Bruno Capra

The αδ method for modelling expert judgement and combination of non-destructive testing tools in risk-based inspection context: application to marine structures

Owners of civil infrastructure base their maintenance decision schemes mainly on both structural integrity assessment and consequence analysis. Some inputs come from information collected by inspections with non-destructive or destructive tools. Uncertainties and errors of measurement can lead to bad decisions but are rarely integrated into the decision process. Currently, risk-based inspection (RBI) provides the basic concepts for optimising the maintenance plans of existing structures while insuring satisfactory safety and availability of the structure during its service life. It relies both on reliability computations and probabilistic modelling of inspection results. This last point leads to introduce the probability of detection and the probability of false alarms that are usually considered as parameters in RBI. However, when data from inter-calibration campaigns are available, the whole receiver operating characteristics curves should be used. Then, the comparison of non-destructive testing tools in terms of cost or benefit is difficult as well as the method for optimising a given technique. This article presents the αβ method that gives a new performance indicator in this context. It is applied to the field of inspection of harbour structures.

Time-function reliability of harbour infrastructures from stochastic modelling of corrosion

This article summarises research led during the second phase of the French GEROM (risk management of maritime and river harbour structures) project in order to quantify the risks associated with vulnerable structures. A reliability analysis is applied here to steel sheet-pile seawalls. For this purpose, a stochastic (spatial-temporal) model of steel corrosion is proposed, based on a statistical analysis of data collected from wharves located in several French ports and of various ages. The predictions obtained from the corrosion model are then integrated into a reliability analysis to carry out a time-function reliability analysis of corroded harbour structures. The results are then compared and analysed both in terms of reliability and sensitivity to basic random variables. This approach allows suggesting preliminary requirements about maintenance optimisation.

Simulation par éléments finis du comportement mécanique de poutres en béton corrodées par un milieu marin

ABSTRACT This article presents the models and the assumptions retained by OXAND within the framework of the Rances beams benchmark. This project deals with the numerical simulations of the mechanical behaviour of corroded beams. Numerical modelling is presented for two computer codes (Cast3M and Atena). The comparison between numerical and experimental results is presented for the two codes. The influence of various parameters on the results of simulations is also approached.