Structural assessment of prestressed beams with natural corrosion

An experimental campaign carried out on prestressed bridge beams corroded in a marine environment is analyzed in order to understand the failure modes related to the deterioration phenomena and setup models for capacity assessment. Three main failures modes were identified: shear in the web, shear failure in corroded zones with prestress loss and flexural failure for corroded strands in tension; this last mode becomes dominant for increasing corrosion. A truss model was used for flexure and shear resistance, considering the presence of both bottom pretensioned strands breaks and a draped post-tensioned tendon cuts. The development of new anchorage at the sides of the damaged zones of the strands was modeled. Corrosion effects are modeled reducing the reinforcement cross-section and bond, and modifying the prestressing distribution and the truss angle for shear. The accuracy of the model predictions relies on the corroded cross section loss input. In the light of the comparison of test and models results a methodology setup in the literature is here extended with scenarios considering higher levels of corrosion damage.