1. Introduction
Valid bridge designs according to most modern design codes
should ensure that the probability of failure remains under a
given critical limit throughout the design life time.
The reliabilityof a structure is the inverse of the probability of failure and
can be computed by comparing the loading with the resistance
of a structure [1,2].
Any structure is exposed to environmental
influences, service loading and permanent loads which can all be
seen to cause small portions of damage accumulating over time.
In general terms, this accumulated damage can be interpreted
as reducing the structural resistance, and therefore the structural
reliability of a structure.
On the other hand, code-specific loading
also changes, and in the case of traffic loading on bridges these
loads have increased significantly over time in most design codes.