Study On Setting Method Of Early Warning Limits Of Suspension Bridge Health Monitoring System Considering Temperature Influence

In recent years,bridge collapse accidents have emerged in an endless stream.Long-span bridges are the lifeline of the country or region,and they are costly.Once a collapse accident occurs,it will have a huge negative impact.In order to grasp the "health" status of long-span bridges in time and prevent the occurrence of sudden collapse accidents,it is necessary to apply scientific methods to monitor the health of large bridges.However,the existing health monitoring system has reported missing,misreported or not reported.In the final analysis,the warning threshold of the health monitoring system is not reasonable.Therefore,this paper is based on the main bridge of the Guanting Reservoir Bridge suspension bridge for health monitoring.Research on the method of setting the system warning limit.The main work of this paper is as follows:1.The model modification theory based on the response surface method is discussed in detail,and the implementation process of the response surface method is introduced.The finite element model of the suspension bridge is modified step by step based on the measured data and response surface method in the construction monitoring process.Firstly,the response surface method is used to modify the main tower model,and then the length correction of the main cable and the sling is performed by using the measured data during cable formation.Finally,the response surface method is used to modify the elastic modulus of the stiffening beam system and the main cable.2.The temperature field and temperature effect analysis method is verified by the measured temperature data in the construction monitoring of the suspension bridge.Based on the detailed analysis results of the space temperature field,the temperature effect variation of the suspension bridge in one day is calculated,and the measured stress cable force is measured.The data is compared and verified.The research results show that the proposed method can calculate the temperature field and temperature effect of the suspension bridge more accurately.3.Based on the finite element model modification,a method for setting the warning limit of the health monitoring system considering the combination of the uneven temperature field of the bridge and the influence line loading method is proposed.The eight-point deflection of the main beam and the change in anchor cable force were selected as early warning indicators.The temperature effect of the suspension bridge was calculated,and the change laws of various early warning indicators of the suspension bridge under ambient temperature were summarized.The influence line loading method was used to calculate the response of the suspension bridge under the most unfavorable load of 1 and 1.4 times the full width,and the changes of the early warning indicators of the bridge under the two working conditions were obtained.Yellow or red warning limits for each indicator.