Robustness Evaluation of Existing Valuable Structures: Study of the P.L. Nervi Autogrill Motta on the A4 Motorway in Italy

The preservation of valuable heritage structures increasingly requires methodologies that ensure structural safety without compromising architectural authenticity. This paper develops and applies a multistep methodology for robustness assessment to the Autogrill Motta, an iconic reinforced concrete building designed by Pier Luigi Nervi in 1965–1967 and spanning across the A4 motorway in Italy. Two complementary scenarios were considered: (1) a threat-independent extreme event, analyzed through the alternate load path (ALP) method, and (2) a threat-dependent scenario simulating progressive reinforcement deterioration due to corrosion. Linear finite-element models and nonlinear simulations were used to capture redistribution capacity and progressive damage mechanisms. Results showed that the structure, although safe under current loading, exhibits vulnerability to extreme events but can sustain up to 50% reinforcement loss without collapse, reflecting its inherent redundancy. These findings highlight the resilience of Nervi’s design and the importance of robustness evaluation as a tool for safeguarding heritage reinforced concrete structures. More broadly, the study stresses the need for dedicated guidelines addressing robustness in existing historic buildings, aligning safety requirements with preservation strategies based on minimum intervention.