Research On Response Surface Method Of Cable Stay Damage Identification Based On Deflection Monitoring

Cables are the key force-bearing components of cable-stayed bridges.Cable corrosion caused by environmental factors or cable fatigue caused by long-term dynamic loads will cause the stiffness and strength attenuation of stay cables,which will affect the safe operation of cable-stayed bridges.How to identify the damage of stay cables in real time and scientifically evaluate the health state of stay cables have important theoretical significance and practical value for ensuring the safety of cable stayed bridges.A new method for identifying cable damage of cable-stayed bridges based on bridge deflection monitoring is proposed.The research take that using the deflection increment of upstream measurement points identify cable damage of upstream cables as an example.The main contents include:(1)Establish the finite element analysis model of the Wuhu Yangtze River Bridge on the Ansys.Consider geometric nonlinear of the structure,and revise the model according to the measured data.Use area reduction of the stay cable to simulate the damage.(2)Investigate the law of the deflection increment of the main beam when the stay cable has been damaged under the uniform load,and construct the response surface function with the deflection increment of the measurement points as the independent variable and the position or degree of the damage as the dependent variable,then use the function to identify the damage of stay cable.Optimize the response surface function according to the quantitative analysis of the main factors which affect accuracy of the identification.(3)Investigate the variation law of the deflection increment of the main beam when the stay cable has been damaged under the combined action of uniform load and overall temperature rise and down,and perform sensitivity analysis of the damage identification index of the response surface function to optimize the method of identifying the position and damage degree of the stay cable.(4)Investigate the variation law of the deflection increment of the main beam when the stay cable has been damaged under the action of uniform load and moving load,and perform sensitivity analysis of the damage identification index of response surface function to optimize the method for identifying the position and damage degree of the stay cable.The deflection increment of the main beam caused by the damage of the stay cable includes damage identification information.Using the response surface method,the functional relationship between the deflection increment of measurement points and the position or damage degree of the damaged stay cable can be established respectively.Damaged stay cable can be identified by the function accurately.In the engineering application,the response surface function can be optimized from the aspects of function form,sample sampling method,designing of the location and number of measurement points,and identification range.