Wavelet-based multi-resolution decomposition of long-term monitoring signal of in-service strain

Long-term monitoring of in-service structures under operational conditions plays an important role in the practice of structural condition assessment via monitoring. The most common measurements in structural monitoring are strain and vibration. In-service monitoring of strain response is aimed to acquire information about stresses experienced by a structure under operational conditions. However, strain not only arises from stresses but also from temperature influences and from inherent changes inside the material. Long-term monitored strain signals under in-service circumstance are physically resulted from a multi-path combination of these effects which play different roles in contribution to stress quantities. And it is desirable to present strain components individually or process them independently, especially when each effect on structural behavior needs to be quantified. In this study, an approach of wavelet-based multi-resolution analysis (MRA) is proposed and applied in component estimation of monitored strain signals in Tsing Ma Bridge (TMB) which has been instrumented with a long-term structural health monitoring (SHM) system. By wavelet multi-resolution decomposition, strain components due to temperature and traffic effects are extracted from the raw measurements individually and the structural behaviours of TMB deck truss due to different effects are revealed thereafter.