Proposal for reinforcement of concrete bridges using external pretension techniques

Abstract

The aging of infrastructure and the increase in vehicular loads, which often exceed design forecasts, represent a critical challenge for the management of concrete bridges both nationally and internationally. This study proposes and experimentally evaluates a strengthening technique for bridge decks, based on the combination of external prestressing and the addition of metal elements. The main objective is to restore and enhance the load-bearing capacity of damaged or deficient structures efficiently and with minimal traffic disruption. The methodology involved constructing a full-scale model of a typical deck, consisting of prestressed girders and a concrete slab. This model was subjected to an accelerated aging process through cyclic loads that induced a controlled cracking state, simulating in-service damage. Subsequently, it was repaired and strengthened by applying an external prestressing system with an effective force of 28 tons, complemented by metal stiffeners and deviators. The results of the bending tests up to failure demonstrated an increase in the ultimate resisting moment of more than 80% compared to the unreinforced model, significantly exceeding the initial target of 33%. It is concluded that the proposed technique is highly effective in recovering and substantially improving the load capacity of bridge decks, offering a viable and rapidly executable solution for adapting them to the demands of modern freight trains.