PSI - Issue 78

Marco Gaetani d’Aragona et al. / Procedia Structural Integrity 78 (2026) 968–975

971

where F y and F u are the yield load and ultimate load of the rebar, respectively. β Fy and β F u are empirical factors, that depends on the average corrosion degree Δm, the nature of exposure, the typology of bar and its position with respect to concrete and the kind of corrosion attack. In a similar way, a reduction of the ultimate strain alternative exponentially decaying formulation: ( ) * exp su su su m     −   = (6) Regarding the concrete, the volumetric expansion of corroded bars generates tensile strain orthogonal to the principal compression stress direction, longitudinal microcracks and reduction of compressive strength. In particular, the formulation proposed by Coronelli & Gambarova (2004), modified by De Domenico et al. (2023): Where k is an empirical parameter influenced by the diameter and surface roughness of the reinforcing bars, ε c0 is the strain at peak compressive, while b₀ represents the original section width prior to corrosion. The variable n corresponds to the number of cracks (typically equal to the number of bars in the compressed region) and w cr indicates the average width of corrosion-induced cracks. This crack width is governed by multiple factors, including the expansive volume of corrosion products, corrosion level, concrete cover-to-bar diameter ratio, concrete strength, and degree of confinement. In this study, w cr is estimated using the empirical formulation by Andrade et al. (2016), which accounts for the effects of concrete tensile strength, corrosion level, and geometric characteristics such as cover thickness relative to bar diameter. 4. Flexural behavior of corroded RC members Several approaches have been proposed to numerically simulate corrosion in RC columns with flexural behavior (De Domenico et al., 2023; Di Carlo et al., 2017). In this section, the fiber-based modeling strategy proposed in De Domenico et al. (2023) is adopted. In this strategy, the degradation of material parameters due to corrosion is implemented at the fiber level via suitable stress-strain laws depending on the position of the fiber in the cross section. The concrete cross-section is discretized into three different zones adopting distinct constitutive relationships (Fig. 2): (a) the concrete cover (deteriorated), (b) the ineffective confined concrete (deteriorated), and (c) the effective confined concrete (not deteriorated). Both concrete cover and ineffective confined concrete (delimited by a width of 2  from the internal side of stirrups) are subjected to corrosions, thus stress-strain law are obtained considering strength and ductility modification parameter  fc for the corresponding section fibers. * 0 0 c 1 1 c c f  =  c c cr f f f n w  k b  = +  (7)

Corroded longitudinal rebar

Steel02

2 φ

Concrete02

concrete cover ineffective confined concrete

Concrete04

2 φ

b c

effective confined concrete

Concrete04

stirrup

h c

(a)

(b)

Fig. 2. (a) discretization of the corroded section with (b) corresponding cross-sectional fiber model.