Removing Environmental Influences in Health Monitoring for Steel Bridges Through Copula Approaches

Maintenance of civil infrastructure has become a keen technical issue nowadays for modern cities. This is particular important for the bridge structures which contains large potential risks. For most bridge structures, they may experience lots of environmental and operational conditions. A real and accurate understanding of the influences from these external conditions is necessary in the monitoring of bridges. However, many previous study still cannot depict the relations between the structural safety and environmental influences very well. Suitable multivariate models are demanded to extract the information of dependences between the bridges and its associated environment. In this study, a copula-based feature sensitive indicator is proposed for the bridge structural health monitoring for removing the operational and environmental conditions. Changes in the modal parameters with the time are firstly identified by the copula statistical properties and then removed through an appropriate copula model. A case study is performed based on the observed vibration data collected from a seven-span plate steel Gerber bridge. The data including the temperature and acceleration for the past ten years is utilized to test the applicability of the proposed approach. Based on the results, the selection of the best copula model in characterizing the monitored time series will be discussed. Certain improvement in the bridge structural health monitoring will also be investigated.