Reinforced concrete (RC) is a material widely used in the construction of civil engineering facilities because of its high durability. However, there are some environmental actions that can affect considerably their performance, serviceability and safety. This study will focus on the behaviour of offshore RC structures subjected to chloride ingress. RC for these applications will be placed in a severe environment characterised by complex mechanical actions (cyclic loading) and mechanisms of degradation (corrosion, fatigue, bio colonisation, etc.), which significantly affect their durability and increases reinforcement corrosion initiation risks . The corrosion can affect the service capacity and safety of RC resulting in significant inspection, repair and loss of production costs .
Description du poste
In this context, a comprehensive lifetime assessment of corrosion initiation risks will be crucial to optimise the durability performance of RC under these conditions. Under offshore conditions, the RC components will be subjected to complex cyclic mechanical loading generating multiaxial stresses of varying amplitude and with various stress ratios. These stresses will be characterised by very high load frequencies [3,4] and produce concrete cracking. In parallel, chloride ingress from the surrounding environment leads to corrosion initiation when a significant amount of chlorides reaches the reinforcing bars or tendons [5–8]. Chloride ingress could be accelerated in a cracked concrete  and therefore produce premature corrosion initiation. Corrosion will generate a significant reduction of structural lifetime, increase maintenance costs and compromise structural serviceability and safety [2,10].
The main objective of this study will be to use the domain decomposition technique to model chloride ingress in sound and cracked reinforced concrete structures subjected simultaneously to several exposure zones. The first part of this work will focus on a literature review and modelling of chloride ingress mechanisms in sound concrete. A two-dimensional numerical model  developed in FreeFEM is available for this task. The coupling of this model with the domain decomposition algorithm available on FreeFEM will be the main objective second part of the study. Finally, the study will include the effects of concrete cracking on the chloride ingress process by considering that concrete cracking will affect the concrete diffusivity.
The main outcomes of the study will be disseminated throughout publications in journal papers and communications in scientific conferences. This work will be carried out in the framework of the project BUENO (Reinforced concrete for floating wind turbines) funded by the Pays de la Loire Regional Council at the Research Institute in Civil and Mechanical Engineering, University of Nantes, France.
Modalités de candidature
Jusqu’au 26 mars 2020