Retrofit of Gerber saddles in RC bridges: review and application of post-tension techniques

Numerous reinforced concrete road bridges have adopted the Gerber scheme due to their inherent advantages, featuring Gerber saddles (or half-joints) as critical structural components. Despite these benefits, this type of bridge faces certain drawbacks, primarily related to Gerber saddles deterioration, which leads to issues like reinforcement corrosion, concrete cracking and spalling. As a result, ensuring necessary safety standards may require the implementation of specific retrofit interventions for many bridges over time. The paper initially outlines retrofit techniques reported in the literature. Subsequently, numerical simulations assess the efficacy of a particular technique employing post-tensioning intervention, chosen for its practicality. Advanced nonlinear finite element models analyse the effects of post-tensioning on the load-bearing capacity of a selected Gerber saddle. This analysis includes simulated chloride-induced corrosion scenarios to determine optimal prestress levels for desired performance enhancements.