The Rehabilitation of Segmental Bridges Subjected to Time-dependent Deflections Through Additional Prestressing

Segmental bridges built by cantilevering with in-situ casting in the ‘60s-‘80s of the XX Century present a central hinge on the main span or a central simply supported span between the two cantilevers (drop-in span). Due to time-dependent phenomena like creep of concrete and to unexpected loss of prestressing, several bridges of this typology show an abnormal deflection at hinges causing discomfort of traffic as well as insufficiencies of checks at Service and Ultimate Limit States. Moreover, these bridges are today at the end of their nominal service life, impacting significantly on Italian road network. A methodology for retrofitting these bridges by partial recovering of deflection and overall strengthening is proposed through the application of additional prestressing, especially in segmental bridges with variable box cross-section. The proposed solution supplies a global rehabilitation strategy aiming to improve the performance of the bridge, providing robustness and increasing of the service life.