PSI - Issue 78

Simone Reale et al. / Procedia Structural Integrity 78 (2026) 1657–1664

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The residual area in a given pit location A C,P can be estimated according to Equation (5) (Ghosh and Sood, 2016): , = [1− 2 ( ) 0 ][ , ( )− 02 4 ]+ , ( ) (5) Strategy 2 introduces the reduction of steel yielding strength f y , ultimate strength f u , cover concrete compressive strength f c and core concrete compressive strength f c ’ . Deterioration models developed by Du et al. (2005a) have been applied to estimate the time-variant values of f y and f u : , = (1 − 0.005 ) ,0 (6) , = (1 − 0.005 ) ,0 (7) In Equations (6)-(7), f y,0 and f y ,c are the yield strength in pristine and corroded condition, f u,0 and f u,c are the ultimate strength in pristine and corroded condition, and φ is the percentage mass loss of corroded reinforcement. φ can be estimated as per Equation (8): = 0 − , 0 ∙ 100 [%] (8) Where A 0 and A s,c are respectively the reinforcement area in pristine and corroded condition. The reduction of f c due to microcracks caused by the expansion of corrosion products is included through the model reported in (Coronelli and Gambarova, 2004). The time varying value of f c is computed through Equation (9): , ( )= 1+0.1∙( 1 ( 0 ) ) (9) where ε c0 is the strain at peak compressive stress and ε 1 is the average tensile strain in cracked concrete. ε 1 can be computed as per Equation (10), based on (Molina et al., 1993): 1 ( )= ∑ 2 ( −1) , ( ) 0 (10) where n bars is the number of compressed bars, b 0 is the section width in pristine condition, υ rs is the ratio of volumetric expansion of oxides and d rs,i (t) is the depth of corrosion attack on the i-th bar. The reduction of f c ’ due to the reduced confinement level f l ’ c is modeled according to (Andisheh et al., 2021): ′ = 0 (2.254√1+ 7.94 ′ − 2 ′ −1.254) (11) Strategy 3 includes reduction of steel ultimate strain ε su (Du et al., 2005b) and core concrete ultimate strain ε cu (Andisheh et al., 2021): , = (1 − 0.05 ) ,0 (12) =0.004+ 1.4 ℎ ′ (13) In Equations (12)-(13), ε su,0 and ε su,c are the steel ultimate strain in pristine and corroded condition, ε cu c is the core concrete ultimate strain in corroded condition, ρ s is the volumetric transverse reinforcement ratio of confined core, f yh is the yield strength of transverse reinforcement and ε su c is the ultimate strain of corroded transverse reinforcement.