PSI - Issue 84

Paolo Andrea Miglietta et al. / Procedia Structural Integrity 84 (2026) 1111–1118 P.A. Maglietta et al. / Structural Integrity Procedia 00 (2026) 000–000

1116

6

At each time step (from year 0 to 100), concrete and steel mechanical properties were modified as a function of damage level, as described in Section 2. In Fig. 2a-c, the M- χ relationships up to the ultimate limit state at different time intervals are provided. The obtained curves related to the 16 th , the 50 th and the 84 th percentiles are reported, sampled from the 81 combinations obtained for each year considered. A significant reduction of the flexural performance is detected regarding P16 results (Fig. 2a), starting from the 70 th year, due to the combined effect of rebars corrosion and concrete cracking. Conversely, the curves associated with both P50 and P84 (Fig. 2b-c) remain substantially unchanged. The V- γ relationships for the same time steps are shown in Fig. 3a-c. A marked reduction in both ultimate shear and corresponding strain is observed for P16 (Fig. 3a) curves, due to the pronounced influence on the stirrups corrosion on the shear strength. In contrast, only a slight decrease in V u and γ u is observed in P50 curves (Fig. 3b), whereas P84 curves (Fig. 3c) result to be unchanged throughout the entire service life.

Table 1. Percentile values sampled from statistical distributions of random input parameters. Parameter (symbol) Units 16 th percentile 50 th percentile 84 th percentile Relative humidity (RH) % 67.00 73.00 80.00 Rainfall days per year (n RD ) - 38.00 47.00 57.00 Concrete cover thickness (c) mm 27.00 35.00 43.00 Concrete compressive strength (f c ) MPa 53.00 58.00 63.00

Table 2. Values of deterministic input parameters. Parameter Units Value

Parameter

Units

Value

Steel yield strength (f y )

MPa

480.00 Water/cement ratio (w/c)

-

0.50

Steel ultimate strength (f t ) MPa

570.00

Thickness of porous layer (δ 0 ) μm

10.00 28.00

Steel ultimate strain (ε u )

%

10.00 20.00

Time of curing (t 0 ) CO 2 concentration

days kg/m

Temperature (T)

°C

0.0082

3

Fig. 2. Time-dependent M- χ relationships of the pier cross -section: (a) 16 th percentile (P16); (b) 50 th percentile (P50); (c) 84 th percentile (P84).

Fig. 3. Time-dependent V- γ relationships of the pier cross -section: (a) 16 th percentile (P16); (b) 50 th percentile (P50); (c) 84 th percentile (P84).