature increases. As part of an inter-university experimental program, initial results are presented in the paper. They address the evaluation of temperature variations on concrete elements reinforced with AFRP and GFRP rebars, varying the thickness of the concrete cover and the shape of the cross-section, in absence of transverse reinforcement. Results obtained confirm the influence of temperature variations on the state of strain and stress within FRP reinforced concrete elements and the necessity of a minimum concrete cover to be provided in order to avoid the formation of through cracks. Comparisons between experimental and theoretical predictions, the latter obtained by means of analytical and numerical models, are presented. The progress of the experimental investigation will provide an opportunity to improve the effectiveness of theoretical models and their use for practical detailing.