Cable Tension Measurement And Condition Assessment For The Cable-Stayed Bridges

The stay cable is one of the principal force members of the cable-stayed bridges, cable tensions are always used for evaluation the work state of cable-stayed bridges,and frequency method which based on circumstance vibration is the popularity method to measurement of cable tension. Damper be setted in most cable-stayed bridges to avoid vibration of the stay cable which effected the vibration frequency of stay cable. The theoretic analysis and test research of measurement of cable tension and evaluate the estate of cable tensions are conducted in this paper. The main works and results are as followings:1.The motion equations of the cable-damper system are formatted, which provide the theory for analyze the relationship of modal frequency of stay cable with damper and damper parameters;2.The relationship of modal frequency of stay cable with damper and damper parameters are investigated. the curves of modal frequencies versus relative distance of attached damper and damping coefficient are obtained. the precise measurement of cable tension for the stay cable attached dampers can be achieved if the high modal frequency of the stay cable and L-x_d used for cable length are adopt; andthe precise measurement of cable tension for the stay cable attached dampers also can be achieved by solve the motion equations of the cable-damper system if damping coefficient can be attain;3.Taking Jiujiang Bridge as background, the disciplinarian of the changed of cable tensions and versus the distributing of cable tensions in this bridge are obtained by FEM analysis;4.Based on the health monitoring of Jiujiang Bridge, three BP neural networks be created and simulation trainned for condition assessment of cable tensions.And results show that the trained neural network can accurately evaluate the state of cable tensions.