Titel_SS06

(Brent) #1

12
th
Lecture: Reliability Based Assessment and Inspection of
Structures


Aim of the present lecture


The present lecture addresses the problem of assessing and maintaining structures for the
purpose of ensuring that their condition is appropriate for their intended use over their life
time. First the general philosophy for reassessment is outlined utilizing the systems risk
framework previously introduced for the purpose of general risk assessment (Lecture 4) and
for the purpose of risk assessment of structural systems (Lecture 9). Thereafter the theoretical
Bayesian framework for reassessment of structures is introduced where it is highlighted that
reassessment is indeed a decision problem of how the benefit to be obtained from the
structure can be maximized by means of collection of information and by means of changes
of the structure or its use. Subsequently, the main component in reliability based assessment
of structures is introduced, namely Bayesian updating and it is outlined how updating might
be performed at two levels; updating of the models of random variables and updating of the
reliability in regard to a given limit state. Following this it is illustrated how the decision
analysis can provide a systematic approach for different types of reassessment problems.
Finally, a number of reassessment problems, typically occurring in structural engineering, are
addressed and by means of very simple examples it is illustrated how these may be solved.


Based on the introduced material in this lecture it is aimed for that the students should acquire
knowledge and skills in regard to:


 What is the principle difference between the design of a new structure and the
assessment of an existing structure?
 When is an assessment of a structure necessary?
 What is the main concern when a structure is assessed?
 In which principal ways can the reliability and serviceability be ensured during its
service life?
 How to proceed with an assessment in a practical way?
 How may Bayesian updating be used in assessment?
 How can prior, posterior and pre-posterior decision analysis provide decision support in
assessment of structures?
 How may inspections be planned over the lifetime of a structure to ensure that the
structure satisfies given requirements to reliability?
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