Structural Safety Assessment of Existing Bridge Decks: Numerical Analysis Assisted by Field Test Results

The resilience of a metropolitan area relies on the structural safety of bridge structures that must be protected against any type of hazard. Indeed, bridges represent essential elements of the transportation system and play a crucial role in emergency situations for ensuring rescue activities. Many Italian bridges are approaching their natural service life and are affected by ageing and material deterioration (especially, corrosion of steel) due to the lack of periodical maintenance plans. Therefore, it is necessary to develop efficient and reliable procedures for the structural safety assessment of existing bridges. This work proposes an experimental-numerical methodology, illustrated in the context of a case study involving the prestressed concrete deck of the Longano viaduct (Sicily, Italy), which combines field test results (free vibration tests and static load tests) with numerical simulation. A nonlinear finite element model is calibrated based on field test results and used to explore the load-bearing capacity of the bridge deck at ultimate limit states under different hypothetical corrosion scenarios of the prestressing strands. The proposed methodology provides preliminary information on the structural health of existing bridge decks (under both serviceability and ultimate conditions) prior to performing extensive material test campaigns and can be applied to other similar bridges to rapidly detect vulnerable portions of a large infrastructure network.