International audienceThis 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
Abstract:This paper focuses on the study of the built assets of French harbour owners with a view to providing elements which can be used in risk analysis. The structures' functions and position in the system are identified and their relative strategic importance for economic, touristic developments and national defence is highlighted. The results are presented by focusing the analysis on observed levels of heterogeneity, especially the description of the construction techniques, the materials used and the ages of the built assets.
International audienceOwners of civil infrastructure base their maintenance decision schemes mainlyon both structural integrity assessment and consequence analysis. Some inputs come frominformation collected by inspections with non-destructive or destructive tools.Uncertainties and errors of measurement can lead to bad decisions but are rarelyintegrated into the decision process. Currently, Risk Based Inspection (RBI) provides thebasic concepts for optimizing the maintenance plans of existing structures while insuringsatisfactory safety and availability of the structure during its service life. It lies both onreliability computations and probabilistic modeling of inspection results. This last pointleads to introduce the Probability of Detection, and the Probability of False Alarms thatare usually considered as parameters in Risk Based Inspection. However, when data frominter-calibration campaigns are available, the whole Receiver Operating Characteristicscurves should be used. Then the comparison of Non destructive Testing tools in terms ofcost/benefit is difficult as well as the method for optimizing a given technique. This paperpresents the αβ method that gives a new performance indicator in this context. It isapplied to the field of inspection of harbor structures
Optimization of maintenance and design of coastal steel infrastructure needs for long-term predictive degradation models. The phenomenon of corrosion in the offshore and coastal environment is very complex due to the stochastic and changing nature of the environment (temperature, water chemical properties) and the multiple involved processes in competition. In the GEROM French project, the objective was to build a database of the residual thickness measured from ultrasonic measurements on sheet piles and piles carried out during 40 years in commercial and military harbors along the French coast. A total amount of 35,460 measurements were gathered. After a detailed analysis of the data and statistical modeling, a probabilistic model of corrosion is proposed for sheet piles. It relies on a piecewise description of the process with the depth depending on the exposed zone and a time-dependent evolution of parameters of the gamma probability density function.
Abstract:The French harbour system has an essential role: on the one hand for French business, tourism and industry; and on the other hand for European defence. Consequently, maintenance of harbour assets is a stake of major importance. This paper focuses on the analysis of actual maintenance practices, associated constraints, but also capacities to fulfil maintenance programs of the built assets of French harbour owners. The needs in risk management and control are also highlighted. The results are presented by focusing the analysis on observed levels of heterogeneity. UNE VERSION TRADUITE EN FRANCAIS EST DIPONIBLE EN LIGNE : Revue Paralia -n° 2 (2009) IntroductionThe challenge for the owners consists in guaranteeing the operation of ageing structures (wharves, dry docks, dikes, etc.) with necessary levels of safety, reasonable costs and acceptable availability conditions. Moreover, the opportunities for harbour development are more and more limited in the face of increasing environmental constraints and decreasing space available for development with low costs for building.To deal with this problem, the GEROM project (Risk Management of maritime and river structures in harbours) was created within the GIS MRGenCi (Grouping of Scientific Interest "Risk management in Civil Engineering") and lies on a partnership between Oxand and the Research Institute in Civil and Mechanical engineering of Nantes. The GEROM project was undergone from 2006 to 2009. In the first phase, with the support of the CETE de l'Ouest (Ministry of ecology, energy, sustainable development and town and country planning), a national inquiry was carried out with owners about the technical management of their harbour structures. This paper focuses on maritime harbours only. The national inquiry was prepared with the aim of a risk analysis and the results are presented by centring the analysis on the observed levels of heterogeneity. Due to the multiple topics addressed during the national investigation, results are presented in two parts. This paper deals with the second part and is focused especially on: a) Current practice of maintenance (policies and strategies). b) Organization, constraints. c) Capacities to fulfil operations (maintenance programs).
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