SHMS-based bridge rating method for long span cable-supported bridges

To ensure safety and functionality of long span cable-supported bridges, a bridge rating method is currently used by the Hong Kong bridge management authority as guidance in determining the time intervals for inspection and the actions to be taken in the event of defects being identified. This bridge rating method is based partly on engineering analysis and partly on practical experience. There is insufficient link between the existing bridge rating method and the structural health monitoring system (SHMS). This paper therefore presents a SHMS-based bridge rating method for the Tsing Ma suspension bridge in Hong Kong. The fuzzy based analytic hierarchy approach is employed, and the hierarchical structure for synthetic rating of each structural component of the bridge is proposed. The criticality and vulnerability analyses are performed largely based on the field measurement data from the SHMS installed in the bridge to offer relatively accurate condition evaluation of the bridge and to reduce uncertainties involved in the existing rating method. The procedures for determining relative weighs and fuzzy synthetic ratings for both criticality and vulnerability are suggested. The fuzzy synthetic decisions for inspection are made in consideration of the synthetic ratings of all structural components. The results show that the proposed method is feasible and it can be used in practice for long span cable-supported bridges with SHMS.