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With 80% of European trade exchange and a key role for European defense, harbours play a key socio- economic role. Inspection of wharves is very expensive due to the relative inaccessibility of components (need of a boat, team …) and the economical impact (service breakdown). Harbor concrete structures are designed to fulfill their function during a long time period (50 to 70 years). For RC structures exposed to marine environments, chloride-induced corrosion leads to deteriorations that can be associated to different exposure conditions: tidal, splash and atmospheric. The on-site assessment of the corrosion condition of the reinforcement in concrete relies on a corrosion diagnosis, which consists in different techniques and among them non destructive techniques (NDT )such as half-cell potential, resistivity and corrosion measurements. Thus the added value of SHM and accelerated tests in laboratory can be analyzed by comparing the maintenance with SHM with an optimized maintenance planning based on NDT.

This paper concerns preventive maintenance strategy against reinforced concrete corrosion. Describing the spatial variability of concrete degradation is of utter importance in such a study. We propose in this study a method to improve spatial correlation characterization using limited quantity of measurements (only one trajectory). It is based on windowing method. We could obtain the distribution of values of the parameter of the continuous autocorrelation function when using the proposed method. The data used in this study were collected within the ANR- EVADEOS project. The parameters measured are: porosity, saturation degree, concrete density and carbonation depth. A preventive maintenance strategy should be supported by predictive models. We focused on concrete carbonation models. Sensitivity analysis of these models to input random fields (RF) is hence carried out. Results highlight which parameters should be stated as RF.

Tomorrow’s Megastructures exploitation will require robust management policies, including Non- Destructive Techniques measurements and Structure Health Monitoring. These inspections strategies already allow acquisition of large amounts of data at reasonable cost. However, the bigger the structure, the costlier the data collecting. This raises the question of spatial optimization, closely related to the determination of spatial variability. Related studies have so far characterized it using covariograms on raw data without paying attention to their conditions of validity. As this lack of rigor may lead to severe misestimating, we propose a mathematically rigorous spatial variability assessment procedure and apply it to measurements coming from the Île de Ré bridge diagnosis, performed during the DéCoF-Ré (Décision par diagnostic de Corrosion en toute Fiabilité sur le pont de l’île de Ré) project. This unique data set of resistivity and corrosion potential measurements allow us to begin a spatial variability database for marine concrete structures.

Tensioned textile membrane structures are now common in the field of construction and they are the subject of a standardization process to harmonize the design rules among Europe. The stiffness of the structure relies on the pretension of the membrane, which can be provided mechanically or pneumatically. The stiffness of pneumatic structures depends on the internal pressure. They are able to support external loads which are much more important than their own weight. A first reliability study is conducted on a two parallel inflatable beams structure, which can be used as a footbridge. The serviceability limit states (SLS) and ultimate limit state (ULS) are defined. The reliability analysis is conducted with the FORM method, providing reliability indices as well as sensitivity factors.

Main damage occurring on reinforced concrete (RC) structures can be attributed to the corrosion of the rebar. Chloride ions penetration and/or carbonation, as major causes of RC corrosion, are well understood for onshore structures. When dealing with structures in marine environment, more parameters must be considered, as the different exposure zones (tidal, splash and atmospheric) will have a significant influence on the corrosion behavior.This article deals with the corrosion diagnosis of the piers of the ile de Ré bridge. The objective is to provide an effective method to identify the different exposure zones based on the non-destructive measurements (half-cell potential) that are modelled taking into account the influence of the tide.

40th IABSE Symposium : Tomorrow's Megastructures, NANTES, FRANCE, 19-/09/2018 - 21/09/2018; For RC structures exposed to marine environments, chloride-induced corrosion leads to deteriorations that can be associated to different exposure conditions: tidal, splash and atmospheric. The on-site assessment of the corrosion condition of the reinforcement in concrete relies on a corrosion diagnosis which consists in different techniques and among them non destructive techniques such as half-cell potential, resistivity and corrosion measurements. Although the two first techniques are commonly used, variability and uncertainties in NDT condition assessment remain factors that need to be better understood in order to increase the reliability of the diagnosis particularly in the case of marine structures (in comparison with atmospheric structures for which literature is more important). The objectives of the Project DéCoF-Ré (2014-2017) were to study both the concrete durability and the corrosion state of the piers of the Ile de Ré bridge which is located in the French Atlantic coast. Concerning the corrosion study, visual inspections, rebar localization, half-cell potential mapping, electrical concrete resistivity mapping and corrosion rate measurements were performed during three years in order to analyse the influence of the measurement procedures, the investigated zones (pier number, side, height) and the environments (tide level, climatic conditions). This paper focuses on the resistivity measurements conducted with a four electrodes arrangement probe (Wenner type) on the piers of the Ile de Ré bridge using a vessel. Although resistivity values cannot directly provide an information on the passive/active state of the rebar because the measurement qualifies the electrical resistivity of the concrete cover (and not the resistivity of the steel/concrete interface which is usually obtained by Linear Polarisation Resistance measurements), it is a useful non destructive technique to point out the areas where the corrosion might be strongest. The purpose of this paper is to outline the errors made while measuring the resistivity given the uncertainty assessment based on both (i) the repeatability tests and (ii) the material local anisotropy and measurement's variability. Moreover, a model based on the evaluation of Probability of Wrong Assessment is proposed to help the owner of the bridge in taking a decision.

Spatial variability is an essential key in modeling material properties, loading or the deterioration process in structural engineering degradation. Non-destructive Testing (NDT) technique is a crucial tool to characterize this spatial variability. In this paper, we propose an original approach that enables to characterize the spatial variability of structure through discrete and limited measurements in efficient and accurate way. An adaptive approach based on two indicators errors is performed to model the quantities of interest. Firstly, an error indicator is run to estimate an accurate parameter of fluctuations using Maximum Likelihood Estimate (MLE) from a set of measurements. Secondly, the accuracy of the estimated moments of the field from the current number of measures is revised by analyzing the behavior of the second indicator. The advantage of this approach is that the spatial correlation is not neglected between measurements and the range of the correlation is given in good way within a desirable threshold. The potential of the presented approach is demonstrated through numerical examples with synthetic and experimental data.