EVALUATIONS ON DYNAMIC BEHAVIORS AND ITS ENVIRONMENTAL INFLUENCE FACTORS OF BRIDGE BASED ON LONG TERM MONITORING

摘要

Vibration-based damage identification of structures is a popular method adopted for bridge condition assessment based on measurement data by health monitoring systems. However, influenced by some environmental factors, such as temperature, traffic loads, wind and rainfall etc., dynamic properties of bridges would change also. In this paper, one year monitoring data of Donghai Bridge were analyzed and some statistical results were presented. Based on correlating analysis and coherence analysis, the main environmental factors influencing structural modal parameters, were confirmed. It was showed that the temperature and structure vibration magnitude were two main influencing factors on the variation of bridge modal frequencies. A lab test using a RC continues girder bridge model was carried to validate the effect of environmental temperature to the variation of modal frequencies of bridge. Finally, a formula was proposed for eliminating the components of modal frequency variations due to environmental temperature and vibration magnitude and a criterion was suggested for alarming abnormal condition of bridge structures.