ABSTRACT
Risk and Reliability concepts are not generally understood by bridge engineers
because they are not explicitly used in the everyday practice of bridge
assessment or design. In the last decade or so, however, there seems to have
been a growing appetite to understand both the concepts, and the practical
application of them to make more confident decisions about the maintenance
requirements and priorities of a bridge stock. Very good overviews of the
meaning and application of reliability methods have been produced by Bailey
(1996), Rosowsky (1997) and Melchers (1999) but essentially reliability is
a probabilistic way of defining the limit states performance of a bridge system
or bridge component. This is expressed as the probability of a certain event
(limit state) occurring, the most important of which is that of collapse.