In-service condition assessment of bridge deck using long-term monitoring data of strain response

Continuous awareness of the evolution of the structural condition of bridge structures is of great value for bridge owners, as it allows them to make informed decisions regarding the maintenance and management of these public facilities. Structural condition assessment via monitoring has gained in popularity in recent years, because it can provide structural engineers with plentiful information on the structural condition through various sensors. A key issue for successful application of monitoring technologies for condition assessment is how to realize meaningful interpretations of monitoring data. In this study, an approach to structural condition assessment of in-service bridge deck making use of long-term monitoring data of strain response is proposed and applied to the instrumented Tsing Ma Bridge. The proposed method consists of structural assessment at two levels: (1) deck truss component level and (2) deck cross-section level. As long-term monitoring data of dynamic strain under the in-service condition physically result from a combination of live loads and environmental variations, a wavelet multiresolution decomposition method is first applied to extract live-load effects from the raw measurement data. Based on the extracted data, stress-response histories are derived, and the statistical characteristics (sample means and sample SDs) of peak stresses are explored for stress-level assessment of deck truss components. Dynamic internal forces (axial force, shear force, and moment) of the monitored deck sections are subsequently evaluated by synthesizing the internal forces of the corresponding truss members. Then, internal force-level assessment of the deck sections is carried out for various loading conditions such as monsoon, typhoon, and with and without railway traffic.