Damage detection of long-span cable-supported bridges

In Hong Kong, a sophisticated long-term monitoring system called Wind and Structural Health Monitoring System (WASHMS) has been devised by the Highways Department of the Hong Kong SAR Government to monitor the structural health and performance of three long-span cable-supported bridges after their construction. This on0-structure instrumentation system consists of about 800 permanently installed sensors, including vibration transducers which makes it possible to monitor deterioration and detect potential structural damage from vibration measurement. The basic premise of vibration-based damage identification is that damage will alter the mechanical properties of a structure, which, in turn, alters the dynamic response of the structure. In the present study, in order to understand the effect of structural damage on the dynamic properties in the three brides, precise three-dimensional finite element models for the bridges have been formulated for simulation study. Various damage scenarios and the corresponding modal sensitive analyses are pursued. A neural network based multi-stage diagnosis strategy is then applied to identify damage occurrence, location and type for the three bridges, in accordance with the WASHMS. Finally, the potential application of some innovative techniques for damage detection of large-scale structures and future perspective in this field are briefly addressed.