Design And Research On Health Monitoring System Of Badong Yangtze River Bridge

In the construction of transportation infrastructure,bridges are one of the key structures that span natural obstacles such as large rivers,canyons and lakes.The construction of these key structures is important,and operation and maintenance are equally important.Ignoring the collapse caused by operation and maintenance,it is not uncommon,which not only brings huge loss of life and property,but also causes serious and bad social impact.Long-term automated monitoring and evaluation during the operation of these critical buildings is very important.As a large bridge spanning the Yangtze River,the Badong Yangtze River Bridge is an important part of the operation period to ensure the safety of the bridge during its operation period.Based on the concrete project of the Badong Yangtze River Bridge,this paper researches and develops the health monitoring system of the bridge based on summarizing and studying the current domestic and international bridge health monitoring and evaluation techniques.The main work of this paper includes:(1)This paper first introduces the research status and development trend of bridge health monitoring,analyzes the importance of health monitoring system to the safe operation of the bridge,and then proposes a reasonable health monitoring plan for the Badong Yangtze River Bridge: using software to control the operating system as a platform.With data management as the center,it adopts the functional mode combining sensor system,data acquisition transmission and processing system,safety assessment and early warning system.The health monitoring system has the advantages of strong practicability,good compatibility,safety and reliability.(2)Using the Midas/civil software to carry out finite element analysis of the Badong Yangtze River Bridge,and study the static response of the structure under different loads such as movement and temperature.Through analysis,it is found that the main beam is in the traditional section except 1/2L,1/4L.In addition to the obvious change in stress,a significant change in stress occurs at a distance of 40.4m from the mid-span.It is also found through analysis that a significant stress change occurs at the position of the tower at a distance of 59 m from the main beam.When determining the stress monitoring position,the two locations are included in the stress monitoring range.At the same time,the dynamic characteristics analysis of the Badong Yangtze River Bridge is carried out.(3)Through the finite element analysis,the static and dynamic characteristics of the bridge are mastered,the sensitive position of the structure is found,and the reasonable optimal arrangement of the sensor is provided.According to the analysis results,the health monitoring project of the bridge is developed,including the cable tower displacement,main beam deflection,cable tension,structural strain and temperature,expansion joint displacement,main beam dynamic characteristics,etc.According to the analysis result,the threshold of the monitoring index is determined,and the sensor type is selected according to the threshold.In the optimization of the main beam dynamic sensor layout,the genetic algorithm is used as the basic algorithm for calculating the optimal embedding point of the sensor.It is realized by Matlab program,and the superiority of embedding 10,20 and 30 power sensors is compared and analyzed.The solution for embedding 20 power sensors in the main beam is finally determined.(4)Combining the latest research results of bridge safety assessment at home and abroad,the safety evaluation model of the Badong Yangtze River Bridge based on the analytic hierarchy process and the principle of variable weight integration is proposed.The initial weight of the bottom monitoring index is calculated based on the finite element analysis results.The weighting principle is used to correct the weight.In order to score each monitoring data sequence under the same standard,mathematical data is used to perform dimensionless processing on each monitoring data sequence.An evaluation strategy combining static assessment and dynamic assessment is proposed,and a health monitoring assessment algorithm program is developed based on the established assessment model.(5)According to the requirements of the monitoring system,the data acquisition and transmission subsystem of the health monitoring system is researched and designed.The data collection and transmission operation process is designed specifically,and a reasonable data collection and storage strategy is proposed.According to the characteristics of data collection and use,the data management subsystem is designed to solve the problem of data redundancy.Finally,through the design of the user interface system,the display of the data is completed.