PSI - Issue 84

Rosario Montuori et al. / Procedia Structural Integrity 84 (2026) 967–974

972

%Obs = observable percentage of the element. Based on the indices associated with each element constituting the bridge structure, it is then possible to determine two global indices: the Maximum Damage Index (MDI), corresponding to the most damaged element of the structure, and the Global Damage Index (GDI), providing an overall measure of the damage condition of the entire bridge structure. They are expressed as: = [ ] [ ~ ] (3) = ∑ ∑ [ ~ ] (4) Level 2 Local structural assessment The local structural assessment makes it possible to assign a weight to the intrinsic characteristics of the structure in the risk evaluation, independently of the specific defect patterns and structural issues detected during inspections. This assessment is based on three coefficients: Structural age coefficient, defined as a function of the number of years (n) the structure has been in service: = { . < . + − < < > (5) Structural scheme coefficient, defined as a function of the structural typology: ={ 1 0.95 ℎ (6) Sensitivity to deterioration coefficient, defined as a function of the structural material: ={ 1 − 00..9957 (7) The structural age coefficient increases with the service life of the bridge structure, reflecting the increased likelihood of deterioration phenomena in older structures. The structural scheme coefficient differentiates between statically determined and statically indeterminate structural systems, assigning a lower value to the latter due to the distribution effects. The sensitivity to deterioration coefficient accounts for the vulnerability of the structure to degradation mechanisms as a function of the construction material, with particular attention to masonry structures, which are generally less sensitive to deterioration processes. Level 3 Territorial assessment The territorial assessment is independent of both the intrinsic structural characteristics of the bridge structure and its current damage condition. Instead, it considers the role assumed by the structure within the territorial and road network context in which it is located. This assessment is based on two specific indices: the Importance Coefficient and the Indirect Damage Coefficient. The Importance Coefficient depends on both the traffic intensity coefficient K t and the alternative route coefficient K pa and is defined as: = . + + [ . ~ ] (8)