There is a growing need for a more accurate assessment of the load carrying capacity of highway bridges. The traditional approach
is based on consideration of individual components rather than structures. Consequently, the acceptance criteria are formulated in terms of the
allowable stress, or ultimate moment, in a component. However, it has been observed that the load carrying capacity of the whole structure
(system) is often much larger than what is determined by the design of components. The difference can be attributed to the system
behaviour.
Quantification of this difference is the subject of the system reliability. There is a need to take advantage of the available system reliability
methods and advanced structural analysis methods and apply them in the design of bridges and evaluation of existing structures. The current
advanced analytical procedures allow for a numerically accurate but deterministic analysis of strain/stress in a bridge. Mathematical procedures
exist for the calculation of reliability for various idealized systems: parallel, series, and combinations. There are also new developments in
materials, technology, and field testing which can be used to improve bridge design and evaluation. This paper deals with calculation of the
reliability of the whole bridge structure, taking into account realistic boundary conditions, and
site-specific load and resistance parameters. |