Page 534 - Marine Structural Design

510 Pari IV Structural Reliability

elementskomponents based on the results of risk-based inspection. For the extrinsic damage
of each individual structure, the knowledge-based diagnosis method should be developed. The
systematic knowledge-based diagnosis process is a potential means to identify the extrinsic
damages.
Knowledge systems routinely do diagnosis reasoning using three methods: model-based
diagnosis, heuristic classification, and case-based reasoning. Our system uses a combination
of each of these methods:
Model-Based Diagnosis (MBD) to identify the details of a large class of possible problems,
heuristic classification to identify the presence of a set of idiosyncratic problems, and Case-
Based Reasoning (CBR) to compare observation with previously identified cases.
An ‘optimum’ inspection method could include:
Developing a standard task checklist to ensure that relevant data and tasks are not lost
because of distractions or workload
Performing global surveys to develop situation awareness for potential expected and
unexpected damage and defects
Inspecting high likelihood of damages or defect ‘parts’ and high consequence parts. If
something ‘suspicious’ is found, the inspection is intensified by model-based diagnosis,
heuristic classification, and case-based reasoning until root causes (not symptoms) are
determined
Periodic inspections, decreasing the time between inspections as the rate of degradation or
likelihood of defects and damage increase
Inspecting after accidents or ‘early warning’ signals are detected
Implement the long-term and short-term maintenance and repair strategies based on the
inspection results
Update the IMMR (Inspection, Maintenance, Monitoring, and Repair) plan based on the
survey results and the results fiom maintenance and repair
Performing inspections that are independent fiom the circumstances that cause potential
defects and damage
Using qualified and experienced inspectors that have sufficient resources and incentives to
perform quality inspections
Prior to the commencement of any general survey, a standard checklist and procedure should
be established fiom the Structural Life-Cycle Information Management System, in order to
carry out an effective evaluation of the structure’s general condition:

Structural drawing
Operating history and conditions
Previous damage/defects inspection results
Condition and extent of protective coatings
Classification status, including any outstanding conditions of class
0
Previous repair and maintenance work
0
Previous information on unpredictable damage or defects