The PARC_CL 2.1 Crack Model for NLFEA of Reinforced Concrete Elements Subjected to Corrosion Deterioration

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This work aims at investigating the seismic response of existing reinforced concrete core‐wall buildings with corroded bars erected in the marine environments, with the main focus on the dependency of seismic fragility curves on aging and degradation effects caused by environmental actions. The structural capacity is predicted by nonlinear finite‐element analyses, where the effect of chloride corrosion is implemented within the framework of PARC_CL_2.1 crack model. The proposed methodology is applied to a pre‐code six‐story reinforced concrete (RC) building with moment‐resisting (MR) frames and an internal core assumed as a testbed. For a given exposure class, pushover analyses are performed for different ages of the building. Time‐dependent fragility curves are then obtained through a procedure based on incremental static analysis. Different corrosion scenarios are assessed by considering deterioration effects applied either on the sole RC walls or on both walls and columns. The obtained results highlight that time‐dependent fragility curves are strongly affected by corrosion, therefore the date of construction should be considered in seismic risk mapping, not only for evaluating the effect of obsolete standard codes used in the design but also in terms of damage induced by aging and deterioration.

Section: Modeling Of Corrosion Effects In Rc Wallsmentioning

confidence: 99%

Section: Modeling Of Corrosion Effects In Rc Wallsmentioning

confidence: 99%

Section: C(xt) [%]mentioning

confidence: 99%

Section: Case Study Building and Modeling Assumptionmentioning

confidence: 99%

C (x, t) = C_{i} + (C_{italicsa} - C_{i}) [1 - \erf (\frac{x}{2 \sqrt{D_{cl} t}})],

Section: Case Study Building and Modeling Assumptionmentioning

confidence: 99%

See 3 more Smart Citations

Time‐dependent seismic fragility curves for existing RC core‐wall buildings exposed to corrosion

Michelini

Belletti

Franceschini

et al. 2022

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Toward the definition of equivalent damage parameters for the assessment of corroded RC structures

Casprini

Passoni

Marini

et al. 2022

The effects of reinforcement corrosion need to be included in the assessment of existing Reinforced Concrete structures for a reliable evaluation of the structural performances over time and a correct choice of the renovation strategy. The DEMSA protocol proposes straightforward tools available to professional engineers, enabling the calibration of equivalent damage parameters able to describe corrosion effects starting from environmental easy-measurable conditions. Guidance to implement the equivalent damage parameters describing corrosion effects at a sectional level in the structural analyses is provided. Then, a simplified approach to model the corrosion attack distribution along the bar length is proposed. Finally, nonlinear static analyses are carried out on reference RC frames subjected to different corrosion patterns by adopting fiber modeling technique, to show how the equivalent damage parameters allow detecting the impact of corrosion effects on the structural performances, in terms of internal actions distribution, reduction of stiffness, strength, and ductility.

Capacity assessment of uncorroded and corroded dapped‐end beams by NLFE and strut‐and‐tie based methods

Belletti,

Calcavecchia,

Ferretti

et al. 2024

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The verification of dapped‐end beams degraded by corrosion is a problem, especially for existing bridges in service. This paper proposes a nonlinear finite element (NLFE) modeling procedure and a simple strut‐and‐tie based procedure for predicting the response of dapped‐end beams subjected to chloride corrosion. Firstly, the finite element modeling strategy, based on the adoption of multilayer shell elements and the PARC_CL 2.1 crack model is described. Then, the degradation effects on concrete, rebars, and steel‐to‐concrete interaction are defined as a function of the propagation period of corrosion. In particular, the effects of corrosion on the reinforcement are modeled by applying a reduction of tensile strength that considers for both the reduction of cross‐section and the ultimate strain caused by pitting. Concrete splitting cracking due to volume expansion during rust formation is modeled by reducing the mechanical properties of concrete. Corrosion effects in steel‐to‐concrete interaction are modeled by applying a bond strength decay to the spring elements connecting corroded rebars—modeled with truss elements—and concrete multilayer shell elements. The proposed finite element procedure is used to study two scenarios based on different spatial distributions of corrosion‐prone areas. Subsequently, a simplified analytical approach based on the strut‐and‐corroded tie method—called S&CT method—is proposed and compared with the finite element outcomes. Finally, the validations of the two proposed methods are presented with respect to a corroded dapped‐end beam, showing that corrosion of rebars affects the resistance mechanisms of the dapped‐end beam, by reducing both resistance and ductility. The proposed simplified analytical S&CT method provides conservative and safe results compared to the numerical NLFE model and to experimental data.