PSI - Issue 84

Lorenzo Principi et al. / Procedia Structural Integrity 84 (2026) 73–80

78

Output Layer Neurons Hidden Layers Number Hidden Layers Neurons

5 1

Max iterations number

69

Batch size (*)

- -

27

Initial learning rate (*)

Activation function

Hyperbolic Tangent

Optimization algorithm

L-BFGS

(*) Only for ADAM and SGD algorithms

3.3.2. Performance Analysis In Step 2 of Phase III, the optimal ANN is evaluated for performance, as reported in Figure 3 and Table 8. The model attains an F1-score of 0.71, demonstrating robust performance across all classes. Table 8. Classification Report for CER. Class Precision Recall F1-score Samples L - - - 0 ML 0.86 0.86 0.86 7 M 0.69 0.77 0.73 26 MH 0.72 0.75 0.73 44 H 0.68 0.56 0.61 27 Metric Training Samples Test Samples F1-Score 0.79 417 0.71 104 Figure 3. Confusion Matrix for CER. 4. Case Study The ANN developed in Chapter 3 is applied to predict the CER along a road corridor traversing a seismically active region with heterogeneous hazard distribution. The dataset includes 95 bridges along the 95 km-long Italian State Highway 77 (SS77), which connects the Apennine Mountains to the Adriatic coast (Figure 4).

(a) (b) Figure 4. Location of the SS77 in Italy (in blue) (a), and its position within the regional road network of the Marche region (in red and black, respectively) (b). Bridge lengths range from 7 to 543 m, with 75% shorter than 200 m. Maximum spans vary from 5.5 to 77 m (mean 29.5 m), and most bridges have 1-5 spans (mean 4). Traffic volumes (ADT/ADTT) increase from the inland toward the coast (Figure 5a-b). P.R.C. decks, corresponding to bridges built between 1945 and 1980 under Bridge Design Code B, are most frequent, while newer steel-concrete bridges (built after 1980 under Bridge Design Code C) are mainly located inland (Figure 5c), both types predominantly employ beam schemes, with some culverts using slab schemes. Primary obstacles include roads and rivers, whereas natural discontinuities are more common inland (Figure 5d). All bridges accommodate loads up to 60 tons and provide alternative routes. Seismic design is more prevalent inland, where PGA increases from 0.15-0.175 g to 0.225-0.250 g (Figure 6e-f).