Suspension bridges are highly nonlinear structures in which the live load distribution among its members is dependent on their current stress. As such, a proper, accurate model of the bridge in its current state is needed to adequately determine its ability to withstand the design loads. The combination of topographic measurements, impact testing on cables and OMA can be used to update the model used in design with real data, which can validate (or counter) the assumptions made.

This paper presents a case study of a suspension bridge in Argentina. The bridge had been retrofitted to carry higher dead loads, and the owner requested the cables to be measured and tensioned if necessary, following broad acceptance criteria. With no previous data nor design targets, an experimental campaign was carried out to determine the current cable tensions and the dynamic properties of the bridge, which were then used to update a numerical nonlinear model originally used for strength verification. Structural analysis using the updated model differed greatly from the results with the original version, highlighting the importance of considering as-built conditions and establishing appropriate acceptance criteria.

Further discrepancies and structural defects found during the experimental campaign also underscored certain limitations of models typically used for structural analysis in the design or verification stages. A higher level of detail may be needed in digital twin applications in order to fully incorporate all data collected, as otherwise crucial details which relate to structural safety may be ignored.