Research On Global Response Of Long-span Cable-stayed Bridge Based On Monitoring Data

The long-span bridge is the key node of highway and railway connection.Based on theon-the-spot monitoring data,it is of great scientific significance to reveal the relationship between structural response and environmental factors to ensure the safety,verification and development of bridge service.In the past,the study on the relationship between the environment and the overall response of the long-span cable-stayed bridge is lack of long-term monitoring data.The analysis objects are relatively simple and less effective health monitoring indicators are given.Based on the long-term mass monitoring data of Anqing Yangtze River Bridge,this paper systematically analyzes the overall response characteristics such as the overall displacement and modal frequency under the influence of environmental factors such as wind speed and air temperature.The main results are as follows:(1)Through the statistical analysis of the environmental monitoring data of the bridge for two consecutive years(including mean value,extreme value,difference,etc.),the trend and fluctuation law of wind speed and ambient air temperature at the bridge site are given,and the special events are detailed analyzed and found that are in the design range,compared with the bridge design reference value,verifying the rationality of the bridge design.(2)Through the statistical analysis of the monitoring data of the overall displacement response of the bridge for two consecutive years,the variation law of the whole displacement response of the structure is revealed,and it is verified that it is within the allowable geometric deformation range.The high order spectrum theory is applied to the structural integral acceleration response In the spectrum analysis,the feasibility and advantage of the application of the traditional spectrum analysis method in the field of structural health monitoring are proved by the fourth-order cumulant reconstruction power spectrum,and the modal frequency of the bridge is identified and analyzed.(3)Based on the statistical analysis of environmental action and the analysis of the overall response of the structure,the correlation between the two is studied.The positive correlation between the mean value of the transverse displacement of the main girder and the transverse velocity of the transverse bridge is established.The positive correlation between the mean value and the mean temperature and the mean value of the mean velocity and the mean value of the bridge,and the positive correlation between the mean value and the meanvalue of the bridge tower.According to different time scale,its monthly and annual fit relationship is given.(4)The relative motion law of the top and span of the bridge between the north and south bridges of the bridge is analyzed,and the law of the motion law and the change of the temperature is obtained.On the basis of the positive correlation regression model of the mean value and the mean temperature of the tower top span,the definition of thermal expansion coefficient of cable-stayed cable is proposed and the calculation method is calculated.The coefficient of thermal expansion of cable stayed cable of Anqing Yangtze River Bridge is calculated and calculated.The thermal expansion coefficient of the cable is made.In contrast,it is found that the thermal expansion coefficient of the cable is basically stable under the normal operation of the bridge and does not change with the environment.The long-term change can reflect the structural degradation of the cable structure.Finally,Bridge length and temperature model of cable stayed cable is established,the polynomial exact fitting expression of the model is given,and the early warning of cable structure damage is realized by means of mean control chart.