Extending the life of bridges with external tendons

Historically, expanding economies see a boom in the construction sector followed, some decades later, by issues associated with aging infrastructures. Sometimes, the bridges are performing as expected but a change in the codes or on the traffic loads trigger the need for wider or stronger structures. When this happens, the old paradigm of building bigger and more modern bridges is no longer valid, as we face one of the biggest challenges of our history: climate change. Sustainability is, or hopefully it will soon be, the main criteria when it comes to deciding how to intervene on an aging bridge. It is widely agreed that extending the life of an existing structure is more sustainable than building a new one.

Amongst the many ways of retrofitting a bridge, external tendons made of prestressing steel are a versatile, well proven, and efficient way of strengthening existing structures, whether these were originally fitted with external tendons, or not. For bridges with damaged existing external tendons, specific replacement methods have been developed.

In this paper, we will present a selected number of bridges where external tendons have been added or replaced, focusing on the lessons learnt whether for future strengthening projects or for the design of new structures.