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Abstrait:
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Bridges are generally designed for a life time of 120 years. The structural behaviour and material
degradation mechanisms are considered during the design stage in order to achieve this design life.
The life time of the structure, which is subject to a variety of loads and exposed to certain
environmental conditions, depends therefore to a large extent on the assumptions made during the
design stage. However, experience has shown that especially loading conditions i.e. traffic loading
is likely to deviate from the assumptions made during the design stage. Further, the impact of
exceptional events such as earthquakes could affect the integrity of the structure. The degradation of
a structure very often has not progressed very far and when the structure is monitored, it is possible
to extend maintenance free periods. Further, with monitoring hard- and software becoming more
and more sophisticated, it is possible to have this information readily available any time. Therefore,
it is recommended that monitoring regimes are considered as an integral part of the design and
become part of the maintenance schedule of any major infrastructure project. In short, monitoring
regimes can be used to optimise spending on maintenance. In this paper, one possible use of
structural monitoring is shown on the example of the bridge over the river Reuss in Wassen,
Switzerland. The cost of the monitoring regime is compared to the cost savings made by it over the
lifetime of the project. In addition, the design criteria of such a system required to achieve a
permanent monitoring throughout the lifetime of a structure are explained and the use of the data
for a bridge maintenance strategy is shown. Monitoring regimes can be used as a maintenance tool
to optimise spending over the life time of the object and, ultimately, to safe costs.
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