Strengthening of the Riddes Viaduct Through UHPFRC-Based Rehabilitation

Abstract

Built in the mid-1970s, the Riddes viaduct is an important viaduct in the Canton of Valais in Switzerland. Thorough inspection of the viaduct revealed structural deterioration of concrete due to alkali–aggregate reaction, as well as corrosion of the prestressing tendons. In an effort to restore the structural integrity of the viaduct, a retrofit intervention that consists of adding a 50 mm layer of an Ultra-High Performance Fibre Reinforced Concrete (UHPFRC) to the deck was proposed. The layer is characterized by its low permeability and excellent mechanical properties. The contribution of the overlay to the load-carrying capacity and stiffness of the viaduct was investigated through a continuum finite element model. Results of the model revealed that the UHPFRC layer significantly enhances the flexural and torsional strength and stiffness of the box girder and ameliorates tensile cracking. The retrofit intervention was deemed beneficial, and the rehabilitation process was carried out.