The Research On Deflection Measuring System Of Chongqing DaFoSi Bridge Of Changjiang River With Opto-electronic Level System In Connected Pipes

The monitoring of long-span bridges has important meaning. The measurement of deflection of a bridge is crucial constituent part in the monitoring of bridges.The majority of existing methods about bridge deflection measurement can not accomplish the real-time and long-range measurement .The ultrasonic method based on connected pipes still has shortage in precision and speed of measurement.To satify the need of deflection measurement of the DaFoSi Bridge of ChangJiang River, an opto-electronic measurement method is to be used to improve on the method based on connected pipes.Furthermore,we will design an automatic opto-electronic deflection measurement system based on connected pipes which can be practised in the long-span bridge.The thesis refers to several facets below,(1).Discuss important meaning of the deflection monitoring of the DaFoSi Bridge of ChangJiang River and introduce the principle of existing deflection measurement methods of bridge so far. Through comparison and analysis ,bring forward the research content based on the connected pipes methods.(2).Discuss the factors which cause the bridge's deflection and pay more attention on the effect of the variry of cable's temperature on the bridge's deflection.Then to bring forward the need of deflection measurement of the DaFoSi Bridge of ChangJiang River.(3).Put forward two structure scheme of opto-electronic deflection measurement sensor, light transmitting with non-mechanical scanning and light reflecting with non-mechanical scanning after compared exisiting methods of liquid level measurement to satify this needAfter the comparison,an opto-electronic deflection measurement sensor based on light reflecting with non-mechanical scanning be confirmed.Then the concrete design is to carry out ,which includes the design of reflective surface,the design of PDS(photo detective subassembly)'s bracket, the design of floater and the design of shaking-absorbed accessory .During the process,there are a series of caculations and emulations.At last, the opto-electronic deflection measurement sensor has been designed and produced.(4).On the hand of signal acquiring and processing ,a PCB has been designed based on the processor,DSPTMS320C32,produced by TI Corp.At the same time,a doable arithmetic on signal processing has been put forward.(5).On the hand of the remote conveying and communicating of the signal,thestandard of RS-485 is utilized to achieve the communication between the sensors and host computer.(6) Verify the validity of the deflection measurement system through the experiments in the laboratory and the practice in the deflection measurement of ChongQing DaFoSi Bridge of ChangJiang River.To our satisfaction,all the measuring results from the measurement locale are accurate and convincing comppared with the results calculated by the theory which makes it clear that the system can meet the demands of measuring upon the DaFoSi Bridge of ChangJiang River.The system has achieved the long-time and real-time automatic deflection measurement of the bridge at first time in our country,and the system has passed the appraisal of the experts consigned by the ministry of communications so the system has the practical value on the long-span bridge's deflection measurement.