PSI - Issue 78

Andrea Dhima et al. / Procedia Structural Integrity 78 (2026) 1366–1373

1370

* f c

1

(2)



= =

2

Xn



f

bars

c

1

K + 

b c 

2

where f c c is the uncorroded compressive strength, K is a constant equal to 0.1, X is the corrosion penetration, b is the width of the cross–section, ε c2 is the yield strain of the concrete, and n bar s is the number of bars in the compression zone. For the deteriorated compressive strength of the concrete, an average value was considered for the sections subject to corrosion, using the following formulation: * is the corroded compressive strength, f

fc

A fc A fc A CNC CNC CC CC CCE CCE  + +



*

(3)

f c

=

A CNC ACC ACCE + +

where β is the ratio of the compressive strength of the un-degraded concrete to that of the degraded concrete, fc CNC is the un-degraded compressive strength of the unconfined concrete, fc CC and fc CCE are the un-degraded compressive strength of the confined concrete in the degraded and un-degraded areas, respectively, A CNC is the area of degraded unconfined concrete, A CC is the area of degraded confined concrete, and A CCE is the area of effective confined concrete not subject to degradation. 4. Analysis of corrosion scenarios The detailed assessment carried out in Section 2 according to the Italian guidelines does not account for the potential reduction in structural capacity induced by the corrosion of the reinforcement bars. To evaluate the influence of this degradation in the girder beams under traffic loads, three corrosion scenarios were analysed: 1) Uniform degradation of confined and unconfined concrete, affecting only the passive reinforcement. 2) Nonuniform degradation of confined and unconfined concrete, affecting both the passive and prestressing reinforcement. 3) A specific degradation scenario corresponding to the case study under analysis as identified during on-site inspections. These scenarios are presented in Figure 3 with the corresponding M-N domains. The adopted method follows the approach proposed by (Di Sarno & Pugliese, 2020), which considers the effective properties of the deteriorated steel reinforcement and concrete, according to Equations (1) and (3), respectively.

(a)

(b) (c) Fig. 3. Effect of corrosion on girder sections: (a) scenario 1; (b) scenario 2, (c) scenario 3.

In each degradation scenarios, the depth of corrosion penetration X was gradually increased from 0.5 mm to 2.0 mm. This range was chosen as the compressive strength of deteriorated concrete shows an exponential reduction in the presence of high corrosion penetration in reinforced bars (e.g., a reduction of 80% for a penetration of 2 mm). The progressive reduction in flexural capacity is presented in Table 3.