This study introduces the Interdependent Network Design Problem (INDP), concerned with defining the minimum-cost reconstruction strategy of a par

International audienceCorrosion induced by chloride ions has become a critical issue for many reinforced concrete structures. The chloride ingress into concrete has been usually simplified as a diffusion problem where the chloride concentration throughout concrete is estimated analytically. However, this simplified approach has several limitations. For instance, it does not consider chloride ingress by convection which is essential to model chloride penetration in unsaturated conditions as spray and tidal areas. This paper presents a comprehensive model of chloride penetration where the governing equations are solved by coupling finite element and finite difference methods. The uncertainties related to the problem are also considered by using random variables to represent the model's parameters and the materials' properties, and stochastic processes to model environmental actions. Furthermore, this approach accounts for: (1) chloride binding capacity; (2) time-variant nature of temperature, humidity and surface chloride concentration; (3) concrete aging; and (4) chloride flow in unsaturated conditions. The proposed approach is illustrated by a numerical example where the factors controlling chloride ingress and the effect of weather conditions were studied. The results stress the importance of including the influence of the random nature of environmental actions, chloride binding, convection and two-dimensional chloride ingress for a comprehensive lifetime assessment

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Microbiologically induced deterioration (MID) causes corrosion of concrete by producing acids (including organic and inorganic acids) that degrade concrete components and thus compromise the integrity of sewer pipelines and other structures, creating significant problems worldwide. Understanding of the fundamental corrosion process and the causal agents will help us develop an appropriate strategy to minimize the costs in repairs. This review presents how microorganisms induce the deterioration of concrete, including the organisms involved and their colonization and succession on concrete, the microbial deterioration mechanism, the approaches of studying MID and safeguards against concrete biodeterioration. In addition, the uninvestigated research area of MID is also proposed.

Structural deterioration is becoming a major problem when considering long term performance of infrastructures. The existence of a corrosive environment, cyclic loading and concrete cracking cause structural strength degradation. The interaction of these conditions can only be taken into account when modeling the coupled action. In this paper, a new model to assess lifetime of RC structures subject to corrosion-fatigue deterioration processes, is proposed. Separately, corrosion leads to cross section reduction while fatigue induces the nucleation and the propagation of cracks in steel bars. When considered together, pitting corrosion nucleates the crack while environmental factors affect the kinematics of crack propagation. The model is applied to the reliability analysis of bridge girders located in different chloride-contaminated environments. Overall results show that the coupled effect of corrosion-fatigue on RC structures affects strongly its performance leading to large reduction in the expected lifetime.

International audienceChloride ingress is one of the major causes of reinforced concrete (RC) deterioration. Free chloride induces the corrosion of rebars, reducing the material strength, and therefore, the structural behav- ior. This paper highlights the importance of chloride content measuring, and also summarizes the state of the art of non-destructive and in situ techniques for measuring chloride content into con- crete structures. These techniques have been developed over the past twenty years, and they have been shown as good alternatives in durability field. They are based on three methods: electrical resistivity (ER), ion selective electrode (ISE) and optical fiber sensors (OFS)

a b s t r a c tReinforced concrete (RC) structures are subjected to environmental actions affecting their performance, serviceability and safety. Among these actions, chloride ingress leads to corrosion and has been recognized as a critical factor reducing service life of RC structures. This paper presents a stochastic approach to study the influence of weather conditions and global warming on chloride ingress into concrete. The assessment of chloride ingress is carried out on the basis of a comprehensive model that couples the effects of convection, chloride binding, concrete aging, temperature and humidity. A simplified model of temperature and humidity including seasonal variations and global warming is also proposed in this work. Three scenarios of global warming are defined based on: gas emissions, global population growth, introduction of new and clean technologies and use of fossil sources of energy. The proposed approach is illustrated by a numerical example where the preliminary results indicate that climate changes may yield to significant lifetime reductions.