Durability of pultruded fibre-polymer composite structures under various environmental conditions over a period up to 25 years

The durability of two different types of structures and deck units composed of glass fibre-polymer composites exposed to various environmental conditions were investigated. The Pontresina Bridge and Eyecatcher Building were exposed to an alpine and urban climate for 25 years, respectively, and a pultruded deck unit was immersed in water for 8 years. The assessment included visual inspection of adhesively bonded and bolted joints, and fibre blooming, full-scale static loading, and investigations of coupons specimens taken from the Pontresina Bridge and the deck unit. Adhesively bonded joints did not show any visual damage. The stiffness of the Pontresina Bridge remained unchanged over 25 years. The elastic modulus of the coupons from both showed no significant decrease. However, the tensile strength in the coupons exposed to Alpine climate decreased to approximately 70% of its initial value after 25 years of service and reduced to 64% after 8 years of water immersion. A logarithmic model was developed to predict the reduction in strength over 50 years of service, however long-term data is still required to validate these predictions.