Traffic volume estimation and load capacity evaluation using dynamic responses acquired in the structural health monitoring of a cable-stayed bridge

The effective condition assessments of existing structures will be realised if not only the structural responses but also the information about input loads can be understood from the structural health monitoring (SHM) data. This paper presents analysis of the response data acquired by a SHM system installed on an in-service cable-stayed bridge in Thailand (Bangkok). The SHM system consists of many kinds of sensors including accelerometers and temperature sensors. In addition, the vehicle counting system has been actually installed for the perpose of checking the traffic condition in this bridge. The relationships between the dynamic responses, and the temperature and the traffic volume of the bridge were investigated. The results revealed that the traffic volume was a dominant factor that influenced on variances of the responses. Then, the traffic effects were more investigated by using finite element (FE) models. The results showed that not only the traffic volumes, but also vehicle speeds had effects on the dynamic responses. In the case of the same traffic volumes, the response amplitudes decreased when the speeds of vehicles decreased. Furthermore, some of the response features that showed high correlations were then selected for constructing a linear regression model to estimate the total traffic volume per five minutes. The constructed model then showed the accurate fitting performance to the data, and it was also capable of predicting the traffic volume on the bridge. In addition, the predicted traffic volume could be used for identifying traffic conditions on the bridge.