Anticipation of repair need of bridges besed on visual inspection of Finnish bridges

All bridge structures are usually exposed to outdoor climate and are therefore deteriorated by several different degradation mechanisms, whose progress depend on many structural, exposure and material factors. Finnish bridges are very often made of concrete, and the decks of steel bridges are usually of concrete. Under Finnish climatic conditions frost damage to concrete together with corrosion of reinforcing steel constitute the major degradation mechanism that causes the need to repair concrete structures.

The repair need of concrete structures depends on already existing damage in the structure and damage facing it in the near future. Usability of repair techniques depends not only on existing damage but also on the type of structure and service life of repair.

An essential factor in determining the success of systematic bridge management is the detection of damage. Each Finnish bridge managed by the Finnish Road Administration is inspected visually every fifth year. These general inspections have been made for over 20 years. As a result we have an extensive, growing database which can be used for anticipating the repair need of bridge structures.

On the basis of that database deterioration models have been established for every type of structural member of bridges. These models are tools for finding appropriate repair methods for damages and they allow optimal timing of condition investigations and repair work.