Temperature and mass loading compensation for long-term bridge monitoring

摘要

In the framework of this contribution continuously recorded long-term acceleration response data of a bridge along the A13 Brenner Motorway in the Austrian Alps are used to identify the time-history of one natural frequency of the bridge structure. The frequency is variable with respect to time, induced by the seasonal changes of the environmental temperature and by the varying mass distribution due to traffic loads. In this paper approaches are presented that allow a compensation of both effects on the identified frequency. In the first step, the mass loading effect is quantified by means of a stochastic simulation model. In this model statistically evaluated data of the complete traffic volume and of the truck traffic are considered. A time series model is employed that captures the impact of the environmental temperature on the frequency and simultaneously describes the dynamic behaviour of the underlying complex process properly. The combined application of both compensation procedures yields modified time-histories of the frequency. Based on these compensated frequency, possible structural changes of the bridge during the remaining life cycle of the structure can be identified more unambiguously.