Structural Health Monitoring of a Composite Bridge

The investigated two span composite bridge with a total length of about forty meters was built in 2006 for car traffic and is located in the Southwest of Luxembourg. It is a replacement for a bridge that was no longer sufficient to fulfil today’s requirements of traffic loads. A monitoring system with acceleration sensors, strain gauges and temperature sensors has been installed to assess the state of the structure, to predict the durability and to investigate the traffic flow in addition to conventional visual inspection. In this paper it is shown how all in-situ measurements of the structural response are used to improve and update a finite element (FE) model. The bridge itself is presented together with the installed monitoring system as well as the done experiments and their results. Different possibilities for the determination of modal properties and the dynamic behaviour of the structure are shown to improve the health monitoring. The paper firstly deals with the aims of the research project in which the monitoring system is a part of. Second, the bridge and the data acquisition are introduced and first tests and results are presented. A FE model is adjusted to simulate the real bridge behaviour and finally, first conclusions are drawn. One main aspect is the behaviour of the eigenfrequencies at different temperatures. With the monitoring system it was possible to demonstrate an extreme coherence of frequency and temperature at this bridge which is not favourable to the interpretation of structural health monitoring concerning damage detection.