ABSTRACT
A significant amount of the bridges in the Italian road infrastructures were built in the period of strong economic development between the 1950s and 1970s. The most used technologies were certainly reinforced concrete (RC) and prestressed concrete (PC). The progressive development of degradation phenomena, the increase in loads and traffic volumes, and the approaching to the end of the service life for which they were designed require a careful assessment of the current level of safety and functionality. This work focuses on the proposal and the evaluation of a new consolidation system for prestressed concrete beams, to be used in the consolidation of girder bridges. The system consists of two arch-shaped steel trusses placed alongside the sides of the beam to be consolidated. The efficiency of the system with respect to parameters variability is described also focusing on the ratio between the load discharged by the consolidation system and the total applied load. Referring to a case study, the consolidation of a PC beam is presented adopting the proposed system with respect to the usually adopted external prestressing technique. The performance of the proposed retrofitting systems is also evaluated at increasing degradation levels. The cross sections properties of the steel arch shaped trusses are defined by means of a structural Multi-Object optimization process using Genetic Algorithm (GA), identifying the minimum steel consumption and the maximum stiffness of the retrofitting system.
