Experiences with monitoring systems for bridges and tunnels

In Belgium, a large number of bridges, fly-overs and tunnels were built, all part of the expansion of the railway network. A considerable percentage of the large and medium span bridges amongst them were subjected to test loading, using heavy construction lorries or test trains before completion, during which strains and sometimes accelerations were measured for comparison with the basic design premises.

For the study of the long-term behaviour of important civil structures, it often becomes necessary to resort to long-term monitoring of certain structural parameters, such as the strains, temperatures, accelerations, and eigenfrequencies of key components. Especially when the nature of the structures necessitates the use of an independent power source for the measurement system and prohibits the use of wired connections with the environment, a fully autonomous measurement system becomes necessary. This research paper discusses two such applications and the possible pitfalls in developing such a monitoring system.